Final Exam Review Worksheet
KEY
Honors Biology
THIS IS NOT AN INCLUSIVE LISTING OF MATERIAL ON THE EXAM!
Genetics
1. Define the following terms:
 Allele- a version of a gene (e.g., IA, IB, and i in human blood type or T, t for pea plant
height).
 Gene- In a genetic sense, it is the genetic instructions to encode for a trait, for example
hair color. In molecular biology, it is a DNA sequence that encodes a product, beginning
with a promoter, followed by the coding region, and ended by the terminator.
 Recessive allele- most often a damaged gene that no longer encode a protein. It is
masked by the functional, dominant gene.
2. Describe Mendelian genetic inheritance.
Genes have two different forms, or alleles, which are either dominant (A) or recessive (a). Each
organism contains two alleles of a gene; one inherited from the mother, the other the father.
These alleles need not be identical (i.e., heterozygotes have both a dominant and recessive
allele). Dominant alleles are always expressed over recessive alleles (Aa is phenotypically the
same as AA). The recessive trait can only be seen in homozygous recessive organisms (aa).
3. What is the difference between
 Genotype and phenotype- genotype is the combination of alleles present in an
organism—it can be homozygous (both the same) or heterozygous (different). The
phenotype is the physical appearance of the organism.
 Dominant and recessive- dominant alleles most often encode functional proteins;
recessive alleles are damaged genes. Dominant traits are always expressed over
recessive traits.
 Haploid and diploid- Haploid organism only contain one copy of each chromosome, and
thus one copy of each gene. Diploids contain two versions of each chromosome, and
thus two versions of each gene.
4. What are Mendel’s Law of Segregation and his Law of Independent Assortment?
The Law of Segregation says that parents only give one of their two alleles for each trait to their
offspring (for example, a heterozygous Aa parent produces gametes that contain just A or a).
The Law of Independent Assortment says that alleles on different chromosomes are sorted
without any consideration to one another. (See below).
5. What are the possible gametes that are formed after a bird with the genotype LlWw goes
through meiosis?
They assort independently, so all possible combinations are LW, Lw, lW, and lw.
6. In a certain species of plant, yellow flowers (F) are dominant to blue flowers, and three leaf
clusters (L) are dominant to two leaf clusters. You mate two dihybrids together. What
percentage of the offspring would you expect to have
yellow flowers and three leaves? What percentage would
have blue flowers and two leaves?
P: FfLl x FfLl
Possible gametes for each: FL, Fl, fL, fl
F1 Results:
Yellow flowers and three leaves: 9:16 or 56%
Blue flowers and two leaves: 1:16 or 6%
7. Describe the following inheritance patterns:
 Lizards come in a wide range of colors, from pale green to very dark green and every
shade in between- Polygenic inheritance
 A species of platyhelminthes has been found that has either brown stripes, black stripes,
or both black and brown stripes simultaneously- Codominance
 You discover that male gerbils suffer from a respiratory disease far more than female
do- Sex linked traits
Biotechnology
8. What are the following biotech tools used for?
 Electrophoresis- a tool to separate molecules by size (N.B.-you should know how
electrophoresis works)
 PCR- a tool that amplifies (makes copies of) DNA molecules (N.B.-you should know how
PCR works)
 Plasmids- circular pieces of DNA, most often found in bacteria. They can be used to host
cloned DNA
Evolution
9. Describe Charles Darwin’s Theory of Natural Selection.
(i) More organisms are born than can ever survive; (ii) there is a constant struggle for life; (iii) all
organisms differ from each other, and these differences are heritable; (iv) only those organisms
best suited to the environment survive to pass their genes onto their offspring. Those least
suited die, removing their ineffective genes from the gene pool.
10. Briefly summarize the following lines of evidence that support Darwin’s theory
 Artificial Selection- humans change plants and animals over time. It circumstantially
implies that if controlled human breeding creates new forms, differential survival in the
wild could do the same.
 Fossil Evidence- evolution is slow; the only way for humans to see it is if there is a very
long record of life forms on the planet. Fossils provide this record of past life forms.
