Ecosystems and Energy Flow
In this section you will learn:
 3 components of an Ecosystem are habitat, community
& population
 A habitat is the place where an organism lives
 A population is all the organisms of one type living in a
particular area
 A community is all the different types of organisms
living in a particular area
 Examples of food chains:Grass
Rabbit
Fox
 The arrows in food chains and food webs represent the
direction of energy flow
 Producers are organisms that make their own food
 Examples of producers are green plants
 Primary consumers are organisms that eat producers
 Examples of primary consumers are rabbits
 Secondary consumers are organisms that eat primary
consumers
 Examples of secondary consumers are foxes
 A herbivore eats only plants
 A carnivores eat only other animals (meat)
 Omnivores eat both plants and animals
 A strong relationship exists between predators and
prey. Prey are the organisms being eaten and the
predators are the organisms that eat them.
 If prey numbers increase, predator numbers will
increase
 A decomposer is an organism that breaks down dead
organisms
 Examples of decomposers are – bacteria and fungi
 Energy is lost from a food chain by heat, movement,
 The niche of an organism is the role it plats within an
ecosystem
 Pyramids of energy represent the energy levels at each
stage in a food chain
 Pyramids of numbers represent the numbers of
organisms at each stage in a food chain
 Pyramid of biomass represents the mass of organisms
at each stage in a food chain
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Activities:
Completed
Notes:
Glow – Unit 2 –
Reading:
Int 2 Biology Text Book (Torrance)
Int 2 Biology Success Guide
Questions:
Int 2 Biology Text Book
Applying Your Knowledge
Multiple Choice Book
Additional Activity:
Comments:
104 - 119
28 - 31
109, 115
116 - 119
57 - 68
Factors affecting variety in an Ecosystem
In this section you will learn:
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“Biodiversity” is the range of species in an ecosystem
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A stable ecosystem is one that has a wide range of
species and food webs
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A “species” is a group of organisms that can
interbreed and produce fertile offspring
The removal of one or more species has a dramatic
effect on other organisms/populations in a food web.
“Adaptation” is when organisms have adapted to suit a
particular habitat and niche
An example of a physical adaptation in an animal
would be Darwin’s finches – adaptations of beak shape
and size in order to eat different foodstuffs
An example of a physical adaptation in a plant would
be reduced leaves like spines in cacti in order to
reduce water loss in deserts
Examples of Environmental stimuli that organisms
may respond to include light and humidity
An example of a behavioural adaptation to an
environmental stimuli in animals and its survival value
would be woodlice moving from a light area to a dark
area. This increase their survival chances as birds
can’t see them in the dark
Examples of things that plants compete for include
light, root space, water, soil nutrients
Examples of things that animals compete for include
food, water, shelter
Pollution and habitat destruction to decrease species
biodiversity.
Human activities can decrease biodiversity e.g.
overfishing, deforestation, increased fuel usage
leading to pollution
High intensity grazing will maintain species diversity
because strong competitors are kept at bay allowing
weaker competitors to survive
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Very high or low intensity or grazing will decrease
diversity because:Low intensity of grazing will allow stronger
competitors to succeed and other species will not
survive thus reducing diversity
Very high intensity grazing causes no species to
succeed in a given are
Examples of continuous variation in plants are stem
length, root length, petal size
Examples of continuous variation in animals are
height, mass, ear length
Examples of discontinuous variation in plants include
flower colour, petal colour,
Examples of discontinuous variation in animals is skin
colour, coat colour, eye colour, wing type,
Continuous variation is a factor that can be measured
Discontinuous variation is a factor that can be
grouped or categorised
Activities:
Completed
Notes:
Glow – Unit 2
Reading:
Int 2 Biology Text Book (Torrance)
Int 2 Biology Success Guide
Questions:
Int 2 Biology Text Book
Applying Your Knowledge
Multiple Choice Book
Additional Activity:
Comments:
120 - 159
32 - 35
125, 142, 146, 152
152 - 159
68 -82
Factors affecting variation in a species
In this section you will learn:
Reproduction
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Sexual reproduction affects variety in a species
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In flowering plants the site of fertilisation is in the
ovary
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In flowering plants the:Male sex cell is called Pollen, and is produced in the
anthers
Female sex cell is called an Ovule, and is produced in
the ovary
Gametes are another word for sex cells
In mammals the: Male sex cell is called Sperm, and is produced in the
testes
Female sex cell is egg an Egg, and is produced in the ovary
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In mammals, the site of fertilisation is in the eg. tube
(oviduct)
Fertilisation in when the nucleus of a male sex cell
fuses with the nucleus of a female sex cell
The cell that is produced after fertilisation is called
a Zygote
Variation occurs due to the random combination of
parental gametes.
