Biology

Question 1

A student postulated that the sodium pump directly causes action potentials along neurons. Is this hypothesis reasonable?

No; action potentials result in an increased permeability of the plasma membrane to sodium.

No; the myelin sheaths of neurons prevent movement of ions across the plasma membranes of the neurons.

Yes; sodium is transported out of neurons during action potentials.

Yes; action potentials are accompanied by the hydrolysis of ATP.

Answer 1

No; action potentials result in an increased permeability of the plasma membrane to sodium.

Question 2

Presumably, hyperglycemia promotes cellular dehydration because:

glucose, as an energy source, accelerates the osmotic work performed by plasma membranes.

glucose, as an energy source, accelerates plasma membrane ion exchange pumps.

glucose molecules raise the osmotic pressure of the extracellular space.

glucose molecules are exchanged for water molecules across the plasma membrane.

Answer 2

glucose molecules raise the osmotic pressure of the extracellular space.

Question 3

You would expect to find ice in the extracellular fluid.

Which of the following parts in the frozen body of a freeze-tolerant frog would contain ice?

I. Cytoplasm

II. Blood plasma

III. Lymph

A. II only

B. III only

C. I and II only

D. II and III only

Answer 3

D. II and III only

ice in the cytoplasm (III) would be lethal because ice crystal formation within the cells disrupts structural organization

Question 4

The lipases catalyze the hydrolysis of fats and other carboxylic acid esters. The lipases illustrate the fact that:

some enzymes are molecules other than proteins.

most enzymes interact with only one specific substrate molecule.

some enzymes interact with several different substrate molecules that have similar chemical linkages.

some enzymes interact with many biologically active substrate molecules of dissimilar structures and linkages.

Answer 4

some enzymes interact with several different substrate molecules that have similar chemical linkages.

Question 5

Which of the following recombinant processes depends on the F factor plasmid?

Transformation

Transduction

Conjugation

Translocation

Answer 5

Conjugation

Question 6

What happens when you inhale?

Answer 6

Diaphragm contracts

external intercostal muscles contract

pressure is lower than atm pressure (neg pressure) which is generated by alveolar sacs

Question 7

In the macronucleus, the genes for rRNA are located extrachromosomally. This suggests that the rRNA genes are:

nonlinear.

nonfunctional.

self-replicating.

rearranged.

Answer 7

self-replicating.

this is like mtDNA

Question 8

An extra S phase occurs during amitotic division in a small macronucleus to minimize fluctuations in DNA content. This is most likely triggered by the presence of:

low concentrations of DNA in the macronucleus.

centromeres in the macronucleus.

high concentrations of DNA in the micronucleus.

mitotic enzymes in the micronucleus.

Answer 8

low concentrations of DNA in the macronucleus.

Question 9

In a mating of two Tetrahymena strains that are homozygous in their macronuclei and heterozygous in their micronuclei for a recessive gene, what percentage of the F1 generation will express the recessive phenotype?

0%

25%

50%

100%

Answer 9

25%

Question 10

The antisense molecules bind specifically to the sense mRNA.

When used as described in the passage, antisense drugs prevent:

DNA replication.

RNA transcription.

RNA translation.

cell replication.

Answer 10

RNA translation.

Question 11

Which of the following nucleotide sequences describes an antisense molecule that can hybridize with the mRNA sequence 5′-CGAUAC-3′?

5′-GCTATG-3′

5′-GCUAUG-3′

3′-GCUAUG-5′

3′-GCAUAG-5′

Answer 11

3′-GCUAUG-5′

When the RNA molecules hybridize, the antisense molecule would line up in an antiparallel fashion with the sense molecule, meaning its 3′ end would line up with the 5′ end of its complement.

Question 12

Control of heart rate, muscle coordination, and appetite is maintained by the:

hypothalamus, cerebrum, and brain stem, respectively.

brain stem, hypothalamus, and cerebrum, respectively.

cerebellum, hypothalamus, and brain stem, respectively.

brain stem, cerebellum, and hypothalamus, respectively.

Answer 12

brain stem, cerebellum, and hypothalamus, respectively.

Question 13

Sarah noted that her skin blood vessels were usually constricted to conserve body heat in the cold environment of the mountains. However, her skin blood vessels would occasionally dilate for short periods of time. What would be the most probable physiological purpose for this periodic vasodilation?

Maintain normal skin tone

Maintain sufficient oxygenation of cells

Reduce excessive blood pressure

Maintain normal muscle tone

Answer 13

Maintain sufficient oxygenation of cells

Question 14

Which of the following characteristics clearly marks fungi as eukaryotes?

They have cell walls.

They contain ribosomes.

They contain mitochondria.

They exhibit sexual reproduction.

Answer 14

They contain mitochondria.

Question 15

In mammals, which of the following events occurs during mitosis but does NOT occur during meiosis I?

Synapsis

The splitting of centromeres

The pairing of homologous chromosomes

The breaking down of the nuclear membrane

Answer 15

The splitting of centromeres

One of the key differences between mitosis and meiosis occurs during their respective anaphases. During anaphase of mitosis, sister chromatids are pulled apart at the centromeres, each becoming an independent chromosome in the two diploid daughter cells. During anaphase I of meiosis I, homologous pairs of chromosomes are separated into the two daughter cells. However, each chromosome still consists of two sister chromatids joined to each other at the centromere. It is not until anaphase II of meiosis II that the centromere is split and the sister chromatids separate.

Question 16

The Tm represents the rate of plasma filtration that just exceeds the:

rate of concentration of the substance in the glomerular filtrate.

rate of concentration of the substance in the urine.

capacity of the kidney tubules to reabsorb the substance.

capacity of the bladder to store and excrete the substance.

Answer 16

capacity of the kidney tubules to reabsorb the substance.

Question 17

The increased blood pressure resulting from the higher-than-normal concentration of ADH most likely affected the urinary output of a substance by increasing the:

glomerular filtration rate.

Tm of solutes.

water reabsorption from the tubules.

concentrating ability of the loop of Henle.

Answer 17

glomerular filtration rate.

The best answer is that increased blood pressure will affect the glomerular filtration rate, answer choice A. Tm is a characteristic that depends on the characteristics of the cells lining the renal tubules and independent of blood pressure, so answer choice B is not correct. Water resorption and concentrating ability are the same, so answer choices C and D are essentially the same. Increasing blood pressure should increase flow of fluid through the kidney system and decrease, rather than increase, water reabsorption, so these answer choices are incorrect.

Question 18

The two primary factors that normally determine the level of blood pressure are:

the blood concentration of L-NMMA and norepinephrine.

the cardiac output and the resistance to blood flow.

the blood volume and the amount of L-arginine in the diet.

the heart rate (heartbeats/minute) and the cardiac stroke volume.

Answer 18

the cardiac output and the resistance to blood flow.

Two factors that normally determine the blood pressure are the cardiac output and the resistance to blood flow. Cardiac output (stroke volume x heart rate) determines the amount of blood pumped into the system by the heart per unit time. The resistance to blood flow is primarily determined by the caliber of the small arteries, arterioles, and precapillary sphincters. Thus blood pressure equals total peripheral resistance times cardiac output, a relationship analogous to Ohm’s law for electrical circuits

Question 19

An intravenous infusion causes a sharp rise in the serum level of albumin (the major osmoregulatory protein in the blood). This will most likely cause an:

increase in the immune response.

increase in tissue albumin levels.

outflow of blood fluid to the tissues.

influx of tissue fluid to the bloodstream.

Answer 19

influx of tissue fluid to the bloodstream.

Question 20

Would an increase in the level of plasma aldosterone be expected to follow ingestion of excessive quantities of NaCl?

No; aldosterone causes Na+ reabsorption by kidney tubules.

No; aldosterone causes Na+ secretion by kidney tubules.

Yes; aldosterone causes Na+ reabsorption by kidney tubules.

Yes; aldosterone causes Na+ secretion by kidney tubules.

Answer 20

No; aldosterone causes Na+ reabsorption by kidney tubules.

Question 21

Most bacterial cells and human cells are alike in:

the ability to produce ATP via ATP synthase.

the chemical composition of their ribosomes.

their enclosure within cell walls.

the shape of the self-replicating structures that carry their DNA.

Answer 21

the ability to produce ATP via ATP synthase.

Question 22

Why do calcium supplements often include vitamin D?

Vitamin D is needed to prevent rickets.

The activated form of vitamin D stimulates the absorption of calcium into the blood.

The activated form of vitamin D enhances the action of calcitonin.

The activated form of vitamin D enhances the uptake of calcium by bone tissue.

Answer 22

The activated form of vitamin D stimulates the absorption of calcium into the blood.

Question 23

A low level of calcium in the plasma will trigger an increase of:

I. osteoclast activity.

II. parathyroid hormone.

III. vitamin C.

A. I only

B. I and II only

C. I and III only

D. II and III only

Answer 23

B. I and II only

Question 24

Under what condition would the level of calcitonin tend to increase?

When there is a dietary deficiency of calcium

When there is a dietary deficiency of vitamin D

When the level of calcium in the plasma is high

When the level of parathyroid hormone is too low

Answer 24

When the level of calcium in the plasma is high

Question 25

Two neighboring lizard populations would be considered separate species if:

one population inhabited the forest and the other lived in a field.

one population had a UV-reflective dewlap and the other did not.

they did not communicate with each other.

they did not interbreed and produce fertile offspring.

Answer 25

they did not interbreed and produce fertile offspring.

Question 26

Dewlaps that reflect UV light would evolve by natural selection only if:

individuals with UV-reflective dewlaps produced more offspring than did individuals without them.

individuals with UV-reflective dewlaps were better able to communicate than individuals without them.

individuals with UV-reflective dewlaps were less subject to predation than individuals without them.

individuals with UV-reflective dewlaps mated more frequently than did individuals without them.

Answer 26

individuals with UV-reflective dewlaps produced more offspring than did individuals without them.

Question 27

Aldosterone stimulates Na+ reabsorption by the kidneys. What changes in blood volume and pressure would be expected as a result of aldosterone deficiency?

Increased volume and increased pressure

Increased volume and decreased pressure

Decreased volume and increased pressure

Decreased volume and decreased pressure

Answer 27

Decreased volume and decreased pressure

Question 28

The sequence of events in the human menstrual cycle involves close interaction among which organs?

Hypothalamus-thyroid-ovary

Hypothalamus-pituitary-ovary

Pituitary-thyroid-ovary

Pituitary-adrenal glands-ovary

Answer 28

Hypothalamus-pituitary-ovary

Neither the thyroid gland nor the adrenal glands are particularly involved in the menstrual cycle. The hypothalamus exerts control over the pituitary hormones involved in menstruation by secreting hormone-releasing factors into the pituitary portal circulation. The gonadotropic hormones FSH and LH produced by the pituitary and the ovarian hormones estrogen and progesterone all have a role in regulating the human menstrual cycle. Therefore, close interaction among the hypothalamus, the pituitary, and the ovary is necessary for the human menstrual cycle.

Question 29

In which organelle of a eukaryotic cell is the pyrimidine uracil, as part of uridine triphosphate (UTP), incorporated into nucleic acid?

The nucleus

The Golgi bodies

The ribosomes

The endoplasmic reticulum

Answer 29

The nucleus

Question 30

Of the following tissues, which is NOT derived from embryonic mesoderm?

Circulatory

Bone

Dermal

Nerve

Answer 30

Nerve

The question asks the examinee to identify the tissue that is NOT of mesodermal origin. Of the tissues listed, the only one that does not arise from the mesoderm during embryonic development is nervous tissue (D). Nervous tissue arises developmentally from ectoderm, not mesoderm.

Question 31

Which of the following changes would NOT interfere with the repeated transmission of an impulse at the vertebrate neuromuscular junction?

Addition of a cholinesterase blocker

Addition of a toxin that blocks the release of acetylcholine

An increase in acetylcholine receptor sites on the motor end plate

Addition of a substance that binds to acetylcholine receptor sites

Answer 31

An increase in acetylcholine receptor sites on the motor end plate

Question 32

Muscles with striated fibers are the primary muscle type in:

the heart.

the uterus.

arteries and veins.

the small intestine.

Answer 32

the heart.

The question asks the examinee to identify the body organ or structure from the options listed in which the primary muscle type contains striated muscle fibers. Skeletal and cardiac muscles contain striated muscle fibers. Smooth muscles do not. Of the options listed, only A, the heart, is made of cardiac muscle and therefore has striated muscle fibers. The primary muscle type of the uterus (B), arteries and veins (C), and the small intestine (D) is smooth muscle.

Question 33

What is the net volume of fresh air that enters the alveoli each minute, assuming that the breathing rate is 10 breaths/min, the tidal volume is 800 mL/breath, and the nonalveolar respiratory system volume (dead space) is 150 mL?

65 mL

95 mL

6500 mL

7850 mL

Answer 33

6500 mL

The amount of air entering the lungs in a single breath, or tidal volume, is given as 800 mL/breath. Of that 800 mL only 650 mL reaches the alveoli per breath (800 mL of air inhaled minus 150 mL of nonalveolar respiratory volume). Therefore the net volume of air that reaches the alveoli each minute is equal to 650 mL/breath multiplied by 10 breaths/min, or 6500 mL.

Question 34

In almost all vertebrates, when the optic cup fails to develop in the embryo, the lens also fails to form. This constitutes evidence that:

the process of neurulation follows gastrulation.

the eye develops early in vertebrate morphogenesis.

cells may induce neighboring cells to differentiate.

cell differentiation is an “all or none” phenomenon

Answer 34

cells may induce neighboring cells to differentiate.

Question 35

Delayed ovulation, as a cause of tubal pregnancy, would most likely be associated with delayed secretion of which of the following hormones?

Progesterone

Estrogen

HCG

Luteinizing hormone

Answer 35

Luteinizing hormone

The question requires the examinee to identify that luteinizing hormone (D) is the hormone responsible for triggering ovulation. While the sex hormones progesterone (A) and estrogen (B) are either secreted in response to the luteinizing hormone surge or actually trigger the luteinizing hormone surge, respectively, they are not directly involved in triggering ovulation. HCG (C) is the pregnancy hormone, but it doesn’t have a role in the typical ovulatory cycle.

Question 36

Kidney failure during severe dehydration is most likely due to:

inadequate blood volume for effective filtration.

inability to produce sufficient urine.

buildup of salts in the distal tubules.

increased body temperature.

Answer 36

inadequate blood volume for effective filtration.

severe dehydration greatly reduces the volume of filtrate moving through the nephrons of the kidney. If fluid volume is too drastically reduced, the kidney will be unable to effectively do its job of filtering and maintaining homeostasis within bodily fluids.

Question 37

The posttranslational modification of some of the eukaryotic cell’s most abundant proteins is thought to affect the ability of those proteins to condense DNA into 30‑nm fibers. Given this, these proteins are most likely:

tubulins.

histones.

transcription activators.

DNA polymerase subunits.

Answer 37

histones.

Question 38

When viewing an X ray of the bones of a leg, a doctor can tell if the patient is a growing child, because the X ray shows:

cartilaginous areas in the long bones.

bone cells that are actively dividing.

the presence of haversian cells.

shorter-than-average bones.

Answer 38

cartilaginous areas in the long bones.

The question asks the examinee to identify the characteristic that differentiates growing, developing long bones from adult bones. Long bones grow via endochondral ossification, which requires cartilaginous growth plates at the ends of long bones, that thicken as cartilage and later become ossified (A). Dividing bone cells (B) and haversion canals (C) can be present in fully ossified adult bones. Some adults who are short in stature may have fully ossified long bones that are shorter than those of a developing child (D)

Question 39

A bacterium containing genes for sex pilus construction gave rise to a daughter cell lacking these genes. This most probably occurred because:

the bacterial chromosome was not completely replicated prior to cell division.

the cell membrane failed to move the replicated chromosomes apart.

copies of the plasmid containing the genes were not equally distributed to the new daughter cells.

one copy of the plasmid containing the genes was digested by a bacterial lysosome.

Answer 39

copies of the plasmid containing the genes were not equally distributed to the new daughter cells.

Question 40

At the end of his initial hospital stay, a few E. coli cells remained in the patient’s colon, even though he was taking antibiotics. These cells were most likely present because:

the antibiotics caused drug-resistance mutations to occur in the bacterial DNA.

the bacteria in the patient developed an immune reaction to the antibiotics.

the patient’s colon cells became increasingly resistant to the antibiotics during his hospitalization.

chance mutations in a few E. coli before the treatment made these cells and their descendants antibiotic-resistant.

Answer 40

chance mutations in a few E. coli before the treatment made these cells and their descendants antibiotic-resistant.

Question 41

Tests performed on the M. tuberculosis strain infecting the patient’s coworker indicated that the strain was susceptible to both ampicillin and kanamycin, and the coworker was successfully treated. Keep in mind that the patient was previously treated with the same antibiotics for an E. coli infection. The M. tuberculosis most likely survived in the patient because it had:

undergone conjugation with cells of resistant E. coli.

undergone an antibiotic-induced mutation that conferred antibiotic resistance.

reproduced more rapidly than the strain in the coworker.

adapted to its new environment by modifying its metabolism.

Answer 41

undergone conjugation with cells of resistant E. coli.

Conjugation is the direct contact (via a sex pilus) of bacteria that transfer the F factors. F factors can contain antibiotic resistance!

Question 42

Following the antibiotic treatment, the patient’s colon will be recolonized by other bacteria. The factor that will ultimately determine whether antibiotic-resistant E. coli cells will persist in the colon at this time is E. coli’s ability to:

produce more viable descendants than the other bacteria.

produce more vitamin B12 than the other bacteria.

metabolize glucose faster than the other bacteria.

cause fewer incidences of diarrhea or constipation than the other bacteria.

Answer 42

produce more viable descendants than the other bacteria.

Question 43

From which germ layer(s) do the tissues of the heart and blood vessels differentiate?

I. Ectoderm

II. Mesoderm

III. Endoderm

A II only

B III only

C I and II only

D I and III only

Answer 43

A II only

Question 44

In eukaryotes, oxidative phosphorylation occurs in the mitochondrion. The analogous structure used by bacteria to carry out oxidative phosphorylation is the:

cell wall.

ribosome.

nuclear membrane.

plasma membrane.

Answer 44

plasma membrane.

Question 45

Which organ is involved in regulation of all of the following: acid-base balance, blood pressure, water balance, and removal of nitrogen wastes?

Liver

Spleen

Kidney

Large intestine

Answer 45

Kidney

Question 46

Which of the following organelles most resembles the Golgi apparatus when an intact eukaryotic cell is viewed under the electron microscope?

Nucleolus

Mitochondrion

Plasma membrane

Smooth endoplasmic reticulum

Answer 46

Smooth endoplasmic reticulum

Question 47

Which of the following processes is LEAST directly influenced by adrenergic drugs?

Peristalsis

Secretion of digestive enzymes

Enzymatic breakdown of food molecules

Nutrient delivery to muscles and organs

Answer 47

Enzymatic breakdown of food molecules

the sympathetic nervous system ihibits both peristalsis and secretion of digestive enzymes. It also increases blood glucose concentration and causes dilation of blood vessels that supply the deep muscles and internal organs which aids in nutrient delivery

Question 48

When an AP reaches a nerve terminal, what happens?

Answer 48

It triggers the opening of Ca2+ channels. Calcium flows into the nerve terminal and this triggers a series of events that cause the vesicles containing a neurotransmitter to fuse with the plasma membrane to be released into the synapse

Question 49

If a cell’s membrane potential changes from –60mV to –70mV after treatment with an adrenergic drug, the NE receptor is most likely linked to:

a G-protein.

adenylate cyclase.

a sodium channel.

a potassium channel.

Answer 49

a potassium channel.

• 60 is sodium
• 70 is potassium which is resting potential.

Question 50

The osmotic concentration of plasma proteins in the venous side of capillaries helps reduce the amount of interstitial fluid in tissues by inducing:

passive H2O diffusion along a concentration gradient.

passive ion diffusion along an electrochemical gradient.

facilitated ion transport along an electrochemical gradient.

active H2O transport mediated by an ATP-dependent pump.

Answer 50

passive H2O diffusion along a concentration gradient.

Question 51

Capillaries in the kidney and elsewhere in the body maintain fluid homeostasis by balancing hydrostatic and osmotic pressures. Which of the following is the initial effect of a blood clot forming on the venous side of a capillary bed?

Net fluid flow in the direction of interstitial spaces will increase.

Net fluid flow in the direction of interstitial spaces will decrease.

Capillary osmotic pressure will increase.

Capillary osmotic pressure will decrease.

Answer 51

Blood flows from arteries to capillaries to veins. If blood flow is blocked on the venous side, blood will accumulate in the capillaries. Thus, hydrostatic pressure would build up in the capillaries, causing a net increase in fluid into the interstitial spaces.

Net fluid flow in the direction of interstitial spaces will increase.

Question 52

Bicarbonate ions in the blood and the dialysate are important for maintaining physiological levels of:

water.

chloride.

hydrogen ions.

glucose.

Answer 52

hydrogen ions.

Question 53

Radioactively labeled uracil is added to a culture of actively dividing mammalian cells. In which of the following cell structures will the uracil be incorporated?

Chromosomes

Ribosomes

Lysosomes

Nuclear membrane

Answer 53

Ribosomes

Uracil is a component of RNA. rRNA makes up ribosomal subunits so uracil will be found in ribosomal structures.