Bio 104-Exam 3

Single-celled Paramecium live in pond water (a hypotonic environment relative to the cytosol). They have a structural feature, a contractile vacuole, which enables them to osmoregulate. If sucrose or saline was added to the pond water in different concentrations (in millimolars, mM), under which conditions would you expect the contractile vacuole to be most active?(A) 0.0 mM sucrose (B) 0.05 mM saline (C) 0.08 mM sucrose (D) 1.0 mM saline

(A) 0.0 mM sucrose

Filtration takes place in the structure labeled ________. (A) A (B) B (C) C (D) E

(A) A

Osteoporosis is a condition in which the density of bones is decreased so much that the individual is at a higher risk of fractures. The more calcium in the bones, the better the bone density. Which of the following would produce the greatest increase in bone calcium levels? (A) calcitonin injection (B) calcitonin receptor blocker (C) parathyroid hormone injection (D) glucagon receptor blocker

(A) calcitonin injection

Oxytocin and antidiuretic hormone (ADH) are synthesized in the ________ but released from the ________. (A) hypothalamus; posterior pituitary (B) adenohypophysis; posterior pituitary (C) posterior pituitary; anterior pituitary (D) hypothalamus; anterior pituitary

(A) hypothalamus; posterior pituitary

Compared to wetland mammals, water conservation in mammals of arid regions is enhanced by having more ________. (A) juxtamedullary nephrons (B) urinary bladders (C) ureters (D) podocytes

(A) juxtamedullary nephrons

Rapid changes to skin color in many vertebrates is under the control of ________. (A) melanocyte-stimulating hormone (B) adrenocorticotropic hormone (C) thyroxine (D) melatonin

(A) melanocyte-stimulating hormone

Phytochrome plays a critical role in seed germination. Which of the colors maximizes the seed germination? (A) red (B) blue (C) violet (D) orange

(A) red

Selective secretion of toxins and drugs takes place in the structure labeled ________. (A) A (B) B (C) C (D) D

(B) B

A cluster of tumor cells that produces and secretes growth factors to induce surrounding cells to grow and divide is showing which type of cell-to-cell signaling? (A) autocrine (B) paracrine (C) endocrine (D) neuroendocrine

(B) paracrine

Removing which of the following glands would have the most wide-reaching effect on bodily functions of an adult human? (A) adrenal glands (B) pituitary gland (C) thyroid gland (D) ovaries (in female) or testes (in male)

(B) pituitary gland

In a lactating mammal, the two hormones that promote milk synthesis and milk release, respectively, are ________. (A) prolactin and calcitonin (B) prolactin and oxytocin (C) follicle-stimulating hormone and luteinizing hormone (D) luteinizing hormone and oxytocin

(B) prolactin and oxytocin

After blood flow is artificially reduced at one kidney, you would expect that kidney to secrete more of the hormone known as ________. (A) angiotensinogen (B) renin (C) antidiuretic hormone (D) atrial natriuretic peptide

(B) renin

Put the steps of the process of signal transduction in the order they occur. 1. A conformational change in the signal-receptor complex activates an enzyme. 2. Protein kinases are activated. 3. A signal molecule binds to a receptor. 4. Target proteins are phosphorylated. 5. Second messenger molecules are released. (A) 1, 2, 3, 4, 5 (B) 3, 1, 2, 4, 5 (C) 3, 1, 5, 2, 4 (D) 1, 2, 5, 3, 4

(C) 3, 1, 5, 2, 4

Mammalian eyes sense light because the photoreceptor cells have molecules called opsins, which change structure when exposed to light. Which of the following plant molecules would be analogous to mammalian opsins in their light-sensing ability? (A) auxin and phytochrome (B) auxin and Pfr (C) Pfr and phytochrome (D) cytokinins and phototropins

(C) Pfr and phytochrome

If a portion of the pancreas is surgically removed from a rat and the rat subsequently loses its appetite, one explanation is that the removed portion contains cells that secrete a chemical signal that somehow stimulates appetite. Given this scenario, what type of chemical signaling is occurring? (A) autocrine (B) paracrine (C) endocrine (D) neuroendocrine

(C) endocrine

A cell with membrane-bound proteins that selectively bind a specific hormone is called that hormone's ________. (A) secretory cell (B) endocrine cell (C) target cell (D) regulatory cell

(C) target cell

Which of the following environmental factors can be sensed by plants? I) gravity II) pathogens III) wind IV) light (A) only I and III (B) only I, II, and IV (C) only II, III, and IV (D) I, II, III, and IV

