Midterm Review
Chapter 1
Biology and You
7 Characteristics of Living Things
1.
2.
3.
4.
5.
6.
7.
Cellular organization
Reproduction
Metabolism
Homeostasis
Heredity
Responsiveness
Growth & development.
Levels of Organization in
Living Things
1.
2.
3.
4.
5.
6.
Organelles
Cells
Tissues
Organs
Organ system
Organism
Science vs. Biology
• Science
Process of thinking & learning about the
world
• Biology
Study of life
Steps of the Scientific Method
1. State the problem based on
observations.
2. Research the problem.
3. Form a hypothesis.
4. Test the hypothesis (experiment).
5. Collect and analyze the data.
6. Form a conclusion.
7. Report the results.
Control vs. Variable
• Control
 The standard of comparison for the
experimental group
 Receives no experimental treatment
• Variable
 The one factor that differs among the
test groups.
 Part of the experimental group
Independent vs. Dependent
Variable
• Independent variable – factor changed
by the experimenter (the factor tested)
- a good experiment tests one
variable.
• Dependent variable – factor that
depends on the value of the
independent variable (a result
measured).
Independent vs. Dependent
Variable
Observations
• Qualitative
 Observations that deal with the
characteristics of the object such as
hardness, texture, beauty, etc.
• Quantitative
 Observations that deal with numbers
such as the mass, how many, how long,
etc.
Theory vs. Hypothesis vs.
Prediction
•
Theory
 A set of related hypotheses that have been tested and
confirmed many times by many scientists.
 Unites and explains a broad range of observations.
•
Hypothesis
 An educated guess based on observations & research
that can be tested.
•
Prediction
 Expected outcome of a test assuming the hypothesis
is correct.
Base Units of the Metric System
•
Meter
 Measures length
•
Liter
 Measures volume
•
Gram
 Measures mass
•
Celsius
 Measures temperature
Chapter 6: Chromosomes
& Cell Reproduction
Section 1: Chromosomes
Chromosomes
• Chromosomes are DNA & its
associated proteins.
 We have 46 chromosomes or 23
pairs of chromosomes.
• In a prokaryotic cell, it is the
main ring of DNA.
Autosomes vs. Sex Chromosomes
•
Autosomes are any chromosomes that are
not directly involved in determining the
sex of an individual.
 We have 22 pairs.
•
Sex chromosomes contain genes that will
determine the sex of the individual.
 We have one pair.
 Females are XX.
 Males are XY.
Gametes
• Gametes are an organism’s
reproductive cells.
 Female’s gametes are eggs or ova.
 Male’s gametes are sperm.
Haploid vs. Diploid
• Haploid refers to a cell (gamete) that
contains only 1 set of chromosomes.
 It is represented by “n.”
• Diploid refers to a somatic or body
cell that contains 2 sets of
chromosomes.
 It is represented by “2n.”
Define Meiosis
• A process in cell division during which the number
of chromosomes decreases to half the original
number by two divisions of the nucleus, which
results in the production of sex cells (gametes or
spores)
Define Diploid
• A cell that contains
2 sets of haploid
chromosomes
• Body or somatic
cells contain a
diploid number of
chromosomes.
Define Haploid
• Describes a
cell, nucleus or
organism that
has only one
set of unpaired
chromosomes.
Define Gamete
• A haploid reproductive cell that unites
with another haploid reproductive cell to
form a zygote or fertilized egg.
Define Transformation
• The transfer of genetic material in the
form of DNA fragments from one cell to
another or from one organism to another.
Define Bacteriophage
• A virus that
infects bacteria.
Define DNA Replication
• The process of making a copy of DNA
Define Base Pair Rule
• The rule stating that cytosine pairs with
guanine and adenine pairs with thymine in
DNA and that adenine pairs with uracil in
RNA.
Define Complementary
• A characteristic of nucleic acids in
which the sequence of bases on one
strand determines the sequence of
bases on the other.
Define Transcription
• The process of forming a nucleic acid by
using another molecule as a template;
particularly the process of synthesizing
RNA by using one strand of a DNA
molecule as a template.
Define Codon
• A three nucleotide sequence that encodes an
amino acid or signifies a start or stop signal
Define Translation
• The portion of protein synthesis that takes
place at ribosomes and that uses the codons
in mRNA to specify the sequence of amino
acids in a polypeptide chain.
