Biology HSC Notes
Module 5: Hereditary
IQ5.1 Reproduction.…………………………………………………………………………………….…. 4
IQ5.2 Cell Replication...………………………………………………………………………………….. 7
IQ5.3 Polypeptide Synthesis.………………………………………………………………..……… 9
IQ5.4 Genetic Variation..………………………………………………………………………..……… 11
IQ5.5 Inheritance Patterns in a Population.…………………………………………..… 13
Modelling.……………………………………………………………………………………………………..…… 15
Module 6: Genetic Change
IQ6.1 Mutation.…………………………………………………………………………………………………. 23
IQ6.2 Biotechnology...……………………………………………………………………………………. 28
IQ6.3 Genetic Technology..…………………………………………………………………………… 30
Module 7: Infectious Diseases
IQ7.1 Causes of Infectious Diseases.………………………………………………………………
IQ7.2 Responses to Pathogens...…………………………………………………………………….
IQ7.3 Immunity.………………………………………………………………………………………..………….
IQ7.4 Prevention, Treatment Control.……………………………………………………………
Modelling.…………………………………………………………………………………………………………..
Module 8: Non-Infectious Diseases
IQ8.1 Homeostasis.………………………………………………………………
IQ8.2 Causes and Effects...…………………………………………………………………….
IQ8.3 Epidemiology.………………………………………………………………………………………..………….
IQ8.4 Prevention.……………………………………………………………
IQ8.5 Technologies and Disorders.……………………………………………………………
Modelling.…………………………………………………………………………………………………………..
Practicals…………………………………….………………………..………………………………………………………
Working Scientifically + Skills ….………………………….…………………………………………………..
Module 5: Hereditary
IQ5.1 Reproduction.…………………………………………………………………………………….…. 4
IQ5.2 Cell Replication...………………………………………………………………………………….. 7
IQ5.3 Polypeptide Synthesis.………………………………………………………………..……… 9
IQ5.4 Genetic Variation..………………………………………………………………………..……… 11
IQ5.5 Inheritance Patterns in a Population.…………………………………………..… 13
Modelling.……………………………………………………………………………………………………..…… 15
IQ5.1 Reproduction
Inquiry question: How does reproduction ensure the continuity of a species?
Methods of Asexual Reproduction
 1 parent
 Genetically identical via mitosis
 Reproduction among unicellular, colonial and
multicellular organisms
Plants
Vegetative Propagation is the growth of new plants off
parent plant. For example:
 Runners: stems growing along the surface of
soil that produce shoots, turning into individual
plants
o E.g. strawberry plants

Bulbs: bud cells that grow off bulbs
underground to develop new plants
o E.g. onions
 Rhizomes: underground horizontal stems that
give rise to shoots at each
node
o E.g. ginger
What are the methods of asexual reproduction
for plants?
What is vegetative propagation?
What are the 3 types of vegetative propagation?
Fungi
When conditions are favourable, fungi will reproduce
asexually via mitosis by:
 Budding: fungus develops a growth that breaks
off the parent to form spores
 Fragmentation: pieces of hyphae can separate
and become new colonies.
 Spores: genetically identical cells to the parent,
which are distributed into the environment by
wind or vectors.
What are the 3 ways that fungi can reproduce
asexually?
What happens during budding?
What happens during fragmentation?
How are fungi spores produced?
Bacteria
Binary fission is a form of reproduction commonly
performed by unicellular organisms (no DNA, no need
to undergo Anaphase)
 Cell replicates bacterial chromosomes before
growing to x2 its original size
 Cell undergoes cytokinesis, producing 2
daughter cells (clones of parent)
How does bacteria reproduce?
What type of organism performs binary fission?
Protists
Protists are unicellular eukaryotes that undergo
mitosis and cytokinesis to distribute chromosomes
and separate equally.
 Budding: new organism grows off parent body to
form a new colony
 Binary fission: cell undergoes cytokinesis,
producing 2 daughter cells with equal DNA
Advantage of asexual reproduction: rapid population
increase, no mating required, able to reproduce
under external pressure.
Disadvantage of asexual reproduction: lack of
diversity, reduced ability to adapt to external
pressures
What are the advantages of asexual
reproduction?
What are the disadvantages of asexual
reproduction?
Methods of Sexual Reproduction
 2 parents that contribute half of genetic
information to offspring
 Genetically non-identical via meiosis
 Reproduction among multicellular plants and
animals
 Advantage for changing environments
Animals
Internal fertilisation is the fertilisation of eggs inside
female body
 Occurs between terrestrial animals (e.g.
mammals, reptiles)
Advantage of internal fertilisation: higher survival
rates of offspring, moist environment providing
gamete with nutrients to grow
Disadvantage of internal fertilisation: fewer offspring
are produced, higher risk of sexually transmitted
infections
What is internal fertilisation?
What are the advantages of internal fertilisation?
What are the disadvantages of internal
fertilisation?
External fertilisation is the fertilisation of egg outside
female body
 Occurs between aquatic animals (e.g. fish)
Advantage of external fertilisation: increased number
of offspring produced, time and energy efficient
Disadvantage of external fertilisation: requires
aquatic environment, decreased survival rate of
offspring due to predators.
What is external fertilisation?
How do protists distribute chromosomes and
separate equally?
What are the two ways that protists can
reproduce?
What are the advantages of external fertilisation?
What are the disadvantages of external
fertilisation?
Plants
Pollination is the transfer of male gametes (pollen) to
the female ovules.
 Pollen reaches the stigma, travels down the
style, fertilises with ovule in the ovary and
germinates into a fruit
 Causes: wind, self, insects, birds, fertilisation
etc
Steps of fertilisation:
1. Ovary releases an egg and travels through the
fallopian tube.
2. Sperm enters ovary and meets egg in fallopian
tube, forming a zygote.
3. Newly formed zygote moves down fallopian tube
towards uterus
Angiosperms: Flowers and Seeds
 Male and female reproductive organs are
contained within the flower
o Anther (male): produces pollen
o Filament (male): supports anther
o Stigma (female): sticky bulb that catches
pollen
o Style (female): passageway for pollen
o Ovary (female): holds eggs awaiting
fertilisation
o Ovum (female): egg grows that grows into a
seed after fertilisation
What are the steps of fertilisation?
Implantation: attachment of the fertilised egg to the
lining of the uterus.
Amniotic sac: fluid filled bag where embryo grows,
providing cushioning and protection.
Placenta: provides nutrients and removes wastes for
embryo survival.
Umbilical cord: connected to placenta, providing
embryo with nutrients to grow.
Zygote implants into the uterine wall where the
embryo starts to grow. The amniotic sac, placenta
and umbilical cord form as well.
Label
the parts of a plant.
How is pollen transferred from one flower to
another?
Fungi
When conditions aren’t favourable, fungi will
reproduce sexually (to prevent extinction) via meiosis
by:
 Spores combine to form a new non-identical
fungus
Hormones are chemical messengers produced by the
body, which travel in the blood to other cells to
perform specific roles.
Phases in the ovarian cycle
How do fungi reproduce when conditions aren’t
favourable?
Advantage of sexual reproduction: variation in
population, better adaptability to environment.
Disadvantage of sexual reproduction: time and energy
consuming, requires a mating partner, fewer
offspring produced
What are advantages of sexual reproduction?
What are disadvantages of sexual reproduction?
Features of fertilisation, implantation and hormonal
control of pregnancy and birth in mammals
Fertilisation is the fusion of egg and sperm in the
reproductive tract of females.
Follicle Stimulating Hormone (FSH) pushes the ovule
to mature.
Luteinising Hormone (LH) stimulates the release of
egg (ovulation).
Gonotrophic Hormone (GnRH) stimulates the release
of FSH and LH.
 It’s secreted in the hypothalamus
 Causes FSH and LH to be secreted from the
pituitary gland
 Signals release of oestrogen and progesterone
from the ovaries
Inhibin stops FSH and LH being released.
What are the hormones involved in the ovarian
cycle?
Follicular phase
 Ovulation occurs at day 14
o The rise of oestrogen causes a spike
What day in the follicular phase does ovulation
occur?
Luteal phase
Corpus Luteum produces progesterone and oestrogen
until placenta takes over.
 It produces progesterone and oestrogen
Progesterone facilitates the regrowth of the uterine
lining, and inhibits the release of further LH and FSH.
 At this point, the uterus is being prepared to
accept a fertilised egg
o If fertilisation occurs, progesterone stays high
and FSH decreases
 If fertilisation doesn’t occur, then the levels of
progesterone drop
o This allows for the next menstrual cycle to
commence
What happens during the luteal phase?
What does the corpus luteum produce?
Pregnancy Hormones
Human Chorionic Gonadotropin (hCG) supports the
function of the corpus luteum and prevents the body
from registering the zygote as foreign.
Progesterone inhibits contractions and strengthens
pelvic wall muscles for labour.
Oestrogen helps and maintains the growth of uterine
lining, also stimulating breast growth and milk duct
development for lactation.
What
hormones are involved with pregnancy?
Birth Hormones
Oxytocin
 It inhibits the production of progesterone and
stimulates contractions
 Involved in the contractions that take place
during labor and birth

Plays a role in the release of milk during
breastfeeding
Prostaglandin stimulates further contractions and
makes uterus more sensitive to oxytocin.
Prolactin increases milk production and breast size.
Relaxin loosens uterine muscles and prepares body
for birth.
Estriol
 Inhibits further production of progesterone
 Increases smooth muscle cells of the uterus for
oxytocin
What are the hormones involved with birth?
Evaluate the impact of scientific knowledge on the
manipulation of plant and animal reproduction in
agriculture
Artificial insemination
 Sperm from a selected male with desirable
traits is artificially transferred to a female.
 This process is commonly used with species of
large mammals, such as cows and sheep, and
with endangered animals
 Advantages
o Used to inseminate large numbers of females
o Transport of semen is easier than transporting
a whole animal and the semen can be stored
for long periods of time
 Disadvantages
o Can’t guarantee ‘favourable’ trait is passed on
o Reduced genetic variations makes
populations susceptible to changes in the
environment (e.g. disease)
What is the process of artificial insemination?
What are the advantages and disadvantages of
artificial insemination?
Artificial pollination
 Pollen from a selected plant with desirable
traits is artificially transferred to the female
stigma of another plant
 Advantages:
o Used to pollinate many flowers with the pollen
from plants with desirable traits
o Useful and an easy way of breeding new
varieties of plants
 Disadvantages:
o Can’t guarantee ‘favourable’ trait is passed on
o Reduced genetic variation makes populations
susceptible to changes in the environment
(e.g. new disease)
How does artificial pollination occur?
What are the advantages and disadvantages of
artificial pollination?
Cloning
 Process by which genetically identical copies of
an organism are made without using the
process of sexual reproduction
 The most common method is grafting
 Advantages:
o Cloned plants have identical requirements in
similar ways to produce similar yields at the
same time
o Guaranteed to express desired trait
 Disadvantages
o Offspring are genetically identical – increases
risk of disease susceptibility
o Cloning is expensive with limited advantages
over reproductive technologies
o Cloning of animals has raised ethical
questions about the cloning of humans and
life expectancy of cloned animals
How does cloning occur?
What are the advantages and disadvantages of
cloning?
Selective breeding placing male and female in an
enclosed environment to reproduce.
+ increased sales, increased desired traits, improves
quality and yield
- Reduces biodiversity, reduces genetic variation and
gene pool
What is selective breeding?
What are the advantages and disadvantages of
selective breeding?
IQ5.2 Cell Replication
Inquiry question: How important is it for genetic material to be replicated exactly?
Model the process of mitosis + meiosis:Mitosis:
somatic cells replicated, allowing for growth and
repair.

Cells are diploid due to having 2 chromosomes
in each dividing cell
Steps of mitosis:
Interphase: chromatids undergo cell replication to
prepare for cell division.
Prophase: duplicated chromosomes condense and
attach to spindle fibres.
Metaphase: homologous chromosomes line up in the
middle
Anaphase: homologous chromosomes separate and
move to opposite ends of the cell.
Telophase: nuclear membrane starts to reform
around chromosomes
Cytokinesis: cells divide, leaving 2 identical daughter
cells.
Bonds = weak hydrogen bonds
What are the steps involved in mitosis?
Meiosis: cell division for sexual reproduction that
produces 4 daughter cells.
 Role is for sex reproduction
 Produces haploid cells due to cell division
resulting in 4 single chromosomes
Steps of meiosis:
Interphase: DNA replicates to produce 2 chromatids =
1 chromosome.
Prophase I: chromosomes condense and crossing
over occurs between homologous chromosomes.
Metaphase I: homologous pairs line up in the middle.
Anaphase I: homologous pairs are pulled to opposite
ends of the cell.
Telophase I: cytokinesis (division) of cells occurs,
producing 2 diploid daughter cells.
Prophase II: chromosomes condense
Metaphase II: chromosomes line up in the middle of
the cell.
Anaphase II: chromatids are separated and pulled
towards opposite ends of the cell
Telophase II: cytokinesis splits the dividing cell,
resulting in 4 haploid daughter cells.
What are the steps involved in meiosis?
Modelling DNA Replication using Watson and Crick
DNA model
Nucleotide composition, complementary base pairing
and bonding:
Nucleotide = phosphate  sugar  nitrogenous
base
Nitrogenous base pairing = adenine + thymine;
cytosine + guanine
Each DNA strand composed of a sugar-phosphate
backbone and is parallel the other
 Nitrogenous bases were connected with
hydrogen bonds and had to pair with its
complementary base (e.g. A with T and C with G)
 Each DNA strand serves as a template for
replication = semi-conservative DNA
 DNA instructs the formation of proteins
1
4
2
3
5
Thus, Watson and Crick could form the hypothesis
about DNA’s structure by building physical models of
how the atoms fit together, leading to
groundbreaking discoveries
What role did Watson and Crick play in the
discovery of a double helix DNA?
Draw out a nucleotide composition and label the
parts.
DNA Replication:
* Occurs during Synthesis (S) phase of cell cycle
Main enzymes: DNA helicase, DNA polymerase, DNA
ligase, Primer
Step 1: DNA double helix unwinds with the use of DNA
helicase and the two strands separate, creating a
replication fork.
Step 2: a primer is attached to the DNA and DNA
Polymerase attaches free nucleotides to its
complementary base pairs on the leading strand (3’
to 5’).
Step 3: On the lagging strand (5’ to 3’), ligase
attaches the Okazaki fragments to form one
continuous strand.
* Leading strand is continuous (in the direction of
replication fork)
* Lagging strand requires Okazaki fragments to
attach fragments with the use of ligase to form 1
continuous strand.
Step 4: the resulting DNA molecules each contain
half of the original DNA molecule and a newly
synthesised strand (semi-conservative DNA).
What are the steps involved in DNA Replication?
Cell Replication:
G1: growth phase
where all organisms but nucleus double
Synthesis: DNA replication
G2: checks and edits
Mitosis: PMAT
Cytokinesis: split parent cell into 2 daughter cells
What are the steps involved in cell replication?
Assess the effect of cell replication on the continuity
of species
Mitosis:
 Cell growth and repair = increases chance of
surviving and reproducing
 Ability of individuals to reach maturity to
produce offspring = continuation of species
 However, if a cell is incorrectly replicated, it
impacts genotype + phenotype of organism
What is the effect of mitosis on the continuity of
species?
Meiosis:
 Allows for variation amongst new offspring =
better adaptability to changing environments
 Processes such as crossing over, random
segregation and independent assortment
increase variation in gene pool and offspring
o Crossing over: exchange of genetic material
of non-sister chromatids during Prophase I
o Random segregation: chromatids segregate
(split), the set of chromosomes in the
daughter cells is random.
o Independent assortment: pairs of
homologous chromosomes arrange
independently to each other
= heavily affects continuity of species
What is the effect of meiosis on the continuity of
species?
IQ5.3 Polypeptide Synthesis
Inquiry question: Why is polypeptide synthesis important?
Molecule
Nucleotide
DNA
RNA
Deoxyribose sugar
Ribose sugar
A phosphate group
Contains bases ATGC Contains bases
AUGC
Structure
Double stranded
Single stranded
(helix)
Base pairing G -- C
G -- C
rule
A --- T
A --- U
Construct appropriate representations to model and
compare the forms in which DNA exists in eukaryotes
and prokaryotes
Prokaryotes
Located in cytoplasm
Circular DNA
Not as repetitive
Transcription + translation
happen simultaneously in
cytoplasm
Contains plasmids
Eukaryotes
Located in nucleus
(mitochondria or
chloroplast)
Linear DNA
More repetitive
Transcription (in nucleus)
and translation (in
cytoplasm) does NOT occur
simultaneously
Doesn’t contain plasmids
Compare the forms of prokaryotic and eukaryotic
cells.
Model the processes of polypeptide synthesis,
including:
Transcription and Translation are the
processes used to transform DNA into proteins.
Transcription turns DNA  RNA (intermediary
molecule) to express genetics.
1. Initiation: RNA polymerase (enzyme) binds to
promoter, signalling DNA to unwind
2. Elongation: Nucleotides added to the mRNA
strand using complementary base pairing
3. Termination: RNA polymerase stops coding and
the mRNA strand is complete, detaching from
DNA
Translation turns mRNA  amino acid
1. Initiation: mRNA and tRNA molecule attach to
ribosome
2. Elongation: ribosome matches complementary
tRNA molecules to the mRNA by matching anticodon sequences, forming a polypeptide chain
3. Termination: when a stop sequence is reached,
the ribosome releases the mRNA and
polypeptide molecule
What are the steps involved in transcription?
What are the steps involved in translation?
Assessing the importance of mRNA and tRNA
mRNA is important in ensuring that the
organism’s genes code for the correct mRNA
codons = allows correct tRNA molecule to form
correct amino acid = functional protein.
Investigate the structure and function of proteins in
living things
Elements of a protein: carbon, hydrogen, oxygen,
nitrogen and sometimes sulfur
Why is mRNA important in polypeptide
synthesis?
tRNA is important in ensuring that its
anticodon specifies and binds to the correct
amino acid, ensuring functional polypeptide
chain that allows protein-folding to occur
correctly.
Why is tRNA important in polypeptide synthesis?
Analysing the function and importance of polypeptide
synthesis
Function: creates proteins that code for specific
bodily functions.
Importance: without polypeptide synthesis,
organisms wouldn’t be able to live, repair and
reproduce.
e.g. Haemoglobin is a protein molecule that carries
oxygen in red blood cells around our body. Without it,
our body wouldn’t be able to undergo cellular
respiration = impacting the continuity of species
What is the function and importance of
polypeptide synthesis?
Each of
these
amino acids are linked together by peptide bonds.
Structure (aka folding) of proteins:
Primary: unique sequence of amino acids connected
by peptide bonds in a linear form.
Secondary: chain folded into alpha-helix and betapleated sheets.
Tertiary: polypeptide folding into a 3D structure.
Quaternary: more than one polypeptide chain bond
together
What is the structure of proteins?
Function of proteins
Assessing how genes and environment affect
phenotypic expression
Phenotype: physical trait of an organism that is
determined by the genotype/genetic makeup
Genotype + environment = phenotype
Genotype: an individual’s genetic makeup (e.g.
regulatory sequences, non-coding regions) determine
and influence how a trait is phenotypically expressed.
Environment: mechanisms such as physical (e.g.
light, temperature) and chemical factors (e.g.
hormones, environmental toxins) affect gene
expression and cellular function.
Therefore, the relationship between an organism’s
genotype and environment determines phenotypic
expression which can.
How does the genotype and environment of
individuals affect their phenotype?
What are the different categories of proteins?
What is the function of each protein within these
categories?
IQ5.4 Genetic Variation
Inquiry question: How can the genetic similarities and differences within and between species be
compared?
Conduct practical investigations to predict variations
in the genotype of offspring by modelling meiosis,
including the crossing over of homologous
chromosomes, fertilisation and mutations
Mutation is a permanent alteration to the nucleotide
sequence of an organism’s genome
Crossing over results in genetic variation due to the
exchange of genetic information of homologous
chromosomes during meiosis I, resulting in the
chromosomes having a unique genotype.
Fertilisation: During the formation of the zygote, it
receives 50% of each parent’s genetic material. Thus,
fertilisation enables genetic variation due to the
inheritance of both parent’s genetics
Mutations contribute to genetic variation due to the
change in DNA sequences, resulting in a change in an
individual’s phenotype.
How does crossing over impact the genotype of
individuals?
How does fertilisation impact the genotype of
individuals?
How do mutations impact the genotype of
individuals?
Model the formation of new combinations of
genotypes produced during meiosis,
Mendel proposed a model whereby one could predict
the ratios of various types of offspring from any two
specific parents. The model is known as the modern
synthesis which combines the understanding of
Mendelian genetics with Darwinian evolution.
Interpreting examples of autosomal, sex-linkage, codominance, incomplete dominance and multiple
alleles
Genes are found on chromosomes and determine
characteristics that are inherited.
Alleles are different forms of the same gene and
occur in pairs in diploid individuals.
Rhesus factor: (Rh⁺ Rh⁺) or (Rh⁺ Rh⁻) = Rh⁺, (Rh⁻
Rh⁻) = Rh⁻
Rh⁺ = positive blood type
Rh⁻ = negative blood type
Blood Type
A (Co-dominant)
B (Co-dominant)
AB (Co-dominant)
Alleles/Genotype
Iᴬ Iᴬ, Iᴬi
Iᴮ Iᴮ, Iᴮi
Iᴬ Iᴮ
Antigen
A
B
A+B
Diploid individuals have 2 alleles of each gene
Haploid cells have 1 allele of each gene.
Autosomal Inheritance: Offspring will inherit one set
of autosomal chromosomes from each parent (44 =
22 pairs)
Autosomal dominant: Trait is determined by the
expression of 1 allele (e.g. AA, Aa).
E.g. Huntington’s disease
Autosomal recessive: Trait is determined by the
expression of 2 alleles for a particular gene (e.g.
aa)
E.g. Sickle Cell Anaemia
Sex-Linkage Inheritance: traits are passed on the sex
chromosomes (X and Y).
 As sex-linked traits are passed on the X
chromosome, men have a higher chance of
being affected by it, whilst females either are
carriers or are affected by it.
Incomplete Dominance: 2 paired alleles aren’t
equally expressed, creating a hybrid of the 2 alleles =
blended phenotype.
e.g. a red flower and a white flower = a pink flower
* Notation for incomplete dominance is used to
represent the allele that doesn’t show.
e.g.
Parent generation: red flower x white flower
: CᴿCᴿ x CʳCʳ
F1 : CᴿCʳ, CᴿCʳ, CᴿCʳ, CᴿCʳ
Therefore, the offspring are 100% pink
Co-dominant: both alleles are equally expressed,
creating a new phenotype that’s a hybrid of the 2
alleles.
e.g. red and white flower creating a red and white
striped flower
e.g. Red bull X White Cow = Roan calf (hybrid)
CᴿCᴿ x CᵂCᵂ = CᴿCᵂ
Multiple alleles: 3 alleles exist from a single trait
(e.g. blood type).
Alleles for blood type: Iᴬ, Iᴮ, and i
O (Recessive)
ii
No
antigen
What are the different types of inheritance
patterns?
Monogenetic inheritance: characteristics controlled
by a single gene loci.
Polygenic inheritance: characteristics are controlled
by more than two loci.
What is the difference between monogenetic
inheritance and polygenic inheritance?
Continuous variation is the differences between
individuals in a species that are quantitative
(measurable) – e.g. eye colour, height, skin colour,
weight
Discontinuous variation is the differences between
individuals in a species that is qualitative (categoric)
– e.g. blood type, colour
What is the difference between continuous
variation and discontinuous variation?
Constructing and interpreting information and data
from pedigrees and Punnett squares
Punnett square is a diagram used to predict the
genetic outcome of offspring inheriting a trait.
 Mendel’s ideas and logic can be represented
using a Punnett square to predict the features of
offspring in a genetic cross
 The probability can be written as a ratio (3
dominant : 1 recessive) or as a percentage (e.g.
25% probability that they will be short)
* Remember homozygous = 2 of the same allele,
heterozygous = 2 different alleles.
* Interpret the information:
Meaning
1.Symbol
What are the probabilities
of
Female,
without
trait
offspring genotypes
2. What are the probabilities of
Female, with trait
offspring phenotypes
3. What are the ratios of
Male, without
different genotypes
and trait
phenotypes
trait
e.g. in peas, theMale,
allelewith
for purple
flowers (P) over the allele for
Mating
pair
white flowers (p).
a heterozygous
purple flower isOffspring
cross-bred with a
homozygous white flower. What
are the potential offspring of this
cross?
Cross 1
P: AA x aa
Gametes
A
A
a
Aa
Aa
a
Aa
Aa
100% of F₁ offspring are Aa and therefore have long
wings
Cross 2
P: Aa x aa
Gametes
A
a
a
Aa
aa
a
Aa
aa
50% of F₁ offspring are Aa and therefore exhibit the
trait.
50% of F₁ offspring are aa and therefore exhibit the
trait.
Dihybrid cross is a cross between two different genes
that differ in two observed traits
Pedigrees can be used to record
phenotypes over several
generations within a family to
work out the genotypes of family
members.
Parent genotypes: paternal = Pp, maternal = pp
A test cross is
used to determine if an organism
exhibiting a dominant trait is homozygous or
heterozygous for a specific allele.
e.g. a test cross is used to determine if an organism
has long wings (AA, Aa) or short wings (aa):
Autosomal Dominant
 If both parents are affected and an offspring is
unaffected, the trait must be dominant (parents
are both heterozygous)