(D) I, II, III, and IV

Polypeptides can have which of the following types of effects? I) autocrine II) paracrine III) endocrine (A) only I and III (B) only II and III (C) only I and II (D) I, II, and III

(D) I, II, and III

Testosterone is an example of a chemical signal that affects the very cells that synthesize it, the neighboring cells in the testis, along with distant cells outside the gonads. Thus, testosterone is an example of ________. I) an autocrine signal II) a paracrine signal III) an endocrine signal (A) only I and II (B) only II and III (C) only I and III (D) I, II, and III

(D) I, II, and III

The body's reaction to parathyroid hormone (PTH), raising plasma levels of calcium, can be opposed by ________. (A) thyroxine (B) epinephrine (C) growth hormone (D) calcitonin

(D) calcitonin

Osmoregulatory adjustment via the atrial natriuretic peptide system can be triggered by ________. (A) sleeping for one hour (B) severe sweating on a hot day (C) eating a pizza with olives and pepperoni (D) drinking several glasses of water

(D) drinking several glasses of water

If a person loses a large amount of water in a short period of time, he or she may die from dehydration. Antidiuretic hormone (ADH) can help reduce water loss through its interaction with its target cells in the ________. (A) anterior pituitary (B) posterior pituitary (C) bladder (D) kidney

(D) kidney

Which of the following statements are correct? I) Hormones often regulate homeostasis through antagonistic functions. II) Hormones of the same chemical class usually have the same function. III) Hormones are secreted by specialized cells usually located in exocrine glands. IV) Hormones are often regulated through feedback loops. (A) only II and III (B) only I and III (C) only III and IV (D) only I and IV

(D) only I and IV

Following a stressful stimulus, the fight-or-flight response will cause ________. (A) glucose to be stored in liver cells (B) epinephrine to be released from the anterior pituitary (C) an increase release of thyroid hormones (D) the breakdown of glycogen into glucose

(D) the breakdown of glycogen into glucose

Which of the following has both endocrine and exocrine activity? (A) the pituitary gland (B) parathyroid glands (C) salivary glands (D) the pancreas

(D) the pancreas

Antidiuretic hormone (ADH) and the renin-angiotensin-aldosterone system (RAAS) work together in maintaining osmoregulatory homeostasis through which of the following ways? A) ADH regulates the osmolarity of the blood by altering renal reabsorption of water, and the RAAS maintains the osmolarity of the blood by stimulating both Na+ and water reabsorption. B) ADH and the RAAS work antagonistically; ADH stimulates water reabsorption during dehydration, and the RAAS causes increased excretion of water when it is in excess in body fluids. C) Both stimulate the adrenal gland to secrete aldosterone, which increases both blood volume and pressure via its receptors in the urinary bladder. D) ADH and the RAAS combine at the receptor sites of proximal tubule cells, where reabsorption of essential nutrients takes place.

A) ADH regulates the osmolarity of the blood by altering renal reabsorption of water, and the RAAS maintains the osmolarity of the blood by stimulating both Na+ and water reabsorption.

You may have observed plants rotate towards a light source, thereby increasing the plant's ability to intercept light energy and increase photosynthesis. You, however, are given the task of preventing grass seedlings from rotating toward the light. Using your knowledge of phototropism, which of the following experimental procedures would you use to complete your task? A) Cover the growing tip of the grass seedling with black paper. B) Supply the seedlings with very dim light (red light does not induce a bend). C) Cover the portion of the seedling below the tip with a black shield. D) Supply the seedling with nutrient-rich fertilizer solution.

A) Cover the growing tip of the grass seedling with black paper.

Like other osmoregulatory animals that live in marine environments, sharks maintain tissue concentrations of sodium, potassium, and chloride that are hypoosmotic to the seawater. In contrast to the bony marine fishes, however, sharks do not need to drink seawater. Why? A) High urea and trimethylamine oxide concentrations keep shark tissues slightly hyperosmotic relative to seawater, so water is absorbed passively. B) Sodium, chloride, and potassium do not influence water balance in shark tissues. C) Shark blood is hypotonic to the surrounding tissues, so water always moves passively into the tissue from the blood. D) Sharks excrete large quantities of salt through their gills in exchange for water

A) High urea and trimethylamine oxide concentrations keep shark tissues slightly hyperosmotic relative to seawater, so water is absorbed passively.