Define Anticodon
• A region of tRNA that consists of 3 bases
complementary to the codon of mRNA.
Define Restriction Enzymes
• An enzyme that destroys or cuts foreign DNA
molecules by cutting them at specific sites.
Define Gel Electrophoresis
• The process by which electrically charged
particles suspended in gel move through the
gel because of the influence of an electric
field.
Define Plasmid
• A circular DNA
molecule that is
usually found in
bacteria and that
can replicate
independent of the
main chromosome
Define Recombinant DNA
• DNA molecules that are artificially created
by combining DNA from different sources.
Define Vector
• In biology, any
agent , such as a
plasmid or a virus,
that can incorporate
foreign DNA and
transfer that DNA
from one organism
to another
Define Antibody
• A protein that reacts to a specific antigen or
that inactivates or destroys pathogens or
toxins.
Describe the structure of DNA
(Parts, shape, components)
1.
Made up of
2. A Nucleotide is made up
many nucleotides of a sugar, nitrogen base and
A, T, C, G
phosphate
3.
Double helix in
shape (Twisted
Ladder)
List the differences between
DNA and RNA
• DNA
Double stranded
Deoxyribose
Thymine present
Found In Nucleus
1 type
Master copy
• RNA
Single stranded
Ribose
Uracil present
Found in nucleus &
cytoplasm
3 types
Blue print
What is replication and when
and where does it occur?
• DNA is copied
• Occurs in the nucleus
• Takes place during the
synthesis phase of the cell
cycle.
• Enzymes separate the two
strands
• New strands are
synthesized by base-pairing
with the original strand
List the different forms of RNA and
explain the functions of each.
• Messenger RNA - carries
instructions for making a
protein from a gene on the DNA
in the nucleus and delivers it to
the site of translation.
(mailman)
• Ribosomal RNA – responsible
for ribosome function. (factory)
• Transfer RNA - single strands
of RNA that temporarily carry
a specific amino acid. (delivery
man)
List where the following
processes occur
• DNA Replication - Nucleus
• Transcription - Nucleus
• Translation – In the cytoplasm at the
ribosome
Who was Chargaff and what
rule did he propose?
• American Biochemist
• Studied the nucleotide composition
of many samples of DNA.
• Amounts of nucleotides varied with
each sample of DNA.
• Thymine equals Adenine
and Guanine = Cytosine.
Describe the process of
transformation?
• Transformation, a change in genotype
caused when cells take up foreign
genetic material.
How does natural selection help to drive a
species to change over a long period of time?
• Within each species, variety exists.
• With natural selection, if the environment changes,
sometimes a trait that was favorable will now be
unfavorable.
• Those with the favorable adaptation will survive,
reproduce and pass their genes onto their
offspring
• Example: Darwin’s Finches
– Beak size and food
availability
Complete the following:
• P1 ♀ Ff x Ff ♂ F = freckles present
f = no freckles
F
f
FF
Ff
Genotype Ratio:
Ff
ff
Phenotype Ratio:
F
f
1 FF : 2 Ff : 1 ff
3 Freckles: 1 No
Freckles
What do the letters on the outside
of the Punnett square represent?
• The parents’
gametes
Dad’s sperm
Mom’s eggs
What do the letters on the inside of
the punnett square represent?
• The probability of what the genetic
make up of the baby will be
How many of the offspring
would have freckles?
• 3 out of the 4
• The child has a ¾, 75% or 3 out 4
chance of having freckles
Protein Synthesis = Transcription
(Nucleus) and Translation (Ribosome)
DNA CODE: CGT
ATG
GCC
TAT
ACA
ATA
GCG
mRNA CODE: GCA___UAC____CGG___AUA____UGU___UAU___CGC_
tRNA CODE: CGU
AUG
GCC
UAU
ACA
AUA
GCG__
AMINO ACID alanine/tyrosine/arginine/isoleucine/cysteine/tyrosine/arginine
SEQUENCE
Produce the complementary strand of DNA for the strand of DNA below:
DNA CODE:
CGT
ATG
GCC
TAT
ACA
ATA
GCG
_GCA__ _ TAC___ CGG____ATA__ _TGT__ TAT_ _ CGC
4 steps to transfer a gene from a
member of one species to another.
• DNA is cut using restriction enzymes.
The DNA of the vector is cut with the
same restriction enzyme.
• The DNA fragments containing the
gene of interest are combined with the
DNA fragments from the vector using
DNA ligase and the host cell takes up
the recombinant DNA.
