300 ❯ STEP 5. Build Your Test-Taking Confidence
- D—Habituation is the loss of responsiveness to
unimportant stimuli or stimuli that do not provide
appropriate feedback. This is a prime example of
habituation. - A—Directional selection occurs when members
of a population at one end of a spectrum are
selected against, while those at the other end are
selected for. Taller giraffes are being selected for;
shorter giraffes are being selected against. - A—When interbreeding ceases because some
sort of barrier separates a single population into
two (an area with no food, a mountain, etc.), the
two populations evolve independently, and if
they change enough, then, even if the barrier is
removed, they cannot interbreed. This is allopatric
speciation. - D—Chapter 19, despite being last, is a very
important chapter. The experiments are very well
represented on the AP Biology exam, and you
should read this chapter carefully and learn how to
design and interpret experiments. - C
- A
- D
- B—The endosymbiotic theory proposes that
mitochondria and chloroplasts evolved through
the symbiotic relationship between prokaryotic
organisms. - D—Fibroblast growth factoris said to be involved,
but fibroblast cells are not. - D—Posttranscriptional modification actually
occurs in the nucleus. - C—Genetic drift is a change in allele frequen-
cies that is due to chance events. When drift
dramaticallyreduces population size, it is called
a “bottleneck.” - A—Neutrophils are phagocytic cells of the
immune system. They roam the body looking
for rubbish to clear. - C—Only photosystem I is involved in the cyclic
reactions. Photosystem II is not. - A—Genetics has no memory... it will be 1 ⁄ 2
forever. - A—DNA migrates from a negative charge to a
positive charge. The rest are true. - B—0.04 = q^2. Therefore, the square root of
0.04=q=0.20 and p+q=1. So p+0.20=1.
Therefore,p=0.80, and 2pqis the frequency
of the heterozygote condition: 2(0.20)(0.80) =
0.320=32 percent. - C—Phytochrome is an important pigment to
the process of flowering. Of its two forms, the
active form, Pfr, is responsible for the production
of the hormone florigen, which is thought to
assist in the blooming of flowers. - D—Secondary carnivores > primary carnivores >
primary consumers = herbivores > primary
producers. - C—The example to know is the cattle egrets that
feast on insects aroused into flight by cattle graz-
ing in the insects’ habitat. The birds benefit
because they get food, but the cattle do not appear
to benefit at all. - B—Conjugation is the sexual reproduction of
bacteria. - B—In competitive inhibition, an inhibitor mol-
ecule resembling the substrate binds to the active
site and physically blocks the substrate from
attaching. - C—The other four are the four main factors that
can affect enzyme efficiency. - B—The activation energy of a reaction is the
amount of energy needed for the reaction to
occur. Notice that the activation energy for the
enzymatic reaction is much lower than the
nonenzymatic reaction. - D
- B
❯ Answers and Explanations for Practice Exam 2
PART A: MULTIPLE-CHOICE QUESTIONS