 Homologous Structures & Vestigial Structures- Homologous structures are those that are
shared by organisms who are evolutionary related. Vestigial structures are parts of an
organism that may have had a use in the past, but are now useless. They imply both
changes over time and common ancestry.
 Protein and DNA Similarities- comparing the order of bases in DNA and amino acids in
proteins between different organisms can indicate relationships. The more similar the
DNA or protein sequence, the more closely related they are.
11. What is the modern, molecular definition of evolution?
Evolution is the change in allele frequencies over time.
12. Genetic drift is evolution, but not natural selection. Define genetic drift, and give two common
forms of genetic drift.
Genetic drift is the change in allele frequency over time due to random factors, not survival of
the fittest. Two common forms are founder’s effect—a small group of organisms with an allele
frequency deferent than the original breaks away from the main group to form a new colony—
and bottlenecks—a catastrophe destroys a huge number of organisms leaving only a few
random survivors with a different allele frequency than the original population.
13. You analyze the gene pool of a certain organism. You find that the dominant allele makes up
78% of the pool.
 What is the recessive allele frequency? p=0.78, so since p+q=1 then q=0.22
 How many heterozygotes would you expect? 2pq= 2*0.78*.22= 34%
14. You are studying a population of songbirds. You find that 27% of the population is homozygous
dominant for a particular trait.
 What are the dominant and recessive allele frequencies? Given p2=0.27, so p=0.52 
q=0.48
 What percentage of the birds would you expect to be homozygous recessive?
q2=0.48*0.48= 23%
15. Describe directional, stabilizing, and disruptive selection.
Directional selection occurs when the ends of a range of traits is selected for, like the darkest
colored moths in a forest. Over time, the average color of the moths shifts to a darker color.
Stabilizing selection favors the average organisms, and selects against the extremes of the traits.
The opposite is disruptive selection, which selects against the average, favoring the extreme
ends. In extreme cases, all of the average creatures can be selected against, creating two
isolated populations of creatures (and possibly speciation).
16. Some of the most pronounced evolutionary changes are those that lead to speciation. What is
speciation?
Speciation occurs when a small group of organisms amasses so many mutations it no longer
mates with other groups; it only mates within its own group, with its own isolated gene pool. In
order for speciation to occur, the two separated groups must (i) become reproductively isolated,
and (ii) each develop unique mutations.
17. What is the difference between allopatric and sympatric speciation?
Allopatric speciation occurs when two groups of organisms become physically isolated.
Sympatric speciation occurs with pockets of organisms next to each to other; another factor
must prevent them from mating together.
18. Briefly describe three ways sympatric speciation can occur.
o
o
o
o
o
o
Ecological isolation: organisms in different niches in the same ecosystem
Temporal isolation: mating season timing changes
Behavioral isolation: changes in mating rituals
Mechanical incompatibility: sexual organs no longer “fit”
Genetic incompatibility: though egg and sperm fuse, DNA is no longer compatible and
the zygote aborts
Hybrid inferiority: groups produce offspring, but the offspring are sterile or weak
19. What is sexual selection? How does it relate to natural selection?
Sexual selection occurs when one sex (typically the female) will only select certain partners to
mate with. Selection is often based on a single characteristic, like size, strength, or possession of
a particular attribute (like the size of a peacock’s tail). Oftentimes, the selection is for only the
best partners, so only the best traits are passed onto the young, as in natural selection.
20. There are two theories that describe exactly how organisms can change over time: gradualism
and punctuated equilibrium. Describe them.
Gradualism (expressed by Darwin) says that organisms slowly change constantly over time.
Punctuated equilibrium says that organisms go through long periods with little change, then
experiences periods of rapid change when the environment changes.
Evolution of Life on Earth
21. How old is the Earth? When did life first appear?
It is estimated that the planet Earth is 4.557 billion years old. The best conjecture places the first
life forms at 4.0-3.5 billion years ago.