All affected individuals must have at least one
affected parent
 If both parents are unaffected, all offspring
must be unaffected (homozygous recessive)
Autosomal Recessive
 If both parents are unaffected and an offspring
is affected, the trait must be recessive (parents
are heterozygous carriers)
 If both parents show a trait, all offspring must
also exhibit the trait (homozygous recessive)
X-Linked Dominant


If a male shows a
trait, so too must
all daughters and his mother
An unaffected mother can’t have affected sons
(or an affected father)
X-Linked Recessive
 If a female shows a trait, so too must all
sons as well as her father
 An unaffected mother can have affected
sons if she is a carrier (heterozygous)
 X-linked recessive traits tend to be more
common in males (this is not sufficient
evidence though)
Collect, record and present data to represent
frequencies of characteristics in a population, in
order to identify trends, patterns, relationships and
limitations in data, for example:
Examining frequency data
Genetic variability in a population can be determined
by analysing the relative proportion (ratio or
percentage) of a given phenotype, genotype or allele
within the population.
Allele frequency is a measure of how common an
allele is within a population.
Bi-allelic: only 2 possible allele outcomes within a
population.
Multi-allelic: more than 2 allele variants per gene
Population genetics studies how the ratios of alleles
in the gene pool of a population change overtime. It’s
a way of comparing genetic similarities and
differences within and between species.
Allele frequency can be calculated by:
=
number of an allele in a population
total number of alleles in the population
Most genes are bi-allelic, however some are multiallelic. To calculate the total number of alleles in a
multi-allelic, you have to add together all the different
alleles in that population. (e.g. three for ABO blood
groups)
Example: Feather colour in Andalusian chickens is
coded for by a single gene, which has two possible
alles: black (B) which is dominant over white (b).
∴ Different combinations of alleles and the resulting
phenotypes are:
 Homozygous dominant: two copies of the B
alleles (BB), which gives the chicken black
feathers
 Heterozygous: one copy of the B allele and one
copy of the b allele (Bb), giving the chicken blue
feathers
 Homozygous recessive: two copies of the b
allele (bb), giving the chicken white feathers
Imagine a population of 1000 Andalusian chickens.
Each population has two copies of each gene, so
there are 2000 alleles for the feather colour gene in a
population. We’re told that of these 2000 alleles,
1200 are B and 800 are b.
If 1200 of the alleles are B, then:
1200
Allele frequency for B = 2000
= 0.6
If 1200 of the alleles are B, then the number
of b alleles must be 800, so:
800
Allele frequency for b = 2000
= 0.4
Analysing single nucleotide polymorphism (SNP)
Single Polymorphism are sections of non-coding DNA
that are repeated multiple times.
To be counted as a SNP, the altered DNA sequence
must occur in at least 1% of the population.
 String of repeated nucleotide units that are 2-5
bases long (e.g. CGA CGA CGA CGA CGA where
the nucleotide unit is CGA and is repeated 5
times)
 The number of times a repeat is given between
individuals allows identification of different
DNA profiles (individuals)
 STRs are non-coding DNA
IQ5.5 Inheritance Patterns in a Population
Inquiry question: Can population genetic patterns be predicted with any accuracy?
Investigate the use of technologies to determine
inheritance patterns in a population using, for
example
Steps of PCR: PCR is a specific technique that
amplifies DNA, making lots of copies.
1. Denaturation: PCR mixture reaches 95℃ and
DNA is denatured to form 2 single strands
2. Annealing: PCR reaction mixture is cooled to
55℃, allowing the primers to anneal (bind) to
the template strand
3. Extension/elongation: PCR reaction mixture is
heated to 72℃ and DNA polymerase moves
down the template strand, synthesising the new
DNA
What are the steps involved in PCR?
DNA sequencing: is the process of determining the
sequence of nucleotides in a piece of DNA.
Methods of DNA sequencing include:
 Manual: Sanger chain termination method
 Automatically using a DNA sequencer
DNA sequencing:
(a) Gel Electrophoresis
1. Collect a DNA sample
2. Extract DNA from sample
3. Amplify DNA (using PCR)
4. Perform Sanger sequencing reaction (using a
chain terminating nucleotide to identify the
position of each nucleotide)
* Chain terminating nucleotide stops DNA synthesis
as nucleotides can’t attach to it.
5. Determine DNA sequence by running all 4 PCR
reactions on electrophoresis gel to determine
the lengths of the fragments in each reaction
e.g. GGATGGCCATC – match each fragment on gel
electrophoresis with its associated reaction to
determine complementary base and therefore, DNA
sequence
What are the steps involved in DNA sequencing?
Application of DNA sequencing: testing for genetic
diseases/disorders, biological research at the
molecular level, providing evidence for evolution,
personal identification.
When is DNA sequencing used?
DNA profiling (or fingerprinting) refers to the process
of analysing DNA variations for the purpose of
identification.
Genetic markers are regions of DNA which usually
vary between individuals – used to construct DNA
profiles
 DNA profiles are based on STRs
What is DNA Profiling?
(a) Gel Electrophoresis
1. Collect a DNA sample
2. Extract DNA from sample
3. Amplify STR fragments (using PCR) with the use
of primers
4. Determine the length of STR via gel
electrophoresis
Largest fragments (most STR repeats)  smallest
fragments (least STR repeats)
e.g. CGA, 5 has 6 repeats, whereas CGA, 2 has 3
repeats
What are the steps involved in gel
electrophoresis?
Application of DNA Profiling:
1. Determining Parentage (determining someone’s
biological parents)
People inherit half the number of chromosomes from
each parent, so their DNA profiles consist of a
combination of their parents’ alleles
Population genetics is the study of genetic variation
within a population.
Gene pool: alleles of all the genes in a particular
population.
 Factors affecting gene pool are the size of the
population, mutation, natural selection, genetic
drift, diversity of environment and migration
patterns.
 Genetic differences between species can be
used to determine the evolutionary history of
populations
* The more similar gene pools are more closely
related than those that are less similar
The use of population genetics data in conservation
management
* Bands that match parent
show that the trait must
have come from them.
* It can also be
presented in an
electropherogram.
2. Identification of an
unknown person
DNA profiles can be used to determine the identity of
an unknown person through:
1. Forensics investigations to determine a suspect
of the crime or victim who is unrecognisable
2. After natural disasters to determine the identity
of people killed
A sample is taken from the scene and is used to
generate a DNA profile – look for the individual that
has the most number of bands matching with the
scene.
Can be presented as via
electrophoresis gel
Or through
electropherogram
When is DNA profiling
used?
Investigate the use of data analysis from a largescale collaborative project to identify trends,
patterns and relationships, for example
Aim: ensure that species of concern are able to adapt
to selection pressures.
 Factors that affect variation include: size, gene
flow, genetic drift, mutation etc
What is the main aim of conservation
management?
How does sequencing large populations help
scientists understand genetic inheritance?
Method: Field observation by sampling and statistical
analysis - distribution and abundance of a species.
DNA analysis (SNPs, GWAS, haplotypes) →
determines kinship lineages, improved scientific
understanding of microevolution by selection and
mutation.
How does DNA analysis assist in conservation
management?
Enabled scientists to identify sections of the genome
that are essential for adaptation to the environment
→ identify deleterious alleles and any mutations that
can enhance biological functions
Modern koala populations → two biogeographic
barriers that have emerged in the last ice age (20
000 years ago) led to a split in the koala population.
* Reduced the distribution of koalas from further
habitat fragmentation and other selective pressures
including those instigated by human activity (fur
trade, habitat clearing, disease)
* Current research is being implemented on local
scales to collect DNA samples and analyse genetic
variation in koala populations.
Population genetics studies used to determine the
inheritance of a disease or disorder





Haplotype is a group of alleles inherited
together from parents. They are tightly linked in
a cluster on a certain chromosome
Haplogroup is a group of similar haplotypes
which share a common ancestral SNP
By sequencing large populations, scientists
have been able to gather information on how
specific DNA sequences are passed through
generations.
This has allowed research into how genetic
diseases are spread throughout a population
through inheritance.
This information can be used to suggest to
individuals that are affected by genetic
diseases that can be inherited, commonly noninfectious, the probabilities that offspring will
inherit it too.
What is the difference between haplotype and
haplogroup?
Population genetics relating to human evolution
Anthropological genetics is the science of using
genetic data to understand human evolution.
Aim: to determine the origin of modern human
civilisation and the evolutionary pathway leading to
modern day human civilisation
 Genetic data favours the replacement
hypothesis

Mutation, natural selection, genetic drift and
gene flow are responsible for patterns of
diversity in human populations
What is the aim of anthropological genetics?
2 theories that support this:
1. Multiregional Hypothesis (MRE): relies on fossil
evidence to suggest gene flow between
neighbouring populations, tracing back to homo
erectus leaving Africa 2 million yrs ago and
evolving into modern humans
2. Replacement Hypothesis (Out of Africa
hypothesis): relies on mtDNA (mitochondrial
DNA) to suggest that a second migration
happened from Africa about 100,000 years ago.
What did mtDNA suggest?: it suggested that
populations contained ancient alleles that were
scattered globally. Scientists discovered that most
of the variations of mtDNA sequences occurs in
African populations, as well as Europeans, Asians,
Indigenous Australians, Americas, and Pacific
Islands
Why was mtDNA chosen?: due to its pattern of
maternal inheritance, providing evidence of descent
from ancestral populations
What are the two theories that support
anthropological genetics?
Modelling
Modelling DNA in prokaryotes VS eukaryotes
Prokaryote
Circular DNA
Eukaryote
Contain plasmids (circular DNA molecules)
Modelling the processes involved in cell replication (DNA replication and cell division – mitosis, meiosis)
1
4
2
3
5
Advantages/disadvantages of using models to explain biological concepts?
Advantage
Help communicate difficult concepts
Often cheaper and easier to use/access models
Model of Mitosis
Disadvantage
Can lead to inaccurate representations
Can give people an ‘incorrect’ misunderstanding
Model of Meiosis
Model of
Polypeptide
Synthesis
Structural levels of proteins:
1
2
3
4
5
6
Stages of mitosis under a microscope:
1. Interphase: DNA replicates
2. Prophase: chromosomes appear and split into chromatids
3. Metaphase: chromosomes align on equator
4. Anaphase: daughter chromosomes segregate
5. Telophase: daughter chromosomes move to opposite ends of dividing cell
5. Cytokinesis: cytoplasm divides
Module 6: Genetic change
IQ6.1 Mutation.…………………………………………………………………………………………………. 23
IQ6.2 Biotechnology...……………………………………………………………………………………. 28
IQ6.3 Genetic Technology..…………………………………………………………………………… 30
IQ6.1 Mutation
Inquiry question: How does mutation introduce new alleles into a population?

Mutagenic Agents:
 Mutations caused by mutagens are mostly
carcinogenic (cancer-causing)
 This is because mutagens cause changes in cell
division, leading to increased replication of
mutated cells = growth of tumour (lump of
mutated cells)
Metals
o Cause: heavy metals (e.g. nickel) breaks
backbone of DNA and inhibits enzymes
responsible for DNA repair
o Effect: Reduces accuracy of DNA replication,
increasing risk/chance of mutations.
o Bases can be mistakenly replaced for each
other (e.g. nitrous acid replacing C for U),
resulting in incorrectly paired nucleotide
sequences.
Chemicals incorporate, insert and make gaps as a
result of the base changes.
What are mutagenic agents?
What are chemical mutagens?
Explain how a range of mutagens operate, including
but not included to:
1. Electromagnetic radiation (physical):
 Short wavelength, high energy wave
 Ionising radiation
o Cause: radiation has the potential to ionise
and break DNA nucleotide bonds
o Effect: passing of mutation onto offspring
 UV Radiation
o Cause: specific wavelengths of UV light
disrupt
o Effect: forms pyrimidine dimers in DNA
between two adjacent thymine bases and/or
two cytosine bases
Example: gamma-ray, x-ray
What are the two types of chemical mutagens?
Mutation: permanent alteration to the nucleotide
sequence in an organism’s genome.
Mutagen: environmental agents that damage DNA,
resulting in mutations
What is electromagnetic radiation?
What are the two types of electromagnetic
radiation?
2. Chemical mutagens:
 Radioactive agents
o Cause: release of radiation via agents (e.g.
uranium) penetrates the cell
o Effect: Creates structural disruptions in cell,
causing incorrect pairing and thus mutations
3. Naturally Occurring Mutagens:
 Present within natural environments, however
may cause mutations
 Risk of mutation increases with increased
frequency/length of exposure
 Consists of biological and non-biological
mutagens
Biological Mutagens:
 Viruses
o Cause: viruses insert their DNA into host cells
(body of organism)
o Effect: disrupts normal cell function and may
lead to lasting mutational changes
 Bacterial Infections
o Cause: can induce inflammation of normal
functioning body cells
o Effect: reduces efficiency of DNA repair
system, increasing rate of mutation
 Transposons
o Cause: DNA segments that spontaneously
fragment and relocate/multiply within a
genome
o Effect: if inserted into chromosomal DNA, they
disrupt DNA functioning
Non-biological Mutagens:
 Metals: mercury and cadmium that occur
naturally in the environment
What are the two types of naturally occurring
mutagens?
What are examples of each type of naturally
occurring mutagen?
Compare the causes, processes and effects of
different types of mutations
(1) The origin (cause) of the mutation
Whether the mutation is spontaneous or induced.
(2) Amount of genetic material changed
Whether it’s a point mutation or a frameshift
mutation.
(3) Effect of the mutation on DNA
Insertion, substitution or deletion.
(4) Effect of the mutation on phenotype
Harmful, neutral or beneficial mutation
(5) Heritability of mutations
Somatic or germline mutation
What are the 5 factors that will help to determine
what type of mutation it is?
Point mutation: are those which only change or affect
one (or a few) nucleotides within a gene sequence.
Cause: errors in DNA replication (spontaneous or
induced)
Process:
Insertion: mutations in which extra base pairs are
inserted into a new place in the DNA.
Substitution: mutations in which a base is
exchanged for another
Deletion: mutations in which a section of DNA is
lost, or deleted.
Effect:
Silent: codon codes for the same amino acid
Missense: codons code for different amino acid
Nonsense: functioning protein changes to a stop
codon
Neutral: changed codons still codes for same type of
amino acid = little impact
Example: sickle cell anaemia (genetic disorder) is
caused by a substitution in base sequence = resulting
in sickle shaped red blood cells.
What is a point mutation?
What is the cause of a point mutation?
What is the process of a point mutation?
What is the effect of a point mutation?
Chromosomal mutation: are those which change or
affect a long segment of DNA (i.e. a significant
portion of a chromosome).
Cause: errors in cell division and crossing over in
meiosis
Process:
Changes in chromosome structure:
Deletion: Part of the chromosome is lost
Inversion: a piece of chromosome drops out, rotates
180° and is rejoined.
Translocation: A piece of a chromosome breaks off
and rejoins with another chromosome.
Duplication: an extra piece of chromosome is
added.
Changes in chromosome numbers:
Aneuploidy: When the overall chromosome number
of the offspring is different to the parent organisms
Polyploidy: When an organism contains more than
two sets of homologous chromosomes
Effect: harmful, neutral or beneficial
Example:
Aneuploidy: Down Syndrome (Trisomy 21) - (Trisomy
21 - three copies of Chromosome 21), resulting in
47 chromosomes instead of 46
Polyploidy: foetus has 3 copies of every homologous
chromosome instead of usual 2 copies.
What is a chromosomal mutation?
What is the cause of a chromosomal mutation?
What is the process of a chromosomal mutation?
What is the effect of a chromosomal mutation?
What are examples of chromosomal mutations?
Interpreting a Karyotype
This is what a
person’s entire
genome looks like.
 It has 46 individual chromosomes
 23 pairs of chromosomes
When observing a karyotype, you need to look at:
 The number of chromosomes (need to ensure
there are 46 chromosomes and 23 pairs)

The appearance of the chromosomes: shape,
length and structure
Each person has 2 of each type of chromosome.
 1 donated in the egg by the mother
 1 donated in the sperm by the father
Chromosomes 1-22 are autosomal chromosomes and
23 is the sex chromosome.
Distinguish between somatic and germ-line
mutations and their effect on an organism
Mutations exert their effects at cellular, individual
and population levels:
1. Cellular level: type of cell affected by a mutation
determines the extent of its influence.
2. Individuals: differ in their phenotypic effect
(can be physical, behavioural or physiological
change) and can be harmful, beneficial or
neutral in impact.
3. Population level: mutations are the direct
source of all new alleles and introduce genetic
variation into a population.
What levels do the mutations exert their effects?
Germ-line mutation: mutation that occurs within
gametes (sex cells/reproductive cells).
 Has no phenotypic effect due to being recessive,
unless offspring inherits two copies of the gene
 If mutation occurs before fertilisation, it will be
passed onto offspring
 If it develops after fertilisation, it won’t be
replicated by cell division (only will affect
specific cell that’s mutated)
What is a germline mutation?

Mutations in coding DNA affect the type or
sequence of amino acids in a protein endproduct
 Associated with human genetic diseases
Impact: mutations in coding DNA significantly alter
protein structure and function, potentially leading to
a range of effects, from no change to complete loss of
function
What is coding DNA?
What is the impact of a mutation in coding DNA?
‘Non-coding’ DNA: sequences that don’t code for a
protein and play an important role in regulating gene
activity.
 Contains regulatory DNA sequences that
promote ‘switch on’ genes or shut down ‘switch
off’ genes
What is non-coding DNA?
Types of Regulatory DNA Sequences:
Promoters: provide binding sites for the protein
machinery that carries out transcription.
Enhancers: provide binding sites for proteins that
help activate transcription.
Silencers: provide binding sites for proteins that
repress transcription.
Transposons are DNA sequences that move from one
location to another. This typically occurs when viruses
insert their DNA into bodily cells, enabling them to
transmit the virus to other cells in the body.
Impact: can disrupt gene regulation, potentially
leading to altered gene expression or even disease.
Somatic mutation: mutation occurring within body
cells (non-reproductive cells).
 Occur in somatic cells due to errors in
replication (mitosis)
 Spontaneous mutation may occur in S phase of
cell cycle and can develop into a tumour if not
repaired in G2 phase
 Some mutations result in tissue cells turning
into cancerous cells = cancer
 Many mutations occur as physiological changes
(e.g. mutations for Cystic Fibrosis, Tay-Sachs
disease)
What are types of regulatory DNA sequences?
What is a somatic mutation?
Meiosis: alleles are re-combined and sorted in
random ways such as:
 Crossing over: homologous chromosomes
exchange segments of DNA, resulting in new
combinations of alleles on each chromosome.
 Independent assortment: random alignment of
homologous chromosome pairs leads to different
Assess the significance of ‘coding’ and ‘non-coding’
DNA segments in the process of mutation
‘Coding’ DNA: sequences that code for a protein.
What role do promoters, enhancers and silencers
play in gene regulation?
What are transposons, and how do they move
within the genome?
How can transposons impact gene regulation and
potentially lead to disease?
Investigate the causes of genetic variation relating to
the processes of fertilisation, meiosis and mutation

combinations of maternal and paternal
chromosomes in gametes.
Random segregation: chromosomes are
randomly pulled to opposite poles, resulting in
each gamete containing a random mix of genetic
material
What are the ways meiosis contributes to genetic
variation?
What happens during crossing over?
What happens during independent assortment?
What happens during random segregation?
Fertilisation: alleles from 2 different organisms are
brought together to generate new phenotypes.
 Each gamete is non-identical, so the
combination of genes in the zygote is random
 The chances of producing identical offspring is
low
 Fertilisation increases the number of possible
allele combinations, contributing to genetic
diversity in populations
How does fertilisation contribute to genetic
variation?
Mutation is the only source of new alleles in a
population, playing a crucial role in long-term genetic
variation.
 Point Mutation: changes to the base sequence
of a gene alters the structure and function of
the resulting protein
 Chromosomal mutation: structural changes to
chromosomes affect multiple genes and the
protein produced
 Non-disjunction events: failure of chromosomes
to separate properly during meiosis, leading to
gametes with abnormal numbers of
chromosomes
What are the different types of mutations that
can occur?
What is the effect of each of these mutations on
the genetic variation of individuals?
Mutations may be:
 Beneficial: provide a selective advantage
 Neutral: no effect on phenotype
 Harmful: may cause genetic disorders or reduce
survival.
What are the 3 different impacts of mutations?
Evaluate the effect of mutation, gene flow and
genetic drift on the gene pool of populations
Mutation: permanent alteration to the nucleotide
sequence in an organism’s genome.
Gene pool: total collection of alleles for all genes in a
population.
Gene flow: transfer of genetic variation (different
alleles) from one population to another.
Genetic drift: change in allele frequency within a
population due to random sampling events.
Mutation:
 Effect on gene pool: increases genetic variation,
neutral or harmful impact on variation in gene
pool in the long-term
How does a mutation affect the gene pool of a
population?
Gene flow (migration):
 Increases genetic diversity
 Prevents loss of genetic diversity in
small/isolated populations
 Removes alleles through emigration or
introduces new ones via immigration
 Maintains species ability to adapt to changing
environments
Evaluation:
 Important in small populations where effects of
genetic drift can be harmful
 Gives populations access to new adaptive traits
What role does gene flow play in maintaining
genetic diversity?
Genetic drift:
 Loss of alleles and reduced genetic variation
 Reduced variation in gene pool
 Doesn’t favour beneficial traits (due to changes
being random)
Bottleneck effect: population drastically reduced by a
disaster; surviving gene pool may not represent the
original.
Founder effect: a small group establishes a new
population, carrying only a fraction of original alleles.
Evaluation:
 Reduces genetic diversity in small populations
 Loss of advantageous alleles
 Increase risk of extinction due to lack of
adaptive variation
How does genetic drift reduce genetic variation,
and why is it more significant in small
populations?
Explain the bottleneck and founder effects and
their impact on allele frequencies.
IQ6.2 Biotechnology
Inquiry question: How do genetic technologies affect Earth’s biodiversity?
Investigate the uses and applications of
biotechnology (past, present and future)
Biotechnology: the use of biological systems,
processes and organisms in the creation of new
products and technologies.
 Goal of biotech is to improve quality of human
life
 Most significant role of biotech is in medicine,
agriculture and industry
Uses of biotechnology:
1. Past: fermentation, plant and animal selective
breeding, agriculture, medicine and antibiotic
production
2. Present: technologies to manipulate DNA
(splicing, application and recombining),
technology to analyse and visualise DNA (Gel
electrophoresis, DNA profiling, DNA
sequencing)
3. Future: customised pharmaceuticals,
nanoscience, synthetic biology, gene drives,
biofuels
How was biotechnology used in the past?
How is biotechnology being used in the present?
How will biotechnology be used in the future?




