AP BIOLOGY 2019/2020 WINTER ASSIGNMENT Q&A
Winter Break MCQ HOMEWORK
1 | P a g e
Directions: Each of the questions or incomplete statements below is followed by four suggested answers or
completions. Select the one that is best in each case and then fill in the corresponding circle on the answe...
winter break mcq homework 1 | p a g e directions each of the questions or incomplete statements below is followed by four suggested answers or completio
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AP BIOLOGY Page |1
Winter Break MCQ HOMEWORK
Directions: Each of the questions or incomplete statements below is followed by four suggested answers or
completions. Select the one that is best in each case and then fill in the corresponding circle on the answer sheet.
1. In mammals, an increase in the concentration 3.
of sodium in the blood triggers the release of
antidiuretic hormone (ADH) from the pituitary
gland. As the concentration of sodium in the
blood returns to previous levels, the release of
ADH from the pituitary gland is reduced.
Based on the information presented, which of the
following describes the most likely role of
ADH in maintaining blood osmolarity?The
enzyme’s active site binds to and stabilizes the
substrate that are similar in shape and structure
to glucose.
(A) ADH promotes an increase in the movement
of sodium into the bloodstream.
(B) ADH promotes an increase in the movement
of water in the bloodstream.
(C) ADH promotes an increase in the excretion of
water from the body.
(D) ADH promotes an increase in the secretion of
additional ADH from the pituitary gland.
2. A cell is treated with a drug that prevents the
formation of new lysosomes. The cell
continues to transcribe the genes that code for The p53 protein regulates a cellular response to DNA
the hydrolytic enzymes that are normally damage. Based on the diagram above, which
found in lysosomes and continues to translate of the following best describes the role of p53
the mRNAs for those proteins on membrane- in the response to DNA damage?
bound ribosomes. The hydrolytic enzymes are
most likely to accumulate in which of the (A) Phosphorylated p53 binds to DNA and repairs
following cellular structures? the damage.
(A) Nucleus (B) Phosphorylated p53 stimulates transcription of
(B) Mitochondrion p21, and the resulting p21 protein suppresses
(C) Smooth endoplasmic reticulum cell division until the DNA damage is
(D) Golgi complex. repaired.
(C) Phosphorylated p53 binds cyclin-Cdk
complexes, and the resulting protein complex
repairs the DNA damage.
(D) Phosphorylated p53 activates p21 proteins and
the p21 proteins in turn repair the DNA
damage.
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4. The diagram above illustrates feedback control as exerted by the hormone thyroxine. Following surgical
removal of the thyroid gland, the level of TSH in the blood will increase. Which of the following best explains
this increase?
(A) Residual blood thyroxine, from prior to thyroid gland removal, will bind ot cells in the anterior pituitary,
signaling more TSH secretion.
(B) Thyroxine will remain bound to thyroxine receptors on various body cells, and these body cells will secrete
additional hormones that stimulate the anterior pituitary to secrete TSH.
(C) Thyroxine that was stored in the anterior pituitary prior to thyroid gland removal will signal more TSH
secretion
(D) A decrease in thyroxine levels means a loss of inhibition to the hypothalamus and anterior pituitary, leading to
increased TSH secretion.
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5. The figure above shows a model of a ligand precursor being cleaved to produce an active ligand that binds to a
specific receptor. Which of the following is most likely to reduce the binding of the active ligand to its receptor?
(A) A change in the cytoskeletal attachment of transmembrane proteins
(B) The presence of a large amount of the precursor form of the ligand
(C) An increase in the ratio of the number of unsaturated to the number of saturated fatty acid tails of the membrane
lipids
(D) A mutation in the receptor gene that causes a substitution of a charged amino acid for a nonpolar amino acid in
the ligand binding site of the receptor
6. The illustration above depicts a neuromuscular junction of a patient with an autoimmune disorder.
Acetylcholine is a stimulatory neurotransmitter. Which of the following would be the most likely result of the
continued presence of the antibody?
(A) An increase in action potentials in the motor neuron and constant nerve pain
(B) A decrease in action potentials in the muscle, causing muscle weakness and fatigue.
(C) A decrease in the opening of sodium-gated channels in the muscle, causing less sodium to be released from the
muscle
(D) An increase in the opening of sodium-gated channels in the motor neuron because of the accumulation of
acetylcholine in the junction
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7. Paramecia are unicellular protists that have contractile vacuoles to remove excess intracellular water. In an
experimental investigation, paramecia were placed in salt solutions of increasing osmolarity. The rate at which
the contractile vacuole contracted to pump out excess water was determined and plotted against osmolarity of
the solutions, as shown in the graph. Which of the following is the correct explanation for the data?
(A) At higher osmolarity, lower rates of contraction are required because more salt diffuses into the paramecia.
(B) The contraction rate increases as the osmolarity decreases because the amount of water entering the paramecia
by osmosis increases.
(C) The contractile vacuole is less efficient in solutions of high osmolarity because of the reduced amount of ATP
produced from cellular respiration.
(D) In an isosmotic salt solution, there is no diffusion of water into or out of the paramecia, so the contraction rate is
zero.
8. A human kidney filters about 200 liters of blood each day. Approximately two liters of liquid and nutrient waste
are excreted as urine. The remaining fluid and dissolved substances are reabsorbed and continue to circulate
throughout the body. Antidiuretic hormone (ADH) is secreted in response to reduced plasma volume. ADH
targets the collecting ducts in the kidney, stimulating the insertion of aquaporins into their plasma membranes
and an increased reabsorption of water. If ADH secretion is inhibited, which of the following would initially
result?
(A) The number of aquaporins would increase in response to the inhibition of ADH.
(B) The person would decrease oral water intake to compensate for the inhibition of ADH.
(C) Blood filtration would increase to compensate for the lack of aquaporins.
(D) The person would produce greater amounts of dilute urine.
9. Researchers claimed that a particular organelle originated from a free-living prokaryotic cell that was engulfed
by a larger cell, as shown in Figure 1.
Figure 1. A model showing a cell engulfing a smaller cell.
Which of the following provides evidence to best support the researchers’ claim?
(A) The organelle has a phospholipid membrane
(B) The organelle has protein in the membrane
(C) The organelle has a double membrane.
(D) The organelle as an internal environments that is similar to the cytosol of the larger cell.
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