How does the toxin of Vibrio cholerae cause profuse diarrhea? A) It modifies a G protein involved in regulating salt and water secretion. B) It modifies adenylyl cyclase and triggers excess formation of cAMP. C) It signals IP3 to act as a second messenger for the release of calcium. D) It modifies a ligand-gated ion channel.

A) It modifies a G protein involved in regulating salt and water secretion.

If an animal cell suddenly lost the ability to produce GTP, what might happen to its signaling system? A) It would not be able to activate G proteins on the cytoplasmic side of the plasma membrane. B) It would be able to carry out reception and transduction but would not be able to respond to a signal. C) It would use ATP instead of GTP to activate G proteins on the cytoplasmic side of the plasma membrane. D) It would not be able to activate receptor tyrosine kinases.

A) It would not be able to activate G proteins on the cytoplasmic side of the plasma membrane.

In which of the following ways do plant hormones differ from hormones in animals? A) Plant hormones frequently travel through the air as a gas. B) Animal hormones are only local regulators. C) Plant hormones commonly travel through the soil from one plant to another. D) Animal hormones typically travel from the hormone producing cell to an adjacent responding cell through gap junctions.

A) Plant hormones frequently travel through the air as a gas.

Not all intercellular signals require transduction. Which one of the following signals would be processed without transduction? A) a lipid-soluble signal B) a signal that is weakly bound to a nucleotide C) a signal that binds to a receptor in the cell membrane D) a signal that binds to the extracellular matrix

A) a lipid-soluble signal

Consider this pathway: epinephrine → G protein-coupled receptor → G protein → adenylyl cyclase → cAMP The second messenger in this pathway is ________. A) cAMP B) G protein C) adenylyl cyclase D) G protein-coupled receptor

A) cAMP

Aspirin and ibuprofen both ________. A) inhibit the synthesis of prostaglandins B) inhibit the release of nitric oxide, a potent vasodilator C) activate the paracrine signaling pathways that form blood clots D) stimulate vasoconstriction in the kidneys

A) inhibit the synthesis of prostaglandins

Urea is produced in the ________. A) liver from NH3 and carbon dioxide B) liver from glycogen C) kidneys from glycerol and fatty acids D) bladder from uric acid and water

A) liver from NH3 and carbon dioxide

What are the primary sites of auxin (IAA) production in plants? A) shoot apical meristem and young leaves B) roots C) seeds D) ripening fruits

A) shoot apical meristem and young leaves

Plant hormonal regulation differs from animal hormonal regulation in that ________. A) there are no dedicated hormone-producing organs in plants as there are in animals B) all production of hormones is local in plants with little long-distance transport C) only animal hormone concentrations are developmentally regulated D) only animal hormones may have either external or internal receptors

A) there are no dedicated hormone-producing organs in plants as there are in animals

A signal transmitted via phosphorylation of a series of proteins is generally associated with which of the following events? A) conformational changes to each protein in the series B) binding of a hormone to an intracellular receptor C) activation of a ligand-gated ion channel D) production of ATP in the process of signal transduction

A)conformational changes to each protein in the series

Which of the following statements about a G protein signaling pathway is true? A) A G protein-coupled receptor bound to GTP is in its active state. B) A G protein bound to GTP is in its active state. C) A G protein bound to GDP is in its active state. D) Hydrolysis of bound GTP by a G protein activates the G protein

B) A G protein bound to GTP is in its active state.

Which of the following statements best summarizes the acid growth hypothesis in an actively growing shoot? A) Auxin stimulates proton pumps in the plasma membrane and tonoplast. B) Auxin-activated proton pumps lower the pH of the cell wall, which breaks bonds and makes the walls more flexible. C) Auxins and gibberellins together act as a lubricant to help stretch cellulose microfibrils. D) Auxins activate aquaporins that increase turgor pressure in the cells.

B) Auxin-activated proton pumps lower the pH of the cell wall, which breaks bonds and makes the walls more flexible.

Tadpoles must undergo a major metamorphosis to become frogs. This change includes reabsorption of the tail, growth of limbs, calcification of the skeleton, increase in rhodopsin in the eye, development of lungs, change in hemoglobin structure, and reformation of the gut from the long gut of an herbivore to the short gut of a carnivore. Amazingly, all of these changes are induced by thyroxine. What is the most likely explanation for such a wide array of effects of thyroxine? A) There are many different forms of thyroxine, each specific to a different tissue. B) Different tissues have thyroxine receptors that activate different signal transduction pathways. C) Some tissues have membrane receptors for thyroxine, while other tissues have thyroxine receptors within the nucleus. D) Different releasing hormones release thyroxine to different tissues.

