Positive feedback differs from negative feedback in that

Positive feedback differs from negative feedback in that

A) the effector's response increases some parameter (such as body temperature), whereas in negative feedback it can only decrease the parameter.
B) positive feedback benefits the organism, whereas negative feedback is detrimental.
C) the positive feedback's effector responses are in the same direction as the initiating stimulus rather than opposite to it.
D) positive feedback systems have only effectors, whereas negative feedback systems have only receptors.
E) positive feedback systems have control centers that are lacking in negative feedback systems.


Answer: C

Which process in the nephron is least selective?

Which process in the nephron is least selective? 

A) reabsorption
B) active transport
C) secretion
D) salt pumping by the loop of Henle
E) filtration


Answer: E

Connective tissues typically have

Connective tissues typically have 

A) many densely packed cells with direct connections between the membranes of adjacent cells.
B) a supporting material such as chondroitin sulfate.
C) relatively few cells and a large amount of extracellular matrix.
D) the ability to transmit electrochemical impulses.
E) the ability to shorten upon stimulation.


Answer: C

Antidiuretic hormone (ADH) functions at the cellular level by

Antidiuretic hormone (ADH) functions at the cellular level by 

A) causing an increase in the number of aquaporin molecules of collecting duct cells.
B) decreasing the speed at which filtrate flows through the nephron, leading to increased reabsorption of water.
C) triggering the synthesis of an enzyme that makes the phospholipid bilayer more permeable to water.
D) causing membranes to include more phospholipids that have unsaturated fatty acids.
E) stimulating the reabsorption of glucose through channel proteins.


Answer: A

Low selectivity of solute movement is a characteristic of

Low selectivity of solute movement is a characteristic of 

A) filtration from the glomerular capillaries.
B) H+ pumping to control pH.
C) secretion along the distal tubule.
D) salt pumping to control osmolarity.
E) reabsorption mechanisms along the proximal tubule.


Answer: A

A primary reason that the kidneys have one of the highest metabolic rates of all body organs is that

A primary reason that the kidneys have one of the highest metabolic rates of all body organs is that 

A) they are the body's only means of shedding excess nutrients.
B) they operate an extensive set of active-transport ion pumps.
C) they store the body's excess fats.
D) they have membranes of varying permeability to water.
E) they have an abundance of myogenic smooth muscle


Answer: B

The reason that the steroid hormone aldosterone affects only a small number of cells in the body is that

The reason that the steroid hormone aldosterone affects only a small number of cells in the body is that

A) it is unable to enter nontarget cells.
B) nontarget cells convert aldosterone to a hormone to which they do respond.
C) only its target cells contain aldosterone receptors.
D) nontarget cells destroy aldosterone before it can produce any effect.
E) only its target cells get exposed to aldosterone


Answer: C

Prolactin stimulates mammary gland growth and development in mammals and regulates salt and water balance in freshwater fish. Many scientists think that this wide range of functions indicates that prolactin

Prolactin stimulates mammary gland growth and development in mammals and regulates salt and water balance in freshwater fish. Many scientists think that this wide range of functions indicates that prolactin

A) is a nonspecific hormone.
B) interacts with many different receptor molecules.
C) is derived from two separate sources.
D) is an evolutionarily conserved hormone.
E) has a unique mechanism for eliciting its effects.


Answer: D

Ammonia

Ammonia 

A) has low toxicity relative to urea.
B) is the major nitrogenous waste excreted by insects.
C) is soluble in water.
D) can be stored in the body as a precipitate.
E) is metabolically more expensive to synthesize than urea.


Answer: C

Interstitial fluid is

Interstitial fluid is 

A) the route for the exchange of materials between blood and body cells.
B) identical to the composition of blood.
C) found only in the lumen of the small intestine.
D) the internal environment inside animal cells.
E) the fluid inside the gastrovascular cavity of Hydra.


Answer: A

Examine Figure 32.1. Near a goose's abdomen, the countercurrent arrangement of the arterial and venous blood vessels causes

Examine Figure 32.1. Near a goose's abdomen, the countercurrent arrangement of the arterial and venous blood vessels causes

A) the blood in the feet to be as warm as the blood in the abdomen.
B) the temperature at the abdomen to be less than the temperature at the feet.
C) the loss of the maximum possible amount of heat to the environment.
D) the venous blood to be as cold near the abdomen as it is near the feet.
E) the temperature difference between the contents of the two sets of vessels to be minimized.


Answer: E

Unlike most bony fishes, sharks maintain body fluids that are isoosmotic to seawater, so they are considered by many to be osmoconformers. Nonetheless, these sharks osmoregulate at least partially by

Unlike most bony fishes, sharks maintain body fluids that are isoosmotic to seawater, so they are considered by many to be osmoconformers. Nonetheless, these sharks osmoregulate at least partially by

A) monitoring dehydration at the cellular level with special gated aquaporins.
B) using their gills and kidneys to rid themselves of sea salts.
C) possessing a special adaptation that allows their cells to operate at an extraordinarily high salt concentration.
D) tolerating high urea concentrations that balance internal salt concentrations to seawater osmolarity.
E) synthesizing trimethylamine oxide, a chemical that binds and precipitates salts inside cells.


Answer: D

If a person loses a large amount of water in a short period of time, he or she may die from dehydration. ADH can help reduce water loss through its interaction with its target cells in the

If a person loses a large amount of water in a short period of time, he or she may die from dehydration. ADH can help reduce water loss through its interaction with its target cells in the

A) anterior pituitary.
B) kidney.
C) adrenal gland.
D) bladder.
E) posterior pituitary


Answer: B

Fight-or-flight reactions include activation of

Fight-or-flight reactions include activation of 

A) the thyroid gland, leading to an increase in the blood calcium concentration.
B) the anterior pituitary gland, leading to cessation of gonadal function.
C) the pancreas, leading to a reduction in the blood sugar concentration.
D) the adrenal medulla, leading to increased secretion of epinephrine.
E) the parathyroid glands, leading to increased metabolic rate.


Answer: B

During mammalian labor and delivery, the contraction of uterine muscles is enhanced by oxytocin. This is an example of

During mammalian labor and delivery, the contraction of uterine muscles is enhanced by oxytocin. This is an example of

A) a negative feedback system.
B) a hormone that is involved in a positive feedback loop.
C) signal transduction immediately changing gene expression in its target cells.
D) a hormone that acts in an antagonistic way with another hormone.
E) the key role of the anterior pituitary gland in regulating uterine contraction.


Answer: B

Compared to wetland mammals, water conservation in mammals of arid regions is enhanced by having more

Compared to wetland mammals, water conservation in mammals of arid regions is enhanced by having more

A) ureters.
B) juxtamedullary nephrons.
C) urinary bladders.
D) podocytes.
E) Bowman's capsules.


Answer: B

A human who has no access to fresh water but is forced to drink seawater instead

A human who has no access to fresh water but is forced to drink seawater instead 

A) will excrete more water molecules than taken in, because of the high load of ion ingestion.
B) will risk becoming overhydrated within 12 hours.
C) will thrive under such conditions, as long as he has lived at the ocean most of his life.
D) will find that drinking saltwater satiates his thirst.
E) will develop structural changes in the kidneys to accommodate the salt overload.


Answer: A

The thin horizontal arrows in Figure 32.1 show that

The thin horizontal arrows in Figure 32.1 show that 

A) the goose's legs get progressively warmer as the blood moves away from the abdomen to the feet.
B) the warmer arterial blood can bypass the legs as needed, when the legs are too cold to function well.
C) the warmer venous blood transfers heat to the cooler arterial blood.
D) the arterial blood is always cooler in the abdomen, compared to the temperature of the venous blood in the feet of the goose.
E) the warmer arterial blood transfers heat to the cooler venous blood.


Answer: E

Excretory structures known as protonephridia are present in

Excretory structures known as protonephridia are present in 

A) cnidarians.
B) earthworms.
C) vertebrates.
D) insects.
E) flatworms.


Answer: E

The nitrogenous waste that requires the most energy to produce is

The nitrogenous waste that requires the most energy to produce is 

A) urea.
B) uric acid.
C) ammonia.
D) ammonium.


Answer: B

The nourishment, insulation, and support for neurons is the result of activity by the

The nourishment, insulation, and support for neurons is the result of activity by the 

A) intercalated disks.
B) glial cells.
C) adipose tissue.
D) endocrine system.
E) smooth muscles.


Answer: B

Blood is best classified as connective tissue because

Blood is best classified as connective tissue because 

A) its cells are separated from each other by an extracellular matrix.
B) its cells can move from place to place.
C) it is found within all the organs of the body.
D) it is contained in vessels that "connect" different parts of an organism's body.
E) it contains more than one type of cell.


Answer: A

For hormones that homeostatically regulate cellular functions,

For hormones that homeostatically regulate cellular functions, 

A) the circulating level of a hormone is held constant through a series of positive feedback loops.
B) endocrine organs release their contents into the bloodstream via specialized ducts.
C) it is impossible to also have neural regulation of that system.
D) negative feedback typically regulates hormone secretion.
E) both lipid-soluble hormones and water-soluble hormones bind to intracellular protein receptors.


Answer: D

Urea is produced in the

Urea is produced in the 

A) liver from NH3 and CO2.
B) kidneys from glycerol and fatty acids.
C) bladder from uric acid and H2O.
D) liver from glycogen.
E) kidneys from glucose.


Answer: A

Increased ADH secretion is likely after

Increased ADH secretion is likely after 

A) drinking lots of pure water.
B) ingestion of ethanol (drinking alcoholic drinks).
C) eating a small sugary snack.
D) sweating-induced dehydration increases plasma osmolarity.
E) blood pressure is abnormally high.


Answer: D

The body's reaction to PTH (parathyroid hormone), a reduction in plasma levels of calcium, can be opposed by

The body's reaction to PTH (parathyroid hormone), a reduction in plasma levels of calcium, can be opposed by

A) thyroxine.
B) calcitonin.
C) growth hormone.
D) epinephrine.
E) glucagon.


Answer: B

Portal blood vessels connect two capillary beds found in the

Portal blood vessels connect two capillary beds found in the 

A) hypothalamus and thalamus.
B) hypothalamus and anterior pituitary.
C) posterior pituitary and thyroid gland.
D) anterior pituitary and posterior pituitary.
E) anterior pituitary and adrenal gland.


Answer: B

The osmoregulatory/excretory system of a freshwater flatworm is based on the operation of

The osmoregulatory/excretory system of a freshwater flatworm is based on the operation of 

A) protonephridia.
B) metanephridia.
C) ananephredia.
D) Malpighian tubules.
E) nephrons.


Answer: A

The body's automatic tendency to maintain a constant and optimal internal environment is termed

The body's automatic tendency to maintain a constant and optimal internal environment is termed 

A) physiological chance.
B) static equilibrium.
C) estivation.
D) homeostasis.
E) balanced equilibrium.


Answer: D

Muscles are joined to bones by

Muscles are joined to bones by 

A) loose connective tissue.
B) spindle fibers.
C) tendons.
D) ligaments.
E) Haversian systems.


Answer: C

A cell with membrane-bound proteins that selectively bind a specific hormone is called that hormone's

A cell with membrane-bound proteins that selectively bind a specific hormone is called that hormone's

A) secretory cell.
B) plasma cell.
C) endocrine cell.
D) regulatory cell.
E) target cell.


Answer: E

The osmolarity of human urine

The osmolarity of human urine 

A) can be four times as great as the normal osmolarity of human plasma.
B) is always greater than the plasma osmolarity.
C) is determined primarily by the concentration of glucose.
D) is always exactly equal to the plasma osmolarity.
E) is always less than the plasma osmolarity.


Answer: A

Juxtamedullary nephrons can concentrate salt effectively in the renal medulla because of their long

Juxtamedullary nephrons can concentrate salt effectively in the renal medulla because of their long 

A) Bowman's capsules.
B) loops of Henle.
C) glomeruli.
D) distal convoluted tubules.
E) proximal convoluted tubules.


Answer: B

Most types of communication between cells utilize

Most types of communication between cells utilize 

A) the exchange of cytosol between the cells.
B) the release of chemical signals by the cell sending the message.
C) the movement of the cells.
D) the exchange of DNA between the cells.
E) a direct electrical connection between the cells.


Answer: B

The hypothalamus

The hypothalamus 

A) secretes tropic hormones that act directly on the gonads.
B) functions only as an endocrine target, by having lots of receptors on its cells.
C) does not have any hormone receptors on its cells.
D) includes neuronal cells that terminate in the posterior pituitary.
E) functions only in neuronal transmission.


Answer: D

Abnormally reduced somatic growth (dwarfism) can be a consequence of decreased hormone secretion from the

Abnormally reduced somatic growth (dwarfism) can be a consequence of decreased hormone secretion from the

A) adrenal gland.
B) pancreas.
C) anterior pituitary gland.
D) kidneys.
E) posterior pituitary gland.


Answer: C

All hormones

All hormones 

A) are lipid-soluble molecules.
B) are protein molecules.
C) are carried to target cells in the blood.
D) elicit the same biological response from all of their target cells.
E) are produced by endocrine glands.


Answer: C

In animals, nitrogenous wastes are produced mostly from the catabolism of

In animals, nitrogenous wastes are produced mostly from the catabolism of 

A) phospholipids and glycolipids.
B) triglycerides and steroids.
C) starch and cellulose.
D) proteins and nucleic acids.
E) fatty acids and glycerol.


Answer: D

In a positive-feedback system where hormone A alters the amount of protein X,

In a positive-feedback system where hormone A alters the amount of protein X, 

A) a decrease in A always produces an increase in X, which results in an increase in A.
B) it is impossible to predict how A and X affect each other.
C) an increase in A always produces an increase in X, which results in an increase in A.
D) an increase in X always produces a decrease in A, which results in a decrease in X.
E) a decrease in X always causes a decrease in A, which causes an increase in X.


Answer: C

Coordinating body functions via chemical signals is accomplished by

Coordinating body functions via chemical signals is accomplished by 

A) the respiratory system.
B) the endocrine system.
C) the integumentary system.
D) the excretory system.
E) the immune and lymphatic systems.


Answer: B

Fibroblasts secrete

Fibroblasts secrete 

A) calcium phosphate for bone.
B) chondroitin sulfate.
C) fats.
D) proteins for connective fibers.
E) interstitial fluids.



Answer: D

In humans, the transport epithelial cells in the ascending loop of Henle

In humans, the transport epithelial cells in the ascending loop of Henle 

A) have 50% of their cell mass made of smooth endoplasmic reticulum.
B) are not in contact with interstitial fluid.
C) are the largest epithelial cells in the body.
D) have plasma membranes of low permeability to water.
E) are not affected by high levels of nitrogenous wastes.


Answer: D

The type of muscle tissue surrounding internal organs, other than the heart, is

The type of muscle tissue surrounding internal organs, other than the heart, is 

A) smooth muscle.
B) cardiac muscle.
C) skeletal muscle.
D) striated muscle.
E) intercalated cells.


Answer: A

Ammonia is likely to be the primary nitrogenous waste in living conditions that include

Ammonia is likely to be the primary nitrogenous waste in living conditions that include 

A) a moist system of burrows, such as those of naked mole rats.
B) lots of seawater, such as a bird living in a marine environment.
C) lots of fresh water flowing across the gills of a fish.
D) a terrestrial environment, such as that supporting crickets.
E) lots of seawater, such as the environment of a marine mammal (e.g., a polar bear).


Answer: C

Compared to the seawater around them, most marine invertebrates are

Compared to the seawater around them, most marine invertebrates are 

A) hypoosmotic.
B) isoosmotic.
C) hyperosmotic.
D) hyperosmotic and isoosmotic.
E) hypoosmotic and isosmotic.


Answer: B

Among the following choices, the most concentrated urine is excreted by

Among the following choices, the most concentrated urine is excreted by 

A) desert tortoises.
B) frogs.
C) birds.
D) kangaroo rats.
E) humans.


Answer: D

The necropsy (postmortem analysis) of a freshwater fish that died after being placed accidentally in saltwater would likely show that

The necropsy (postmortem analysis) of a freshwater fish that died after being placed accidentally in saltwater would likely show that

A) high amounts of salt had diffused into the fish's cells, causing them to swell and lyse.
B) the kidneys were not able to keep up with the water removal necessary in this hyperosmotic environment, creating an irrevocable loss of homeostasis.
C) loss of water by osmosis from cells in vital organs resulted in cell death and organ failure.
D) brain cells lysed as a result of increased osmotic pressure in this hyperosmotic environment, leading to death by loss of autonomic function.
E) the gills became encrusted with salt, resulting in inadequate gas exchange and a resulting asphyxiation.



Answer: C

With its abundance of collagenous fibers, cartilage is an example of

With its abundance of collagenous fibers, cartilage is an example of 

A) adipose tissue.
B) connective tissue.
C) reproductive tissue.
D) nervous tissue.
E) epithelial tissue.



Answer: B

The osmoregulatory/excretory system of an earthworm is based on the operation of

The osmoregulatory/excretory system of an earthworm is based on the operation of 

A) metanephridia.
B) ananephredia.
C) protonephridia.
D) nephrons.
E) Malpighian tubules.


Answer: A

You have in your possession a microscope slide with meiotic cells on it and a light microscope. What would you look for if you wanted to identify metaphase I cells on the slide?

You have in your possession a microscope slide with meiotic cells on it and a light microscope. What would you look for if you wanted to identify metaphase I cells on the slide?

A) a visible nuclear envelope
B) separated sister chromatids at each pole of the cell
C) tetrads lined up at the center of the cell
D) a synaptonemal complex
E) a cleavage furrow



Answer: C

The process is preceded by replication of the DNA.

The process is preceded by replication of the DNA.

A. The statement is true for mitosis only.
B. The statement is true for meiosis I only.
C. The statement is true for meiosis II only.
D. The statement is true for mitosis and meiosis I.
E. The statement is true for mitosis and meiosis II.



Answer: D

Independent assortment of chromosomes occurs

Independent assortment of chromosomes occurs

A. The statement is true for mitosis only.
B. The statement is true for meiosis I only.
C. The statement is true for meiosis II only.
D. The statement is true for mitosis and meiosis I.
E. The statement is true for mitosis and meiosis II.


Answer: B

Centromeres uncouple and chromatids are separated from each other.

Centromeres uncouple and chromatids are separated from each other.

A. The statement is true for mitosis only.
B. The statement is true for meiosis I only.
C. The statement is true for meiosis II only.
D. The statement is true for mitosis and meiosis I.
E. The statement is true for mitosis and meiosis II.


Answer: E

A cell divides to produce two daughter cells that are genetically identical.

A cell divides to produce two daughter cells that are genetically identical.

A. The statement is true for mitosis only.
B. The statement is true for meiosis I only.
C. The statement is true for meiosis II only.
D. The statement is true for mitosis and meiosis I.
E. The statement is true for mitosis and meiosis II.


Answer: A

Which of the following is true of the process of meiosis?

Which of the following is true of the process of meiosis?

A) Two diploid cells result.
B) Four diploid cells result.
C) Four haploid cells result.
D) Four autosomes result.
E) Four chiasmata result.


Answer: C

Which of the following happens at the conclusion of meiosis I?

Which of the following happens at the conclusion of meiosis I?

A) Homologous chromosomes are separated.
B) The chromosome number is conserved.
C) Sister chromatids are separated.
D) Four daughter cells are formed.
E) The sperm cells elongate to form a head and a tail end.



Answer: A

Centromeres of sister chromatids uncouple and chromatids separate.

I. prophase I II. metaphase I
III. anaphase I IV. telophase I V. prophase II VI. metaphase II
VII. anaphase II
VIII. telophase II

Centromeres of sister chromatids uncouple and chromatids separate.

A) II
B) III
C) IV
D) V
E) VI


Answer: E

Synapsis of homologous pairs occurs; crossing over may occur.

I. prophase I V. prophase II
II. metaphase I VI. metaphase II
III. anaphase I VII. anaphase II
IV. telophase I VIII. telophase II

Synapsis of homologous pairs occurs; crossing over may occur.

A) I
B) II
C) IV
D) VI
E) VII


Answer: A

Which of the following terms belongs with the words synapsis, tetrads, and chiasmata?

Which of the following terms belongs with the words synapsis, tetrads, and chiasmata?

A) haploid
B) crossing over
C) autosomes
D) prophase II
E) fertilization


Answer: B

How do cells at the completion of meiosis compare with cells that have replicated their DNA and are just about to begin meiosis?

How do cells at the completion of meiosis compare with cells that have replicated their DNA and are just about to begin meiosis?

A) They have twice the amount of cytoplasm and half the amount of DNA.
B) They have half the number of chromosomes and half the amount of DNA.
C) They have the same number of chromosomes and half the amount of DNA.
D) They have half the number of chromosomes and one-fourth the amount of DNA.
E) They have half the amount of cytoplasm and twice the amount of DNA.


Answer: D

After telophase I of meiosis, the chromosomal makeup of each daughter cell is

After telophase I of meiosis, the chromosomal makeup of each daughter cell is

A) diploid, and the chromosomes are composed of a single chromatid.
B) diploid, and the chromosomes are composed of two sister chromatids.
C) haploid, and the chromosomes are composed of a single chromatid.
D) haploid, and the chromosomes are composed of two sister chromatids.
E) tetraploid, and the chromosomes are composed of two sister chromatids



Answer: D

Which of these statements is false?

Which of these statements is false?

A) In humans, each of the 22 maternal autosomes has a homologous paternal chromosome.
B) In humans, the 23rd pair, the sex chromosomes, determines whether the person is female (XX) or male (XY).
C) Single, haploid (n) sets of chromosomes in ovum and sperm unite during fertilization, forming a diploid (2n), single-celled zygote.
D) At sexual maturity, ovaries and testes produce diploid gametes by meiosis.
E) Sexual life cycles differ with respect to the relative timing of meiosis and fertilization


Answer: D

In animals, meiosis results in gametes, and fertilization results in

In animals, meiosis results in gametes, and fertilization results in

A) spores.
B) gametophytes.
C) zygotes.
D) sporophytes.
E) clones


Answer: C

Eukaryotic sexual life cycles show tremendous variation. Of the following elements, which do all sexual life cycles have in common?

Eukaryotic sexual life cycles show tremendous variation. Of the following elements, which do all sexual life cycles have in common?

I. alternation of generations
II. meiosis
III. fertilization
IV. gametes
V. spores



A) I, IV, and V
B) I, II, and IV
C) II, III, and IV
D) II, IV, and V
E) all of the above



Answer: C

Which of the following is the term for a human cell that contains 22 pairs of autosomes and two X chromosomes?

Which of the following is the term for a human cell that contains 22 pairs of autosomes and two X chromosomes?

A) an unfertilized egg cell
B) a sperm cell
C) a male somatic cell
D) a female somatic cell
E) both A and D


Answer: D

The human X and Y chromosomes are

The human X and Y chromosomes are

A) both present in every somatic cell of males and females alike.
B) of approximately equal size.
C) almost entirely homologous, despite their different names.
D) called "sex chromosomes" because they determine an individual's sex.
E) all of the above


Answer: D

How do the two members of a pair of homologous chromosomes differ from each other?

How do the two members of a pair of homologous chromosomes differ from each other?

A) their length
B) the identity and relative position of the genes present on each of the chromosomes
C) their staining patterns
D) the position of the centromere within each of the chromosomes
E) the precise sequence of the DNA within each of the chromosomes



Answer: E

Which of the following statements about genes is incorrect?

Which of the following statements about genes is incorrect?

A) Genes correspond to segments of DNA.
B) Many genes contain the information needed for cells to synthesize enzymes and other proteins.
C) During fertilization, both the sperm and the ovum contribute genes to the resulting fertilized egg.
D) Under normal circumstances, each chromosome contains precisely one gene.
E) Genetic differences can result from changes in the DNA called mutations.


Answer: D

What is a genome?

What is a genome?

A) the complete complement of an organism's genes
B) a specific sequence of polypeptides within each cell
C) a specialized polymer of four different kinds of monomers
D) a specific segment of DNA that is found within a prokaryotic chromosome
E) an ordered display of chromosomes arranged from largest to smallest



Answer: A

Which of the following is (are) true concerning cyclin-dependent kinase (Cdk)?

Which of the following is (are) true concerning cyclin-dependent kinase (Cdk)?

A) Cdk is inactive, or "turned off," in the presence of cyclin.
B) Cdk is present throughout the cell cycle.
C) Cdk is an enzyme that attaches phosphate groups to other proteins.
D) Both A and B are true.
E) Both B and C are true.


Answer: E

Which of the following is true concerning cancer cells?

Which of the following is true concerning cancer cells?

A) They do not exhibit density-dependent inhibition when growing in culture.
B) When they stop dividing, they do so at random points in the cell cycle.
C) They are not subject to cell cycle controls.
D) B and C only
E) A, B, and C



Answer: E

Nerve and muscle cells are in this phase

Nerve and muscle cells are in this phase

A. G0
B. G1
C. S
D. G2
E. M


Answer: A

The "restriction point" occurs here.

The "restriction point" occurs here.

A. G0
B. G1
C. S
D. G2
E. M


Answer: B

Triggers the cell's passage past the G2 checkpoint into mitosis

Triggers the cell's passage past the G2 checkpoint into mitosis

A. PDGF
B. MPF
C. protein kinase
D. cyclin
E. Cdk


Answer: B

A protein maintained at constant levels throughout the cell cycle that requires cyclin to become catalytically active

A protein maintained at constant levels throughout the cell cycle that requires cyclin to become catalytically active

A. PDGF
B. MPF
C. protein kinase
D. cyclin
E. Cdk


Answer: E

A protein synthesized at specific times during the cell cycle that associates with a kinase to form a catalytically active complex

A protein synthesized at specific times during the cell cycle that associates with a kinase to form a catalytically active complex

A. PDGF
B. MPF
C. protein kinase
D. cyclin
E. Cdk


Answer: D

A general term for enzymes that activate or inactivate other proteins by phosphorylating them

A general term for enzymes that activate or inactivate other proteins by phosphorylating them

A. PDGF
B. MPF
C. protein kinase
D. cyclin
E. Cdk


Answer: C

What causes the decrease in the amount of cyclin at a specific point in the cell cycle?

What causes the decrease in the amount of cyclin at a specific point in the cell cycle?

A) an increase in production once the restriction point is passed
B) the cascade of increased production once its protein is phosphorylated by Cdk
C) the changing ratio of cytoplasm to genome
D) its destruction by a process initiated by the activity of MPF complexes
E) the binding of PDGF to receptors on the cell surface


Answer: D

Cells that are in a nondividing state are in which phase?

Cells that are in a nondividing state are in which phase?

A) G0
B) G2
C) G1
D) S
E) M



Answer: A

If mammalian cells receive a go-ahead signal at the G1 checkpoint, they will

If mammalian cells receive a go-ahead signal at the G1 checkpoint, they will

A) move directly into telophase.
B) complete the cycle and divide.
C) exit the cycle and switch to a nondividing state.
D) show a drop in MPF concentration.
E) complete cytokinesis and form new cell walls.


Answer: B

The somatic cells derived from a single-celled zygote divide by which process?

The somatic cells derived from a single-celled zygote divide by which process?

A) meiosis
B) mitosis
C) replication
D) cytokinesis alone
E) binary fission


Answer: B

Measurements of the amount of DNA per nucleus were taken on a large number of cells from a growing fungus. The measured DNA levels ranged from 3 to 6 picograms per nucleus. In which stage of the cell cycle was the nucleus with 6 picograms of DNA?

Measurements of the amount of DNA per nucleus were taken on a large number of cells from a growing fungus. The measured DNA levels ranged from 3 to 6 picograms per nucleus. In which stage of the cell cycle was the nucleus with 6 picograms of DNA?

A) G0
B) G1
C) S
D) G2
E) M



Answer: D

Movement of the chromosomes during anaphase would be most affected by a drug that

Movement of the chromosomes during anaphase would be most affected by a drug that

A) reduces cyclin concentrations.
B) increases cyclin concentrations.
C) prevents elongation of microtubules.
D) prevents shortening of microtubules.
E) prevents attachment of the microtubules to the kinetochore.


Answer: D

Which of the following is false regarding the bacterial chromosome?

Which of the following is false regarding the bacterial chromosome?

A) It consists of a single, circular DNA molecule.
B) DNA replication begins at the origin of replication.
C) Its centromeres uncouple during metaphase of mitosis.
D) It is highly folded within the cell.
E) It has genes that control binary fission



Answer: C

During which phases of mitosis are chromosomes composed of two chromatids?

During which phases of mitosis are chromosomes composed of two chromatids?

A) from interphase through anaphase
B) from G1 of interphase through metaphase
C) from metaphase through telophase
D) from anaphase through telophase
E) from G2 of interphase through metaphase



Answer: E

The correct sequence of steps in the M phase of the cell cycle is

The correct sequence of steps in the M phase of the cell cycle is

A) prophase, prometaphase, metaphase, anaphase, telophase.
B) prophase, metaphase, prometaphase, anaphase, telophase.
C) prophase, prometaphase, metaphase, anaphase, telophase, cytokinesis.
D) prophase, metaphase, anaphase, telophase, cytokinesis.
E) cytokinesis, telophase, prophase, prometaphase, metaphase, anaphase.


Answer: C

Chromosomes first become visible during ________ of mitosis.

Chromosomes first become visible during ________ of mitosis.

A) prometaphase
B) telophase
C) prophase
D) metaphase
E) anaphase


Answer: C

Which of the following organisms does not reproduce cells by mitosis and cytokinesis?

Which of the following organisms does not reproduce cells by mitosis and cytokinesis?

A) cow
B) bacterium
C) mushroom
D) cockroach
E) banana tree


Answer: B

How do the daughter cells at the end of mitosis and cytokinesis compare with their parent cell when it was in G1 of the cell cycle?

How do the daughter cells at the end of mitosis and cytokinesis compare with their parent cell when it was in G1 of the cell cycle?

A) The daughter cells have half the amount of cytoplasm and half the amount of DNA.
B) The daughter cells have half the number of chromosomes and half the amount of DNA.
C) The daughter cells have the same number of chromosomes and half the amount of DNA.
D) The daughter cells have the same number of chromosomes and the same amount of DNA.
E) The daughter cells have the same number of chromosomes and twice the amount of DNA.



Answer: D

Regarding mitosis and cytokinesis, one difference between higher plants and animals is that in plants

Regarding mitosis and cytokinesis, one difference between higher plants and animals is that in plants

A) the spindles contain microfibrils in addition to microtubules, whereas animal spindles do not contain microfibrils.
B) sister chromatids are identical, but they differ from one another in animals.
C) a cell plate begins to form at telophase, whereas animals a cleavage furrow is initiated at that stage.
D) chromosomes become attached to the spindle at prophase, whereas in animals chromosomes do not become attached until anaphase.
E) spindle poles contain centrioles, whereas spindle poles in animals do not.



Answer: C

Cytokinesis usually, but not always, follows mitosis. If a cell completed mitosis but not cytokinesis, the result would be a cell with

Cytokinesis usually, but not always, follows mitosis. If a cell completed mitosis but not cytokinesis, the result would be a cell with

A) a single large nucleus.
B) high concentrations of actin and myosin.
C) two abnormally small nuclei.
D) two nuclei.
E) two nuclei but with half the amount of DNA.


Answer: D

All of the following occur during mitosis except the

All of the following occur during mitosis except the

A) condensing of chromosomes until they become visible.
B) uncoupling of chromatids at the centromere.
C) formation of a spindle.
D) synthesis of DNA.
E) disappearance of the nucleolus


Answer: D

All of the following occur during prophase of mitosis in animal cells except

All of the following occur during prophase of mitosis in animal cells except

A) the centrioles move toward opposite poles.
B) the nucleolus can no longer be seen.
C) the nuclear envelope disappears.
D) chromosomes are duplicated.
E) the spindle is organized.



Answer: D

A cell containing 92 chromatids at metaphase of mitosis would, at its completion, produce two nuclei containing how many chromosomes each?

A cell containing 92 chromatids at metaphase of mitosis would, at its completion, produce two nuclei containing how many chromosomes each?

A) 12
B) 16
C) 23
D) 46
E) 92



Answer: D

If cells in the process of dividing are subjected to colchicine, a drug that interferes with the functioning of the spindle apparatus (its de-polymerization) which stage will mitosis be arrested?

If cells in the process of dividing are subjected to colchicine, a drug that interferes with the functioning of the spindle apparatus (its de-polymerization) which stage will mitosis be arrested?

A) anaphase
B) prophase
C) telophase
D) metaphase
E) interphase



Answer: D

Centromeres uncouple, sister chromatids are separated, and the two new chromosomes move to opposite poles of the cell.

Centromeres uncouple, sister chromatids are separated, and the two new chromosomes move to opposite poles of the cell.

A. telophase
B. anaphase
C. prometaphase
D. metaphase
E. prophase



Answer: B

This is the longest of the mitotic stages

This is the longest of the mitotic stages

A. telophase
B. anaphase
C. prometaphase
D. metaphase
E. prophase



Answer: D

Centrioles begin to move apart in animal cells.

Centrioles begin to move apart in animal cells.

A. telophase
B. anaphase
C. prometaphase
D. metaphase
E. prophase



Answer: E

Two centrosomes are arranged at opposite poles of the cell.

Two centrosomes are arranged at opposite poles of the cell.

A. telophase
B. anaphase
C. prometaphase
D. metaphase
E. prophase



Answer: C

If there are 20 chromatids in a cell, how many centromeres are there?

If there are 20 chromatids in a cell, how many centromeres are there?

A) 10
B) 20
C) 30
D) 40
E) 80



Answer: A

The centromere is a region in which

The centromere is a region in which

A) chromatids are attached to one another.
B) metaphase chromosomes become aligned.
C) chromosomes are grouped during telophase.
D) the nucleus is located prior to mitosis.
E) new spindle microtubules form.



Answer: A

Chromosomes become visible during

Chromosomes become visible during

A) metaphase.
B) prophase.
C) interphase.
D) prometaphase.
E) anaphase.



Answer: B

Signal transduction pathways benefit cells for all of the following reasons except

Signal transduction pathways benefit cells for all of the following reasons except

A) they help cells respond to signal molecules that are too large or too polar to cross the plasma membrane.
B) they enable different cells to respond appropriately to the same signal.
C) they help cells use up phosphate generated by ATP breakdown.
D) they can amplify a signal.
E) variations in the signal transduction pathways can enhance response specificity.



Answer: C

The cleavage of glycogen by glycogen phosphorylase releases ________.

The cleavage of glycogen by glycogen phosphorylase releases ________.

A) glucose-1-phosphate
B) cellulose
C) galactose-1-phosphate
D) fructose-1-phosphate
E) nothing; glycogen phosphorylase cannot cleave glycogen



Answer: A

A(n) ________ is an example of a signal molecule that can bind to an intracellular receptor and thereby cause a gene to be turned on or off.

A(n) ________ is an example of a signal molecule that can bind to an intracellular receptor and thereby cause a gene to be turned on or off.

A) ion
B) protein
C) carbohydrate
D) nucleic acid
E) steroid



Answer: E

Which example below is a protein that can hold several other relay proteins as it binds to an activated membrane receptor?

Which example below is a protein that can hold several other relay proteins as it binds to an activated membrane receptor?

A) active transcription factor
B) third messenger
C) ligand
D) scaffolding protein
E) protein kinase



Answer: D

The response of a particular cell to a signal depends on

The response of a particular cell to a signal depends on

A) its particular collection of signal receptor proteins.
B) its relay proteins.
C) the proteins needed to carry out the response.
D) A and B only
E) A, B, and C



Answer: E