Alters genetic composition
Cost and access
Health risks
Moral and religious issues
What are some ethical implications of
biotechnologies?
Evaluating the potential benefits for society of
research using genetic technologies
Medicine:
 Customised treatments (e.g. for rare and
undiagnosed diseases)
 Genetic engineering (e.g. recombinant DNA
Technology) – e.g. human insulin
How is biotechnology used in medicine?
Agriculture:
 Increased yield production of crops
 Plants can be made pest resistant (e.g. Bt
cotton)
 GM Plants: Enhance nutrient levels (e.g. higher
protein or iron content in rice)
 GM Animals: e.g. Atlantic salmon that grows
faster and larger = better for economy and
starvation
How is biotechnology used in agriculture?
Analyse the social implications of biotechnology and
ethical uses of biotechnology, including plant and
animal examples
Social implications:
 Expensive (those who need it the most can’t
afford it – e.g. Golden Rice, BT Cotton
 Patented technologies prevent some farmers
from accessing it
 Privacy (e.g. DNA profiling and genetic
sequencing) requires storage of genetic
information – without proper legislation info can
be misused
What are social implications of biotechnology in
agriculture?
How can biotechnology raise privacy concerns?
Ethical implications:
 Animal welfare
 Legal concerns
Industrial:
 Enzymes have been/are used in food production
and brewing
 Recombinant DNA techniques have been used
to manufacture enzymes, making the process
quick and efficient to produce large yields at a
time
 Genetically engineered plants and bacteria (E.
Coli)
How is biotechnology used in industries?
Researching future directions of the use of
biotechnology
 Medical biotechnology is a subdivision of the
biotechnology field
 Future lies in the prevention, control and
treatment of diseases
 Holds advancements in gene therapy
Pharmacogenomics
 Personalised medicine, where treatments are
tailored to the genetic profile of individual
patients
 Minimises harm to healthy cells
What are the future directions of
pharmacogenomics?
Gene therapy
 Preventing germline mutations being passed
onto future generations
 Corrects genetic errors in individuals = ability to
live a healthier lifestyle
What is the future direction of gene therapy?
Nanomedicine
 More precise and effective treatment
 Enhances individual’s immune response and
edit individual’s genomes
What is the future direction of nanomedicine?
Plant vaccines
 Vaccines where desired antigen protein is
inserted into the plant genome
What are the positive changes made to earth’s
biodiversity due to genetic technologies?
Negative:
Reduced genetic diversity:
 Cloning and selective breeding reduces
genetic diversity = decreased variation in gene
pools
 Monocultures are more vulnerable to disease
or environmental changes as they are
producing genetically similar crops or
livestock
Risk of extinction:
 GEO may outcompete natural species,
reducing natural biodiversity and altering
ecosystems
 Cross-breeding between wild and genetically
modified species can contaminate gene pools
and reduce adaptability to changing
environments
What are the negative changes made to earth’s
biodiversity due to genetic technologies?
What is the future direction of plant vaccines?
Evaluating the changes to the Earth’s biodiversity due
to genetic techniques
Positive:
Increased genetic diversity through biotechnology:
 Genetic techniques (e.g. genetic engineering
and transgenic organisms) can introduce new
genes and variation = boosting biodiversity
 Biotechnology can prevent extinction by aiding
reproduction, enhancing survival and
reintroducing them into ecosystems
Improved agricultural biodiversity
 GMO crops = increased food production
 Prevents loss of biodiversity through
conservation management strategies
IQ6.3 Genetic Technologies
Inquiry question: Does artificial manipulation of DNA have the potential to change populations forever?
Investigate the uses and advantages of current
genetic technologies that induce genetic change
Reproductive technologies:
Advantage: identification of genetic disorders and
risk factors, understanding of evolutionary
relationships, forensic biology
3. Gene therapy
Use: medicine
Advantage: treatment of diseases (e.g. Cystic
Fibrosis)
4. CRISPR
Use: molecular biology
Advantage: efficient and cost-effective for gene
therapy/transgenics
What are the different recombinant DNA
technologies, its use and advantages?
1. Artificial Insemination
Uses: livestock industry (animal production), fertility
treatment (humans).
Advantages: efficient, able to synchronise
pregnancies and bypass issues of fertility.
2. In Vitro Fertilisation (IVF)
Uses: fertility treatment (humans)
Advantages: able to freeze embryos, genetic
screening
3. Artificial pollination
Uses: pollinating crops, genetic experiments
Advantages: controlled inheritance of favourable
traits
What are the different reproductive technologies,
its use and advantages?
Compare the processes and outcomes of reproductive
technologies, including but not limited to:
What are the different reproductive
technologies?
What is the process of each reproductive
technology?
What is an advantage of each reproductive
technology?
Investigate and assess the effectiveness of cloning,
including but not limited to:
Cloning: process of making a genetically identical
copy of something.
Cloning Techniques
1. Whole-organism cloning
Uses: livestock industry
Advantages: definite inheritance of desirable traits
2. Therapeutic cloning
Uses: medicine
Advantages: stem cells are able to differentiate into
any cell
3. Gene cloning
Uses: medicine and industrial
Advantages: production of biologically relevant
proteins
What are the different cloning technologies, its
use and advantages?
Recombinant DNA Techniques
1. Transgenesis
Uses: agriculture, environmental biotechnology
Advantages: creation of organisms with multiple
functions, transference of favourable traits, reduce
pesticide use, exploit biological phenomena
2. Gene sequencing
Use: medicine, genetic research
Gene cloning: process of making an exact copy of a
particular gene (e.g. used in the production of largescale insulin) via recombinant DNA or PCR.
What is gene cloning
How is it done?
Whole organism cloning: process of cloning an entire
organism through Somatic Cell Nuclear Transplant
(SCNT), Artificial Embryo Twinning in animals, and
cuttings, grafting and tissue cultures in plants.

What is whole organism cloning?
Recombinant DNA Technology: Series of techniques
used to manipulate and isolate DNA segments of
interest.
 It
How is it done?
Somatic Cell Nuclear Transplant (SCNT):
1. Somatic cell is removed from targeted organism
2. Unfertilised egg is removed from a donor and
denucleated (nucleus has been removed)
3. Denucleated egg and DNA is fused and
undergoes cell division until embryo is formed
4. Embryo is then implanted into a surrogate
organism and gives birth to an organism which
is genetically identical to the donor

This can be within the DNA of the same
organism, or a different organism
Recombinant DNA can occur naturally or can
occur using biotechnology
What are the steps of somatic cell nuclear
transplant (SCNT)?
Artificial Embryo Twinning:
1. Egg is fertilised by sperm, forming a cell
2. Cell develops, forming a clump of identical,
unspecialised cells
3. Identical cells are split, forming embryos
4. Embryos are transplanted into new mother
5. Surrogate mother gives birth to genetically
identical offspring
What are the steps of artificial embryo twinning?
Therapeutic Cloning/gene therapy:
 Cloning cells and tissues to cure/prevent a
variety of diseases and disorders
 It is also used for basic research to understand
genetic controls
allows for the creation of multiple gene copies,
and the insertion of foreign genes to introduce
new traits
What is therapeutic cloning/gene therapy?
What is Recombinant DNA Technology?
How effective is cloning?
 Gene cloning: highly effective for producing
hormones and enzymes for disease treatment
and industrial processes
 Gene therapy: ineffective due to immune
response, short cell lifespan and costs
associated.
 Whole organism cloning: ineffective as it’s time
consuming, expensive and success isn’t
guaranteed.
The aim of recombinant DNA technology is to insert a
gene from one species into the genome of another.
The process involves:
1. The required gene is isolated from a cell.
2. A piece of circular DNA known as a plasmid is
removed from bacteria.
3. Two pieces of DNA are cut using the same
restriction enzyme.
4. The fragments produced have matching sticky
ends (sections of single-stranded DNA with
exposed nucleotide bases at the end of a
double-stranded molecule
5. The bacterial plasmid is cut at two points using
the same restriction enzymes.
6. As the sticky ends of the human gene and the
plasmid come together, they can join up via
base pairing (aka annealing)
How effective is each cloning technique?
Describe techniques and applications used in
recombinant DNA technology, for example
Recombinant DNA: DNA containing genes from two or
more different sources.
7. DNA fragments are joined by the enzyme DNA
ligase. Joined fragments can form a circular
plasmid of a linear molecule.
8. The plasmid is inserted back into a bacterial
cell, where multiple copies of the gene can be
produced.
9. Once multiple copies of the gene have been
produced, the gene can be inserted into an egg
cell of another species and, after fertilisation,
becomes part of the newly formed organism’s
DNA.
What is the aim of recombinant DNA technology?
What are the steps involved in recombinant DNA
technology?
Medical
Techniques: Therapeutic cloning, gene cloning, gene
sequencing, CRISPR
Benefits: personalised medicine for disorders =
better treatment, treatment of genetic diseases
leading to potential cures, improved diagnostic tools
What are the techniques and benefits involved in
medical applications?
Industrial
Techniques: gene cloning, transgenesis
Benefits: increased speed to chemical reactions,
creation of organisms which produce industrially
significant products
What are the techniques and benefits involved in
industrial applications?
Evaluate the effect on biodiversity of using
biotechnology in agriculture
Types of recombinant DNA technologies:
 Transgenesis: agriculture (development of pestresistant crops), environmental biotechnology
 Gene sequencing: medicine (development of
personalised treatments), genetic research
 Gene therapy: medicine (reprogramming of
dysfunctional cells/tissues)
 CRISPR: molecular biology (gene editing tool)
What are the types of recombinant DNA
technologies?
Application of recombinant DNA:
 Food industry: genetically modified food (e.g.
Golden Rice) to help with major issues such as
starvation.
 Agriculture: allows scientists to modify the
genetic makeup of crops to improve yield,
quality and resistance to pests and diseases.
What are the different applications of
recombinant DNA?
Evaluate the benefits of using genetic technologies in
agricultural, medical and industrial applications
Agricultural
Techniques: selective breeding, artificial
insemination, transgenesis
Benefits: creation of crop and livestock species which
exhibit favourable traits, creation of organisms that
don’t require pesticides, increased food security as a
solution to global poverty and food shortages
What are the techniques and benefits involved in
agricultural applications?
Positives: insect resistant, increases productivity and
efficiency, effectively increases genetic diversity
Negatives: agricultural practices have always posed a
threat to biodiversity, ability to out-compete unmodified crops = establishment of monocultures
What are the positives and negatives of
biotechnology on biodiversity?
Interpret a range of secondary sources to assess the
influence of social, economic and cultural contexts
on a range of biotechnologies
Social:
* Physical and societal setting in which people live
 A society’s values, education, laws and
priorities shape public attitudes and the use of
biotechnologies
 Ethical debates, privacy concerns and public
trust influence acceptance of the use of these
technologies
e.g. DNA fingerprinting is widely accepted in some
countries for forensic use, however there is great
concern around the genetic privacy of individuals
tested.
What is the social influence on biotechnologies?
Economic context:
 Wealthier nations have more access to
advanced biotech compared to developing
countries
 Biotechnology can either reduce or exacerbate
wealth disparities
e.g. GM crops increase yields and lower costs,
benefiting large-scale farmers. However patents and
high seed prices can exclude smallholder farmers and
perpetuating economic inequality.
What is the economic influence on
biotechnologies?
Cultural context:

Religious, moral and traditional beliefs affect
how biotechnology is perceived and used
e.g. In some Islamic countries, IVF is accepted within
marriage but embryo freezing or surrogacy may be
restricted
What is the cultural influence on
biotechnologies?
Module 7: Infectious Diseases
IQ7.1 Causes of Infectious Diseases.………………………………………………………………
IQ7.2 Responses to Pathogens...…………………………………………………………………….
IQ7.3 Immunity.………………………………………………………………………………………..………….
IQ7.4 Prevention, Treatment Control.……………………………………………………………
IQ7.1 Causes of Infectious Diseases
Inquiry question: How are diseases transmitted?
Classifying different pathogens that cause disease in plant and animals
Pathogen is an infectious agent that is capable of causing a disease in a host.
Host is any organism that carries another organism (e.g. bacteria) or agent (e.g. virus)
Infectious disease a disease that is caused by a pathogen or infectious agent and can be passed onto other
organisms
Chitin: tough exoskeleton that protect arthropods and cell wall of fungi.
Classification
Abnormally folded protein
that causes progressive
neurodegenerative
conditions.
Classification
Microscopic organisms that
infect hosts (e.g. plants,
animals) and uses host’s
machinery to replicate.
Classification
Cellular (eukaryotes,
bacteria and archaea), or
according to shape
(spherical, rod-shaped,
spiral or comma-shaped).
Classification
Unicellular, eukaryotic
organisms.
Flagellates: propelled by
flagellum
Ciliates: propelled by cilia by
beating rapidly
Amoebae: use pseudopods
to move around
Sporozoa: protozoans that
don’t have structures for
motion and reproduce by
releasing spores.
Classification
Fungi can be multicellular
(e.g. mould) or unicellular
(e.g. yeast), and affect both
plants and animals.
Classification
Classified according to
where they live:
Pathogen: Prion
Structure
Transmission
Misfolded cellular protein
Direct: consuming infected
containing of mostly betabeef
pleated sheets.
Indirect: contaminated
surgical instruments
Pathogen: Virus
Structure
Transmission
Protein coat enclosing
Indirect: airborne
genetic material (DNA and
transmission or intermediary
RNA).
Pathogen: Bacteria
Structure
Transmission
Single-celled prokaryotic
Direct: close contact
organisms that have a cell
indirect: contaminated
wall and no membraneintermediary
bound organelles.
Pathogen: Protozoa
Structure
Transmission
Has a membrane-bound
Indirectly via a vector (e.g.
nucleus, organelles and cell insect bites), or faecal-oral
membrane, however doesn’t route
have a cell wall.
Example
Humans: Creutzfeldt-Jakob
Disease (CJD)
Cattle: Bovine Spongiform
Encephalopathy (BSE)
Example
Influenza, COVID-19,
Measles
Example
Salmonella
Example
Malaria, Giardia
Pathogen: Fungi
Structure
Transmission
Eukaryotic organism
Indirectly: close contact or
composing of a cell wall
with contaminated objects.
made of chitin.
Example
Yeast infection (e.g.
athletes’ foot), thrush
Pathogen: Microparasite
Structure
Transmission
Visible to the naked eye,
Ectoparasite: indirectly via
multicellular eukaryotic
vectors or intermediaries.
organisms.
Example
Ectoparasite: fleas,
mosquito, ticks, leeches
Ectoparasite: live on the
outside of the body.
Endoparasite: live inside
host’s body.
Endoparasite: faecal-oral
route
Endoparasite: flatworm,
roundworm
Investigating the transmission of a disease during an
epidemic
Symptoms: fever, watery nasal discharge, hacking
cough, loss of appetite and muscle pain, depression
and labouring breathing.
Transmission: directly (between horses) and
indirectly (through humans who: carry virus,
contaminated shoes, clothing, grooming
equipment, food and water buckets)
Management of outbreak:
1. Implementing a lockdown
2. Management centre is setup
3. Quarantine those exposed
4. Spread of the disease is mapped
Control of future outbreaks:
1. Mass vaccination
2. Restrict importation of live horses
3. Strict biosecurity measures are implemented for
subjected imported horses
4. Public education
5. Provide biosecurity training
Epidemic: large outbreak of an infectious disease in a
community, population or region over a specific
period of time.
Pandemic: epidemic that’ spread over multiple
countries/continents
Endemic: something that belongs to a particular
people/country
Exotic: originating in
Enzootic: endemic in an animal population
Orthomyxovirus: a family of virus
Case study: Equine Influenza Virus
(Horse flu) is an exotic equine disease that is highly
contagious, affecting horses and donkeys but not
humans.
Cause: EIV  equine-1 and equine-2
Design and conduct a practical investigation relating to the microbial testing of water or food samples
Practical Investigation: Microbial Testing of Water Samples
Aim: To investigate the types and frequency of microbial growth present in different water samples (tap, pond
water, and sea water) using agar plates.
Hypothesis: Different types of water (tap water, pond water, and sea water) will contain varying types and
frequencies of microbial growth when incubated on agar plates.
Risk
Precautions
Seal Petri dishes and do not open.
Sterilise all equipment after experimental use.
Microbes grown are pathogenic to humans
Do not handle water samples directly. Wear gloves, safety
glasses and lab coat at all times.
Keep in sealed vessels.
Materials:
 8 agar plates
 Sterilised water
 Pond water sample
 Sea water sample
 Inoculation loop
 Parafilm or tape for sealing plates
 Bunsen burner (for sterilising work area)
 Personal protective equipment (PPE): gloves, lab coat, safety glasses
Method:
1. Light a Bunsen burner and place the inoculation loop in the flame, moving it back and forth 3 times to sterilise
it.
2. Label 8 agar plates as follows: 2 x ‘nothing’ (control), 2 x ‘sterilised water’, 2 x ‘pond water’, and 2 x ‘sea
water’.
3. Seal the two control agar plates labelled 'nothing' with parafilm and set them aside.
4. For the 'sterilised water' group: Open one plate carefully at a 45° angle. Using an inoculation loop, swab the
surface with sterilised water, then seal with parafilm. Repeat for the second plate.
5. Repeat step 4 using pond water for two more plates.
6. Repeat step 4 using sea water for another two plates.
7. Incubate all sealed agar plates at 37°C for 24 hours.
8. After incubation, remove all plates from the incubator and observe any colony growth on each plate.
9. Record observations about microbial colonies—note their colour, shape, size, and how many colonies are
present on each plate
Variables:
 Independent variable: Type of inoculum used (sterilised/pond/sea/nothing)
 Dependent variable: Types and frequency of microbial growth observed on each plate
 Controlled variables: Temperature during incubation (30°C), length of incubation period (three days), amount
of liquid added to each plate
Controls:
Agar plate left uninoculated (‘nothing’) acts as a negative control; agar inoculated with sterilised water checks if
contamination occurs from handling.
Conclusion:
By comparing colony growth across different samples you can determine which types of microbes are present in
various environments—demonstrating that different sources contain different microorganisms.
Procedures to reduce cross-contamination:
It’s important to minimise the possibility of
contamination by microbes in the environment,
scientific equipment and on the skin = invalid results
1. Wipe all surfaces with alcohol solution to
minimise risk of contamination
2. Remove all unnecessary objects
3. Sterilise test tubes by moving them through the
blue flame of a Bunsen burner
4. When opening the Petri dish, lift the lid at an
angle no greater than 45℃.
5. Don’t breath or cough over the open dish and
work as quickly as possible
6. Use an inoculating loop to spread sample onto
nutrient agar.
7. After the dish has been closed, seal it with
sticky tape and label around the edge of the
underside (agar side).
* It’s important to allow oxygen flow (e.g. not closing
lid around crack) as it allows the growth of anaerobic
bacteria = dangerous
* It’s important to write details on the bottom edge of
the agar plate as it allows a clear view of the sample.
s
Investigate modes of transmission of infectious
diseases, including direct contact, indirect contact
and vector transmission
Transmission: involves carrying or transfer of a
pathogen from an infected host to a non-infected
organism.
Reservoir: where the infectious agent lives, grows and
replicates.
Carrier: organism who is able to transmit the disease
without showing any symptoms.
Vector: indirect transfer of the pathogen via another
organism, such as an arthropod.
Modes of transmission depend on the ability of the
pathogen to survive outside a host cell.
 For a disease to spread between organisms, a
‘chain of infection’ has to be present:
1. A host that is susceptible to the disease
2. A pathogen that is capable of causing the
disease
3. A mode of transmission:
What needs to be present for a disease to spread
between organisms?
Direct contact: transmission of pathogen via physical
contact between the host and non-infected organism
 Sexual contact
 Kissing
 Direct contact with bodily fluids or blood
 Direct contact with wounds
e.g. Skin infections, glandular fever, herpes
3. When a healthy organism is inoculated with
the pure culture, it develops the same
symptoms as the original sick organism
4. Isolate and re-grow microorganism from
newly infected organism
What did Robert Koch develop?
What are the 4 postulates?
Louis Pasteur
 Disproved the theory of spontaneous generation
 Proposed germ theory of disease (all things
come from pre-existing things)
What did Louis Pasteur disprove and propose?
What his experiment that he performed?
Experiment: Swan-neck flask experiment
What is direct contact?
Indirect contact: when a host and another organism
have no direct contact with each other but transmit
pathogen via a vector (insect) or intermediary
(inanimate object).
 Airborne transmission (inhalation of droplets)
 Touching an infected surface
 Contaminated food/water
 Infected surgical instruments
e.g. measles, influenza, COVID-19
What is indirect contact?
Vector transmission: transfer of pathogen via another
organism, such as an insect (e.g. mosquito).
e.g. malaria, dengue fever
What is vector transmission?
Investigate the work of Robert Koch and Louis
Pasteur, to explain the causes and transmission of
infectious diseases, including:
Robert Koch
 Developed a procedure for isolating and
identifying microbes causing diseases
 Postulates: links microbial growth as causative
agent for disease
1. In all organisms with the disease, the
microorganism must be present
2. Microorganisms must be isolated, and grown
in pure culture
1. Take flasks with bent
(swan) necks. Particles
in the air can’t travel through the necks without
getting stuck. Fill with broth.
2. Apply heat to both flasks, bring to boil. This
sterilises the contents of the flask
3. Break the neck of one flask
4. Observe growth of microorganisms in broth
a. Flask with broken neck = microbe growth
b. flask without broken neck = no growth
Assess the causes and effects of diseases on
agricultural production, including but not limited to:



Agriculture is a form of primary industry 
involving the cultivation of crops and pastures
Strict biosecurity measures prevent disease
transmission from pathogens
Introduction of new plant diseases can
devastate crops, including forestry and
agriculture
Endemic diseases: diseases consistently present
within a country or origin.
Exotic diseases: disease has been introduced to an
area.
Epizootic: animal equivalent of a human epidemic.
Complex interplay of three factors contribute to the
development of infectious diseases in organisms:
Pathogen factor: ability to
transfer between hosts and
virulence factors (e.g.
adhesion and invasion of host
tissues, successful
establishment inside host
tissues)
Host factor: susceptible to
disease, access to pathogen,
concurrent disease = weakened immunity, putting
stress on the host.
Environmental factors: overcrowding + lack of
hygiene = build-up of wastes, leading to an
environment which favours the growth of pathogens.
Plant diseases:
What are the three factors that contribute to the
development of infectious diseases in organisms?
What are the causes of infectious diseases in
plants?
Factors contributing to the risk of infectious disease:
1. Increased mobility of human populations
 Travellers import livestock into Australia, which
carries diseases
2. Rise of intensive and industrial-type agriculture
 Increase in population results in a change in
livestock production
 Feedlots are used to feed animals, however,
carry a higher risk of disease outbreak
3. Increase in use of aquaculture
 Antimicrobials used to therapeutically control
outbreaks
4. Change in land use
 Deforestation and irrigation practices may
change the distribution of insects in a specific
environment, leading to destruction of crops
5. Climate change
 Leads to an increase in insects, increasing the
risk of diseases
6. Antimicrobial resistance
 Humans are overusing antibiotics to treat
animal diseases
e.g. Bovine Mastitis
7. Pesticide resistance
 Overuse of herbicides, pesticides = increased
weed resistance to pesticides
8. Loss of genetic diversity
 Lack of variation = decreased resistance to
diseases
9. Increase in hobby farmers
 Farmers who are inexperienced (novice),
unknowingly causing harm
Effects of infectious diseases in plants:
 Biological effects on the individual plant, such
as:
o Death of plant = destruction of tissues
(necrosis)
o Abnormal growth = discolouration of tissues
and wilting
 Social and economic effects on the farmer
o Threat of infectious disease places a great
burden on primary producers
o Constant monitoring, early detection and
management assist in controlling the disease
o The most important consequences of a plant
disease outbreak on a farm include: reduced
yields, loss of trading opportunities and
economic loss for the farmer
 Social and economic effects on Australia’s
economy
o The Australian economy relies heavily on the
export of grains, fruits and vegetables to
overseas markets
o Australia’s physical isolation and the
consequent disease-free status of its produce
gives us unique access to markets globally
o The introduction of exotic plant disease into
Australia could have dire consequences for
the national economy
What are the factors that contribute to the risk of
infectious disease?
Fungi: most common cause of plant diseases
 Reservoirs of fungal spores exist in
contaminated seeds
Causes of infectious diseases in plants in agriculture
 In the natural environment, plants are
commonly attacked by pathogens, however have
adapted to fight these diseases
(e.g. abscission (dropping) of infected fruits or
leaves)
 When plants are grown for horticultural or
agricultural purposes, they are grown in higher
densities
o This results in pathogens becoming an issue
for crops and farmers
 If conditions aren’t right for plants, it causes
them stress, reducing their natural ability to
inhibit pathogen invasion and growth
What are the effects of infectious diseases in
plants?
Majority of plant infectious diseases are caused by
types of pathogens, such as:

Transmitted by wind, water and contact with the
normal farming practices
 Fungi enter plants through stomata caused by
mechanical damage = destroys plant tissues
and absorbs nutrients from plants
e.g. Powdery mildew x
Insects + mites: cause direct damage and act as
vectors.
 They lay eggs under leaves, leaving them to
hatch and burrow into the leaf
e.g. fruit flies, mealybugs
Bacteria: found in soil, weeds and seeds.
 Harbour bacteria on hands and equipment
from contaminated plants = passed onto other
plants
e.g. Black Rot
Nematodes: attacks plant roots, creating
galls/lumps which prevent nutrient consumption.
 Infestation can be dealt with repeated
cultivation of soil
Viruses: obligate intracellular parasites
 Stable in environment and attack plant
leftovers after cropping
 Form a reservoir on contaminated equipment
What types of pathogens cause plant diseases?
Case study: Panama Disease
What is it?
 Disease in Cavendish bananas in northern
Queensland in 2015
 It is a soil-borne disease caused by a fungi
(aka Fusarium oxysporum)
 Multiple variations of the disease exist in Asia
and Australia, attacking different types of
bananas
Transmission:
 Infection from root to root contact
 Colonisation of plant and spore formation
 Movement up xylem
 Formation of resting spores in dying plant
 Death of plant and return of resting spores to
soil
 Germination of resting spores to soil
Modes of transmission:
 Contaminated soil and water
 Infected planting material
 Disease through dirty equipment, vehicles and
footwear
Effect on species:
 Extremely difficult to eradicate
 Symptoms include: blocking of vascular
system = food + water starvation, release of
more spores and further transmission to the
rest of the plant and to other plants
Effect on Agricultural production in Australia:
 Infected land becomes unsuitable for banana
cultivation
 Repurposed land for other crops, affecting
local agricultural economies
 Persistence of disease in soil poses a threat to
the suitability of banana farming in Australia
 If the disease spreads further, it could
devastate the industry, significantly affecting
parts of Australia’s agricultural sector
Cost of Disease
 Panama disease has significantly reduced
banana production in affected areas.
 Farmers face increased costs due to the need
for stringent biosecurity measures
 Reduction in banana supply has led to an
increase in banana prices
 Reduced production leads to job losses and
economic hardship
 Infected land becomes unsuitable for banana
cultivation and may need to be repurposed for
other crops, affecting local agricultural
practices and economies
Prevention:
 Australia has implemented strict biosecurity
measures to contain the disease
 Quarantining affected farms
 Monitoring and controlling the movement of
soil and plant material
 Educating farmers on best practices
 Developing disease resistant banana varieties
to suppress the pathogen
 Observing bananas for signs of the disease
and recording them early
Animal diseases:
Epizootic: animal equivalent of a human epidemic.
 World Organisation for Animal Health oversees
and coordinates management of animal
diseases
What is epizootic?
Effect of a disease in farm animals:
 Loss of international trading opportunities
 Economic loss to the farmer due to decreased
yields
 Loss of appetite results in decreased weight =
decreased cost as they aren’t fat
 Death of affected animals
 Low growth rates in young animals
 Human illness and disease
What is the effect of a disease in farm animals?
Case study: Footrot in sheep
Footrot is an infectious disease of the hooves, which
is present in sheep, goats and cattle. The disease is
caused by the pathogenic bacterium Dichelobacter
nodosus, causing painful abscesses between the
toes, lameness and weight loss as grazing is affected.
An outbreak of footrot depends on a number of
factors being present:
 Pathogenic factors: Dichelobacter nodosus
must be present
 Environmental factors: bacterium will only
survive outside of the host cell for a maximum of
4 days. Temperature also plays a role in the
survival of pathogens.
 Host factors: dry feet with intact tissues aren’t
affected, however reservoirs of bacteria may
form in individual animals’ feet
What factors does an outbreak of footrot depend
on?
Name: Japanese Encephalitis
Pathogenic: Virus
Signs/symptoms of the disease: rapid onset of high
fever, headache, neck stiffness, coma, seizures,
disorientation
How is the pathogen transferred?: via a vector
(mosquito), specifically Culex tritaeniorchynchus (a
type of mosquito native to South Asia and some
parts of Africa)
What is the favourable environment for the
pathogen?: warm weather, particularly in the
summer
Describe some preventative measurements:
vaccines are commercially available in several Asian
countries – for both humans and animals.
Identify some online resources that a farmer could
use to learn more about this disease: Government
Health Advisory websites (e.g. World Organisation
for Animal Health, World Health Organisation).
Is this a “notifiable disease?”: Yes, in Australia it
must be reported to the Department of Health.
Investigate the cause and effects of an animal
disease in relation to an agricultural production:
Compare the adaptations of different pathogens that facilitate their entry into and transmission between hosts
Pathogen
How do they enter
the host
How do they
multiply in host
How do they
resist the host
defence
mechanism
Inducing normal,
Invade the
cellular proteins to lymphoid tissue,
mutate into prion
‘piggy back’
form
other proteins
to facilitate
movement
Prion
Ingestion, direct
exposure to
contaminated
tissues, unsterile
medical equipment
Virus
Insects inject toxins
into genetic
material and then
into cell membrane
Bacteria
Chemicals to adhere Binary fission
to host, hold onto
surfaces using pilli
Inject genetic
material into host
cell and replicate
What is the
damage to host?
Neurodigenerative
conditions and
eventually cell
death (apoptosis)
What adaptations
have they made to
enter host
Binding to cellular
receptors,
transversing the
intestinal barrier and
utilising cellular
pathways for transport
and replication.
Adhesion to
Disrupting
Use of surface
host cell surface cellular processes proteins for binding to
receptors.
leading to cell
specific receptors,
Invasion of
damage and
mechanisms for
host’s cell and
death
penetrating cell
replicates
membrane and
integrate genetic
material into host’s
genome
Formation of
Direct tissue
Fimbrae for
biofilm,
damage, toxin
adhesions, ability to
flagellum for
production,
produce enzymes that
movement,
disrupting cellular break down host
secreting toxins functions
tissue and formation
into host cell
of biofilms for
protection and
support.
Protozoan
Through
contaminated water
or faecal-oral route
Asexual
reproduction
Fungus
Inhalation,
ingestion or direct
contact with skin
Spores
MacroParasite
Contaminated
water, food, soil,
insect, bites,
vectors
Lay eggs
Hiding in host
cells, release of
toxin to
suppress
immune system,
intracellular
location
Forming
biofilms,
modifying host’s
immune system
and lysosomal
destruction
Disguising
themselves,
interfering
host’s immune
system
Direct damage to
cells, triggering
immune
responses and
causing tissue
damage
Ability to secrete
effector molecules to
suppress host
defenses, vectors to
bypass barriers
Tissue
destruction, toxin
productoin,
interference with
the host’s immune
system
Infect and kill
host tissue,
extract nutrients
from dead host
cells
Penetrate and infect
host cells, including
producing enzymes to
break down cell walls
and using vectors for
entry
Specialised structures
for attachment,
enzymes to penetrate
host tissues, immune
evasion strategies
IQ7.2 Responses to Pathogens
Plants line of defence:
Biotrophs: invades plant, however doesn’t kill.
Nectrotrophs: invade plant and kill
PAMPs: pathogen associated molecular patterns
Wilting: plant stops collecting water so that the
pathogen doesn’t get to the plant as easily.

Plants are good at avoiding infections, but not
like our immune systems
 Plants respond in passive and active ways
 Plant pathogens divide into 2 types:
o Biotrophs
o Nectrotrophs
 Pathogens can get into conductive tissues via
the leaf through the cytoplasm or cell wall

Pathogens can also get into the conductive
tissue through the stomates
o Results in the plant wilting
What are the two types of plant pathogens?
Root structures:
 Xylem and phloem makeup the vascular tissue
in plants
 Vascular tissue brings up nutrients from the
roots
 If pathogens get into the roots of plants, the
plant receives no water through the xylem and
thus can’t photosynthesise = can’t grow or
survive
 Wilting of a plant occurs if the plant can’t get
enough water
Leaf structures:
 If a pathogen enters a leaf, it can damage the
chlorophyll
 This means that the plant can’t photosynthesise
o Cuticle: First barrier, stops most pathogens
o Cell wall: heavy duty material
o Stomates: close to prevent entry
o Thorns and hairs: repel insects
o Change shape of leaf: pathogen slides off
and prevents water pooling (prevents a
reservoir from forming)
What are the parts of a leaf?
Viruses:
 They spread via a vector and cause isolated
infections or infections that spread throughout
the plant
o This inhibits photosynthesis (damages
chloropast), water and nutrient uptake
o Symptoms: yellowing of leaves, mosaic leaf
pattern, crinkled leaves and growth stunting
Fungal:
 Pathogens secrete enzymes to digest the cell
wall, or enter via stomates
o This allows pathogens to steal the nutrients
from the plant
o The enzymes inhibit photosynthesis, water
and nutrient uptake
o Symptoms: leaf and stem wilting, rusting,
leaf mosaic and mildew
Physical defence systems – barriers to stop infection:
 Drooping leaves  prevents collection of water
 pathogens can’t stay there
 Stomata  close stomata to prevent pathogens
entering
 Hairs  trap pathogens

Waxy cuticles  water can’t settle as easily on
them
 Dropping of leaves  ‘dieback disease’
e.g. eucalyptus
 Bark  strong physical layer of dead cells, that
is compressed by the pressure from inside the
plant
o Stops pathogens from entering the xylem and
phloem
What are the physical defence systems of a
plant?
Example: Phytophthra Cinnamoni
 Species of fungi that thrives in Australian
conditions
 The parasitic mould lives in the soil and attacks
the roots of plants
 Symptoms:
o Yellowing of leaves
o Dieback of leaves
o Splits in the trunks of infected trees
o Darkening of the larger roots
 Transmission:
o Root-to-root contact from the infected roots
coming into contact with uninfected roots
o Physical transportation of the contaminated
roots
 Plant response to infection
o The damaged roots prevent the tree from
absorbing water and other soil nutrients
o Can spread easily, causing disease, death and
extinction of susceptible plants and loss of
habitat for animals
Chemical defence systems (innate system):
1. Gene resistance
 Identifies the pathogen and produces proteins
that will fight the pathogen and stop it from
infecting new cells
2. Basal resistance
 Pathogens have PAMPS (Pathogen Associated
Molecule Patterns) of proteins)
o Helps the plant recognise the pathogen as
non-self, resulting in:
 Fortificiation of plant tissues
 Tighten junctions between cells to inhibit
movement of pathogens
3. Hypersensitive defences (localised response)
 If above fails, then a localised response is
activated
 The cell wall changes and traps the pathogen so
it doesn’t spread
4. System acquired response
 A whole plant response that occurs after an
earlier exposure

Salicylcic acid is accumulated
o This is a broad spectrum protection against
pathogens to help the plant to fight off the
pathogen
What are the chemical defence systems of a
plant?
Investigate the response of a named Australian plant to a named pathogen through practical and/or secondarysourced investigation, for example:
Aim: To investigate the response of a named Australian plant to a named viral or fungal pathogen through a
practical investigation and secondary sources.
Hypothesis: If the eucalyptus is infected with the cinnamon fungus, then it will display symptoms of stress, such as
chlorosis, wilting and ultimately death because the fungus interferes with the chloroplast’s ability to function.
Hazard:
Insects
Hazard
Risk
Bites and allergic reaction
Weather exposure
Skin burns
Precaution
Check areas for insects. Advise
students with allergies.
Sunscreen and limit time exposed.
Evaluation of risks and ethical issues: The risks identified are valid in the study of plants and their pathogens. The
precaution to wear a face mask is an appropriate method to inhibit fungus inhalation as long as the filter is small
enough to allow only gas molecules. Gloves are appropriate as the bites of insects are small compared to the
thickness of materials. However, the list of risks is not exhaustive, and thus, perhaps some hazards can cause
injury. There are no ethical issues with regards to the hazards listed as the plant is not injured in the experiment. In
fact, removing a damaged/infected leaf is of benefit to the plant.
Results: The Eucalyptus plant that is exposed to the fungus cinnamon has chlorosis as evidenced by the yellowing
and blotching of the leaves. The plant was also wilting and upon death, the roots were observed to be blackened
which is also a symptom of infection with the fungus.
Analysis of results: Eucalyptus plant has a negative response to infection by the fungus cinnamon, resulting in
eventual death of the plant. Control of the pathogen is required to minimise the effect of the eucalyptus tree
population.
Analyse responses to the presence of
pathogens by assessing the physical and chemical
changes that occur in the host animals cells and
tissues
o This involves: inflammation, phagocytosis,
fever and apoptosis
What do antigens produce?
Innate Immunity:
 Response to pathogens are NON-SPECIFIC
 Makes up the first and second lines of defence
What is innate immunity?
Adaptive Immunity:
 Specific defence mechanism consisting of
specialised cells
 Immunity is acquired
 Makes up the third line of defence
IMPORTANT TERMS:
Innate Immunity: trait is gentically determined and
present at birth.
Adaptive Immunity: trait is acquired
Self: produced by the body
Non-self: not produced by the body
Antigen: protein markers on pathogens
Antibodies: molecules (chemicals in our body) that
fight pathogens
Non-specific (Innate Immunity):
 Repels all pathogens equally
 Born with it/inherited with non-specific defense
mechanisms
 Includes barriers to infection and innate
immune system
 Doesn’t need to identify/target the specific
pathogen
o Thus, allowing a quicker response
What is innate immunity?
Specific (Adaptive Immunity):
 Targets specific pathogen
o Thus, resulting in a slower response as it
needs to recognise the pathogen first
 Includes the adaptive immune system
 Develops and adapts in response to pathogens
which we encounter and fight off throughout our
lives
What is adaptive immunity?
Antigen:
 Antigens produce an immune response that is
specific to different pathogens and different to
its own cells
 Antigens on pathogens are different to antigens
on human cells
 When a non-self antigen is detected, the second
line of defence is activated
What is adaptive immunity?
Lines of Defence
Physical
barriers (e.g.
skin, mucous
membrane,
sphincters,
cilia, mucus)
Physical
responses
(e.g.
granuloma,
emesis,
wound
healing)
Chemical
defence (e.g.
sebum,
urine, saliva,
gastric
secretions)
1st line of defence (innate): physical and chemical
barriers formed by tissues
 Aims to stop pathogen entry into the body
What is the 1st line of defence?
Physical Barriers
Skin
 Tough, intact outer layer of closely packed cells
 Well supplied with red and white blood cells, as
well as plateletes
Mucous Membrane
 Tissues that line the surface of the respiratory,
digestive, urinary and reproductive tracts
o Thick mucus is produced which is able to trap
pathogens and antigens
o Cilia then transport the pathogen in the mucus
out of the body
 Produced by goblet cells
o Saliva that travel across these membranes
contain enzymes (e.g. lysosomes) that are
able to breakdown pathogens
What is a mucous membrane?
Tight Junctions: protein complex between
2 cells that creates a seal to prevent pathogen entry

Prevents pathogen entry by sealing the spaces
between epithelial cells
o Thus, restricting diffusion of pathogens further
into the body
What are tight junctions?
Mucus
Alimentary canal: long tube that moves food through
during digestion.
 Protects the lining of the body by trapping
foreign substances (e.g. pathogens, dust,
pollen)
 An increased mucus producion in respiratory
tract = sign of infection
 Green mucus = indicates activity of white blood
cells as they secrete iron, containing enzymes to
fight pathogens
 Mucus prevents entry through alimentary canal
by lining it
 Cervical mucus plugs guard pathogen entry
through uterus
How does mucus protect the lining of the body?
Peristalsis
Peristalsis: contraction of intenstinal muscle


Keeps content of digestive system and bowel
moving
Exposing content to chemicals in the canal to
remove harmful microorganisms
What is peristalsis?
Sphincters
 Circular muscle that maintains constriction of a
natural body passage
Found in many parts of the body, such as:
 Lower oesophageal sphincter
 The pyloric sphincter
 Urethal sphincter
What are sphincters?
Physical Responses
Granuloma
 Cells die to seal off an area of tissue that’s
infected and that the body can’t successfully
fight off
o The infection is surrounded by a wall,
preventing the infection from spreading
o ∴ Cells inside the granuloma die
 Debris in the granuloma is destroyed by
macrophages that have engulfed the granuloma
e.g. Tuberculosis and leprosy typically cause
granuloma formations
What is a granuloma?
Vomiting
 A reflex action coordinated by the vomiting
centre of the brain
 Vomit happens in response to many signals (e.g.
presence of pathogens in the gut)
 It’s the body’s way of expelling harmful
substances
* Hypersaliva occurs before vomiting to protect tooth
enamel from stomach acid
What is the purpose of vomiting as a physical
response to pathogens?
Diarrhoea
 Expels micro-organisms quickly from the
gastrointestinal system
What is the purpose of diarrhoea as a physical
response to pathogens?
Increased Urination
 A common response to the bladder lining being
attacked is inflammation (cystitis) and the need
to pass frequent small amounts of urine
o It’s a response mechanism to flush out
pathogens
What is the purpose of increased urination as a
physical response to pathogens?
Wound Healing
 Tissues are exposed to environmental
pathogens + microbiome of the skin when there
is a breach in the body’s barriers
 Symptoms: bleeding if blood vessels have been
damaged
What is the purpose of wound healing as a
physical response to pathogens?
Wound healing priorities:
 Stop the bleeding  vaso constriction
o A platelet plug is formed as well
o Fibrin (type of protein) forms a mesh which
allows clotting to seal the wound
o This is followed by the inflammatory response
 Prevent infection by confronting pathogens
 Heal and repair the wound
What are wound healing priorities?
Chemical Defences

A number of non-specific chemicals are
secreted by the epithelial tissue
o This further prevents pathogens entering the
internal environment of the body
o Secreted by enzymes that are found in tears,
mucus, saliva, urine etc
What is the purpose of tears as a chemical
defence mechanism?
Urine
 Urine is sterile until it leaves the body
 When an animal doesn’t urinate, pathogens can
ascent into the lower urinary tract
 Faceal bacteria (e.g. commensal organisms)
are a threat as they are found on the skin in this
area
 Bladder infections occur when pathogens are
able to enter the bladder
Gastric secretions
 Parietal cells line stomach wall  secrete
hydrochloric acid
 pH of 1-2, which discourages the growth and
survival of microbes
 Pepsin (enzymes) is an antimicrobial agent as
well
 However, many bacterial pathogens have
mechanisms = microbes can survive
o If acid is passed through the intestinal tract, it
can cause gastroenteritis
 As food moves through the stomach, pH
changes rapidly = limits pathogen growth
What is the purpose of urine as a chemical
defence mechanism?
What is the purpose of gastric secretions as a
chemical defence mechanism?
Sebum
 Sebum = oily material secreted by sebaceous
glands
o Purpose: lubricate the skin
o pH is 5.5 (acidic) due to the presence of lactic
acid, amino acids and fatty acids
Vagina
 Chemical defence as it’s an acidic environment
= kills pathogens present
What is the purpose of sebum as a chemical
defence mechanism?
Nasal hairs
 Cilia in nostril traps pathogens and moves them
out of the body
Sweat
 has lysoszyme that’s secreted with sweat
 purpose: break down bacterial cell walls
What is the purpose of sweat as a chemical
defence mechanism?
Saliva
 Produced by salivary glands
 Complex mixture of water, mucus, electrolytes
and enzymes (amylase, antimicrobial
substances and immunoglobin A)
 Saliva flushes microbes and has antimicrobial
properties (e.g. IgA, antimicrobial peptides
(AMPs))
What is the purpose of saliva as a chemical
defence mechanism?
Tears
 Lacrimal glands produce tears
 Glands along eyelid produce sebum-like
substance
 Production of tears = lacrimation  produces a
tear film that covers eye
 Goblet cells assist in distributing film easily
What is the purpose of the vagina as a chemical
defence mechanism?
What is the purpose of nasal hairs as a chemical
defence mechanism?
Investigate and model the innate and adaptive
immune systems in the human body
2nd line of defence (innate): inflammation -physical
and chemical responses of cells
 Non-specific (responds to all pathogens
equally)
 Innate  born with this (isn’t acquired)
White Blood Cells:
1. Phagocytes: Neutrophils, Macrophages, Mast
cells
2. Lymphocites: specialised for adaptive immune
responses
 B cells and T cells
What are the 2 WBC involved in the 2nd line of
defence?
Phagocytosis
Phagocytosis: process by which phagocytes change
their shape so they can surround a foreign particle.