B) Different tissues have thyroxine receptors that activate different signal transduction pathways.

Which observation suggested to Sutherland the involvement of a second messenger in epinephrine's effect on liver cells? A) Receptor studies indicated that epinephrine was a ligand. B) Glycogen breakdown was observed only when epinephrine was administered to intact cells. C) Glycogen breakdown was observed when epinephrine and glycogen phosphorylase were combined in a cell-free system. D) Epinephrine was known to have different effects on many types of cells.

B) Glycogen breakdown was observed only when epinephrine was administered to intact cells.

Why does testosterone, a lipid-soluble signaling molecule that crosses the membranes of all cells, affect only target cells? A) Only target cells retain the appropriate genes regulated by testosterone. B) Intracellular receptors for testosterone are present only in target cells. C) Only target cells possess the cytosolic enzymes that transduce the signal from testosterone to adenylyl cyclase. D) Only in target cells is testosterone able to initiate the phosphorylation cascade leading to activated transcription factor.

B) Intracellular receptors for testosterone are present only in target cells.

What is the most likely mechanism by which testosterone functions inside a cell? A) It acts as a signal receptor that activates tyrosine kinases. B) It binds with a receptor protein that enters the nucleus and activates expression of specific genes. C) It acts as a steroid signal receptor that activates ion channel proteins in the plasma membrane. D) It coordinates a phosphorylation cascade that reduces spermatogenesis.

B) It binds with a receptor protein that enters the nucleus and activates expression of specific genes.

African lungfish, which are often found in small, stagnant pools of fresh water, produce urea as a nitrogenous waste. What is the advantage of this adaptation? A) Urea takes less energy to synthesize than ammonia. B) Small, stagnant pools do not provide enough water to dilute the toxic ammonia. C) The highly toxic urea makes the pool uninhabitable to potential competitors. D) Urea makes lungfish tissue hypoosmotic to the pool.

B) Small, stagnant pools do not provide enough water to dilute the toxic ammonia.

What does it mean to say that a signal is transduced? A) The signal enters the cell directly and binds to a receptor inside. B) The physical form of the signal changes as it passes from the cell membrane to the ultimate intracellular target. C) The signal is amplified, such that even one signal molecule evokes a large response. D) The signal triggers a sequence of phosphorylation events inside the cell.

B) The physical form of the signal changes from one form to another.

Which of the following statements is true of steroid receptors? A) The receptor molecules are themselves lipids or glycolipids. B) The receptor may be inside the nucleus of a target cell. C) The unbound steroid receptors are quickly recycled by lysosomes. D) Steroid receptors are typically bound to the external surface of the nuclear membrane.

B) The receptor may be inside the nucleus of a target cell.

Why are the renal artery and vein critical to the process of osmoregulation in vertebrates? A) The kidneys require constant and abnormally high oxygen supply to function. B) The renal artery delivers blood with nitrogenous waste to the kidney and the renal vein brings blood with less nitrogenous wastes away from the kidneys. C) The kidneys require higher than normal levels of hormones. D) The renal artery and vein are the main pathways regulating how much is produced by the kidneys.

B) The renal artery delivers blood with nitrogenous waste to the kidney and the renal vein brings blood with less nitrogenous wastes away from the kidneys.

Salmon eggs hatch in fresh water. The fish then migrate to the ocean (a hypertonic solution) and, after several years of feeding and growing, return to fresh water to breed. How can these organisms make the transition from fresh water to ocean water and back to fresh water? A) The rectal gland functions in the ocean water, and chloride cells function in fresh water. B) The salt transport mechanisms of the gill epithelia change during migration. C) Salmon in fresh water excrete concentrated urine, and salmon in salt water secrete dilute urine. D) Their metabolism changes in salt water to degrade electrolytes.

B) The salt transport mechanisms of the gill epithelia change during migration.

Which of the following statements describes a likely effect of a drug designed that inhibits the cellular response to testosterone? A) The cytoplasmic levels of cAMP would decrease. B) The transcription of certain genes would decrease. C) The cytosolic calcium concentration would increase. D) The activity of G proteins would decrease.

B) The transcription of certain genes would decrease.

Different body cells can respond differently to the same polypeptide hormones because ________. A) different target cells have different sets of genes B) a target cell's response is determined by the components of its signal transduction pathways C) the circulatory system regulates responses to hormones by routing the hormones to specific targets D) the hormone is chemically altered in different ways as it travels through the circulatory system

B) a target cell's response is determined by the components of its signal transduction pathways

Which of the colors of visible light induces curvature in coleoptile most effectively? A) red B) blue C) violet D) orange

B) blue

If a farmer wanted more loosely packed clusters of grapes, he would most likely spray the immature bunches with ________. A) auxin B) gibberellins C) cytokinins D) abscisic acid

B) gibberellins

Which of the following is the most likely explanation for hypothyroidism in a patient whose iodine level is normal? A) greater production of T3 than of T4 B) hyposecretion of thyroid-stimulating hormone (TSH) C) hypersecretion of thyrotropin-releasing hormone (TRH) D) a decrease in the thyroid secretion of calcitonin

B) hyposecretion of thyroid-stimulating hormone (TSH)

Most scientists agree that global warming is underway; thus, it is important to know how plants respond to heat stress. Which of the following would be a useful line of inquiry to try and improve plant response and survival to heat stress? A) the production of heat-stable carbohydrates B) increased production of heat-shock proteins C) the opening of stomata to increase evaporational heat loss D) protoplast fusion experiments with xerophytic plants

B) increased production of heat-shock proteins

Excretory organs known as Malpighian tubules are present in ________. A) flatworms B) insects C) jellyfish D) sea stars

B) insects

An example of antagonistic hormones controlling homeostasis is ________. A) thyroxine and parathyroid hormone in calcium balance B) insulin and glucagon in glucose metabolism C) progestins and estrogens in sexual differentiation D) epinephrine and norepinephrine in fight-or-flight responses

B) insulin and glucagon in glucose metabolism

An examination of a marine sea star that had died after it was mistakenly placed in fresh water would likely show that it died because ________. A) it was stressed and needed more time to acclimate to the new conditions B) it was so hypertonic to the fresh water that it could not osmoregulate C) its kidney had ruptured D) its cells dehydrated and lost the ability to metabolize

B) it was so hypertonic to the fresh water that it could not osmoregulate

Suppose a plant had a photosynthetic pigment that absorbed far-red wavelengths of light. In which of the following environments could that plant thrive? A) on the surface of a lake B) on the forest floor, beneath a canopy of taller plants C) on the ocean floor, in very deep waters D) on mountaintops, closer to the Sun

B) on the forest floor, beneath a canopy of taller plants

Auxins in plants are known to affect which of the following processes? I. gravitropism of shoots II. maintenance of seed dormancy III. phototropism of shoots IV. inhibition of lateral buds V. apical dominance A) only I and II B) only I, III, and V C) only I, III, IV, and V D) only II, III, IV, and V

B) only I, III, and V

Which of the following is an example of a simple endocrine pathway? A) control of metabolism by thyroid hormones B) release of secretin by cells of the duodenum in response to acid C) release of antidiuretic hormone from the posterior pituitary gland to regulate water balance D) regulation of growth by the production of growth hormone

B) release of secretin by cells of the duodenum in response to acid

The osmoregulatory process called secretion refers to the ________. A) reabsorption of nutrients from a filtrate B) selective elimination of excess ions and toxins from body fluids C) formation of an osmotic gradient along an excretory structure D) expulsion of urine from the body

B) selective elimination of excess ions and toxins from body fluids

Increased antidiuretic hormone (ADH) secretion is likely after ________. A) drinking lots of pure water B) sweating-induced dehydration increases plasma osmolarity C) eating a small sugary snack D) blood pressure becomes abnormally high

B) sweating-induced dehydration increases plasma osmolarity

Which of the following is a correct association? A) kinase activity and the addition of a tyrosine B) phosphodiesterase activity and the removal of phosphate groups C) GTPase activity and hydrolysis of GTP to GDP D) adenylyl cyclase activity and the conversion of cAMP to AMP

C) GTPase activity and hydrolysis of GTP to GDP

Correct and appropriate signal transduction processes are generally under strong selective pressure and are determined by the properties of the molecules involved, the concentrations of signal and receptor molecules, and the binding affinities between signal and receptor. Therefore, a hormone action is very specific in a species at any one point in time. However, there are examples of very diverse functions of a specific hormone between groups of organisms. For example, thyroxin, which is produced in all vertebrates and many invertebrates, can trigger growth, differentiation, metamorphosis, maturation, reproduction, behavior, temperature tolerance, osmoregulation, or seasonal adaptation depending on the organism in which it is produced. What is the most logical explanation for such different responses triggered by thyroxin in organisms? A) The concentration of thyroxin varies in different organisms. Invertebrate organisms do not have as much thyroxin as vertebrate organisms. B) Thyroxin and its receptor molecules have a different binding affinity in different organisms. C) Receptor molecules for thyroxin are located on different tissues in different organisms. D) The function of thyroxin in a particular tissue is determined by the genes that are transcribed by the activated thyroxin receptor.