Genetics
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Chromosomes are found in the nucleus of a cell
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The chromosome complement (number of
chromosomes) in
(i)
human body cells
(2 sets of chromosomes)
(ii)
human gametes (sperm/eggs)
(1 set of chromosomes)
Chromosomes are made from DNA
Chromosomes are important as they contain genetic
information that determines an organism’s
characteristics.
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The basic structure of DNA in is made up of DNA
bases & a backbone
A gene is a small section of a chromosome
The sequence of DNA bases codes for the sequence
of amino acids
The sequence of Amino Acids determines the
structure and function of the protein produced
The structure of a protein is important for its
function as proteins have a specific shape e.g.
enzymes fit specifically to one substrate
Examples of other protein molecules and their
importance:Haemoglobin – carries oxygen
Catalase breaks down hydrogen peroxide
Mitosis is the process of cell division and it produces
cells identical to the parent cell.
Stages of Mitosis
1 – Mother Cell
2- chromosomes become
visible
3- chromosomes line up at
equator
4- chromatids are pulled to
opposite poles by fibres
5- chromatids are divided at
each pole by a membrane
6- 2 cells identical to the
mother cell are produced
Mitosis is important because it makes sure that the
new cells do exactly the same job as the original
mother cell
Meiosis is the production of sex cells (also called
gametes) e.g. sperm and egg cells
Meiosis is important because it ensures that a single
set of chromosomes are produced in gametes. Two
sets of chromosomes are made during fertilisation
Random assortment of chromosomes during meiosis
leads to variation in offspring.
The sex of a human is determined in terms of X and Y
chromosomes.
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XX = Female, XY = Male
Sperm can have an X or a Y chromosome, but eggs
only have an X
Activities:
Completed
Notes:
Glow – Unit 2
Reading:
Int 2Biology Text Book (Torrance)
Int 2 Biology Success Guide
Questions:
Int 2 Biology Text Book
Applying Your Knowledge
Multiple Choice Book
Additional Activity:
Comments:
160 - 184
36 - 41
167, 169, 179
179 – 184
83 - 90
Phenotype and genotype
In this section you will learn:
 Genes are small sections of a chromosome
 Different forms of a gene are called alleles
 Each gamete carries one allele of the gene
 Characteristics are inherited from both parents – one
set of chromosomes are received from the mother and
one set of chromosomes are received from the father
 A Homozygous individual has 2 identical alleles
 A Heterozygous individual has 2 different alleles
 Dominant alleles are always represented by a capital
letter and they hide the recessive alleles
 Recessive alleles are always represented by a small
letter and they are the alleles that are hidden
 Genotype is the genetic make-up of an organisms
(e.g.BB or Ff)
 Phenotype is the appearance of an organism (e.g. Brown
or Black coat)
 The genotype (genetic make up) determines the
phenotype (appearance)
 Examples of the same phenotype with different
genotypes
e.g. Brown (BB) Brown (Bb)
 A monohybrid cross is cross involving parents differing
in one factor
 A true breeding organism is one which has parents with
homozygous alleles and it has homozygous alleles
 In genetics crosses the term P = parents, F1 = 1st
generation and F2 = 2nd generation
 Make sure you can solve problems related to
monohybrid crosses in plants and animals following
crosses from the P generation to the F2 generation,
using dominant and recessive alleles
 Examples of ratios of phenotypes of the F1 and F2
offspring e.g. 3:1
 Sometimes the predicted ratios in monohybrid crosses
are different to the actual observed ratios and this is
due to the fact that “Fertilisation is a random process
involving an element of chance”
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 Co-dominance is when the alleles of a gene are neither
dominant nor recessive.