Phagocytes are specialised WBC or leucocytes
o Protects the body by ingesting unwanted
material in phagocytosis
 They are designed to protect the body against
invaders
What is phagocytosis?
Steps of phagocytosis:
1. The phagocyte engulfs the foreign particle
forming a phagosome
2. A lysosome fuses with the phagosome, forming
a phagolysosome
3. Within the phagolysosome the enzymes break
down the foreign material into smaller pieces
4. The small waste fragments are expelled from
the phagocyte by exocytosis
 This residual vesicle fuses with the plasma
membrane and the contents are released
What are the steps involved in phagocytosis?
Main types of phagocytes include:
Neutrophils:
 Originates in the bone marrow and migrate
through capillary walls to reach infected tissue
 Neutrophils are first to move to the site,
inactivating pathogens
 Phagocytose pathogens in acute infection
o Microbes die due to unfavourable conditions
when engulfed, which is then digested by
enzymes (e.g. proteases)
Where do neutrophils originate?

Specialised immune cells that play a crucial
role in initiating and regulating the immune
responses
What is the purpose of dendritic cells?
Natural Killer Cells:
 White blood cells that destroy infected and
diseased cells
 They release cytoxic chemicals to kill the
pathogen directly
What is the purpose of natural killer cells?
Inflammation Response
 Chemical response helping with wound repair
and leading to pathogen destruction
1. Immune cells (e.g. mast cells) detect the
presence of a pathogen and release
histamines.
2. The histamines act as chemical messengers,
leading to physical changes in the body to kill
the pathogen.
a. Redness: increase in blood flow to the area,
increasing the number of immune cells
moving to the site where the pathogen is
b. Swelling: increase in the permeability of the
membrane, increasing the diffusion of
immune cells into the affected tissue.
c. Pain and heat: these immune cells release
chemotactic factors, chemicals that draw
phagocytes towards the pathogens.
d. Loss of function: occurs as a result of the
symmptoms above
What is the role of neutrophils?
What are the symptoms of infection?
Monocytes:
 Live a longer life and helps with chronic
infection
 Circulate the blood until attracted to inflammed
tissue
o It undergoes transformation into macrophages
and dendritic cells
o It’s then recruited to the site of infection
 On the surface of the monocytes are toll-like
receptors (TLRs) which recognise specific
pathogens associated molecular patterns
(PAMPs) released from bacterial cells
o This removes microbes, lipids and dying cells
through phagocytosis
Goals of inflammation:
 Confine the pathogen to one area
 Destroy the pathogen
 Remove the pathogen, its products and
damaged tissue
What is the role of monocytes?
Dendritic Cells:
What are the goals of inflammation?
The Complement System
Complement system: set of more than 20 soluble
proteins that assist other defence mechanisms.
 The complement system is activated when
pathogens are detected in the body
 Proteins can stimulate phagocytes that become
more active in the presence of a pathogen

Proteins are made in liver cells and
macrophages
What is the goal of the complement system?
Fever
 The hypothalamus contains cells that regulate
body temperature and keep it within normal
range (37˚C)
 Body may increase temperature upon detection
of pathogens
o Does this by releasing ‘fever-causing’
chemicals known as pyrogens
Purpose: kill/limit growth of pathogens and enhance
the activity of white blood cells
What is the purpose of a fever?
Cytokines
Cytokines: chemical signals released by cells in
response to pathogens.
 Cytokines bind to receptors and trigger an
immune response in the receiving cell
o Promotes activation, proliferation and
differentiation
 Promotes the development and differentiation
of T and B lymphocytes
 They do this by signalling to uninfected cells to
destroy RNA and reduce protein synthesis
 Cells also undergo apoptosis
e.g. Interleukin (IL), interferons
What are cytokines?
B cells are produced in the bone
marrow until they mature
Once matured, they are released into
the blood
they travel to the lymphoid tissue
where they accumulate and wait until
a pathogen breaks into the body
What do cytokines promote?
3rd line of defence (adaptive immune response):
Antibody mediated (B cells) and Cell Mediated (T
cells)
When a B cell Comes into contact with
an antigen, it becomes activated
Antibody-Mediated Immunity
 Also referred to as the humoral immunity
 Refers to the activity of B lymphocyte (plasma
cells and memory-B lymphocytes
Antigen then clones creating many
copies which differentiate into one of
two types: plasma cells and Memory B
Lymphocytes
What is antibody-mediated immunity?
B lympocytes:
 A type of white blood cell that is produced in the
bone marrow
 Produces antibodies (aka immunoglobins)
 When antibodies and antigens bind, the
resulting molecule is called the antigenantibody complex
Lymphoid tissue = spleen and lymph node
What are B lymphocytes?
Where do they originate?
Plasma cells
 Produces antibodies which are released into the
blood stream
 Antibodies are Y Shaped proteins that bind to
specific antigens
o The antigen that triggered the B lymphocyte is
the one the antibody binds to
 Antibody has a shape that is compatible with
the antigen
o Allows antibody to bind with antigen to form an
antibody-antigen complex
o Found in mucus, saliva, tears and breast milk
o Protects against pathogens
What are plasma cells?
What are antibodies?
Antibodies interferre with the functioning of the
pathogen to either:
 Prevent pathogen from causing damage
 Make it easier for the immune system to destroy
it
What is the impact of antibodies interfering with
the functioning of the pathogen?
This occurs in 5 ways:
1. Neutralisation: deactivating a pathogen by
blocking its active site.
 Prevents binding of pathogen to its target
2. Precipitation: antibodies bind to soluble
antigens, causing them to form insoluble
clumps
 Makes phagocytosis more efficient
3. Agglutination: antibodies bind to antigens on
the surface of cells, forming clumps of cells
 Clumps cells together, making phagocytosis
more efficient
4. Activating the competent system: helps to
disarm pathogens
 Enhances the phagocytosis, inflammation and
pathogen removal by cell lysis
5. Opsonisation: bound antibodies ‘tag’ pathogens
for destruction, making it easier for
phagocytosis to locate them.

IgD
o Part of the B receptor
o Activates basophils and mast cells

IgE
o Protects against parasitic worms
o Responsible for allergic reactions

IgG
o Secreted by plasma cells in the blood
o Able to cross the placenta into the foetus

IgM
o May be attached to the surface of a B cell or
secreted into the blood
o Responsible for ealry stages of immunity
What are the 5 ways that antibodies impact the
functioning of pathogens?
Memory B Lymphocytes
 Provide the body with long-term defence against
antigens
 They remain dormant in the lymph tissue until
activated
o If animal is exposed to the same antigen
again, memory cells recognise it and divide to
produce antibody-presenting plasma cells
 Immune response to antigen that the body has
already met is:
o Faster
o Stronger
o Longer lasting
What are memory B lymphocytes?
There are 5 ways immunoglobulin can stop
pathogens:
 IgA

Cell-Mediated Response
 Involves T cells / lymphocyres
 There are 4 types of T lymphocytes:
o Cytotoxic T cell
o Helper T cell
o Suppressor T cell
o Memory T cell
What is the cell-mediated response?
T cells are made in the bone marrow and
then released into the bloodstream
They travel to the thymus gland where they
mature
They are then released into the blood again,
where they circulate into the blood and
lymph fluid in an inactive state.
If a T lymphocyte comes into contact with a
specific antigen, the receptors on its surface
bind and activate the cell.
They do this by releasing cytokines
o Increase the activity of phagocytes
o Help promote inflammation
o Stimulate the production of cytotoxic T
lymphocytes
o Stimulate B lymphocytes to differentiate to
form plasma cells and memory B lymphocytes
What are helper T lymphocytes?
Suppressor T Lymphocytes
 Turns off the immune response after the antigen
is successfully contained, destroyed or removed
What are suppressor T lymphocytes?
Memory T Lymphocytes
 Provides the body with long term defence
against antigens
 Persists after an infection, enabling a larger
and faster response upon reinfection with the
same pathogen
 If the body is exposed to the same antigen, the
memory T cells will recognise it and divide into:
o Cytotoxic T cells
o Helper T cells
What are memory T lymphocytes?
MHCI
 Major Histocompatability complex
 Identifies individual cells as your own
 It’s in every nucleated cell
What is MHCI?
It then divides into the 4 types of T
lymphocytes: cytotoxic, helper, suppressor
and memory
Cytotoxic (Killer T cells)
 Infected cell displays antigens on its surface,
allowing T cells to recognise the pathogen and
kill it
 Kills foreign abnormal and infected cells
o Sometimes also kills the body’s own cells
 Secretes or injects perforin into the target cells
o Chemicals may prevent pathogen from
replicating further or killing the cell
MHCII
 In antigen-presenting cells (e.g. macrophages,
dendritic and B cells)
 Phagocytes have the MCHII – activates the T
cells for humoral and cell mediated responses
What is MHCII?
What are cytotoxic cells?
What do they secrete?
Helper T Lymphocyte
 Doesn’t directly kill pathogens – they help
promote the activites of other immune
responses
IQ7.4 How can the spread of infectious diseases be controlled?
Investigate and analyse the wide range of
interrelated factors involved in limiting local, regional
and global spread of a named infectious disease
Endemic rate of a disease: typical rate at which a
disease occurs in a population.
Epidemic: sudden increase in the number of diseases
– above the endemic rate.
Outbreak: sudden increase in the endemic rate in a
small specific geographical area.
Pandemic: increase in the number of disease in
multiple countries or continents – affects a large
number of people.
Disease incidence: the number of new cases of a
disease diagnosed in a time frame.
Disease prevelance: the number of people in a
population that have the disease at a particular point
in time.
Limiting the spread of infectious diseases
 Endemic level of a disease
o Baseline of disease
o Typical rate at which a disease occurs in a
population
 Epidemic
o Sudden increase in the number of diseases
o Above an endemic rate
 Outbreak
o Sudden increase in the endemic rate in a
small specific geographical area
 Pandemic
o Increase in the number of diseases in multiple
countries or continents – affects a large
number of people
 Disease incidence
o The number of new cases of a disease that are
diagnosed in a particular time frame
 Disease prevalence
o The number of people in a population that
have the disease at a given time
What is a disease incidence?
What is a disease prevalence?
Local
 Neighbourhood, village, town or city
 Influence on spread: sanitation, overcrowding,
local and spiritual beliefs
 Provision of public health information to
improve public knowledge of diseases and
prevention
What is a local area?
Regional
 Geography of a region influences disease
transmission
 May be characterised by: mountains, deserts,
rainforests and grasslands
 Local seasonal variations in temperature and
precipitation patterns may influence the
availability of vectors
What is a regional area?
Global
 Increased movement of people around the world
makes it difficult to manage the spread of
diseases
 Pre-migration medical examinations are carried
out
 Overuse of antibiotics has also influenced the
spread of infection
 Increased movement of people around the world
makes it difficult to manage the spread of
diseases
 Pre-migration medical examinations are carried
out
 Overuse of antibiotics has also influenced the
spread of infection
What is a global area?
What is an endemic level of a disease?
What is an epidemic?
What is an outbreak?
What is a pandemic?


Incubation periods and resistance to
disinfectants also differ
They may persist in the environment or need
direct host-to-host transmission
Pathogen factors
 Some pathogens are highly virulent and
infectious in small numbers

Local spread of Influenza A deals with local
environments (e.g. schools, hospitals, suburbs)
o The spread of the disease varies depending on
the conditions of the environments
 Suburbs with lots of schools may have higher
incidence of influenza due to the large amount
of people that each student comes into contact
with on a regular basis
o The larger the suburb or local population, the
higher the incidence of influenza may be
 Alternatively, sections of the local area with
high population density will have a higher
incidence of influenza A than sections of the
same local area with low population density or
interaction
 Additionally, individuals who live in isolated
regions are less likely to come into contact with
people
What are pathogen factors?
Host factors
 Exposure to pathogen doesn’t always lead to
disease
o However, these defences can be weakened by
factors (e.g. concurrent illnesses,
malnutrition, certain medications)
 People are facing food shortages or living in
developing nations may also have reduced
resistance, making them more vulnerable to
infection
What are host factors?
Environmental/geographical factors
 Certain environments increase the risk of
infectious diseases being spread by allowing
pathogens to build large reservoirs
 Environmental factors (e.g. warm weather,
standing water) support disease carriers like
mosquitos that transmit malaria
What are environmental/geographical factors?
Societal factors
 In Australia, preventable diseases (e.g.
chickenpox) are making a comeback
 Anti-vaccination campaigns may influence
people to get vaccinated
 Lack of education can contribute to poor
decision-making
 Mass human population movement due to
armed conflict is an increasing problem
What are societal factors?
Named infectious disease: Influenza A
Local:
Regional:
 The spread of influenza can occur through the
use of airplanes
o Airplanes can transport affected individuals,
leading to the transmission of disease
o This reduces their risk of getting influenza A
Global:
 Airplanes can also transport affected
individuals to different parts of the world
o Means that Influenza A can transport from one
country to another on mass scale
 Disparity of information provided to individuals
differ between countries
o Some countries might have limited access to
information (e.g. in third world countries)
Investigate procedures that can be employed to
prevent the spread of disease, including but not
limited to:
Hygiene practices
 Hygiene can be divided into 2 types: personal
and community
o Personal:
 Each person keeping their body and any
openings on it clean
 Reduces the risk of pathogens entering
our body
 Hygienic practices:
 Hand washing
 Hair and teeth regularly cleaned
 Cough/sneeze into a tissue
o Community:
 Helps prevent the build-up of pathogenic
organisms in the community
When infrastructure supporting and
maintaining community hygiene fails, there
is a cease of cases
 Community hygiene includes:
 Sewerage and garbage disposal
 Sterilisation and disinfection
 City planning to decrease overcrowding
o Food: guidelines must be followed by food
handlers that have been introduced for
storage, preparation and serving of food.
o Water: it’s important that water quality is
maintained to decrease the risk of pathogens
 Domestic water quality must comply with
strict standards to decrease the incidence
of disease
 Water that has been contaminated could
contain unsafe levels of pathogens and
cause unwanted symptoms

What are personal hygienic practices?
What are communal hygienic practices?
What are food related hygienic practices?
What are water related hygienic practices?
Total death
Mortality = Total exposed × 100
Quarantine
 Quarantine minimises the risk of exotic pests
and diseases entering Australia
o Diseases can be brought into Australia by
people, animals and plants
Animal: Animals that enter Australia are placed into
quarantine to ensure that they are disease-free.
What are animal quarantine procedures?
Plant: involves examining all plants entering Australia
for diseases.
 Live plants must be quarantined until diseases
have had time to develop
What are plant quarantining procedures?
Human:
 Captains of aircraft and ships must notify
Australian Quarantine and Inspection Services
(AQIS) if any passengers or crew show
symptoms of disease
 Aircraft are sprayed with insecticide to
eliminate pests entering into Australia
 Mosquito traps are placed in all international
airports to detect disease-carrying mosquitoes
(vectors)
What are human quarantining procedures?
Northern Australia Quarantine Strategy (NAQS)
 NA is close to countries with exotic diseases and
pests that aren’t found in Australia
 NAQS acts as an early warning system to protect
Australia
 ‘Sentinel’ animals (e.g. cattle, pigs) are
regularly tested for diseases (e.g. Japanese
encephalitis)
 Insect traps are used to monitor for invasive
pests
 Department of Agriculture, Water and
Resources (DAWR) plays a key role in disease
prevention and biosecurity
What is the Northern Australia Quarantine
Strategy (NAQS)?
Vaccination
Vaccine
 Involves the introduction of attenuated
pathogenic particles into the body
o Triggers a small-scale immune response
What is the purpose of a vaccine?
Immunisation:
 Process in which the body reacts to a vaccine by
going through the immune response
o Response produces memory cells, enabling a
faster response of the disease
What is immunisation?
Active Acquired Immunity:
 Some vaccines contain toxoids (modified
toxins)
 Vaccines contain antigens that trigger an
immune response and produce memory cells
o Upon future re-exposure, the secondary
immune response destroys it, preventing
symptoms
It can be either:
 Naturally induced: by experiencing the disease
symptoms
 Artifically induced: through vaccines triggering
immunity
What is active acquired immunity?
What is naturally induced immunity?
What is artificially induced immunity?
Immunity from vaccines is usually lifelong, but:
 Each vaccine is specific to one disease

Some vaccines require booster shots as memory
cells decline over time
Passive Acquired Immunity:
 Involves direct introduction of antibodies into
the body
 This type of immunity is temporary (lasts only a
few months) as no memory cells are formed
 Vaccines are essential for long-term infectious
disease control
Herd immunity: a form of protection given to
individuals against infectious disease when a
population when a significant proportion of the
population have been vaccinated.
Breakdown of the herd immunity: not enough people
in the population are immune to a disease, so the
disease spreads more easily again.
What is passive acquired immunity?
Public Health Campaigns
 Focus is on the management and prevention of
diseases
 Aims to raise awareness and spread
understanding about the causes and impacts of
disease
Resolution: come up with a solution
Information: epidemiological studies
Coordination: solution is implemented on a local,
regional and global
Education: inform public
What are public health campaigns?
Control and/or prevention of infectious disease:
1. Hygiene practice
2. Vaccination
3. Pesticides
4. Genetic engineering
Herbicides: used to kill weeds
 Pesticides are used in agriculture to protect
from crop damage and kill vectors of disease
(e.g. mosquitoes)
 Reduces the occurrence of the disease
 Controls the spread of the disease through the
population
What are pesticides?
Disadvantages of pesticides:
 Vectors and pathogens can develop resistance
against the pesticide, reducing the long-term
effectiveness
 Environmental damage from chemical
pesticides has led to a rise in natural pesticide
use
What are the disadvantages of using pesticides?
Genetic Engineering (GE)
 Alter genetic makeup
 Pest dies upon eating
Investigate and assess the effectiveness of
pharmaceuticals as treatment strategies for the
control of infectious disease, for example:
Chemotherapy: use of any drug to treat any disease.
Antimicrobial agents: designed to control infectious
diseases caused by microbes.
Protease: enzymes that cut viral proteins into pieces
so that they can assemble into their final
configuaration
Steps to take in order to control the disease:
1. Identify the disease
2. Alert the presence of the disease
3. Isolate those infected by the disease
4. Prevent another outbreak of the disease
The main classes of antimicrobials include:
 Antibiotics
o Target bacteria
o Examples: penicillin
 Antivirals
o Target viruses
o Example: Tamiflu
 Antifungals
o Target fungi
o Example: fluconazole
 Antiprotozoals
o Target protozoa
o Example: Doxycycline
What are the steps taken to control the disease?
What are the main classes of antimicrobials?
Pesticides
Antivirals
Pesticides: chemical or biological agents which
control pests, including herbicides, insectidies and
antimicrobioas.
Insectidies: used to kill insects.
Fungicides: used to kill fungal pathogens
Antivirals: a class of antimicrobial used to treat viral
infections by inhibiting the development of the
pathogen inside the host cell.
Reverse transcription: viruses replicate by inserting
their genomic material into the host genome
What are the steps to control and/or prevent
infectious diseases?

Viruses use the host’s cells to produce new virus
particles = making it difficult to stop viral
replication without killing the host cells
Antibiotics
Antibiotics: a class of antimicrobial used to treat
bacterial infections.
 Does this by killing the bacteria or slowing down its
growth

Antibiotic resistance
o Reduces the effectiveness of antibiotics in
controlling infectious disease outbreaks
o Makes antibiotics less effective overtime
o Selection pressures lead to the survival of
bacteria with mutations or genes providing
resistance
What is antibiotics?
Investigate and evaluate environmental management
and quarantine methods used to control an epidemic
or pandemic
Ebola virus disease (2014-2016)
 Ebola virus disease is a severe infection caused
by the Ebola virus
 It is extremely contagious and causes rapid
death
 It’s a ssRNA virus with many subtypes, however
is easily preventable
 It spreads when people have close contact with
bodily fluids and mucous membrane from
infected individuals, including sexual
transmission
 The incubation period is between 2-21 days
 Symptoms: fever, tiredness, headache and a
sore throat, vomiting, rash, diarrhoea, oozing of
blood from the mucous membrane and stools
 Management:
o Intravenous or oral fluids
o Broad-spectrum antibiotics
 Control:
o Environmental and quarantine measures
o Use of PPE
o Training healthcare workers correctly
Interpret data relating to the incidence and
prevalence of infectious disease in populations, for
example:
Mobility of individuals and the portion that are
immune or immunised
Incidence: number of new cases occurring during a
specified time period.
Prevelance: the total number of cases at a
particular point of time.
Incidence =


Number of new cases
Size of population
× 100
New cases occuring during a specified time
Can be a % or number per 100,000 (or 1000
etc)
All new cases
Prevelance = Population during time × 100


All cases: cured, dead, present data
Proportion that have diseases up to a particular
point in time
Mobility:
 How easy it is for a pathogen to spread
 Humans are good carriers
Dengue Fever in South East Asia
 Mosquito-borne viral infection found in tropical
and sub-tropical climates worldwide
 Causes flu-like symptoms and can be potentially
lethal
Evaluate historical, culturally diverse and current
strategies to predict and control the spread of
disease
Epidemiology: the study of the incidence and
distribution patterns of disease that lead to its
cause, management and control.
 Study of how diseases spread
 Study the incidence and distribution
 Helps to figure out the cause, management and
control
Historical control:
 1377: 1st quarantine used to stop disease
spreading – plague
 1467: Plague, leprocy – hospitals on islands –
natural barriers
 In AU:
o 1866: measles
o 1876: scarlet fever
o 1789: small pox
o 1900: Spanish flu
 The response to these diseases laid the
foundation for the public health system in NSW
Investigate the contemporary application of
Aboriginal protocols in the development of particular
medicines and biological materials in Australia and
how recognition and protection of Indigenous culture
and intellectual property is important, for example:
Bush medicine
Bush medicine: Indigenous health practices based
on traditional beliefs and experiences.
 Use of herbs and other plants to produce
treatment for illnesses
 Now people are trying to record knowledge
without the permission of the Indigenous and
Aboriginal Australians
Plants
 Many bioactive compounds found in plants
 Crushed, used as a paste or added to water to
drink
How are aboriginal plants used for medicine?
Witchetty Grub
 Traditionally used as a food source
 Strengthens body, promotes healing
 Treats burns when crushed into a paste
What is witchetty grub?
Mud, sand, dirt and clay
 Applied to skin
 Physical barrier
 Used to treat infections and gastro problems
What are mud, sand, dirt and clay used for?
Desert mushrooms
 Used to treat mouth sores, dry lips
 Natural teething rings
 Pharmaceutical companies isolate active
ingredients for commercial use
 Ethical, moral and legal debates about how to
protect and recognise Indigenous intellectual
property
What are desert mushrooms?
Lemongrass
 Ailments: Assists with fever, diarrhea, ear ache
 Application: boil, cool and apply to skin, eaten
or direct contact to ear
 Found: everywhere where it is raid or semi arid
What is lemongrass used for?
Eucalyptus oil
 Ailments: aches, pain, fever and chills
 Application: leaf infusion, mouth wash,
lozenges, cough suppressant
 Found: everywhere in Australia, except the
middle and desert.
What is eucalyptus oil used for?
The National Aboriginal and Torres Strait Islander
Health Plan:
 Ideas, inteventions, images that can be used
commercially
 AU laws don’t protect Indigenous bush medicine
 Lots of potential for therapeutic medicine
 Since colonisation – knowledge, recorded,
rights given to companies exclude indigenous
people
 Protection complex, traditional knowledge isn’t
owned – some even sacred
What is the National Aboriginal and Torres Strait
Islander Health Plan?
Smoke Bush in Western Australia
 Ailment being treated: Cancer, HIV
 Licensed to collect by a pharmaceutical
company, generally Western Australia
 Smoke bush is traditionally used for healing
 Scientists now investigate it to treat HIV and
cancer
 License excludes Indigenous people of WA in
any royalties or compensation
What is smoke bush in Western Australia?
Considerations:
 Indigenous people have used it for thousands of
years, passed it from generation to generation
Module 8: Non-Infectious Diseases
IQ8.1 Homeostasis.………………………………………………………………
IQ8.2 Causes and Effects...…………………………………………………………………….
IQ8.3 Epidemiology.………………………………………………………………………………………..………….
IQ8.4 Prevention.……………………………………………………………
IQ8.5 Technologies and Disorders.………………………………………………………
IQ8.1 How is an organism’s internal environment maintained in response to a changing external
environment
Construct and interpret negative feedback loops that
show homeostasis by using a range of sources,
including but not limited to:

Counteracting the change: a response occurs
that will reverse (or counteract) the change.
What is the stimulus response model?
Homeostasis: maintenance by an organism of a
relatively constant internal state.
Set point: the ideal or normal value for a specific
internal condition.
Tolerance limits: upper and lower levels of a specific
condition in the internal environment of the body.
What is homeostasis:
 The process by which the body maintains a
constant internal environment
o The body needs nerves and hormones to do
this
o Conditions refer to variables: body
temperature, water availability, blood glucose
levels and CO₂ levels
o Each variable has a tolerance level
What is homeostasis?
Importance of homeostasis:
 Living organisms are made of cells, which must
function efficiently to maintain life
 It is essential that internal conditions be
maintained at a level that allows optimal
functioning of enzymes
o This ensures that optimal metabolic efficiency
is maintained
What is the importance of homeostasis?
Maintenance of homeostasis:
 The nervous system and the endocrine
(hormonal) system are involved in homeostasis
o Some change in the internal environment is
allowed
 Variables in the internal environment, such as
temperature or glucose concentration are
maintained with tolerance limits
o Each of these variables has a set point
 If there is a temperature that exceeds the upper
or lower tolerance limits, a mechanism is
triggered to return the body to the normal range
Stimulus-response model
 The stimulus-response model is the body’s way
of detecting a change in the external or internal
environment, and reacting accordingly
Homeostasis is brought about into two main stages:
 Detecting change: sensory cells or receptors
detect a change in the internal environment.
1.Stimulus:
something
happens to cause
change in the
environment
1.Receptor:
recognise
changes to the
internal condition
of the body
1.Control centre:
information from
sensory
receptors is
compared to the
normal/expected
level
1.Effector:
involved in fixing
the imbalance in
the body (e.g.
muscles, organs
or glands)
1.Response:
restores the body
to the original
state
1. Stimulus: something happens to cause change in
the environment
2. Receptor: recognise changes to the internal
condition of the body
3. Control centre: information from sensory
receptors is compared to the normal/expected
level
 Brain (hypothalamus) or spinal cord (central
nervous system)
4. Effector: involved in fixing the imbalance in the
body (e.g. muscles, organs or glands)
 The hypothalamus sends information to either
the nervous system or endocrine system
o Nervous system: information travels via
electrical impulses along nerve cells
(neurons)
o Endocrine system: uses hormones to act as
chemical messengers sent through the blood
5. Response: restores the body to the original state
What are the steps in the stimulus-response
model?
Negative feedback loop
 Information produced by the feedback causes a
reversal in the effect of the stimulus
 Response always returns to normal level
o E.g. if the body temperature is too high, it will
lower and if the body temperature is too low,
it will increase
What is a negative feedback loop?
Glucose
Concentration
of a substance
in the blood is
too HIGH
Decreased body
temperature
Concentration
of glucose in
the blood is
LOWERED
Insulinsecreting cells
in pancreas
detect change
Blood vessels
constrict,
shivering,
metabolic rate
increases, eret
hair traps air
Additional
insulin is
secreted from
pancreas
Liver absorbs
more glucose
Blood vessels,
muscles, cells,
hair erector cells
Concentration
of a substance
in the blood is
too LOW
Concentration
of glucose in
the blood is
INCREASED
Glucagonreleasing cells
in pancreas
detect change
Liver breaks
down glycogen
and releases
glucose in the
blood
Additional
glucagon is
secreted from
pancreas
Increased body
temperature
Blood vessels,
sweat glands,
cells are
informed that
they need to act
Hypothalamus
activates
heating
mechanisms
Investigate
the
various mechanisms used by organisms to maintain
their internal environment within tolerance limits,
including:

Numerous mechanisms are used by organisms
to maintain their internal environment within
tolerance limits
o Adaptations
o Internal coordination systems (e.g. nervous
and endocrine systems)
Trends and patterns in behavioural, structural and
physiological adaptations in endotherms
Temperature
Blood vessels
dilate, secretion
of sweat,
metabolic rate
decreases
Hypothalamus
recognises the
body is too cold
Hypothalamus
recognises the
body is too hot
Hypothalamus
activates cooling
mechanisms
Endotherms: organisms that are able to maintain
their body temperature within a very narrow range of
tolerance limits.
Ambient temperature: temperature of the
environment.
Thermoregulation: the regulation of body
temperature.
Adaptation: a characteristic that an organism
possesses that will increase the survival and
reproductive chances of an organism in its
environment.
Behavioural: the way an organism acts
Strutural: the physical characteristic of the
organism.
Physiological: the way the organism’s body
functions.
 These organisms rely on internal sources (e.g.
metabolic activity) to maintain their body
temperature
 Endotherms show a combination of adaptations
to assist them in its environment and
thermoregulation
o Those that live in areas of high temperature
need adaptations to reduce their exposure to
heat and increase their ability to lose heat
o Those that live in colder environments benefit
from having adaptations that increase their
ability to gain heat and reduce their heat loss
Behavioural adaptations
 Altering positions/alignment of body to avoid
sunlight
o E.g. red kangaroo will sit in a position where
its hind legs and tail are shaded by the rest of
its body
o E.g. Fairy penguins move into water to cool
down
 Nocturnal activity assists in regulating body
temperature
o Some animals live in habitats when the day
temperature is too hot
 Burrowing assists with cooling animals down
 Migration assists in thermoregulation
o Animals move to another habitat with a
temperature that is within their tolerance
range
What are behavioural adaptations?
Structural adaptations
 Insulation (e.g. fur, hair and feathers trap a
layer of air next to the skin, reducing the
amount of heat lost)
o E.g. the feathers of fairy penguins provide an
insulating layer to reduce the amount of heat
lost
 Surface area to volume ratio is another
important structural component of temperature
regulation
o Polar bears are larger with a small surface
area to volume ratio
 Only a small amount of heat is lost
compared to the volume
o Smaller animals that live in colder
environments (e.g. mountain pygmy possum)
have small ears to reduce SA for heat loss
What are structural adaptations?
Physiological adaptations
 Metabolic activity can be altered to assist the
organism in maintaining its body temperature
within the tolerance range
o In low ambient temperatures, the main source
of heat in the body results from metabolic
activity
o Heat generation occurs from shivering and
increased metabolic rate
o Reduced activity leads to less heat production
to lower the body temperature
 Hibernation is used by some animals to escape
extreme temperatures where:
o Body temperature doesn’t drop below 30˚C,
but the heart rate and oxygen consumption
drop
o E.g. the mountain pygmy possum hibernates
during cold winters to reduce amount of
energy required to keep body warm
 Torpor is a short-term hibernation where:
o The body temperature drops below 30˚C and
metabolism, heart rate and respiratory rate
decreases
o E.g. the common wombat slows its metabolism
to a third of its normal rate on hot days
 Evaporative cooling (e.g. sweating, panting,
licking) is used to cool down the body
o As water evaporates from the body, heat is
removed
 Regulating of blood flow to increase/decrease
amount of heat lost
o Vasodilation increase amount of heat released
o Vasoconstriction decreases amount of heat
released
 Countercurrent exchange allows the warm blood
in arteries to heat the cooler blood in the veins
before blood is returned to the heart
What are physiological adaptations?
Internal coordination systems
 Nervous and endocrine systems are internal
systems that work together to ensure that
homeostasis is maintained
Role: to coordinate and provide pathways of
communication for the negative feedback systems
Receptors
 Receptors are responsible for detecting stimuli
 They contain sensory cells and take numerous
forms depending on the stimuli that activate
them
 They are concentrated in particular areas,
forming sense organs (e.g. eye, ear, tongue)
What are receptors?
What are receptors responsible for?
Interceptors: receptors within the body that detect
internal stimuli related to homeostasis.
 Thermoreceptors: detect change in temperature
o In the skin or hypothalamus
 Chemoreceptors: detect change in certain
chemicals in the body
o In blood certain vessels
 Osmoreceptors: detect change in osmotic
pressure
o Affected by concentration of solutes in the
plasma


Photoreceptors: detect changes in light and
colour
Mechanoreceptors: detect change in pressure,
touch, vibration and sound.
What are the different receptors in the body?
Nervous System
 Neural pathways by which messages travel in
the body
 Nervous system acts as a control centre to
coordinate activities maintaining homeostasis
 Actions may be voluntary or involuntary
Neurons are classified according to their function and
the direction in which the nerve impulses are carried.
 Sensory neurons: carry impulses from the
sensory cells in the PNS to the CNS
 Motor neurons: transfer messages from the CNS
to effectors
o Dendrites are usually short and axon is quite
long
 Interneurons: located within the CNS and are
the link between the sensory and motor
neurons.
o Short dendrites and long/short axons
What is the nervous system?
The nervous system has 2 parts:
 Central Nervous System (CNS)
o Composed of the brain and the spinal cord
 Peripheral Nervous System (PNS)
o Nerves throughout the body that aren’t part of
CNS
o PNS carries nerves to and from the CNS
o The information carried by nerves consists of
‘messages’ transmitted in the form of
electrochemical impulses
What are the 2 parts of the nervous system?
Neurons (aka nerve cells)
 All neurons contain the same three common
structures:
o Cell body that contains a nucleus and many of
the organelles found in other cells
o Dendrites: branching extensions of cytoplasm
and cell body
 Receive messages in the form of impulses
from other axons and conduct impulses
towards cell body
 In sensory neurons, the single, elongated
dendrite is called a dendron
o Axon: a single extension of the cytoplasm and
cell body
 They conduct messages away from the cell
body

Synapse: When a nerve impulse is transferred
from the axon to the dendrites, it crosses a
small gap
o The fibres of the neurons are gathered into
bundles held together by a connective tissue
sheath to form the nerves
 This provides a structured pathway for the
transmission of electrochemical impulses
along the axons of the neurons
o This is the quickest way to initiate responses
by the body to stimuli in order to coordinate
and maintain homeostasis
How are neurons classified?
Transmission of nerve impulses – the action potential
What are neurons?
What are the parts of neurons?
Polarised: describes the state of a membrane when
the inside of the membrane is negative relative to
the outside of the membrane.
 Action potential: the change in electrical
potential of the axon’s cell membrane
o This change is due to the change in ion
concentration on either side of the cell
membrane of the axon
What is an action potential?
Sodium ions (Na⁺), potassium ions (K⁺) and chloride
ions (Cl⁻) are important for the transmission of
electrochemical messages in the nervous system.
Inside the cell are the large M⁻ ions as well.
 These ions are on both sides of the cell
membrane (inside and outside the cell)
 Due to the cell membrane being selectively
permeable, some substances (e.g. K⁺) are
allowed through, however hinders the passage
of Cl⁻, and Na⁺
 The large M⁻ ions are unable to move through
the cell membrane
At rest
 If the neuron isn’t transmitting electrochemical
messages, it is at rest
 In this state, ions inside and outside the cell
attempt to balance themselves out
 There are a large number of Na⁺ ions outside the
cell compared to the number of K⁺ ions inside
the cell
 There are also a large number of organic M⁻
ions trapped inside the cell
Because of this, there are more total negative
charges on the inside of the cell than on the outside.
 The value of this potential difference, called the
resting membrane potential, is -70mV
(millivolts)
 The inside of the membrane is negative in
relation to the outside of the membrane
o Meaning that the membrane is polarised
Action potential – depolarisation and repolarisation
 When a stimulus is detected by a neuron, it
causes sodium channels in the cell membrane
to open
o The ions move into the neuron, reducing the
overall negative charge (there are more ions
outside than inside)
o If the stimulus is ‘strong’ enough, ions will
continue to move into the neuron
o This causes the inside of the membrane to
become more positive in relation to the
outside of the neuron, causing depolarisation
 The potassium channels then open and
potassium ions move out of the neuron, causing
repolarisation of the membrane
 This rapid depolarisation and repolarisation is
called the action potential
This reaction only occurs if the action potential has
reached the threshold, if it is not reached, then there
won’t be an action potential.
Bridging the gap: synapse
 When a nerve impulse reaches the axon
terminal, it moves the synapse to the dendrites
of the next neuron
 The action potential triggers the release of
neurotransmitters (chemicals) from the
synaptic vesicles which move across the
synapse receptors, initiating an action potential
to continue the nerve
impulse
The Central Nervous System
(CNS)
 Made up of the brain and the spinal cord
 Both the spinal cord and the brain are made up
of two types of nervous tissue: grey matter and
white matter
o Grey matter: neuron cell bodies
 In the brain, it tends to be on the outside
 In the spinal cord, it is in the centre
o White matter: nerve fibres surrounded by
myelin sheaths
 This causes the white appearance
What is the central nervous system?
What are the two types of nervous tissue?
The brain
 The main control centre of the body
 Consists of numerous parts that work together
to ensure the efficient functioning of the body
What is the endocrine system?
Pituitary gland
 It releases hormones, often on direction from
the hypothalamus to regulate the activity of
other glands
The
hypothalamus is a small area of the brain and is
located centrally and close to the pituitary gland.
 It’s the control centre for the regulation of
bodily activities that are required to maintain a
stable internal environment
 This is achieved by directing effectors to carry
out a response
o Either by sending messages via neural
pathways or by chemical messages
 The hypothalamus is also the main link between
the nervous system and the endocrine system
o Responsible for hormone secretion
o Directs actions of the pituitary gland in
coordinating other glands to secrete
hormones to maintain homeostasis
The spinal cord
 Extends from the medulla oblongata to the waist
area
 It contains the nerve fibres that provide the link
for the pathway of nerve impulses between the
PNS and the brain
The two main functions of the spinal cord are:
 Acts as a conduction pathway for:
o Nerve impulses from the receptors around the
body to the brain
o Nerve impulses from the brain to the effectors
 Coordinate reflex actions (e.g. removing your
hand quickly when you touch something hot
before you feel the pain)
What are the two functions of the spinal cord?
The Endocrine System
 Regulates the activity of the body through
hormones that are secreted by endocrine glands
 Hormones are transported by the bloodstream
to cells possessing the receptors for the
hormone
 The cells then change their activity to maintain
homeostasis
o This is achieved by influencing the activity of
enzymes or the concentration of enzymes in
target cells
Glands can be stimulated to secrete hormones by
messages from the nervous system, by other
hormones or by receptors located in the particular
gland.
What is the pituitary gland?
There are 2 distinct regions of the pituitary gland:
 The front (anterior)
o Hormones released by the hypothalamus
control the anterior area
o One hormone secreted controls growth
o Other hormones secreted control the activity
of other glands, such as:
 Thyroid
 Adrenal gland
 Gonads (ovaries and testes
 Back (posterior)
o Nerve impulses control the posterior section
o One of the hormones secreted is antidiuretic
hormone (ADH)
 This helps to regulate the concentration of
water in the body
 If receptor cells in the hypothalamus detect
that the levels of water in the body are too
low or too high, it stimulates the pituitary
gland to release ADH
 This acts to conserve or absorb water in the
body by promoting the kidney tubules
The following glands and hormones produced are
involved in the maintenance of stable internal
conditions:
 Thyroid gland
o Located on either side of the neck, it produces
thyroxine (an iodine-containing hormone)
o Thyroxine is produced and regulated by TSH
(thyroid-stimulating hormone), which is
controlled by the hypothalamus
o Thyroxine increases the metabolic rate,
releasing energy and heat to maintain body
temperature
 Parathyroid gland
o Small glands on the thyroid’s surface that
regulates blood calcium levels
o It is crucial for nerve impulse transmission and
muscle contraction
o Low calcium levels trigger the release of PTH,
which acts on:
 Bones: release calcium
 Intestines: absorbs more calcium
 Kidneys: reabsorbs calcium
o High calcium levels stop PTH production
 Adrenal glands
o Located on the top of each kidney and are
made up of 2 distinct parts:
 Adrenal cortex (outer layer): hormone
production regulated via negative feedback
involving the hypothalamus and pituitary
 Adrenal medulla (inner region): controlled
by nerve impulses form the hypothalamus
o Each part has distinct functions and hormone
outputs
 Adrenal cortex
o Stimulated by the hypothalamus (via the
pituitary gland), the adrenal cortex produces:
 Hydrocortisone (Cortisol) and
corticosterone: helps manage stress,
convert nutrients into energy, regulate
cardiovascular function, blood pressure
and suppress inflammation.
 Aldosterone: increases sodium
reabsorption and decreases potassium
reabsorption in the kidneys.
o Low sodium levels trigger more aldosterone,
raising sodium and lowering potassium to
maintain balance
o High sodium/low potassium reduces
aldosterone production
o Sodium levels are crucial for maintaining
blood volume and blood pressure
 Low sodium levels will reduce blood volume
and blood pressure
 Pancreas
o The endocrine portion of the pancreas
consists of structures called pancreatic
Langerhans
 This is where the hormones insulin and
glucagon are produced
 These islets contain two types of cells –
alpha and beta cells
o Chemoreceptors in the beta cells detect high
levels of glucose in the blood and stimulate
the production of insulin
o Insulin causes glucose to be removed in a
number of ways:
 In the liver, the glucose is converted into
glycogen and fat
 Skeletal muscles convert the glucose into
glycogen
 Glucose is converted into fat in fat storage
tissue
o When the levels of glucose decrease, the
production of insulin decreases
What are the types of glands and hormones
involved in the maintenance of stable internal
conditions?
Mechanisms in plants that allow water balance to be
maintained
Transpiration: evaporation of water from the stomata
of leaves
Xerophytes: plants that live in arid conditions and
have adaptations that equip them to achieve this
balance and survive in their hostile environment.
They do this by:
 Reducing the exposure of transpiring plant
structures to sunlight
 Reducing the internal temperature
 Regulating the opening and closing of the
stomata
 Reducing the difference in-water concentration
between the plant and the outside air storing
water
 Producing woody fruits
What are the mechanisms of a plant that allow
water balance to be maintained?
Transpiration
 Lifts water and dissolved ions from the roots to
the top of plants in a continuous transpiration
stream
 It’s a form of evaporative cooling that is
essential in regulating temperature in plants
o Stomata need to be open to allow the
exchange of gases for photosynthesis
o Most of these adaptations are evident as
modifications of leaves
 Having sparsely distributed stomata can be
used to advantage in allowing xerophytes with
reduced leaves to carry out essential functions
to survive in their arid habitat
What is transpiration?
Reducing internal temperature
 Some plants have developed structural features
or physiological mechanisms to reduce internal
temperature
o Leaves may be coated in shiny wax cuticle or a
thick, leathery cuticle
 This ensures epidermal cells are
waterproof, preventing loss of water by
evaporation
o Leaf may have white hairs that reflect sunlight
 Reduces the surface temperature and thus,
reduces evaporation
How do plants reduce the internal temperature?
Reducing the exposure of transpiring plant structures
to sunlight
 Plant organs that have abundant stomata have
the greatest rates of transpiration
 In some plants, the exposure of these organs to
light is reduced by:
o The orientation of the leaves so that stomata
aren’t exposed to direct light
o Reduced SA of organs that have the highest
proportion of stomata
o Complete loss of transpiring plant organs (e.g.
leaves)
How do plants reduce the exposure of plant to
sunlight?
Examples of adaptations that reduce water loss are:
Cladodes: photosynthetic stems
Phyllodes: photosynthetic leaf stalks

Reduced leaf size: smaller leaves, leaves with a
photosynthetic function that is taken over by
cladodes and phyllodes
o Many phyllodes and cladodes have the added
features of hairs and/or sunken stomata
 Reduced size of flowers or no petals: reduce
amount of water required and reduces
evaporation of water from flower surfaces
 Shedding leaves reduces the overall amount of
water lost from leaves
 Orientation of leaves on the stem helps
minimise water loss as the stomata isn’t directly
exposed to sunlight during the hottest part of
the day
What are examples of adaptations that reduce
water loss?
Regulating the opening and closing of stomata
 Some plants minimise the loss of water by only
opening the stomata during cooler parts of the
day
o Evaporation is reduced and water loss is
minimised
 The difference in water concentration between
the plant and the surrounding atmosphere
determines how much water is lost by
transpiration
 Many plants have adaptations allowing them to
create their own smaller ‘microclimate’ in the
air immediately surrounding each leaf
o Structures: hairy leaves, rolled leaves, sunken
stomata trap water in the immediate vicinity =
keeps air surrounding plant humid

These adaptations allow plants to keep their
stomata open for a longer period of time
o Little water is lost so gaseous exchange for
photosynthesis can occur freely
How do plants regulate the opening and closing
of the stomata?
Water storage
 Succulents have adaptations (e.g. fleshy stems,
swollen leaves) that retain moisture when it’s
available
 They then survive by using this moisture during
dry periods
How do plants regulate water storage?
Fruits
 Fruits are structures that are removed from
plants so seeds can be dispersed
 Many plants produce woody fruits rather than
fleshy fruits
o This reduces the amount of water lost from the
plant when the fruits fall off
How do plants use fruits to reduce the amount of
water loss?
IQ8.2 Do non-infectious diseases cause mor
Investigate the causes and effects of non-infectious
diseases in humans, including but not limited to:

The risk of developing a specific non-infectious
disease is influenced by factors, such as:
o Age, gender, economic, social conditions,
culture, race, lifestyle, environment, genetics,
nutrition
Genetic Diseases
Causes:
 Mutation in gene/chromosome
 Gene coding for a specific protein is abnormal
 Abnormal cell division
What is the cause of genetic diseases?
Single-gene abnormalities
 Caused when the person inherits mutated genes
from their parents
o E.g. cystic fibrosis, phenylketonuria
What are single-gene abnormalities?
Cystic fibrosis is a recessive inherited disease caused
by mutation of the cystic fibrosis transmembrane
conduct regulator (CFTR) gene on chromosome 7.
 This faulty gene changes the protein that
regulates the normal movement of sodium
chloride, causing mucus-secreting organs to
produce thick mucus
 Affects the respiratory system, digestive and
reproductive systems
 This mucus causes problems with breathing and
with the digestion and/or absorption of
nutrients
What is cystic fibrosis?
Symptoms:
 Airways: clogging and infection of bronchial
passages interfering with breathing
 Liver: plugging of small bile ducts hinders
digestion and disrupts liver function
 Reproductive tract: absence of fine ducts (e.g.
vas deferens)
 Pancreas: blockages in the ducts prevent the
pancreas from delivering important digestive
enzymes to the bowel
 Small intestine: obstruction of the gut by thick
stool