• The gene is cloned each time the
bacterium, yeast or virus reproduces.
• Cells undergo selection and then are
screened.
Define Genetics
• The science of heredity and the
mechanisms by which traits are passed
from parents to offspring.
Define Heredity
• The passing of genetic traits from parents
to offspring
Define Alleles
• Alternate forms of a gene that governs a
characteristic, such as hair color.
Differentiate between phenotype
and genotype
• Phenotype: is the physical appearance of
the organism in genetics
– EX.
FF  freckles
• Genotype: is the genetic make up of the
organisms typically represented with letters
Define Dominant Gene
• The gene that is going to expressed
(shown) in the offspring
• Normally the allele with the capital letter
Yellow is dominant over
green 
Expressed as “Aa
or AA”
Define Recessive Gene
• The gene that is not seen if a dominant gene
is present but can be passed on in genes
(masked)
• Normally in lower case letters
Green is recessive to yellow 
Expressed as “Aa
or aa”
Explain the difference between
homozygous and heterozygous genotype
• Homozygous: “homo” means “the same”
in Latin: individuals that have identical
alleles for a trait
Ex.
EE (homozygous dominant)
ee (homozygous recessive)
• Heterozygous: “hetero” means “different”
in Latin; individuals that have different
alleles for a trait
Ex.
Ee (heterozygous)
Define F1 Generation
• The first filial generation of offspring obtained
from an experimental cross of two organisms.
Define Probability
• The likelihood that a
possible future event will
occur in any given
instance of the event
• The mathematical ratio
of the number of times
one outcome of any event
is likely to occur to the
number of possible
outcomes of the event
Define Incomplete Dominance
• A condition in which
a trait in an
individual is
intermediate between
the phenotypes of the
individual’s two
parents because the
dominant allele is
unable to express
itself fully.
Define Codominance
• A condition in
which both
alleles for a gene
are fully
expressed.
Define sex-linked trait
• A trait that is determined by a gene found on one
of the sex chromosomes, such as “X” or “Y”.
• Typically occur more often in males than females
• XX female
Ex: hemophilia (X)
colorblindness (X)
• XY  male
hairy ears (Y)
Define Evolution
• A change over time
• A change of the
characteristics of a
population over many
generations
Define Natural Selection
• The process by which individuals that have
favorable variations and are better adapted to
their environment survive and reproduce more
successfully than less well adapted
individuals.
Define Extinct
• Describes a
species of
organisms
that has died
out
completely.
• Ex: Dodo
bird
Define abiotic factors.
• An environmental factor that is not associated
with the activities of living organisms.
• Rocks
•Soil
•Water
•Sunlight
•Air
Define biotic factors.
• An environmental factor that is associated
with or results from the activities of living
organisms.
Define Population
• A group of organisms
of the same species
that live in a specific
area and interbreed
Define community.
• A group of species that live in the same
habitat and interact with each other.
Define habitat.
• The place where an organism usually lives.
• Whose habitat is this?
Define niche.
• The position (way of life) of a species in an
ecosystem in terms of the physical
characteristics (such as size, location,
temperature, and pH) of the area where the
species lives and the function of the species
in the biological community.
Fundamental vs realized niche
• Fundamental niche – entire range of
resources an organism is potentially able to
occupy in an ecosystem.
• Realized niche – the part of the
fundamental niche that a species occupies.
Define ecosystem.
• A community of organisms and their abiotic
environment.
Define biome.
• A large region characterized by a specific
type of climate and certain types of plant
and animal communities.
Define succession.
• The replacement of one type of community
by another at a single location over a period
of time.
Define producer.
• An organism that can make organic
molecules from inorganic molecules; a
photosynthetic or chemosynthetic autotroph
that serves as the basic food source in an
ecosystem.
Define consumer.
• An organism that eats other organisms or
organic matter instead of producing its own
nutrients or obtaining nutrients from
inorganic sources.
Define herbivore.
• An organism that eats only plants.
Define carnivore.
• An animal that eats other animals.
Define omnivore.
• An organism that eats both plants and
animals.
Define detritivore.
• A consumer that feeds on dead plants and
animals; examples include vultures, bacteria
& fungi
Define decomposer.
• An organism that feeds by breaking down
organic matter from dead organisms;
examples include bacteria and fungi.
Who was considered the
“Father of Genetics”?