 Co-dominance example – Brown Cow crossed with a
Black Cow neither one is dominant so the offspring are
Red Cows
 Polygenic inheritance is when several genes interact
with one another and causes a range of phenotypes
 Examples of phenotypes produced due to polygenic
inheritance are skin colour in humans and seed mass in
plants
Environmental impact on phenotype
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The 2 factors that affect the phenotype (final
appearance) of an organism are due to genotype and
the effects of the environment
Example of the effects of different environments on
the phenotypes of organisms with identical genotypes
e.g. twins – one brought up in USA, one brought up in
UK. Look different due to different skin colours
(environment) and one has had a healthy diet so is
thin and the other had an unhealthy diet so is
overweight (environment)
The effects of environment on phenotype have no
evolutionary significance as they are not traits that
can be passed on
Natural selection
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Natural selection is when organisms that are better
suited to the environment survive and breed and
those less well suited die off.
Better adapted organisms are more likely to pass
their characteristics to the next generations and
they have survived long enough to mate and reproduce
Natural selection using the Peppered Moth example
1. 2 forms of moth exist (light and dark forms)
2. Light form had a selective advantage as it was
camouflaged against white lichens growing on trees so
birds could not see them.
3. Before the Industrial Revolution there were lots of
white moths but few dark moths (as dark moths were
easily spotted by birds)
4. After the Industrial Revolution, lichens on trees
died and tree trunks turned black. Then the dark
moths had a selective advantage and survived, mated
and reproduced
5. Now there are more dark moths than light moths
Activities:
Completed
Notes:
Glow – Unit 2
Reading:
Int 2 Biology Text Book (Torrance)
Int 2 Biology Success Guide
Questions:
Int 2 Biology Text Book
Applying Your Knowledge
Multiple Choice Book
Additional Activity:
Comments:
185 – 207
42 - 49
187, 193, 204
204 - 207
91 - 102
Applied Genetics
In this section you will learn:
Selective Breeding
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Selective breeding is when humans are involved in
choosing which plants and animals they should breed
for human benefits.
The benefits of selective breeding are that after a
few generations you will gain plants or animals with
desirable traits
Disadvantages of selective breeding are – it’s takes a
long time and good results are not always guaranteed
Genetic Engineering
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Stages in Genetic Engineering
1 – Identify the required gene from a chromosome
2 – Remove the required gene from chromosome
3 – Insert the gene into a bacterial plasmid
4 – Insert plasmid into bacteria
5 – Bacteria reproduce and make the desired product
(e.g.insulin)
6 – Product purified and ready to use
Advantage of genetic engineering is it is fast (faster
than Selective Breeding)
Disadvantages of genetic engineering is it is
expensive and there may be the possible release of
genetically engineered bacteria into the environment
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Activities:
Completed
Notes:
Glow – Unit 2
Reading:
Int 2 Biology Text Book (Torrance)
Int 2 Biology Success Guide
Questions:
Int 2 Biology Text Book
Applying Your Knowledge
Multiple Choice Book
Additional Activity:
Comments:
208 - 225
50 - 53
209, 213, 218
220 - 225
102 - 108
NAB revision
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Ecosystems and Energy Flow
Factors affecting variety in an eccsystem
Factors affecting variation in a species
Phenotype and Genotype
Applied Genetics
Target Grade
NAB 1st
Attempt
NAB 2nd
Attempt
1. Areas of strength
2. Areas identified as needing further work
3. Tips learned to help answer future questions
Unit 1 AB test
On target?
Welcome to Int 2 Biology.
This booklet is your “learning log” for this unit.
Roughly for each week, it details what we hope to cover. The first table lists the
learning outcomes.
In this section you will learn:

A unicellular organism is made up of only one cell
Tick here once you’ve been
taught this outcome. This will
help you keep track of where
you are and if you’ve missed
any work.
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Tick these boxes when
you have reviewed
this work once and
then when you revise
it again.
The second table lists the suggested activities you should complete each week.
e.g.
The notes section tells you where to
find the Powerpoint for this unit to
catch up on any work missed.
Notes:
Glow – Unit 1 – Living Cells.
Reading:
Int 2 Biology Text Book (Torrance)
Int 2 Biology Success Guide
Questions:
Int 2 Biology Text Book
Applying Your Knowledge
Multiple Choice Book
Additional Activity:
Completed
This is where you can find reading to
47
- 56your understanding of what
expand
is done
16
- 17in class
Activities
to complete to help assess
48,
52, 54
your 731
understanding
of the work
Set
- 33
covered in class. The answers can be
2005 2 B
found in the Study room at the back
of Room 31.
Some weeks I may assign an
extra activity.
Tick each activity as you complete it.
The “Comments” section is for you identify any problems or areas of difficulty you have
and to plan how to address these problems.
Name: