1. a compound that is released by cells in response to injury and in allergic and inflammatory reactions, causing contraction of smooth muscle and dilation of capillaries.

histamine

inhibits growth; closes stomata during water stress

abscisic acid

stimulates cell division by influencing the synthesis or activation of proteins required for mitosis

cytokinin

acts by increasing the plasticity of the cell wall

auxin

a gas that hastens fruit ripening

ethylene

promotes internode elongation, promotes germination of certain seeds

gibberellin

Which of the following most directly controls the flowering response in short day plants?

a. length of the light period

b. length of the dark period

c. relative amount of blue light available during the light period

d. intensity of light during the light period

e. air temperature during the dark period

b

All of the following are plant growth regulators except

a. ethylene

b. indoleacetic acid

c. abscisic acid

d. cytokinins

e. anthocyanin

e

Plants can remove harmful chemicals from the soil by the process of
a. glandular secretion by leaves.
b. CO2 activation.
c. phytoremediation.
d. fertilization.
e. root nodule formation.

c

Plants need ammonia (NH3) to:
a. build amino acids.
b. build fatty acids.
c. build micronutrients.
d. fix nitrogen.
e. deter herbivores.

a

_______________ are chemical substances produced in small quantities in one part of an organism and then transported to another part of the organism, where they bring about physiological responses.
a. Glycoproteins
b. Photosynthates
c. Hormones
d. Heat shock proteins
e. Pulvini

C

Phototropism in plants is mediated by what plant growth substance?

a. auxin

b. colchicine

c. chlorophyll

d. ethylene

e. lenticels

a

External stimuli would be received most quickly by a plant cell if the receptors for signal transduction were located in the
A) plasma membrane.
B) cytoplasmic matrix.
C) endoplasmic reticulum.
D) nuclear membrane.
E) nucleoplasm.

a

Plants growing in a partially dark environment will grow toward light in a response called phototropism. Which of the following statements is true regarding phototropism?
A) It is caused by an electrical signal.
B) One chemical involved is ethylene.
C) Auxin causes a growth increase on one side of the stem.
D) Auxin causes a decrease in growth on the side of the stem exposed to light.
E) Removing the apical meristem enhances phototropism.

C

We know from the experiments of the past that plants bend toward light because
A) they need sunlight energy for photosynthesis.
B) the sun stimulates stem growth.
C) cell expansion is greater on the dark side of the stem.
D) auxin is inactive on the dark side of the stem.
E) phytochrome stimulates florigen production.

C

We know from the experiments of the past that plants bend toward light because
A) they need sunlight energy for photosynthesis.
B) the sun stimulates stem growth.
C) cell expansion is greater on the dark side of the stem.
D) auxin is inactive on the dark side of the stem.
E) phytochrome stimulates florigen production.

B

Which of the following would NOT increase the rate of transpiration in an angiosperm?

a. morning sunshine

b. an increase in temperature from 20 to 30 degrees C

c. an increase in relative humidity

d. an increase in the water content of the soil

e. an increase in air velocity

c

The application of a paste containing auxin in low concentration near the tip of the stem of a young pea seedling growing in diffuse light would be expected to result in. a. inhibition of elongation of the stem.

b. inhibition of elongation of the root.

c. bending of the stem toward the side on which the paste had been applied.

d. bending of the stem away from the side on which the paste had been applied

e. stimulation of bud development

d

Which of the following describes the mechanism by which a plant stem grows toward light?
A) The plant seeks light in order to maximize photosynthesis.
B) Nervelike impulses stimulate contractile cells on the lighted side of the stem.
C) Cells on the dark side of the stem elongate more than those on the lighted side.
D) The plant grows into an open area where its leaves will not be shaded by competing plants.
E) The greater energy supply on the lighted side of the stem stimulates metabolism and growth on that side.

C

The LEAST effective mean of controlling pest species such as rats or roaches over a long period of time is generally to
A) limit food supplies.
B) reduce the number of potential habitats.
C) distribute pesticides throughout the habitat.
D) introduce predators of the pest.
E) introduce a disease which affects only the pest.

C

All of the following statements concerning characteristics of predator-prey relationships are correct EXCEPT:
A) A rise in the population of prey is often followed by a rise in the population of predators.
B) A rise in the population of predators is followed by a decrease in the population of prey.
C) Camouflage is an adaptation that protects prey.
D) The production of large numbers of offspring within very short periods of time ensures the survival of some prey populations.
E) The population of predators most often eliminates the population of prey.

