AP BIOLOGY TESTBANK QUESTIONS
WITH 100% CORRECT ANSWERS
Which of the following best explains why a population is described as the evolutionary
unit?
a. Genetic changes can occur only at the population level.
b. The gene pool in a population remains fixed over time.
c. Natural selection affects individuals, not populations.
d. Individuals cannot evolve, but populations can. - Answer- D. Populations can be
described as the evolutionary unit because changes in the genetic makeup of
populations can be measured over time. Eliminate A, as genetic changes occur only at
the individual level. Only under Hardy-Weinberg equilibrium does the gene pool remain
fixed over time in population. However, this statement does not explain why the
population is the evolving unit, so B is incorrect. C is true but does not answer the
question.
The endocrine system maintains homeostasis using many feedback mechanisms.
Which of the following is an example of positive feedback?
a. Infant suckling causes a mother's brain to release oxytocin, which in turn stimulates
milk production.
b. An enzyme is allosterically inhibited by the product of the reaction it catalyzes.
c. When ATP is abundant, the rate of glycolysis decreases.
d. When blood sugar levels decrease to normal after a meal, insulin is no longer
secreted. - Answer- A. Positive feedback occurs when a stimulus causes an increased
response. B,C,D are examples of negative feedback.
Insulin is a protein hormone that is secreted in response to elevated blood glucose
levels. When insulin binds to its receptors on liver cells, the activated receptors
stimulate phosphorylation cascades that cause the translocation of glucose transporters
to the plasma membrane. Based on the information provided, which of the following
best describes the role of insulin in this liver cell signal transduction pathway?
(A) It acts as a ligand.
(B) It acts as a receptor.
(C) It acts as a secondary messenger.
(D) It acts as a protein kinase - Answer- A. Cells communicate over short distances by
using local regulators that target cells in the vicinity of the signal-emitting cell — a.
Signals released by one cell type can travel long distances to target cells of another cell
type.
Humans have a diploid number ("2n" ) of 46. Which of the following statements best
predicts the consequence if meiosis did not occur during gametogenesis?
, (A) The gametes would get larger from one generation to the next. (B) The chromosome
number would double with each generation.
(C) The chromosome number would be halved with each generation. (D) The
chromosome number would triple with each generation. - Answer- B. Meiosis is a
process that ensures the formation of haploid gamete cells in sexually reproducing
diploid organisms— a. Meiosis results in daughter cells with half the number of
chromosomes of the parent cell. b. Meiosis involves two rounds of a sequential series of
steps (meiosis I and meiosis II).
Mutations in the MYO6 and POU4F3 genes have been associated with a form of
hereditary hearing loss in humans. Researchers studying the genes have proposed that
POU4F3 encodes a transcription factor that influences the regulation of MYO6. Which
of the following questions will best help guide the researchers toward a direct test of
their proposal?
(A) Have mutations in other genes also been associated with hearing loss?
(B) In what types of cells are the mutant forms of the POU4F3 gene expressed?
(C) Are mutations in the MYO6 and POU4F3 genes also found in mice?
(D) Do mutations in the POU4F3 gene affect MYO6 mRNA levels in cells? - Answer- D.
Promoters are DNA sequences upstream of the transcription start site where RNA
polymerase and transcription factors bind to initiate transcription. Negative regulatory
molecules inhibit gene expression by binding to DNA and blocking transcription.
It is estimated that oxygen production first evolved in photosynthetic prokaryotes
approximately 2.7 billion years ago. The first photosynthetic prokaryotes are presumed
to be similar to today's cyanobacteria.
Which of the following best supports the claim that photosynthetic prokaryotes were
responsible for the oxygen in Earth's atmosphere?
(A) The light reactions of photosynthesis split carbon dioxide into carbon and oxygen.
(B) The light reactions of photosynthesis split water into hydrogen ions and oxygen.
(C) The Calvin cycle splits glucose into carbon, hydrogen, and oxygen.
(D) The Calvin cycle splits water into hydrogen ions and oxygen. - Answer- B. releases
energy in glucose to form ATP from ADP and inorganic phosphate, NADH from NAD+,
and pyruvate. Pyruvate is transported from the cytosol to the mitochondrion, where
further oxidation occurs.
In the Krebs cycle, carbon dioxide is released from organic intermediates, ATP is
synthesized from ADP and inorganic phosphate, and electrons are transferred to the
coenzymes NADH and FADH2.
Electrons extracted in glycolysis and Krebs cycle reactions are transferred by NADH
and FADH2 to the electron transport chain in the inner mitochondrial membrane.
When electrons are transferred between molecules in a sequence of reactions as they
pass through the ETC, an electrochemical gradient of protons (hydrogen ions) across
the inner mitochondrial membrane is established. Fermentation allows glycolysis to
proceed in the absence of oxygen and produces organic molecules, including alcohol
and lactic acid, as waste products.
The conversion of ATP to ADP releases energy, which is used to power many metabolic
processes.