22. What do we believe the earliest life forms were like?
According to the concept of parsimony, the first life forms were most likely prokaryotes, the
simplest life forms. They were single celled, heterotrophic, and most likely used RNA as their
primary biomolecules because it can do all of the functions of DNA and enzymes itself.
23. What role did oxygen play in the evolution of life?
Oxygen was not present in the original atmosphere of Earth. It first appeared about 2.7 billion
years ago, as a by-product of photosynthesis, building up to high levels by 2.2 bya. High levels of
oxygen are lethal, and killed off a substantial amount of life on Earth. Eventually life evolved the
ability to protect themselves against it. Oxygen also formed the protective ozone layer that
blocks UV rays from the sun, which finally allowed life to move onto land.
Classification
24. List the taxa of the modern phylogenic scheme from most general to most specific.
Domain, Kingdom, Phylum, Class, Order, Family, Genus, Species
Domains Bacteria and Archea
25. What are the defining characteristics of members of Domain Bacteria and those of Domain
Archea?
Bacteria are prokaryotes (lacking nuclei and all membrane bound organelles). Archaea are also
prokaryotes, but they are biochemical different from bacteria (in fact, they are biochemically
similar to eukaryotes, with similar ribosomes, DNA polymerases, DNA organization, etc.).
26. Bacteria that cause disease often have capsules, pili, and flagella. What are they used for?
A capsule, or glycohalyx, is a slime coating that covers bacteria, protecting them from the
immune system or allowing them to stick to surfaces. Pili are tubes on the surface of bacteria.
They can be used to transfer DNA between different bacteria. Flagella are tail-like structures
used for swimming.
27. Describe some of the special environments Archaea can be found in.
Psychrophiles survive extreme cold; halophiles survive extreme salt concentrations; thermophiles
withstand heat; barophiles withstand high pressure; acidophiles withstand low pH.
Viruses and Prions
28. What is the difference between the lytic and lysogenic cycles?
A lytic virus infects a host cell, injects its genetic material, and then commandeers the cell’s
ribosomes to make new viral coats and DNA polymerase to make copies of the viral genome.
Eventually the cell ruptures and releases the new viruses. Lysogenic viruses insert their DNA into
the host cell’s chromosome. It remains there until the host cell is stressed, and then the viral
DNA jumps out and becomes lytic.
29. What is a retrovirus? What is reverse transcriptase used for?
A retrovirus uses RNA as its genetic material. This gives them a high mutation rate. They use
reverse transcriptase to convert their RNA genome into DNA so that the host cell can process it.
30. Why are viral infections so difficult to treat? What are vaccines?
Viruses do not have enzymes unique to them that can be targeted by antibiotics. Vaccines are
weakened, dead, or parts of viruses, bacteria, or toxic proteins that are injected into healthy
people to train their immune system to recognize the virus as a threat.
31. What is prion? What is a notorious condition it causes?
A prion is an infectious protein. It has the ability to change the tertiary structure of similar,
normal proteins into a dangerous form. Build-ups of prions can kill cells. Common disease forms
are BSE (mad cow disease) and its human form, CJD.
Protists
32. What is formal definition of a protist?
A protist is any eukaryote not a plant, animal or fungus. Functionally, they are often singlecelled eukaryotes.
33. List and describe the three major groups of protists.
The animal-like protists are protozoans. The plant-like protists are the phytoprotists. The
fungus-like protists are the mycoprotists or slime molds.
34. Why are massive groups of cells, like Volvox, classified as protists?
Seaweeds are colonies of identical, undifferentiated cells; Plants are differentiated.
35. What are some of the evolutionary advances made by protists over the prokarya?
Protists were the first eukaryotes. They start to show cellular specialization, like the
Paramecium’s digestive tract. Phytoprotists began to make multicellular colonies. Slime molds
began sexual reproduction.
Fungi
36. What is the formal definition of a fungus?
A fungus is a multicellular absorptive heterotroph with a chitin cell wall.
37. What role do the fungi play in the environment?
They are saprophytes (also called detritivores or decomposers) which break down decaying
material.
38. Describe the reproductive cycle of a common fungus. Pay attention to the haploid and diploid
stages.