E

Why is gas exchange more difficult for aquatic animals with gills than for terrestrial animals with lungs?
a. Water is denser than air.
b. Water contains much less O2 than air per unit volume.
c. Gills have less surface area than lungs.
d. Only A and B are correct.
e. A, B, and C are correct.

D

Which of the following is an example of countercurrent exchange?
a. the flow of blood in the dorsal vessel of an insect and that of air within its tracheae
b. the flow of water across the skin of a frog and that of blood within the ventricle of its heart
c. the flow of water across the gills of a fish and that of blood within those gills
d. the flow of air within the primary bronchi of a human and that of blood within the pulmonary veins
e. the flow of fluid out of the arterial end of a capillary and that of fluid back into the venous end of the same capillary

C

Which of the following is true of both mitochondria and chloroplasts?
(A) They are found in the cells of eukaryotic autotrophs and heterotrophs.
(B) They include stacks of membranes that absorb light.
(C) They include compartments where hydrogen ions are concentrated.
(D) They produce sugars using energy harvested in the cytoplasm.
(E) They break down sugar to produce A TP .C

C

Metabolism of which of the following molecules results in the greatest net usable energy per gram?
(A) A triglyceride
(B) A tripeptide
(C) An alpha-linked disaccharide
(D) A beta-linked disaccharide
(E) Ananabolicsteroid

A

Which of the following immune system cells is most severely depleted by HIV/AIDS ?
(A) Plasma B cells
(B) Memory B cells
(C) Helper T cells
(D) Cytotoxic ("Killer") T cells (E) Memory T cells

C

Which of the following immunogens is MOST effective as a vaccine?
A) chemically inactivated bacteria
B) dead virus
C) live virus
D) toxoid

C

a protein released by animal cells, usually in response to the entry of a virus, that has the property of inhibiting virus replication.

interferon

which of the following is true of humoral immunity but not of cell-mediated immunity?a. it is active in the early years of a person's life
b. it involves the activity of the killer T-cells
c. antigens are recognized in the lymph nodes
d. antibodies are produced in responses to antigens
e. virus-infected cells are the primary target

d

antibodies are made of

proteins

In mammalian defenses against invading pathogens, all of these are considered nonspecific defense mechanisms except

A) antimicrobial proteins.

B) mucous membranes.

C) the inflammatory response.

D) the immune system.

E) the skin.

D

An alarm substance that triggers an inflammatory reaction is

A) pyrogen.

B) thyroxine.

C) immunoglobulin.

D) adrenaline.

E) histamine.

E

What are antigens?

A) proteins that consist of two light and two heavy polypeptide chains

B) proteins found in the blood that cause foreign blood cells to clump

C) proteins embedded in B cell membranes

D) antibody-generating foreign macromolecules

E) Both A and C are correct.

D

What are plasma cells?

A) cells that produce few antibodies

B) the cells that are responsible for the phagocytosis of foreign organisms

C) immature forms of T cells

D) the effector cells of humoral immunity

E) the cells that are responsible for immunological memory

D

Which of the following cell types is responsible for initiating a secondary immune response?

A) stem cells

B) memory cells

C) macrophages

D) B cells

E) T cells

B

Which of the following is true of both T cells and B cells?

A) They are produced from stem cells of the bone marrow.

B) They produce effector cells against specific pathogens.

C) They can attack and destroy invading pathogens.

D) Both A and B are true.

E) A, B, and C are all true.

D

What attracts helper T cells to macrophages?

A) interleukins

B) lymphotoxins

C) antigens

D) interferons

E) antibodies

A

For the questions below, match the following answers with the phrase that best describes them. Each answer may be used once, more than once, or not at all.

A) cytotoxic T cells

B) delayed sensitivity T cells

C ) helper T cells

D) suppressor T cells

E) B cells

form plasma cells that give rise to antibodies

E

For the questions below, match the following answers with the phrase that best describes them. Each answer may be used once, more than once, or not at all.

A) cytotoxic T cells

B) delayed sensitivity T cells

C ) helper T cells

D) suppressor T cells

E) B cells

release cytokines, which activate B cells

C

For the questions below, match the following answers with the phrase that best describes them. Each answer may be used once, more than once, or not at all.

A) cytotoxic T cells

B) delayed sensitivity T cells

C ) helper T cells

D) suppressor T cells

E) B cells

release perforin, which causes target cells to lose their cytoplasm

A

For the questions below, match the following answers with the phrase that best describes them. Each answer may be used once, more than once, or not at all.

A) cytotoxic T cells

B) delayed sensitivity T cells

C ) helper T cells

D) suppressor T cells

E) B cells

release perforin, which causes target cells to lose their cytoplasm

C

Cell-mediated immunity is mostly the function of

A) B cells.

B) complement cells.

C) T cells.

D) cytotoxic cells.

E) erythrocyte

C

A patient can produce antibodies against some bacterial pathogens, but he does not produce antibodies against viral infections. This is probably due to a disorder in which cells of the immune system?

A) B cells

B) T cells

C) plasma cells

D) cytotoxic cells

E) macrophages

B

A polypeptide that lowers the level of glucose by increasing the permeability of the cell

insulin

an iodinated amino acid that increases the oxygen consumption and metabolic rate of nearly all cells

epinephrine

A substance produced by the alpha cells of the pancreatic islets and involved in the increase of glycogenolysis in the liver

glucagon

High levels of this hormone can suppress the body's immune system

glucocorticoids

type of cell responsible for humoral immune response

b cells

Which of the following may be a consequence of excessive secretion of parathyroid hormone?A. convulsive contractions of skeletal muscles
B. gigantism
C. loss of calcium from the blood
D. exhaustion of the immune system
E. loss of calcium from the bone

e

cells that sometimes destroy cancer cells

cytotoxic T cells

a fully differentiated B cell that produces a single type of antibody

plasma cells

a large phagocytic white blood cell with a simple oval nucleus and clear, grayish cytoplasm.

monocytes

a large phagocytic white blood cell with a simple oval nucleus and clear, grayish cytoplasm.

monocytes

1. Cell communication is critical for the function of both unicellular and multicellular eukaryotes. Which of the following is likely true of cell signaling?
   1. cell signaling uses the highest molecular weight molecules found in living cells
   2. Cell signaling has largely been replaced by other cell functions in higher mammals.
   3. Similar cell signaling pathways in diverse eukaryotes are evidence of conserved evolutionary processes.
   4. Cell signaling functions mainly during early developmental stages.

3

1. Production of ATP occurs in all of the following processes EXCEPT

(A) glycolysis

(B) electron transport system and chemiosmosis

(C) light-dependent reactions of photosynthesis

(D) light-independent reactions of photosynthesis

D

When a stimulus is applied to a receptor in the skin, an action potential is propagated along a neuron to the brain, where another signal is sent back to the muscle for a response.

Which of the following best describes what occurs when the action potential reaches a chemical synapse at the

end of an axon?

A. The action potential jumps from one axon to the next connecting axon.

B. The action potential travels through the synapse to the next connecting dendrite.

C. The action potential jumps the synapse to the next connecting dendrite.

DThe action potential causes a release of neurotransmitters that travel across the synapse.

D

Which of the following diagrams best represents hormones-activated gene expression?

A

. Which of the following representations best shows a portion of an axon at rest (before or after an action

potential)?

A

. Precise regulation of specific hormone levels is required for optimal sperm production in mammals, as summarized in the figure above. Anabolic-androgenic steroids (AAS) are synthetic variants of testosterone that are sometimes abused by persons who desire to enhance their athletic performance or alter their physique.
Assuming that AAS function in the same way as naturally occurring testosterone, it is most likely that abuse of

AAS would

A stimulate FSH secretion

B. stimulate testosterone production

C. stimulate LH secretion

D. reduce sperm production

D

1. 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 to 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.

D

Information is transmitted through the nervous system when on e neuron signals another neuron. The structure of neurons enables transmission to proceed quickly and efficiently. Which of the following diagrams correctly identifies both the structure of neurons and the directions of information flow between neurons?

D

The healthy human immune system responds to pathogens with both specific and nonspecific processes of the

following models depicts a nonspecific response?

B

a nerve cell forming part of a pathway along which impulses pass from the brain or spinal cord to a muscle or gland causing movement or release of substance

motor neuron

nerve cells within the nervous system responsible for converting external stimuli from the organism's environment into internal electrical impulses

sensory neuron

nerve cells that allow motor neurons and sensory neurons to communicate

relaty neuron

the most common neuron in the human brain

interneurons

any of the cells in the peripheral nervous system that produce the myelin sheath around neuronal axons

Schwann neuron

the membrane potential is closest to the equilibrium potential for potassium

D

The sodium gates open

A

The membrane's permeability to sodium ions is at its maximum

B

Repolarization is in progress

C

Resting potential

E

Most of the organelles in a neuron are located in the A) dendritic region. B) axon hillock. C) axon.
D) cell body. E) axon terminals.

D

For a neuron with an initial membrane potential at -70 mV, an increase in the movement of potassium ions out of that neuron's cytoplasm would result in A) depolarization of the neuron. B) hyperpolarization of the neuron.
C) the replacement of potassium ions with sodium ions. D) the replacement of potassium ions with calcium ions. E) the neuron switching on its sodium-potassium pump to restore the

B

Though the membrane of a "resting" neuron is highly permeable to potassium ions, its membrane potential does not exactly match the equilibrium potential for potassium because the neuronal membrane is A) fully permeable to sodium ions. B) slightly permeable to sodium ions. C) fully permeable to calcium ions. D) impermeable to sodium ions. E) highly permeable to chloride ions.

B

The operation of the sodium-potassium "pump" moves A) sodium and potassium ions into the cell. B) sodium and potassium ions out of the cell. C) sodium ions into the cell and potassium ions out of the cell. D) sodium ions out of the cell and potassium ions into the cell. E) sodium and potassium ions into the mitochondria.

D

The "threshold" potential of a membrane A) is the point of separation from a living from a dead neuron. B) is the lowest frequency of action potentials a neuron can produce. C) is the minimum hyperpolarization needed to prevent the occurrence of action potentials. D) is the minimum depolarization needed to operate the voltage-gated sodium and potassium channels. E) is the peak amount of depolarization seen in an action potential.

D

The surface on a neuron that discharges synaptic vesicles is the A) dendrite. B) axon hillock. C) node of Ranvier.
D) postsynaptic membrane. E) presynaptic membrane.

E

Action potentials move along axons A) more slowly in axons of large than in small diameter. B) by the direct action of acetylcholine on the axonal membrane. C) by activating the sodium-potassium "pump" at each point along the axonal membrane. D) more rapidly in myelinated than in non-myelinated axons. E) by reversing the concentration gradients for sodium and potassium ions.

D

A common feature of action potentials is that they A) cause the membrane to hyperpolarize and then depolarize. B) can undergo temporal and spatial summation. C) are triggered by a depolarization that reaches the threshold. D) move at the same speed along all axons.
E) require the diffusion of Na+ and K+ through ligand-gated channels to propagate.

C

Which of the following is/are problem(s) that had to be solved as animals increased in size?
I. Decreasing surface-to-volume ratio.
II. Increasing body temperatures.
III. Increasing basal metabolic rates.

A) I & II
B) I & III
C) II & III
D) I & II & III
E) None apply to increasing size.

B

Which of the following is an important distinction between the measurement of basal metabolic rates (BMR) and standard metabolic rates (SMR)?

A) The colder the animal the lower their SMR.
B) BMRs are performed only on ectothermic animals.
C) An organism must be actively exercising for the measurement of BMR.
D) SMRs are determined at a specific temperature.
E) The BMR for a particular animal is usually lower than that animal's SMR.

D

Consider the energy budgets for a human, an elephant, a mouse, and a python (large snake). The --?-- would have the highest total annual energy requirement, and the --?-- would have the highest energy requirement per gram of body weight.

A) elephant; mouse
B) elephant; human
C) human; mouse
D) mouse; python
E) python; mouse

A

After ingestion, the first type of macromolecule to be "digested" by enzymes in the human digestive system is

A) protein.
B) carbohydrate.
C) fat.
D) nucleic acid.
E) glucose.

B

What is the reason that fluid is forced from the bloodstream into the surrounding tissues at the arteriole end of the capillaries?

A. The osmotic pressure of the extracellular fluid is greater than that of the blood.
B. The hydrostatic (fluid) pressure of the blood is less than that of the extracellular fluid.
C. The hydrostatic (fluid) pressure of the blood is greater than the osmotic pressure of the blood.
D. The osmotic pressure of the extracellular fluid is greater than the hydrostatic pressure of the blood.
E. The osmotic pressure of the blood is greater than the hydrostatic pressure of the extracellular fluid.

C

Which of the following is a problem faced by animals as they increase in size?

A) decreasing surface-to-volume ratio
B) reproducing in aqueous environments
C) the tendency for larger bodies to be more variable in metabolic rate
D) A and B only
E) A, B, and C

A

Which statement about standard metabolic rate (SMR) and basal metabolic rate (BMR) is correct?

A) SMR measures energy use during exercise, and BMR is measured at rest.
B) SMR is a measure of metabolic rate in endotherms, and BMR is a measure of metabolic rate in ectotherms.
C) The measurement of both SMR and BMR is temperature dependent.
D) Human females have a higher BMR and a lower SMR than males.
E) Both SMR and BMR are measured in a resting, fasting, nonstressed state.

E

Which of the following is the best example of an effector's response in negative feedback?

A) an increase in body temperature resulting from shivering
B) an increase in body temperature resulting from exercise
C) an increase in body temperature resulting from exposure to the sun
D) an increase in body temperature resulting from fever
E) a decrease in body temperature resulting from shock

A

Which of the following is an example of positive feedback?

A) An increase in blood sugar concentration increases the amount of the hormone that stores sugar as glycogen.
B) A decrease in blood sugar concentration increases the amount of the hormone that converts glycogen to glucose.
C) An infant's suckling at the mother's breast increases the amount of the hormone that induces the release of milk
from the mammary glands.
D) An increase in calcium concentration increases the amount of the hormone that stores calcium in bone.
E) A decrease in calcium concentration increases the amount of the hormone that releases calcium from bone.

C

How does positive feedback differ from negative feedback?

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

B

The temperature difference between arterial blood and venous blood near the goose's body

A) is minimized by countercurrent exchange.
B) is maximized because the blood has run through very cold feet.
C) is minimized by dilation of the capillaries in the feet of the goose, allowing heat to be lost.
D) is more than the difference between the venous blood near the body and the venous blood at the feet.
E) allows the goose to lose maximum heat to the environment

A

An animal that has a high surface-area-to-volume ratio of the body, and takes in all the oxygen it needs through its outer epithelium is most likely which of the following?
(A) a fish
(B) an earthworm
(C) a mamma1
(D) an insect
(E) a snake

B

All of the following statements about neurotrans¬mitters are generally true EXCEPT:
(A) They may cause depolarization or hyperpolarization of the postsynaptic membrane.
(B) They are actively transported across the synaptic cleft.
(C) They are released from membrane-bound packets. called vesicles.
(D) They may be enzymatically degraded at the postsynaptic membrane.
(E) They bind. to specific. receptors on the postsynaptic membrane.

B

In mammals, a decrease in body temperature results in which of the following responses?
(A) Release of thyroxine decreases the rate of metabolism.
(B) Blood vessels close to the surface of the skin constrict.
(C) Increased secretion of epinephrine restricts the amount of sugar released into the circulatory system.
(D) The adrenal glands increase the release of acetylcholine into the circulatory system.
(E) Blood vessels in deep muscles constrict so that heat is conserved.

B

Why are action potentials usually conducted in one direction?
A) The nodes of Ranvier conduct potentials in one direction.
B) The brief refractory period prevents reopening of voltage-gated Na+ channels.
C) The axon hillock has a higher membrane potential than the terminals of the axon.
D) Ions can flow along the axon in only one direction.
E) Voltage-gated

B

In transpiration, water flows up the stem of the plant through which structure

a. phloem

b. xylem

c. lenticels

d. stomata

e. Casparian strip

Xylem

Based on graphs I and II, which of the following is the best conclusion that can be reached?

A. decreases in leaf water potential are caused by increased transpiration

B. the increased rate of transpiration increases leaf water potential

C. the flow of water through the stem has no effect on leaf water potential

d. leaf stomat are closed at 10 am

A

All of the following changes would be likely to decrease the rate of transpiration at 8:00 am EXCEPT

a. causing the stomata to close

b. increasing the humidity of the atmosphere

c. increasing the water potential of the atmosphere

d increasing the water potential of the soil

D