WITH 100% CORRECT ANSWERS
Which of the following best explains why a population is described as the evolutionary
unit?
a. Genetic changes can occur only at the population level.
b. The gene pool in a population remains fixed over time.
c. Natural selection affects individuals, not populations.
d. Individuals cannot evolve, but populations can. - Answer- D. Populations can be
described as the evolutionary unit because changes in the genetic makeup of
populations can be measured over time. Eliminate A, as genetic changes occur only at
the individual level. Only under Hardy-Weinberg equilibrium does the gene pool remain
fixed over time in population. However, this statement does not explain why the
population is the evolving unit, so B is incorrect. C is true but does not answer the
question.
The endocrine system maintains homeostasis using many feedback mechanisms.
Which of the following is an example of positive feedback?
a. Infant suckling causes a mother's brain to release oxytocin, which in turn stimulates
milk production.
b. An enzyme is allosterically inhibited by the product of the reaction it catalyzes.
c. When ATP is abundant, the rate of glycolysis decreases.
d. When blood sugar levels decrease to normal after a meal, insulin is no longer
secreted. - Answer- A. Positive feedback occurs when a stimulus causes an increased
response. B,C,D are examples of negative feedback.
Insulin is a protein hormone that is secreted in response to elevated blood glucose
levels. When insulin binds to its receptors on liver cells, the activated receptors
stimulate phosphorylation cascades that cause the translocation of glucose transporters
to the plasma membrane. Based on the information provided, which of the following
best describes the role of insulin in this liver cell signal transduction pathway?
(A) It acts as a ligand.
(B) It acts as a receptor.
(C) It acts as a secondary messenger.
(D) It acts as a protein kinase - Answer- A. Cells communicate over short distances by
using local regulators that target cells in the vicinity of the signal-emitting cell — a.
Signals released by one cell type can travel long distances to target cells of another cell
type.
Humans have a diploid number ("2n" ) of 46. Which of the following statements best
predicts the consequence if meiosis did not occur during gametogenesis?
, (A) The gametes would get larger from one generation to the next. (B) The chromosome
number would double with each generation.
(C) The chromosome number would be halved with each generation. (D) The
chromosome number would triple with each generation. - Answer- B. Meiosis is a
process that ensures the formation of haploid gamete cells in sexually reproducing
diploid organisms— a. Meiosis results in daughter cells with half the number of
chromosomes of the parent cell. b. Meiosis involves two rounds of a sequential series of
steps (meiosis I and meiosis II).
Mutations in the MYO6 and POU4F3 genes have been associated with a form of
hereditary hearing loss in humans. Researchers studying the genes have proposed that
POU4F3 encodes a transcription factor that influences the regulation of MYO6. Which
of the following questions will best help guide the researchers toward a direct test of
their proposal?
(A) Have mutations in other genes also been associated with hearing loss?
(B) In what types of cells are the mutant forms of the POU4F3 gene expressed?
(C) Are mutations in the MYO6 and POU4F3 genes also found in mice?
(D) Do mutations in the POU4F3 gene affect MYO6 mRNA levels in cells? - Answer- D.
Promoters are DNA sequences upstream of the transcription start site where RNA
polymerase and transcription factors bind to initiate transcription. Negative regulatory
molecules inhibit gene expression by binding to DNA and blocking transcription.
It is estimated that oxygen production first evolved in photosynthetic prokaryotes
approximately 2.7 billion years ago. The first photosynthetic prokaryotes are presumed
to be similar to today's cyanobacteria.
Which of the following best supports the claim that photosynthetic prokaryotes were
responsible for the oxygen in Earth's atmosphere?
(A) The light reactions of photosynthesis split carbon dioxide into carbon and oxygen.
(B) The light reactions of photosynthesis split water into hydrogen ions and oxygen.
(C) The Calvin cycle splits glucose into carbon, hydrogen, and oxygen.
(D) The Calvin cycle splits water into hydrogen ions and oxygen. - Answer- B. releases
energy in glucose to form ATP from ADP and inorganic phosphate, NADH from NAD+,
and pyruvate. Pyruvate is transported from the cytosol to the mitochondrion, where
further oxidation occurs.
In the Krebs cycle, carbon dioxide is released from organic intermediates, ATP is
synthesized from ADP and inorganic phosphate, and electrons are transferred to the
coenzymes NADH and FADH2.
Electrons extracted in glycolysis and Krebs cycle reactions are transferred by NADH
and FADH2 to the electron transport chain in the inner mitochondrial membrane.
When electrons are transferred between molecules in a sequence of reactions as they
pass through the ETC, an electrochemical gradient of protons (hydrogen ions) across
the inner mitochondrial membrane is established. Fermentation allows glycolysis to
proceed in the absence of oxygen and produces organic molecules, including alcohol
and lactic acid, as waste products.
The conversion of ATP to ADP releases energy, which is used to power many metabolic
processes.