39. What are the evolutionary advances of fungi over protists?
Fungi are fully differentiated, multicellular life forms that use sexual reproduction.
Plants
40. What is formal definition of a plant?
A plant is a multicellular photoautotroph with a cellulose cell wall.
41. Describe the evolutionary changes of bryophytes to tracheophytes (pteropsides) to
gymnosperms to angiosperms.
The bryophytes have no vascular systems, so are very short. They reproduce with spores.
Tracheophytes evolved vascular tubes, but still reproduce using spores. Gymnosperms evolved
seeds and wind transport of pollen to the egg. Angiosperms evolved covered, protected seeds
and double fertilization, which provides endosperm to nourish the embryo.
42. Tell how to differentiate between the two classes of angiosperms: the monocots and the dicots.
Monocots have a single cotyledon. Developmentally, they have vascular bundles arranged
randomly in the stem, parallel leaf veins, and net-like root structure. Dicots have two cotyledons.
Developmentally, they have organized vascular bundles, net-like leaf veins, and large taproots.
43. Describe the circulatory system of a plant.
Plants keep their roots hypertonic, so that water from the soil constantly osmoses inside. This is
known as root pressure. Water is drawn up the xylem to the leaves using a number of processes,
the most important being transpiration and cohesion. As water transpires, (evaporates out of
the leaves), as one molecule leaves the leaf, the hydrogen bonds that link it to other water
molecules (the cohesive force) pull adjacent molecules forward. Adhesion of the water to the
walls of the xylem also helps, preventing backflow.
44. Give the plant hormones and list their function.




Auxin: growth (elongation of the meristems)
Ethylene: ripening of fruit
Gibberellins: flowering, seed germination (major life events)
Cytokinin: stimulate cellular division
45. Describe photo-, gravi-, and thigmotropism.
Phototropism is the growth of a plant towards light (it is controlled by auxin). Gravitropism is
the growth of the root toward gravity and the stems against gravity. Thigmotropism is the
response of a plant to contact.
46. Draw the structure of a leaf cross section, and give the role of the
parts.
Cuticle: waterproof, waxy coating
Epidermis: protective outer cell layer
Palisade layer: closely packed photosynthetic cells
Vascular bundles: transport materials
Spongy layer: loosely packed photosynthetic cells, allow gas exchange
Guard cells: open/close the stomata
47. Describe the reproduction of angiosperms. Pay attention to
the diploid and haploid stages.
See adjacent diagram.
Ecology
48. Describe the layers in the environment, from the single organism to the entire planet.
Niche → population → community → ecosystem → biome → biosphere
49. Draw and explain the relevant parts of a typical
population curve.
Exponential
Phase
Carrying
Capacity
Log Phase
50. What is ecological succession? How does primary and secondary succession differ?
Ecological succession is the progression of an ecosystem from barren land to the climax
community. It starts with pioneer organisms, like lichen and moss, which can live on bare rock.
They make soil, which can support significantly larger plants (grass to shrubs to saplings to adult
trees) until the final climax community arrives. Primary succession occurs in areas with no soil,
like a newly formed volcanic island or under a receding glacier. Secondary succession occurs in
areas with existing soil, like in an area cleared by a forest fire or other natural disaster.
51. Describe three types of symbioses.
Symbioses are intimate relationships between two organisms. Mutualism is a relationship where
both organisms benefit. Commensalism is a relationship where one organism benefits and the
other is indifferent to the relationship. Parasitism is when one organism benefits while harming
the other.
52. Be able to discuss chemical cycles in nature, particularly the carbon-oxygen and the nitrogen
cycle.
--Review your notes for this—
53. Know the biomes.
-Savannah
-Chaparral
-Rain Forest
-Deciduous forest
-Desert
-Tundra
-Taiga
-Polar ice
Human Systems
54. Skeletal system. Sketch a long bone, like the femur.
Label the cartilage cap, the marrow, the spongy bone,
the compact bone, Haversian canals, and the
periosteum.
What are the roles of tendons and ligaments?