C) Receptor molecules for thyroxin are located on different tissues in different organisms.

What role do transport epithelia play in osmoregulation of marine fish with bony skeletons? A) They actively transport salt into the animal through the gills. B) They mediate the movement of water from seawater through the gills. C) They are involved in excretion of excess salt. D) They allow the fish to produce dilute urine.

C) They are involved in excretion of excess salt.

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 acts in an antagonistic way with another hormone C) a hormone that is involved in a positive feedback loop D) signal transduction immediately changing gene expression in its target cells

C) a hormone that is involved in a positive feedback loop

Protein kinase is an enzyme that functions in which of the following ways? A) as a second messenger molecule B) as a receptor for various signal molecules C) activates or inactivates other proteins by adding a phosphate group to them D) activates a G protein

C) activates or inactivates other proteins by adding a phosphate group to them

Fight-or-flight reactions include activation of the ________. A) parathyroid glands, leading to increased metabolic rate B) anterior pituitary gland, leading to cessation of gonadal function C) adrenal medulla, leading to increased secretion of epinephrine D) pancreas, leading to a reduction in the blood sugar concentration

C) adrenal medulla, leading to increased secretion of epinephrine

During a stressful interval, ________. A) thyroid-stimulating hormone (TSH) stimulates the adrenal cortex and medulla to secrete acetylcholine B) increased acid in the duodenum stimulates the S cells to release secretin C) adrenocorticotropic hormone (ACTH) stimulates the adrenal cortex, and neurons of the sympathetic nervous system stimulate the adrenal medulla D) the calcium levels in the blood are increased due to actions of two antagonistic hormones, epinephrine and norepinephrine

C) adrenocorticotropic hormone (ACTH) stimulates the adrenal cortex, and neurons of the sympathetic nervous system stimulate the adrenal medulla

Phosphorylation cascades involving a series of protein kinases are useful for cellular signal transduction because they ________. A) are species specific B) always lead to the same cellular response C) amplify the original signal many times D) counter the harmful effects of phosphatases

C) amplify the original signal many times

Growth factors are local regulators that ________. A) are modified fatty acids that stimulate bone and cartilage growth B) are found on the surface of cancer cells and stimulate abnormal cell division C) bind to cell-surface receptors and stimulate growth and development of target cells D) convey messages between nerve cells

C) bind to cell-surface receptors and stimulate growth and development of target cells

In yeast signal transduction, a yeast cell releases a mating factor which ________. A) acts back on the same cell that secreted the mating factor, changing its development B) passes through the membranes of neighboring cells, binds to DNA, and initiates transcription C) binds to receptors on the membranes of other types of yeast cells D) diffuses through the membranes of distant cells, causing them to produce factors that initiate long-distance migrations

C) binds to receptors on the membranes of other types of yeast cells

To maintain homeostasis, freshwater fish must ________. A) excrete large quantities of electrolytes B) consume large quantities of water C) excrete large quantities of water D) take in electrolytes through simple diffusion

C) excrete large quantities of water

Low selectivity of solute movement is a characteristic of ________. A) H+ pumping to control pH B) reabsorption mechanisms along the proximal tubule C) filtration from the glomerular capillaries D) secretion along the distal tubule

C) filtration from the glomerular capillaries

Choose a pair that correctly associates the mechanism for osmoregulation or nitrogen removal with the appropriate animal. A) protonephridium—earthworm B) Malpighian tubule—frog C) flame bulb—flat worm D) exchange across the body surface—snake

C) flame bulb—flat worm

Which one of the following hormones stimulates stem elongation and pollen tube growth? A) auxin (IAA) B) ethylene C) gibberellins D) cytokinins

C) gibberellins

Excessive formation of uric acid crystals in humans leads to ________. A) a condition called diabetes, where excessive urine formation occurs B) a condition of insatiable thirst and excessive urine formation C) gout, a painful inflammatory disease that primarily affects the joints D) osteoarthritis, an inevitable consequence of aging

C) gout, a painful inflammatory disease that primarily affects the joints

Binding of a signaling molecule to which type of receptor leads directly to a change in the distribution of ions on opposite sides of the membrane? A) receptor tyrosine kinase B) G protein-coupled receptor C) ligand-gated ion channel D) steroid receptor

C) ligand-gated ion channel

Which of the following can function in signal transduction in plants? I. calcium ions II. nonrandom mutations III. receptor proteins IV. autochrome V. secondary messengers A) only I, III, and IV B) only I, II, and V C) only I, III, and V D) only II, III, and V

C) only I, III, and V

Which of the following is a type of local signaling in which a cell secretes a signal molecule that affects neighboring cells? A) hormonal signaling B) autocrine signaling C) paracrine signaling D) synaptic signaling

C) paracrine signaling

In animals, nitrogenous wastes are produced mostly from the catabolism of ________. A) starch and cellulose B) triglycerides and steroids C) proteins and nucleic acids D) phospholipids and glycolipids

C) proteins and nucleic acids

Which of the following mechanisms is the correct sequence of events that takes place during the plant responses to internal and external signals? A) transduction, reception, and response B) reception and transduction C) reception, transduction, and response D) reception and response

C) reception, transduction, and response

Birds secrete uric acid as their nitrogenous waste because uric acid ________. A) is readily soluble in water B) is metabolically less expensive to synthesize than other excretory products C) requires little water for nitrogenous waste disposal, thus reducing body mass D) can be reused by birds as a protein source

C) requires little water for nitrogenous waste disposal, thus reducing body mass

When a neuron responds to a particular neurotransmitter by opening gated ion channels, the neurotransmitter is serving as which part of the signal pathway? A) relay molecule B) transducer C) signal molecule D) response molecule

C) signal molecule

When a steroid hormone and a polypeptide hormone exert similar effects on a population of target cells, then ________. A) the steroid and polypeptide hormones must use the same biochemical mechanisms B) the steroid and polypeptide hormones must bind to the same receptor protein C) the steroid hormones affect the synthesis of effector proteins, whereas polypeptide hormones activate effector proteins already present in the cell D) the steroid hormones affect the activity of certain proteins within the cell, whereas polypeptide hormones directly affect the processing of mRNA

C) the steroid hormones affect the synthesis of effector proteins, whereas polypeptide hormones activate effector proteins already present in the cell

Steroid and polypeptide hormones typically have in common ________. A) the building blocks from which they are synthesized B) their solubility in cell membranes C) their requirement for travel through the bloodstream D) their reliance on signal transduction in the cell

C) their requirement for travel through the bloodstream

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) using their gills and kidneys to rid themselves of sea salts B) monitoring dehydration at the cellular level with special gated aquaporins C) tolerating high urea concentrations that are balanced with internal salt concentrations to seawater osmolarity D) synthesizing trimethylamine oxide, a chemical that binds and precipitates salts inside cells

C) tolerating high urea concentrations that are balanced with internal salt concentrations to seawater osmolarity

The detector of light during de-etiolation (greening) of a tomato plant is (are) ________. A) carotenoids B) xanthophylls C) phytochrome D) auxin

C)phytochrome

_______ prevents seeds from germinating until conditions are favorable for the growth of the plant. A) Ethylene B) Zeaxanthin C) Gibberellin D) Abscisic acid

D) Abscisic acid

Which of the following is true during a typical cAMP-mediated signal transduction event? A) The second messenger is the last part of the system to be activated. B) A hormone activates the second messenger by directly binding to it. C) The second messenger amplifies the hormonal response by attracting more hormones to the cell being affected. D) Adenylyl cyclase is activated after the hormone binds to the cell and before phosphorylation of proteins occurs.

D) Adenylyl cyclase is activated after the hormone binds to the cell and before phosphorylation of proteins occurs.

At puberty, an adolescent female body changes in both structure and function of several organ systems, primarily under the influence of changing concentrations of estrogen and other steroid hormones. How can one hormone, such as estrogen, mediate so many effects? A) Estrogen is produced in very large concentration by nearly every tissue of the body. B) Each cell responds in the same way when steroids bind to the cell surface. C) Estrogen is kept away from the surface of any cells, not able to bind it at the surface. D) Estrogen binds to specific receptors inside many kinds of cells, each with different responses.

D) Estrogen binds to specific receptors inside many kinds of cells, each with different responses.

Many plants flower in response to day-length cues. Which of the following statements best summarizes this phenomenon? A) As a rule, short-day plants flower in the summer. B) As a rule, long-day plants flower in the spring or fall. C) Long-day plants flower in response to long days, not short nights. D) Flowering in short-day and long-day plants is controlled by phytochrome.

D) Flowering in short-day and long-day plants is controlled by phytochrome.

A plant scientist was hired by a greenhouse operator to devise a way to force iris plants to bloom in the short days of winter. Iris normally blooms as a long-day (short-night) plant. Which of the following has the best chance of creating iris blooms in winter? A) Artificially increase the period of darkness in the greenhouse. B) Increase the temperature to more closely follow summer temperatures. C) Alternate four hours of darkness with four hours of light repeatedly over each 24-hour period. D) Interrupt the long winter nights with a brief period of light.

D) Interrupt the long winter nights with a brief period of light.

Which of the following statements is true of signal molecules? A) When signal molecules first bind to receptor tyrosine kinases, the receptors phosphorylate a number of nearby molecules. B) In response to some G protein-mediated signals, a special type of lipid molecule associated with the plasma membrane is cleaved to form IP3 and calcium. C) In most cases, signal molecules interact with the cell at the plasma membrane, enter the cell, and eventually enter the nucleus. D) Protein kinase A activation is one possible result of signal molecules binding to G protein-coupled receptors.

D) Protein kinase A activation is one possible result of signal molecules binding to G protein-coupled receptors.

You are dissecting a fish in your biology laboratory section. Your teaching assistant points out a long oval structure and tells you it is an endocrine gland. Which of the following would you then know is a true statement about this structure? A) It secretes a product that is released through a series of ducts. B) The gland's product will only interact with receptors on the cell membrane. C) The gland's product is lipid soluble. D) The gland produces and secretes its product into the blood.

D) The gland produces and secretes its product into the blood.

Hormones are chemical substances produced in one organ that are released into the bloodstream and affect the function of a target organ. Which of the following conditions is required for the target organ to respond to a particular hormone? A) Cells in the target organ must modify their plasma membranes to allow the hormone to enter the cytoplasm. B) The target organ must be the same as the organ that produced the hormone. C) The target organ must have the opposite mating type of the organ that produced the hormone. D) The target organ must have receptors that recognize and bind the hormone molecule.

D) The target organ must have receptors that recognize and bind the hormone molecule.

What role do phosphatases play in signal transduction pathways? A) They transfer a phosphate group from one protein in the pathway to the next molecule in the series. B) They activate protein kinases by phosphorylation. C) They amplify the second messenger cAMP. D) They inactivate protein kinases to turn off signal transduction.

D) They inactivate protein kinases to turn off signal transduction.

The transfer of fluid from the glomerulus to Bowman's capsule ________. A) results from active transport B) transfers large molecules as easily as small ones C) is very selective as to which sub-protein-sized molecules are transferred D) is mainly a consequence of blood pressure in the capillaries of the glomerulus

D) is mainly a consequence of blood pressure in the capillaries of the glomerulus

An excretory system that is partly based on the filtration of fluid under high hydrostatic pressure is the ________. A) flame-bulb system of flatworms B) protonephridia of rotifers C) Malpighian tubules of insects D) kidneys of vertebrates

D) kidneys of vertebrates

Which of the following is characteristic of juxtamedullary nephrons? A) large Bowman's capsule B) absence of proximal tubule C) limited branching of vasa recta D) long loop of Henle

D) long loop of Henle

Which of the following activities would be inhibited by a drug that specifically blocks the addition of phosphate groups to proteins? A) binding of G proteins to G protein-coupled receptors B) ligand-gated ion channel signaling pathways C) adenylyl cyclase activity D) receptor tyrosine kinase activity

D) receptor tyrosine kinase activity

One of the major categories of receptors in the plasma membrane functions by forming dimers, adding phosphate groups, and then activating relay proteins. Which type does this? A) G protein-coupled receptors B) ligand-gated ion channels C) steroid receptors D) receptor tyrosine kinases

D) receptor tyrosine kinases

Apical dominance in plants is under the control of ________. A) sugar B) various plant hormones C) cell division D) sugar and various plant hormones

D) sugar and various plant hormones

Which of the following types of signaling is represented in the figure? A) autocrine B) paracrine C) hormonal D) synaptic

D) synaptic