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Biology
Final Exam Review Packet
STUDY TIPS
 Use your textbook and your notes to prepare yourself for the Final Exam.
 DON’T CRAM! It’s a proven fact: studying for a little bit each day works better
than waiting until the night before the exam.
 Remember to ask questions in class about concepts you want clarified.
GUIDING QUESTIONS FOR FINAL EXAM
9. Genetics (Chapter 10)
a. Describe the work of Gregor Mendel.
Mendel experimented with pea plants and used cross-pollination techniques to
study the inheritance of various factors. He took meticulous notes/
observations and discovered the basic laws of genetics without knowing
anything about DNA or the structure of genes.
b. What is the difference between a dominant and a recessive allele?
A dominant allele is always expressed in the phenotype. A recessive allele is
only expressed if there are no dominant alleles present.
c. What are Mendel’s laws of segregation and independent assortment?
Law of segregation – When an individual produces gametes, the two alleles
for each gene separate so that each gamete only receives one allele.
Law of independent assortment – Allele pairs separate independently during
the formation of gametes. Basically, this means that the inheritance of any one
trait does not affect or influence the inheritance of a second trait (assuming
the traits are on different chromosomes).
d. Draw Punnett squares for the following crosses: Aa x Aa; DdFf x DdFf.
e. Explain the following exceptions to Mendel’s laws and give an example:
i. Incomplete dominance – One allele is not completely dominant over
the other, so the heterozygous condition is an intermediate phenotype.
Example: Japanese snapdragons
RR = red
rr = white
Rr = pink
ii. Codominance – Two dominant alleles.
Example: cattle color
RR = Red WW = white RW = roan (red and white)
iii. Lethal dominance – Heterozygous dominant condition is not viable.
Example: achondroplasia (dwarfism)
AA = not possible Aa = dwarfism
aa = normal height
iv. Multiple alleles – More than two alleles determine the phenotype of a
single trait.
Example: Human ABO blood groups
IA = allele for A blood (dominant) IB = allele for B blood (dominant)
i = allele for O blood (recessive)
f. What are sex-linked traits? Why do they typically affect males more often
than females?
Sex-linked traits are traits on the X chromosome. They typically affect males
more often than females because males (XY) only have one X chromosome
and will therefore express all of their sex-linked recessive alleles. Females
(XX) have two X chromosomes and can be carriers of a recessive sex-linked
trait without expressing the phenotype.
g. What is a pedigree?
10. Molecular Biology (Chapter 11)
a. Describe the structure of DNA.
Shape = double helix. Consists of nucleotides arranged in base pairs. Sugars
and phosphates form the backbone. Strands are antiparallel.
b. Describe the contributions of the following scientists to the discovery that
DNA was the genetic material:
i. Griffith – Injected two types of bacteria into mice. Found that a
mixture of heat-killed pathogenic bacteria and living harmless
bacteria transformed into living pathogenic bacteria and killed mice.
ii. Avery – Confirmed that the transforming agent from Griffith’s
experiment was the DNA from the heat-killed bacteria.
iii. Hershey and Chase – Verified that DNA was the genetic material by
radioactively labeling the proteins and DNA of phage and using a
blender to determine which radioactive component penetrated
bacteria cells.
c. Describe the contributions of the following scientists to the discovery of the
structure of DNA:
i. Chargaff – Determined the base-pairing rules by observing that the
number of A’s always equals the number of T’s in DNA (same for C’s
and G’s).
ii. Franklin – Used X-ray crystallography to determine the double helical
structure of DNA.
iii. Watson & Crick – Built the first accurate model of DNA.
d. How does the structure of DNA suggest a replication mechanism for DNA?
The double helix consists of complementary strands, which suggests that you
could replicate DNA by unzipping the two strands and using each parent
strand as the template for making a new copy of the DNA.
e. Describe the steps of DNA replication.
1. Helicase unwinds the DNA.
2. Primase makes RNA primers.
3. DNA polymerase synthesizes new DNA on the leading strand from 5’ 3’
(working towards the replication fork).
4. On the lagging strand, DNA polymerase works away from the fork,
synthesizing new DNA in short pieces called Okazaki fragments.
5. Ligase joins Okazaki fragments on the lagging strand.
6. DNA polymerase replaces the RNA primers with DNA.
f. What is the difference between the leading and the lagging strand?
Leading strand is synthesizes in continuous fashion, whereas the lagging
strand is synthesized in short pieces and therefore takes longer. This is due to
the antiparallel nature of DNA and the fact that DNA polymerase only works
in the 5’ 3’ direction.
g. What is the central dogma of biology?
DNA  mRNA  protein
h. Compare the structure of DNA with RNA.
DNA: double helix, sugar is deoxyribose, bases A-T, C-G
RNA: single strand, sugar is ribose, bases A-U, C, G
i. Explain what happens during transcription.
DNA is copied into mRNA by RNA polymerase. This needs to happen because
DNA contains the instructions for making protein, but the instructions need to
get from the nucleus (where DNA is stored) to the ribosome (site of protein
synthesis).
j. Explain what happens during translation.
mRNA attaches to the ribosome, which “reads” the mRNA codons (sets of
three bases) at a time and recruits the appropriate tRNA molecule. Each tRNA
molecule is attached to a specific amino acid, the building blocks of protein.