Tendons connect muscle to bone. Ligaments connect
bone to bone.
55. Muscular system. What are the three types of muscles found in the human body?
Skeletal muscle is voluntary, has striations, and many nuclei. Smooth muscle is involuntary, a
single nucleus, and makes up organs. Cardiac muscle is involuntary, striated, and with many
branches.
Sketch the actin-myosin framework inside skeletal muscle. Be able to describe at the molecular
level what happens when a muscle contracts
An impulse from a motor neuron stimulates the muscle.
The impulse causes Ca2+ to flood the cytosol of the muscle
cell. This makes the actin proteins “sticky.” ATP powers
the ratcheting of the myosin heads against the actin
backbone, causing the muscle to contract.
56. Circulatory System. Describe the components of human blood.
Blood is a mixture of various cells suspended in plasma (an isotonic fluid rich with proteins and
dissolved nutrients). These cells include red blood cells, white blood cells (aka macrophages) and
platelets.
Label the structures of the human heart.
Explain how electrical signals control a heartbeat.
An electrical impulse starts in the SA node and travels
across the atria, causing the cardiac muscle cells to
contract. This signal is picked up by the AV node, which
after a slight delay transmits an impulse through the
bundle branches and Purkinje fibers, causing the cardiac muscle cells of the ventricles to
contract.
Sketch an EKG strip. Show the contraction of atria,
ventricles, and repolarization of the ventricles.
57. Respiratory System. Label the structures in the respiratory tract.
Describe the process of breathing.
To inhale, the diaphragm contracts, creating a partial vacuum in
the chest cavity. The lungs fill with air and expand to fill the
vacuum. To exhale, the diaphragm relaxes and pushes against
the lungs, expelling the air.
58. Excretory system. Label the kidneys, ureters, bladder, and urethra.
Label the structures of the nephron: the glomerulus, Bowman’s
capsule, Loop of Henle, collecting duct.
Describe how water is reclaimed in the human kidney.
Water is reclaimed by moderating the amount of sodium chloride ions
pumped into the tissue surrounding the Loop of Henle. The more salt
and other ions present, the more water leaves the loop and is
reclaimed by nearby capillaries. To reclaim even more water, urea is
sometimes pumped from the collecting duct to make the surrounding
tissue more hypertonic so water will osmoses in. This toxic material
then reenters the loop of Henle to resume its trip out of the body.
59. Digestive system. Label the organs of the digestive tract.
Describe where the following biomolecules are digested:




Carbohydrates – salivary amylase in mouth and pancreatic
amylase in the small intestine (SI)
Lipids- mechanical digestion by bile in SI, chemical digestion by
lipase in SI
Proteins- Pepsin in stomach, trypsin and other proteases in SI
Nucleic Acids- Nucleases in the small intestine
Where are nutrients absorbed?
Nutrients are absorbed by the villi and microvilli of the small intestine.
What is the role of the large intestine?
The large intestine reclaims water.
60. Describe the three basic types of neurons.
Interneurons are found in the central nervous system, the brain and the spine. They interpret
signals from sensory neurons, which pick up stimuli from the environment, and stimulate motor
neurons, which control muscles. Sensory and motor neurons are part of the peripheral nervous
system.
61. Describe a reflex arc.
A reflex arc begins with a sensory neuron detecting a stimulus, and transmitting an impulse to an
interneuron in the spine. The interneuron interprets the signal, and if the impulse is significant
enough, it triggers a motor neuron to cause a muscle contraction to pull the body away.
62. Describe the three basic parts of the human brain.
The medulla, or brain stem, controls involuntary muscle functions like heartbeat and breathing,
and maintains homeostasis of conditions like temperature and salt levels. The cerebellum is
involved with muscle coordination and balance. It is the site of “muscle memory”. The cerebrum
is responsible for higher-order thought. It is the site of memory, learning, problem solving, and
emotion.
63. Why does the lung have alveoli, the blood vessels have capillaries, the intestines have villi, the
brain have folds, the neurons have dendrites, the kidneys have nephrons, etc.?
They all increase surface area!!!!