• The father of genetics was
Gregor Mendel.
• Austrian monk born in
1822
• Used true-breeding pea
plants which always pass
on the same characteristics
to the next generation.
• Carefully planned
experiments to test
blending hypothesis of
heredity
Law of segregation
• Mendel’s law that states
that the pairs of
homologous
chromosomes separate
in meiosis so that only
one chromosome from
each pair is present in
each gamete.
Law of independent assortment
• The law that states that genes on
nonhomologous chromosomes separate
independently of one another in meiosis.
What are 3 ways we can predict the
occurrence of a genetic disorder?
• 1. Karyotyping
• Prenatal testing
• 2. Pedigree
• 3. Genetic Counseling
What is a pedigree?
• A family history that shows how a trait is
inherited over several generations
 male
 female
Shaded has disease and
unshaded is normal
List 2 traits that are caused
by multiple alleles
• 1. Blood Typing
– IAIA
I Ai
IBIB IBi
• 2. Rabbit fur color
IAIB ii
What are the 4 different blood
types?
• Blood Typing
– IAIA Iai  A blood
type
– IBIB Ibi  B blood
type
– IAIB
 AB blood
type
– ii
 O blood
type
How do mutations in DNA occur and why
are they important? (Positive and
Negative)
• Types of mutations:
– Point mutations : deletion, insertion, &
substitution
– Gene mutations: deletion, insertion,
duplication, inversion and translocation
• Positive: they give rise to diversity in the
population of a species (THINK: Sneaker Male
Iguana)
• Negative: they can give the population a deadly
gene (THINK: Huntington’s, Parkinson’s and
Mental Retardation)
Where did Darwin conduct
much of his research?
• Galapagos Islands
Describe the idea of natural selection as
witnessed by Darwin?
Darwin observed that each island had a
population of finches.
The finches looked different from one another,
but had many similarities.
The beaks were the biggest difference.
If the birds were on a island with small seeds (wet
season) their beaks were small.
If the birds were on a island with large seeds (dry
season) their beaks were large
The birds with the appropriate beak size for the
island’s food supply survived and reproduced
more.
How does competition help to
drive evolution?
• Competition arises b/c of limited
resources such as food, shelter, and
suitable mates.
• Those w/ adaptations that make them
more fit will survive, reproduce more
successfully and pass on their genes in
the process.
List the different types of fossils
Trace fossil or Imprinting: the outline in a rock
of an organism or a trace
left by an organism
Body Fossil: preserved or
mineralized remains
of an organism
How do vestigial structures help to
support the theory of evolution?
• You an compare the structures that are
shared between species that may not
seemed related.
• The fact that they have the same basic
structure solidifies the facts that they had a
common ancestor
How are amino acid & DNA sequences
used to support the idea of evolution?
• You can compare the DNA/amino acid
sequence between species that may not
seemed related
• The fact that they have a similar DNA/Amino
Acids sequence solidifies the fact that they
had a recent common ancestor
• The greater the differences, the more
distantly related.
What are the differences and similarities
between a food chain and a food web?
•A food chain the pathway of energy transfer
through various stages as a result of the
feeding patterns of a series of organisms.
•A food web a diagram that shows the feeding
relationships between organisms in an
ecosystem.
•They both show energy transfer from one
organism to the next.
Food chain
Food web
What is an energy pyramid? What types of
organisms are found at each level?
•An energy pyramid is a triangular diagram that shows an
ecosystem’s loss of energy, which results as energy passes
through the ecosystem’s food chain
•Each row in the pyramid represents a trophic (feeding) level
in an ecosystem.
•The area of a row represents the pathway of energy transfer
through various stages as a result of the feeding patterns of
a series of organisms.
What % of the energy at a trophic level ends
up in the next trophic level above it?
• 10%
Primary
succession
Secondary
succession
• Secondary succession is
• Primary succession is
the process by which one
succession that begins in an
community replaces another
area that previously did not
community that has been
support life
partially or totally destroyed.
Define symbiosis
• Symbiosis a relationship in which
two different organisms live in
close association with each other
Distinguish between parasitism,
commensalism and mutualism
• Parasitism is a relationship between two
species in which one species, the parasite,
benefits
• from the other species, the host, and usually
harms the host.
• Commensalism is a relationship between two
organisms in which one organism benefits and
the other is unaffected.
• Mutualism is a relationship between two
species in which both species benefit.