The protein is assembled as tRNA molecules bind to the mRNA and the amino
acid that the tRNA delivers is added to the growing protein chain. Translation
always begins with a start codon (AUG, which brings the amino acid Met)
and ends at a stop codon (UGA, UAA, UAG).
k. How does the genetic code provide evidence for evolution?
All living things use the same genetic code, which suggest that this code was
used for protein synthesis in a common ancestor of all living things.
l. What is a mutation?
A change to the DNA.
m. Distinguish between the following types of mutations:
i. Silent – Does not affect protein synthesis – the mutation codes for the
same amino acid.
ii. Missense – A different amino acid is used during protein synthesis (a
substitution).
iii. Nonsense – A premature stop codon.
11. Biotechnology (Chapter 13)
a. What is genetic engineering? Describe some of its uses.
Inserting genes from other organisms. Can be used to make medicines or to
enrich the nutritional value of food.
b. What are restriction enzymes?
Enzymes that cut the DNA at specific target sequences. They are naturally
found in bacteria cells for the sake of defense against viruses. Target
sequences are always palindromes.
c. What is a plasmid?
A plasmid is a small, circular piece of DNA in bacteria cells that replicates on
its own and can be transferred from one bacteria cell to another. Plasmids
can be used to introduce new genes to bacteria.
d. Explain the steps involved in engineering a bacteria that can make human
insulin.
1. Identify the gene of interest (human insulin gene).
2. Isolate the gene of interest from the host chromosome using restriction
enzyme.
3. Use the same restriction enzyme to cut the target DNA (where you will
insert your gene – most likely a plasmid).
4. Mix the DNA together and add ligase to seal the bonds.
5. Transform bacteria (allow bacteria to take up the plasmid).
6. Grow bacteria and test for success of transformation.
e. What is gel electrophoresis?
Using an electric current and agarose gel to separate DNA fragments based
on size. Smaller fragments migrate farther distances due to the negative
charge on DNA molecules.
12. Cellular Respiration (Chapter 7)
a. How does ATP provide energy for cellular work?
ATP has high-energy bonds between its phosphate groups. Breaking the bond
between the 2nd and 3rd phosphate group releases energy that can be coupled
to an endergonic reaction.
b. What is the difference between anaerobic and aerobic respiration?
Anaerobic – does not require oxygen. Consists of glycolysis and either lactic
acid fermentation (muscles) or alcoholic fermentation. Net gain of 2 ATP
molecules per glucose.
Aerobic – requires oxygen. Consists of glycolysis followed by Krebs cycle and
electron transport chain. Net gain of 36-38 ATP molecules per glucose.
c. What is the overall equation for aerobic cellular respiration?
C6H12O6 + 6O2 --> 6CO2 + 6H2O + energy
d. Describe the structure of the mitochondrion.
e. Explain what happens during glycolysis and where it takes place.
Glucose is broken down into two pyruvate molecules. 2 ATP molecules are
needed to start the process, but 4 are produced, resulting in a net gain of 2
molecules. NADH molecules are generated for use in the electron transport
chain. Occurs in the cytoplasm.
f. Explain what happens during the Krebs cycle and where it takes place.
Occurs in the mitochondrial matrix. Each pyruvate molecule is broken down
into carbon dioxide, generating NADH and FADH2 molecules for use in the
electron transport chain as well as a total of 2 ATP molecules per glucose.
g. Explain what happens during the electron transport chain and where it takes
place.
NADH and FADH2 molecules drop off their electrons to proteins in inner
membrane of mitochondria. As electrons are passed along chain, hydrogen
ions are pumped into the intermembrane space. Oxygen ultimately accepts the
electrons and combines with hydrogen ions to create water. Hydrogen ions
flow back through the membrane (down their concentration gradient),
powering an enzyme that makes 32-34 ATP molecules per glucose.
h. Why does fermentation take place in cells that lack mitochondria or when
there is not enough oxygen present?
Fermentation is necessary to recycle the electron carrier NAD+ and to
complete the breakdown of pyruvate.
13. Photosynthesis (Chapter 8)
a. How do autotrophs use light energy to make food?
Sunlight is used to make ATP. ATP is then used to produce sugar molecules
from carbon dioxide and water.
b. What is the overall equation for photosynthesis?
6CO2 + 12H2O + light → C6H12O6 + 6O2 + 6H2O
c. What are the major parts of a leaf and their functions?
d. Describe the structure of the chloroplast.
e. Explain what happens during the light-dependent reactions.
Electrons in chlorophyll molecules (stored in the thylakoid) are excited by
sunlight. These high-energy electrons are passed down an electron transport
chain to generate ATP molecules (as in cellular respiration). Water is split to
replace these electrons, releasing oxygen gas. ATP is used in lightindependent reactions to make sugar.
f. Explain what happens during the dark-dependent reactions.
In the stroma, ATP and carbon dioxide are used to make glucose molecules.
This is also called the Calvin cycle.
g. Identify two factors that affect the rate of photosynthesis.
Temperature
Light intensity
Amount of carbon dioxide
h. Explain the complimentary nature of photosynthesis and cellular respiration.
They are opposite processes – the products of one are the reactants of the other.