Skin: malfunctioning of sweat glands causes
perspiration to contain excessive salt
What are the symptoms of cystic fibrosis?
Phenylketonuria (PKU) is a genetic disease caused by
a mutation of the gene on the chromosome 12.
 Chromosome 12 codes for an enzyme called
phenylalanine hydroxylase (PAH)
 This enzyme is required for the first step in the
breakdown of the amino acid phenylalanine
o ∴ PAH enzyme is not manufactured correctly
and phenylalanine can’t be broken down
o ∴ dangerous build-up of phenylalanine in the
blood and tissues
 This results in development of intellectual
disabilities, delays in development, social,
emotional and behavioural problems,
psychiatric disorders, hyperactivity and risk
of seizures
o PKU is an autosomal recessive disease
o If an individual is diagnosed with PKU, they
must follow a diet low in proteinrich foods (e.g. milk, nuts, eggs
and meat)
 This prevents a build-up of
phenylalanine
 Avoidance of artificial
sweeteners containing
phenylalanine is also
essential
What is Phenylketonuria?
Chromosomal Abnormalities
Syndrome: group of symptoms that occur together
and characterise a particular disease.
Some genetic diseases are caused by mutations of
the chromosomes that carry the genes.
These mutations can take the form of:
 Incorrect number of chromosomes (too many or
not enough)
 Change to chromosome (deletion, insertion,
altered sections)
What are chromosomal abnormalities?
Incorrect number of chromosomes may occur due to:

Non-disjunction: incorrect separation of
chromosomes during cell division
o End result is incorrect number of
chromosomes in the zygote
 Trisomy: one extra chromosome along with the
normal paired chromosome.
o The total number of chromosomes is one more
than the normal diploid number
 Monosomy: one member of a chromosome pair
is missing.
o The total number of chromosomes in the
zygote is one less than the normal diploid
number
What are the reasons that an individual may have
an incorrect number of chromosomes?
Many embryos with an incorrect number of
chromosomes will spontaneously miscarry.
 Embryos with monosomy or trisomy that are
carried to full term will have a syndrome
 The chromosome number that forms the trisomy
or monosomy determines the type of syndrome

Each of these
syndromes are characterised by a different set
of symptoms
Klinefelter Syndrome
 Trisomy involving sex chromosomes
o Males with Klinefelter syndrome have (XXY)
o They have lower
levels of testosterone
and small testes
o They are taller than
average height
Klinefelter Syndrome Karyotype
o Larger breasts and
feminine fat
distribution on abdomen and hips
What is Klinefelter syndrome?
Cri du chat Syndrome
 Rare disease that results from the deletion of a
specific section of chromosome 5
 Individuals with this deletion have intellectual
disabilities
o E.g. a small head, flattened bridge of the nose,
wide-spaced eyes, receding chin and a cry that
sounds like a distressed cat
Turner syndrome is the only full monosomy syndrome
seen in humans
 All other full monosomy syndromes are lethal
and cause spontaneous miscarriage
There are no genes lost in the translocation of genes,
however can alter the phenotype expressed.
 E.g. translocation of the bottom portion of
chromosome 9 to the bottom of chromosome 22
causes acute myelogenous leukaemia
What is turner syndrome?
What is cri du chat syndrome?
Down syndrome is the most common trisomy
syndrome.
 It’s caused by the presence in the zygote of an
extra chromosome 21
 It is named after the first person to recognise
and describe the condition (Langdon Down) in
1866
 Effects:
o Characteristic facial features (e.g. small
flattened skull, almond shaped eyes)
o A protruding tongue
o Small ears that fold over
a bit at the top
o Intellectual disability
o Heart defects
Down Syndrome Karyotype
What is down syndrome?
Diseases caused by environmental exposure
Lifestyle diseases
 Arise as a direct result of the way in which
individuals live their lives
 The most common lifestyle diseases are:
o Cardiovascular disease
o Diabetes
o Cancers
o Chronic lung disease
 Risk factors:
o Tobacco use
o Unhealthy diet
o Physical inactivity
o Harmful use of alcohol
o Exposure to additives and hormones
What are lifestyle diseases?
Atherosclerosis is a common CVD
 Caused by a variety of factors including:
o Insufficient physical activity
o Drinking alcohol
o Exposed to high levels of stress
o Smoking
o Unbalanced diet
 Following these lifestyle habits long-term leads
to the deposition of lipids in the inner walls of
arteries
o Overtime, this becomes thick and rough,
hindering blood flow
o Plaque buildup on the internal wall also
occurs, further reducing elasticity and blood
flow
o This can cause cerebral haemorrhage
(leakage of blood into brain tissue)
o Blood clots form and can cause blockage of
vessel (occlusion)
 If this occurs in the coronary artery, this
may result in cardiac arrest (ischaemic
heart disease)
 If occurs in the brain, it can cause a stroke
(cerebrovascular disease)
o E.g. pollution of air and water, chemicals in
the workplace
Asbestos is a chemical that was historically present
in many products
 Caused when inhaled asbestos fibres cause an
inflammatory reaction in lung tissues
o Inflammation leads to scarring and stiffening
of the lung tissue, making breathing harder
 Leads to persistent cough, chest pain,
appetite loss and enlarged fingertips due
to lack of oxygen to extremities
 Can lead to the development of
mesothelioma
What is the impact of exposure to aspestos?
Heavy chemicals
 Heavy metals such as lead and mercury are
naturally in the environment
 Toxic levels of lead in the body can lead to:
o Developmental delays
o Learning difficulties
o Irritability
o Fatigue and sluggishness
o Weight loss and loss of appetite
o Abdominal pain, vomiting and constipation
What is atherosclerosis?
What is the impact of exposure to heavy metals?
Physical factors
 Exposure to physical factors in the environment
can cause disease
o E.g. UV light, radiation
 These physical factors change the genetic
material of individuals, causing problems with
the correct functioning of the body
 Excessive exposure to UV light can cause skin
cancer
o The UV light causes changes to the DNA of the
skin cells, causing abnormal cell division
o This leads to the formation of basal cell
carcinomas, squamous cell carcinomas or
malignant melanomas
o The most serious is malignant melanomas
which can spread to other areas of the body
Nutritional diseases
 Proper nutrition contributes to a stronger
immune system and a reduced risk of
developing a non-infectious disease (e.g.
diabetes, CVD)
 Nutritional diseases are caused by diets lacking
proper balance and amount of nutrients
o ∴ Malnutrition
 Undernutrition: insufficient intake
 Overnutrition: excessive intake
What is the impact of physical factors?
Exposure to chemicals
 Exposure to surrounding chemicals can cause
disease
What are nutritional diseases?
Undernutrition
Lack of protein and energy-rich food:
 Individuals suffer from kwashiorkor (caused by
a severe lack of protein in the diet)
o Characterised by a swollen belly caused by
fluid retention (oedema)
o Gross food deprivation = severe lack of both
protein and energy intake
 ∴ Causes marasmus (sufferers are
extremely underweight and have lost
subcutaneous fat)
o They are very weak and susceptible to
infection
 Kwashiorkor and marasmus can also occur:
o In patients recovering in hospital and
receiving glucose intravenously for an
extended period of time
o Those suffering from diseases that suppress
the appetite or cause malabsorption of
nutrients
Lack of vitamins:
 A diet lacking vital nutrients can lead to a
nutritional deficiency disease
 Examples of vitamin deficiencies:
o Vitamin A: important for normal growth,
healthy skin and mucous membrane, and
vision
 Lack of Vitamin A = blindness, dry skin and
increased susceptibility to infection
o Vitamin D: initiated by exposure to the sun
 Limited exposure = rickets
 Rickets:
 Children: results in defective
calcification of bones, retardation of
growth and deformities of parts of the
skeleton
 Adults: causes osteoporosis
o Vitamin B:
 Vitamin B1: responsible for growth,
carbohydrate and amino acid metabolism
and functioning of the heart, nerves and
muscles
 Prolonged deficiency of Vitamin B1 in a
child’s diet = beriberi
 This results in retarded growth, weakened
heart muscle, loss of appetite, confusion,
inflammation of the nerves, poor
coordination, tingling and paralysis
o Vitamin C: deficiency in vitamin C results in
scurvy
 Scurvy: causes poor wound healing, joint
pains, bleeding gums, bones that don’t
grow or heal, spontaneous haemorrhaging
 If left untreated, death will occur
What are the impacts of a lack of vitamins?
Lack of minerals:
 Iron: mineral required by the body as an
essential component in the molecule
haemoglobin
o A deficiency of iron = anaemia
 Symptoms: pale skin, weakness, unusual
tiredness, apathy, low resistance to cold
temperatures and difficulty breathing
 Iodine:
o Due to consuming less iodised salt
o Iodine is required to produce thyroxine
o Deficiency causes reduced metabolic rate, low
body temperature and lethargy
o Prolonged iodine deficiency = enlargement of
the thyroid gland, resulting in visible lump
(aka goitre in the throat region)
o Severe iodine deficiency during pregnancy
causes abnormal foetal development =
stunted mental and physical growth
o Source: fish, shellfish and eggs
What is the impact of a lack of minerals?
Eating disorders:
 Anorexia nervosa and bulimia nervosa
 Sufferers experience an intense fear of putting
on weight
o Due to: genetic predisposition, environmental,
social and cultural factors
 Anorexia nervosa is characterised by
psychological disorders, excessive weight loss
and a distorted body image
o Sufferers only focus on their body weight and
ways to keep it to a minimum
o They develop an irrational fear of food and
eating
o Effects: loss of weight, tiredness, anaemia,
impaired digestive function, bruising and low
resistance to disease and infertility
 Bulimia nervosa is caused by psychological
factors where the sufferer is fixated on body
image and demonstrates abnormal eating
behaviours
o Acid in the vomit causes erosion of tooth
enamel = erosion, sensitivity, discolouration
and possible loss of teeth
o Effects on body: same as anorexia nervosa,
however the person doesn’t become thin and
emaciated
o Most common death is due to cardiac arrest
due to an electrolyte imbalance
Overnutrition
 Most common type of overnutrition is obesity
o Cause is consuming more kilojoules than
the energy expended
 Overconsumption of food is due to a number
of factors:
o Psychological
o Cultural
o Economic
 Body mass index (BMI) is a measure of a
person’s total body fat and can be used to
determine whether the person is within a
normal weight range
 Obesity can have a number of adverse health
effects including:
o Increased blood pressure
o Atherosclerosis
o Gallbladder
o Stroke
o Type 2 diabetes
o Increased risk of developing cancer
What is the impact of overnutrition?
Cancer
 Cancer is a disease of the cells of the body
 It occurs when abnormal cells divide in an
uncontrolled way
o These cells invade body tissue and spread to
other tissues and disrupt the normal
functioning of the body
 There are 3 types of proteins that control the
correct functioning of cell division:
o DNA repair genes code for proteins that are
responsible for stopping the cell cycle.
 Other proteins are responsible for removing
damaged regions of DNA and replacing
them
 If these genes mutate, they won’t function
correctly = damaged DNA will be replicated
o Proto-oncogenes code for proteins that
stimulate cell growth and mitosis.
 Mutations of proto-oncogenes lead to
expression of oncogenes that would
normally be ‘silent’
 This causes uncontrolled production of
cells and prevents cell death
o Tumour suppressor genes code for proteins
that will slow down or stop cell growth and
mitosis.
 These genes code for proteins that induce
cell death if there is an uncontrolled
increase in cell numbers
 mutations of tumour suppressor genes halt
the production of proteins that control cell
division and cell death
What are the 3 types of proteins that control the
correct functioning of cell division?
This disruption of the normally regulated cell cycle
leads to uncontrolled cell replication, which:
 Doesn’t allow cells to differentiate, so they can’t
perform the specialised functions necessary for
normal body functioning
 Causes the formation of tumours
Breast cancer:
 BRCA1, a tumour suppressor gene found on
chromosome 17
o It’s responsible for coding for proteins
involved in the repair of the PTEN gene
 Mutations of the BRCA1 gene put women at a
much higher risk of developing this form of
breast cancer
o The PTEN gene is a tumour suppressor gene
limiting the amount of cell division and
encourages cell death
o This regulates the cell cycle and prevents the
excessive proliferation of cells that would
lead to tumours and cancer
o In a normal cell, if there was damage to the
PTEN gene, proteins that have been coded for
by the BRCA1 gene would repair it
 This would then be expressed properly and
cell division would be controlled
o Mutation of the BRCA1 gene results in nonproduction of the proteins necessary for
repairing damage to the PTEN gene
 This results in a lack of control of the cell
cycle and runaway cell division, leading to
the formation of tumours
What is the impact of a mutation of the BRCA1
gene?
Types of tumours
Primary tumour: the area in the body where the initial
malignant tumour develops is called the primary
tumour.
Secondary tumour: a tumour that develops from cells
that have travelled from a primary tumour to a
different part of the body.
Malignant: an abnormal growth of cells (cancer) that
isn’t confined by a boundary and spreads to other
tissues in the body.
Benign tumours: cells remain within the boundary of
the tumour and don’t spread to other body tissues.
 Some benign tumours can be precancerous and
if not treated may develop into cancer
What is a benign tumour?
Malignant tumours: contain abnormal cancerous
cells that aren’t confined by the boundary of the
initial tumour.
 Their cells replicate more quickly
 They redirect the body’s nutrients to them and
away from adjacent normal tissue and can
invade surrounding tissue
 The area in the body where the initial malignant
tumour develops is called the primary tumour
Some risk factors (e.g. lifestyle, environment) can be
minimised. Others (e.g. hereditary, biological factors)
can’t.
What are the causes of cancer?

Some of these abnormal cells can break away
form the tumour, enter the blood or lymphatic
system and travel to a new part of the body.
Melanoma: form of skin cancer
 Disease in which cells in the skin divide
uncontrollably due to changes in the DNA of the
genes that control cell division
 These cells are called melanocytes and contain
the pigment melanin, giving the skin colour
what is melanoma?
What is a malignant tumour?
Types of cancer
 The type of cancer is usually named after the
organ or tissue that the primary tumour forms in
The types of cancer can be classified in several broad
groups:
 Sarcoma forms in muscle, or connective tissue
(e.g. bone, blood vessels)
 Carcinoma forms in epithelial tissue (e.g. skin,
tissue) that lines/covers the internal organs
 Lymphoma and myeloma form in the lymphatic
system and plasma cells of the immune system
 Leukaemia forms in the bone marrow and other
blood-forming tissues
 Central nervous system cancers begin in the
brain or spinal cord
What are the different types of cancer?
Causes of cancer
 There are a number of chemical, physical and
biological agents (aka carcinogens) that can
cause mutations to the genes that control cell
division
In many cases, there is a combination of risk factors
involved in the occurrence of cancer.
 Smoking
 Lack of physical activity
 Exposure to radiation (e.g. UV radiation)
 Contracting particular types of viruses
 Exposure to certain chemicals
 Inheriting mutated genes
The exact cause of melanoma is not known, but the
chance of developing this cancer is increased by:
 Exposure to UV light
 Fai complexion
 Severe sunburn
 History of having skin cancer
 Having many different ty[es of moles or
irregular-looking moles
 Family history
 Exposure to certain environmental conditions or
chemicals
 Compromised immune system
 Older age
 Male gender
What increases the chance of developing
melanoma?
Malignant melanoma tumour initially is confined to
one area, however if left untreated, it will increase in
thickness, spreading to deeper layers within the skin.
 After time, the melanoma will spread to nearby
lymph nodes, lymph vessels and skin
 The cancerous cells will then travel to distant
lymph nodes and other areas of the skin and
organs (e.g. lungs, brain, bones and liver) =
death
Collect and represent data to show the incidence,
prevalence and mortality rates of non-infectious
diseases, for example:
Incidence: number of new cases of that disease
reported in a specific time period.
Prevelance: how many people in the population have
the disease.
Mortality rate: number of deaths due to a particular
disease in a specific period of time.
Age-standardised rate: measure of what the rate
would be if the population had a standard age
structure.

Data relating to the incidence, mortality and
prevalence of many types of non-infectious
diseases can be controlled and analysed to
identify patterns in populations
 Age-standardised rate is a weighted mean of
the age-specific rates and is used so that
comparisons between populations from
different countries/regions can be made
o This data is useful in many ways, including
being used do determine:
 Trends associated with particular
diseases
 Whether certain groups are more
susceptible to particular diseases
 Whether methods in use for preventing
and treating the disease is successful
 The pathway for research and areas to
concentrate on in terms of public health
Diseases caused by environmental exposure:
Melanoma and UV light
Nutritional diseases: Type 2 diabetes
 Incidence
o Number of people with diabetes has
quadrupled over the past 30 years
o Predicted increase in adults with diabetes
between 2010 and 2030 (20% in developed
countries and 69% in developing countries)
 Prevalence
o 1 in 11 adults aged 20-79 years old had
diabetes in 2015, 90% of these cases were
type 2 diabetes
o There is expected to rise to 642 million by
2040
o Asia is the epicentre of the epidemic with
China and India being the top two countries
for type 2 diabetes prevalence
 Mortality rates
o Currently cases 5 million deaths per year
mostly as a result of cardiovascular disease
o Type 2 diabetes is expected to become the
7th most prevalent cause of death globally by
2030
Environmental diseases: Melanoma
 Incidence
o Worldwide, there was 351,880 new cases of
melanoma in 2015
o In Australia, there were an estimated 14,320
new cases diagnosed in 2018
 Prevalence
o Worldwide, melanoma is the 19th most
common cancer with the highest rates
reported in Australia
o In Australia, ~51,697 people are living with
melanoma as of 2012

Mortality rates
o Worldwide, there were 59,782 deaths in
2015
o In Australia, there were an estimated 1,905
deaths in 2018
IQ8.3 Why are epidemiological studies used?
Analyse patterns of non-infectious diseases in
populations, including their incidence and
prevalence, including but not limited to:
 Epidemiological studies play a major role in
identifying patterns in the incidence,
distribution, prevalence and mortality rates of
disease
o Help to investigate the possible causes of
disease and whether certain people are at
greater risk of developing disease
 They help to determine the strategies that would
be most effective in controlling disease in the
population
 Accepted scientific and mathematical models
are used to statistically analyse the data
collected
o It provides information to determine the
trends for the overall population, subsets
and different locations
o Tables and graphs help people to understand
the trends and patterns in data
What is the role of epidemiological studies?
Treatment:
 If the disease is detected early, surgery is the
most effective and common form of treatment
o Removes the tumour and the skin around the
tumour, ensuring no cancerous cells are left
behind to reduce the risk of recurrence
o For more advanced cases, a range of options
are available, including:
 Radiation
 Chemotherapy
 Targeted therapies
 Immunotherapy
o The type of treatment used will depend on
how far the melanoma has progressed and
the person’s age and health
Investigate the treatment/management, and
possible future directions for further research, of a
non-infectious disease using an example from one of
the non-infectious diseases categories listed above
 Treatment of a disease will depend on the type
of disease
o Some non-infectious diseases (e.g. vitamin
or mineral deficiency) require the correct
amount of the vitamin/mineral to b included
in the diet
 Treatment
o Scurvy: supplementing Vitamin C back into
the diet
o Cancer: complex treatments (e.g.
chemotherapy)
o Genetic diseases: screening, early diagnosis
and management of symptoms
What are the treatment options for melanoma?
Melanoma: a disease caused by environmental
exposure
 There are many treatment options available to
sufferers of melanoma, depending on at what
stage the disease is diagnosed
What is chemotherapy?
Radiation:
 When cells are exposed to X-rays, normal cells
can repair their DNA more easily than cancer
cells can
 X-rays damage the DNA of the cancer cells and
kill them
o Radiation can be administered externally or
by placing a radioactive source in the body
near the cancer cells
What is radiation?
Chemotherapy:
 Chemotherapy drugs slow the growth of cancer
cells, however haven’t been very effective in
treating melanoma
Targeted therapies:
 Involve the use of drugs that affect the
molecules controlling the growth of tumour cells
 It effectively stops the growth and spread of the
tumour cells to other organs
 Melanoma cells have mutations that cause the
uncontrolled division of cells, leading to the
growth of tumours
 Targeted therapy drugs interrupt the pathways
that cause this uncontrolled division of
melanoma cells
What are targeted therapies?
Immunotherapy:
 Immunotherapy treatments effectively cause
the body’s own immune system to fight the
melanoma
 This is achieved through two approaches:
o Checkpoint inhibitors: cause the immune
system to recognise and destroy melanoma
cells.
 Cancer cells prevent the body from
recognising the tumour, and this
treatment reverses this effect
o Vaccinations: this is a treatment rather than
a prevention.
 An antigen is produced using melanoma
cells and when injected, allows the
immune system to more easily identify
and destroy the melanoma cells
What is immunotherapy?
Future directions:
 Future research is required to develop targeted
therapies and immunotherapy treatments for
melanoma
 The use of targeted therapies is based on
different types of mutations causing the
uncontrolled cell division
 Further research is required to develop a greater
variety of immunotherapy drugs
 The use of vaccines to treat melanoma is in its
early stages
o More research is required to make further
discoveries
What are the future directions of cancer
treatment?
Evaluate the method used in an example of an
epidemiological study
There are 3 major types of epidemiological studies:
 Descriptive (intervention)
 Analytical (intervention)
 Intervention (experimental)
What are the 3 main types of epidemiological
studies?
Descriptive studies: a study of the patterns of
distribution within and across populations.
 The first type of study conducted when
investigating the cause of a disease
 They provide information about the patterns of
the disease, including:
o Frequency of the disease
o The section of the population that’s affected
o Geographical location
o Whether there was a particular time period
where individuals were affected
What is a descriptive study?
Analytical studies: a study examining known
associations or testing specific hypotheses.
Morbidity: the number of cases of the disease.
Mortality: the percentage of the population that die
from the disease.
Incidence: number of new cases in a specific period.
Prevalence: number of people affected at any one
time.
 Used to collect more data, which is then
statistically analysed to test hypotheses as to
the likely cause(s) of the disease
 Indicators that can be used in these studies:
o Morbidity
o Mortality
o Incidence
o Prevalence
What is an analytical study?
Case-controlled studies
 Compare people with the disease (cases) to
people without the disease (controls) and look
for differences in exposure to the possible
causes of the disease
 A large range of data (e.g. age, sex, diet,
location, lifestyle, occupation and exercise
habits) are collected and then analysed to
determine the likely cause of the disease
What is a case-controlled study?
Cohort studies
 Involve studying 2+ similar groups of people who
are free of the disease
 These groups differ in their exposure to the
potential cause of the disease
o One of the groups is exposed to the possible
cause of the disease and the other group
isn’t and then watched over a long period of
time
What is a cohort controlled study?
Intervention studies: A study which measures the
effectiveness of interventions, such as clinical or
community trials of new treatments.
Placebo: a treatment with no active property, usually
a sugar pill

Used to test the effectiveness of a treatment or
the effectiveness of a public health campaign
 Experimental study:
o Used to test the effectiveness of a new type
of drug
 One group receives the trial drug while
the other group receives a placebo
 The effects of the ‘medication’ are
recorded and analysed to determine the
effectiveness of the drug being studied.
 If it is impossible to set up a randomised
trial, a quasi-experimental study is
carried out.
What are intervention studies?
Errors in epidemiological studies
There are 2 major types of errors in epidemiological
studies
Random errors: Unpredictable variations in the data
and have an inconsistent effect on measurement
within a study
 Makes the study less accurate
 They can occur through differences in the
subjects being studied
 Ensuring the separate groups being studied are
homogenous will increase the precision of the
study and reduce random error
 Ensuring a large sample size can also reduce
random error
What are random errors?
Systematic errors (bias): any process during the study
causing a consistent deviation from what the true
value should be.
What are systematic errors?
Selection bias: bias in selecting subjects to include in
the study.
 Sampling bias: bias in method of choosing
subjects.
 Volunteer bias: bias in choosing subjects who
volunteer themselves.
 Healthy worker bias: bias in choosing subjects
who have a healthy status.
 Prevalence/incidence bias: bias by only
including current cases in the study.
What is a selection bias?
Information bias: errors in taking measurements or
recording information.
 Misclassification bias: some of the subjects
already suffered from the condition and are
undiagnosed at the start of the study.




Recall bias: bias in ability of individuals to recall
information.
Ascertainment bias: which all members of the
study group are not followed up to the same
degree.
Measurement bias: measurements are
consistently inaccurate.
Loss to follow-up bias: not all subjects who
began the study are available at the end of the
study
What is an information bias?
Cofounding factor: type of systematic error occurring
when an unrecognised factor may affecting the
results of a study, leading to bias.
What is a cofounding factor?
Evaluating an epidemiological study: The Pima Indian
population
Benefits of epidemiological studies
 Measuring the degree to which different risk
factors are present in the crisis-affected
community, and the degree to which
populations benefit from interventions to
minimise these risk factors
 Monitoring trends in the occurrence of specific
diseases over time and identifying emergent
threats in a timely fashion
 Discovering the agent, host and environmental
factor that affect community health to provide
scientific basis for prevention of disease and
injury including health promotion
 Identifying at risk population at greater risk of
specific diseases
 Evaluate the effectiveness of health
programmes and services
What are the benefits of an epidemiological
study?
IQ8.4 How can non-infectious diseases be prevented?



Prevention is better than curing the disease.
Strategies to prevent non-infectious diseases
and disorders are important, improving the
overall health and wellbeing of the population
Prevention reduces the financial burden on
individuals and the health system
Use secondary sources to evaluate the effectiveness
of current disease-prevention methods and develop
strategies for the prevention of a non-infectious
disease, including but not limited to:
Educational programs and campaigns
 Many preventable non-infectious diseases are
caused by nutritional imbalances or exposure to
environmental factors
Educational programs: Educating the population on
the non-infectious diseases.
What are educational programs?
Public health campaigns: Providing information to
the population about non-infectious diseases.
 E.g. QUIT Smoking, Slip Slop Slap Seek Slide
What are public health campaigns?
Government legislation
 Prohibit the promotion and marketing of the risk
factor (tobacco, alcohol, unhealthy diet and
lack of physical activity)
o Tobacco Advertising Prohibition Act 1992:
prohibits the advertising and publication of
tobacco advertisements
o 2012: introduction of plain packaging on
cigarettes and graphic health warnings on
packaging
What are examples of gov. legislation?
Genetic
Engineering
Preimplantation
genetic testing
(PGT): can
prevent genetic
disease.
1) Eggs are harvested and collected during a cycle of
IVF.
2) The eggs are fertilised and embryos are grown.
3) One cell from each embryo is removed and tested
for the mutated gene.
4) Those embryos affected were disposed of, while
those unaffected were retained.
5) One embryo is implanted, while the others are
frozen.
What are the steps involved in pre-implantation
genetic testing?
Golden Rice:
 Rice has been genetically engineered to include
a gene from maize and soil bacterium
 The rice then produced beta-carotene which the
body uses to produce Vitamin A
Developing strategies to prevent a non-infectious
disease outbreak
What are the steps to develop strategies to
prevent a non-infectious disease outbreak?
IQ8.5 How can technologies be used to assist people who experience disorders?
Explain a range of causes of disorders by
investigating the structures and functions of the
relevant organs, for example:
The ear
Functions:
 Provides communication between the internal
and external environment
 Helps with balance
What are the functions of the ear?
Structure of the ear:
 The auditory nerve and the brain help with the
ability to hear
 The ear is composed of 3 sections:
o The outer ear (pinna and ear canal)
o The middle ear (ossicles and ear drum)
o The inner ear (the cochlea, auditory nerve
and the brain)
Middle ear
Ossicles:
 Structure: malleolus, incus, stapes
 Function: amplify and transmit vibrations from
the eardrum to the oval window
Oval window:
 Structure: thin, flexible membrane
 Function: transmits vibrations from the stapes
to the fluid in the cochlea
Round window:
 Structure: thin membrane between the middle
and inner ear
 Function: bulge outwards to allow for
equalisation of pressure in the cochlea when
the oval window vibrates
Eustachian tube:
 Structure: connects the middle ear to the
pharynx at the back of the throat
 Function: equalises air pressure on both sides
of the eardrum
What is the structure of the inner ear?
What is the structure of the ear?
Outer ear
Pinna:
 Structure: cartilage outer piece
 Function: collects sound and channels it to ear
canal
Ear canal:
 Structure: a passage comprised of bone and
skin
 Function: leads sound waves to eardrum
Ear drum:
 Structure: thin membrane between the outer
and middle ear
 Function: vibrates in response to sound and
transfers sound vibrations to the ossicles
What is the structure of the outer ear?
Inner ear
Cochlea:
 Structure: snail-shaped spiral tube filled with
fluid
 Function: hair cells act as sound receptors
Organ of Corti:
 Structure: inside cochlea contains receptors
 Function: electrical signals produced for
vibrations
Auditory nerve:
 Transmits nerve impulses to the brain for
interpretation
What is the structure of the inner ear?
Types of hearing loss:
Conductive Hearing Loss:
 Definition: deafness which is caused by damage
to the outer or middle ear
 Result: Leads to reduced or muffled sound
 Causes:
o Malformed structure at birth
o Aging
o Noise strain
o Injury
o Infection
o Blockage due to earwax, a tumour or foreign
item
What is conductive hearing loss?
Sensorineural Hearing Loss:
 Definition: deafness which is caused by damage
to the inner ear/nerve pathways from the inner
ear to the brain
 Result: faint or muffled sound
 Cause:
o malformed/damaged inner ear at birth
o Exposure to damaging noise can cause the
hair cells in the cochlea to become
fatigued/kill them
o Head injury
Parts of a hearing aid:
 Microphone: receives sound waves and changes
them into electrical energy
 Amplifier: makes the signal stronger
 Receiver: changes electrical energy into sound
energy
 Speaker: directs sound energy into the ear
canal
What is sensorineural hearing loss?
Auditory Processing Disorder:
 Definition: not due to damage or defects in the
structure of the ear
 Result: inability to detect the direction of sound
 Cause:
o Processing problems in the auditory areas of
the brain
What is auditory processing disorder?
Mixed
 A mix of 1+ of the types of hearing loss listed
above
Tinnitus:
 Definition: when a sound is heard that isn’t
there
 Result: can include hearing a ringing in the
ears: buzzing, hissing
 Cause:
o Exposure to loud sound
o Injury
o Aging
Technologies that can assist with hearing loss:
 Conductive hearing loss: hearing aids and bone
conduction implant
 Sensorineural hearing loss: hearing aids and
cochlear implants
Hearing aids:
 A battery-operated electronic device that fits
into the hollow outside the ear canal
 It amplifies sound waves within the ear canal
 The eardrum, ossicles and cochlea must still
have an adequate level of function to convert
sound into an electrochemical signal
 Can be used for people with conductive or
sensorineural hearing loss
What is a hearing aid?
What are the parts of a hearing aid?
Advantages:
 Relatively cheap
 Easy to install
Disadvantages:
 Amplify all sounds in an environment and cause
pain
 It doesn’t help people with severe damage to
the inner ear/auditory nerve
What are the advantages and disadvantages of
using a hearing aid?
Bone conductive hearing aid:
 Work by creating sound vibrations that are
conducted directly to the cochlea
 Used for treating conductive hearing loss
 Can bypass a dysfunctional outer and middle
ear but the inner ear must be working
What is a bone conductive hearing aid?
Cochlear Implant:
 It’s used by people with profound hearing loss
 It converts sound into electrical signals and
directly stimulates the auditory nerve
What is a cochlear implant?
Parts of a cochlear implant:
 Receiver: surgically implanted into a patient’s
skull and fine wires connect it to the cochlear
 Microphone: behind the patient’s ear that picks
up sound
 Speech processor: converts the sound to an
electrical signal
 Transmitting coil: sends the message as a radio
signal to the receiver. The wires then stimulate
the auditory nerve, stimulating the brain
What are the parts of a cochlear implant?
Advantages:
 Provides hearing to profoundly deaf people
The eye
1)
Disadvantages:
 Highly expensive
 Operation side effects
 The wearer must learn to interpret sounds again
 Success of the implant system is limited if the
auditory nerve/region of the brain is damaged
What are the advantages and disadvantages of
using a cochlear implant?
Hybrid Cochlear Implant:
 Helps individuals that have high frequency inner
ear hair cell damage
 Different to conventional, shorter electrode,
doesn’t go in deeply
 Preserves the natural low frequency hearing
Reflected rays enter the eye through the pupil.
2) Passes through the iris and lens.
3) Detected by the retina at the back of the eye which
generates nerve impulses.
4) The nerve impulses are sent to the visual part of
the brain via the optic nerve.
What is a hybrid cochlear implant?
Middle Ear Implant:
 Recent technology
 External processor transmits sound
 Internal implanted receiver works by directly
moving the bones
Auditory Brainstem Implant
 Surgically implanted
 Like cochlear implant, but instead directly
stimulates brain stem
Key
parts
of
the eye:
Iris:
 Structure: ring of pigmented muscle tissue
 Function: works to control pupil size and hence
the amount of light entering the eye.
What is an auditory brainstem implant?
What is the structure and function of an iris?
Otitis Media and Grommets
 Tiny tube, inserted to drain fluid from middle ear
What are grommets?
Lens:
 Structure: transparent, biconvex protein disc
that has a bulging shape and is made of protein.
 Function: adjusting its thickness to bend light
so that it focuses directly onto the retina
o Distant objects (>6m)
 Nearly parallel light rays
 Require little bending to be focused
What is a middle ear implant?

o Close objects
 Light rays diverge
 Require more bending to be focused
What is the structure and function of the lens?
Retina:
Structure: thin layer of photoreceptor cells,
which lines the inner back surface of the eye.
o Rods: don’t detect colour and work best at
low light levels
o Cones: detect colour and work best in bright
light
 Function:
o The lens hits the photoreceptors on the
retina
o When photoreceptor cells are exposed to
light, photopigments change shape
o The photoreceptor cells generate an
electrochemical signal that is sent to the
brain to be interpreted
Cornea → aqueous humour → pupil → lens →
vitreous humour → retina
What is the structure and function of the retina?
Type of vision
Shape of lens
Action of muscles of
ciliary body
Distant vision
Elongated
Relaxed
Tension of
Diagram of anterior
suspensory ligament part of the eye,
showing shape of
lens
Taut
Near vision
Rounded, convex
Contracts
Slackened
Visual disorders
Refractive errors:

Result from when light isn’t properly bent onto
the retina so that vision is blurred
o Myopia (short-sight):
Causing the image to form in front of the
retina
 Close objects are clear, but distant
objects are blurry
 Causes:
 The lens is too thick, bending light too
much
 The eyeball is too long, making the
retina further away

o Hyperopia (long-sight):
 Causing the image to form behind the
retina
 Distant objects are clear, but close
objects are blurry
 Causes:
 The lens is too thin, meaning the light
isn’t bent enough
 The eyeball is too short
o Light can’t be focused properly in the same
place onto the retina
 Cataracts: caused by a thickening of the lens in
the eye, making it cloudy and occluded, usually
a result of ageing
 Glaucoma: caused by a buildup of pressure
inside the fluid of the eyes
Technologies to assist with visual disorders
Spectacles
 Frames that hold corrective lenses
 Shape is determined by the visual disorder
 Myopia can be corrected by wearing spectacles
with concave lenses (thicker towards the
outside and thinner towards the centre)
o Lenses bend light rays outwards, diverging
them before they reach the eye
o It extends the focal length of light rays,
allowing the focused image of a distant
object to fall on the retina
 Hyperopia can be corrected by wearing
spectacles with convex lenses
o They are thicker towards the centre and
thinner towards the edges
o Lends bends light rays inwards to converge
before they reach the eye
o This shortens the focal length and allows the
object to fall on the retina
What are spectacles?
Advantages:
 Improving sight
 Relatively inexpensive
What is myopia?
What is hyperopia?
Retina conditions:
 Retinopathy: damage to the retina caused by
changes to the blood vessels surrounding this
region
 Detached retina: caused by a portion of the
retina coming away from the sclera
 Macular degeneration: part of the retina begins
to degrade, affecting central vision
 Colour blindness: occurs when one of the 3
types of colour-detecting cone cells doesn’t
function properly
What are retina conditions?
Other:
 Astigmatism: caused by a cornea when it isn’t
spherical.
Disadvantages:
 Need to be updated when sight changes
 Restrictive – difficult to wear when active
 Delicate and fragile
 Not a permanent fix
What are the advantages and disadvantages of
using spectacles?
Contact lenses
 Basic lense structure is convex in shape
 It’s shaped to fit the curvature of the eyeball
 Contact lenses are much smaller than the
lenses in glasses
What are contact lenses?
Cataract surgery
 Intraocular lens implantation (IOL) corrects
cataracts
 the cloudy lens is removed from the lens capsule
and an artificial lens is inserted
o A surgeon makes a small incision in the eye
and inserts a device that breaks up the
cloudy lens
o An emerging technology is the use of laser
cataract surgery
o Laser is used to break up the lens and to
more accurately place the artificial lens in
the lens capsule
What is cataract surgery?
Advantages:
 Permanent improved sight
Disadvantages:
 Expensive
 Recovery
 Side affects of surgery
What are the advantages and disadvantages of
cataract surgery?
The bionic eye
 Bionic Vision Technologies is developing a
bionic eye to restore vision to people with retinis
pigmentosa
 Eye has a camera attached to glasses which
transmits high-frequency radio signals to a
microchip implanted in the eye
 Electrodes convert signals into electrical
impulses that stimulate cells in the retina to
convert light rays  electrical impulses
 They are then sent to the rain via the optic nerve
The kidney
 Organs that form part of the excretory system
Structure and function of the kidney
 3 main functions of the kidney:
o Filtration
o Reabsorption
o Secretion
 To carry out these functions, the kidney has 3
main regions:
o Cortex
o Medulla
o Pelvis
 The functional unit of the kidney is the nephron
What is the structure and function of the kidney?
Filtration
 Blood flow: heart  aorta  renal artery 
smaller vessels  capillaries
 Each capillary enters a nephron, forming the
glomerulus inside Bowman’s capsule
 Filtration is based on size
o Small molecules pass into Bowman’s
capsule  glomerular filtrate (water,
nitrogenous wastes, amino acids, glucose,
salts)
o Large molecules (proteins, blood cells)
remain in the blood
 Glomerular filtrate continues along tubules for
further processing
What does filtration do?
Reabsorption
 Returns essential components back into the
bloodstream
o e.g. amino acids, glucose, ions, vitamins and
other minerals
 Occurs in the proximal and distal tubules,
through active transport and facilitated
diffusion
 The glomerular filtrate also contains high
concentrations of urea and other wastes
 In the ascending loop of Henle, ions are pumped
into the medulla
o The medulla has a lower concentration of
water compared to the tubules
o Water moves by osmosis out of the
descending loop of Henle
 Water reabsorption occurs throughout the
tubules and the collecting duct, with the
exception of the ascending loop of Henle
What are the common causes of kidney damage?
Symptoms of loss of kidney function include:
 Nausea
 Vomiting
 Loss of appetite
 Fatigue and weakness
 Sleep problems
 Changes in the volume of urine produced
 Decreased mental sharpness
 Hypertension
 Diabetes 1 or 2
 Recurrent kidney infections
 Kidney stones
What does reabsorption do?
Secretion
 Contributes to urine formation in the nephron
 Removes toxic substances from the blood
capillaries and tissues
o E.g. urea, uric, acid, ammonia and hydrogen
ions
o This is done via active transport and diffusion
What does secretion do?
Hormonal regulation:
 Aldosterone (hormone) stimulates the
reabsorption of salt in the loop of Henle
o This regulates the salt and water balance in
the kidney
 Antidiuretic hormone (ADH) stimulates the
reabsorption of water in the kidney
What is hormonal regulation?
Removal:
 Water, nitrogenous wastes and other wastes
that remaining in the collecting duct are known
as urine
o Pelvis of kidney  ureters  bladder 
urethra
What are the symptoms of loss of kidney
function?
Technologies to assist with loss of kidney function
 Renal dialysis carries out some of the kidney
functions to effectively filter blood
o Two types of renal dialysis: haemodialysis
and peritoneal dialysis
Dialysis:
 Purpose: Removes metabolic wastes from the
blood
 How it works:
o Blood pumped through coiled tubes with
artificial semi-permeable membranes
o Tubes are in dialysate (fluid like plasma but
without wastes)
o Blood and dialysate flow in opposite
directions, removing the toxins and wastes
from the blood via diffusion
o Dialysate is continually replaced
 Time: 3-4 hours, 2-3 times per week
 Limitations:
o Only removes limited fluid/wastes
o Some ions (sodium, phosphate, potassium)
don’t diffuse fast, leading to a build up and
needing a special diet
What is removal of wastes?
Loss of kidney function
 Common cause of kidney damage: damage to
nephrons
o Nephrons can’t carry out their filtering,
reabsorption and secretion functions
properly
o This leads to a failure to remove wastes
effectively and an inability to balance water
and salt levels in the blood
Haemodialysis dialysis
What is the purpose of dialysis?
what are the limitations of using dialysis?
Peritoneal dialysis
Advantages:
 Allows individual to live and feel relatively
normal when not in hospital
Disadvantages:
 Time consuming (3-4 hours, 2-3 times/week)
 Effects individuals ability to work and their
financial situation
 Risk of infection or blood clotting
 Doesn’t replace all functions of the kidney
What is peritoneal dialysis?
What are the advantages and disadvantages of
peritoneal dialysis?
Case Study: The Human Genome Project
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The Human Genome Project (HGP) was a massive international scientific endeavour to map and sequence the
entire human genome
It aimed to identify all human genes, determine the sequence of the chemical base pairs and make up human
DNA
Launched in 1990 and completed in 2003, the project significantly advanced our understanding of human
biology and medicine
Working Scientifically + Skills
REFER TO PRACTICAL SCAFFOLD
Questioning and Predicting
1a - Develop and evaluate inquiry questions and hypotheses to identify a concept that can be investigated
scientifically, involving primary and secondary data.
1b – Modify questions and hypotheses to reflect new evidence.
Aim: An aim outlines what you want to investigate, prove or show. It is written in the present tense. You can use the
starting words – To investigate, to show, to compare, to observe. It must include your independent and dependent
variable.
Hypothesis: a hypothesis contains two variables. One is independent (what you, the scientist is changing) and the
other is dependent (what you observe/measure). It does not matter if your hypothesis is supported or rejected by
the experiment. It is simply what you think will happen and WHY?
Planning Investigations
2a – Assess the risks, consider ethical issues and select appropriate materials and technologies when designing
and planning an investigation.
2b – justify and evaluate the use of variables and experimental controls to ensure that a valid procedure is
developed that allows for the reliable collection of data.
2c – evaluate and modify an investigation in response to new evidence.
Independent variable: one variable to manipulate (change) during the experiment.
Dependent variable: one variable to measure.
Controlled variables: the possible variables we need to keep the same.
Experimental control: is the standard for the experiment – the results can be compared to the results of the control
– can you remove the independent variable from this experiment?
Risk assessment: List all the risks associated with the experiment. Complete a table with the headings Hazard,
Risk, Precaution.
Method: this is your ‘recipe’ for your experiment. You need to show what equipment you need to use and also plan
for any repeats/controls.
Conducting Investigations
3a – employ and evaluate safe work practices and manage risks.
3b – use appropriate technologies to ensure and evaluate accuracy.
3c – select and extract information from a wide range of reliable secondary sources and acknowledge them using
an accepted referencing style.
Equipment: what equipment will I use to ensure accuracy in this experiment? Is the equipment sensitive enough?
Processing data and information
4a – select quantitative and qualitative data and information and represent them using a range of formats, digital
technologies and appropriate media
4b – apply quantitative processes where appropriate
4c – evaluate and improve the quality of data
Results: description of what data is showing: observations, quantitative, qualitative, trends.
Evaluate data: is the data showing consistency? What changes do I need to make to my method to improve the
quality of my data?
Analysing data and information
5a – Derive trends, patterns and relationships in data and information
5b – Assess error, uncertainty and limitations in data
5c – Assess the relevance, accuracy, validity and reliability of primary and secondary data and suggest
improvements to investigations.
Trends: What trends, patterns and relationships can you see in your data? Use your data in your answer.
Limitations: Are there any errors or limitations in your data? Is your data exactly how you expected it to be?
Relevancy: Is your data relevant? (has your experiment collected data appropriate to your aim?)
Accuracy: Is your data accurate? (have you used appropriate equipment to collect data? Is the design of the
experiment valid and are your results close to the true values, can they be substantiated in secondary sources?)
Validity: Is your data valid? (are the measurements actually measuring what you intended them to measure?)
Reliability: Is your data reliable? (repetition will only determine reliability – not improve it. Are your results
consistently showing similar data?)
Evaluation of data: What did you find out from completing this experiment? (you need to EXPLAIN your results. Use
your science background and explain why your results are what they are).
Evaluating errors: If you could do this experiment again – what would you do differently and why?
Conclusion: Refer back to your aim and hypothesis and state if and how you met it
Answering Short Answer Questions
 Spend 1.8 marks per minute in the exam
Answer the question in the following order:
1. Identify (name and define)
2. Describe (characteristics and features)
3. Explain (cause and effect = link)
4. Assess/evaluate
Steps on how to answer the question:
1. Identify requirements of the verb for the question
2. Understand the key content of the question (e.g. identify module and section)
3. Highlight other important information in the question (e.g. multiple examples, inclusion of stimuli)
4. Plan your response – write down all ‘key’ words related to the questions
5. Structure response around I. D. E. A and stop at the relevant verb
Identify: recognise and name
Describe: characteristics and features
 E.g. describe the role and changes in levels of a hormone in pregnancy
 I: Progesterone is a hormone that is important in pregnancy
 D: Progesterone and its key functions in pregnancy
Explain: relate cause and effect; make relationships between things evident; provide why and/or how.
 Start sentences with as a result
Assess: make a judgement of value, quality, outcomes, results or size.
Evaluate: make a judgement based on criteria; determine the value of
 Start with an evaluative statement
 Define key terms
 Analyse and refer to stimuli
 Conclude with an evaluative linking sentence