Question 1

Polypeptides can have which of the following types of effects?

Accepted Answer

Polypeptides can have autocrine effects, acting on the same cell that secretes them. They can also have paracrine effects, acting on nearby cells. Finally, some polypeptides can have endocrine effects, acting on distant cells by entering the bloodstream. Therefore, the correct answer is D, all of the above.

Question 2

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?

Accepted Answer

D

Question 3

People with type II diabetes mellitus have defective insulin receptors that cannot respond to insulin properly.Relative to normal individuals,what would be the effect on blood glucose levels of chronic stress that kept blood cortisol levels high?

Accepted Answer

B

Question 4

Which of the following is similar in structure to cholesterol?

Accepted Answer

Cholesterol, testosterone, estradiol, and cortisol are all classified as steroids due to their similar chemical structure. They all contain a four-ring carbon structure known as a steroid nucleus. Therefore, option D is the best choice as it contains three steroids. Leptin, serotonin, luteinizing hormone, insulin, melanocyte-stimulating hormone, oxytocin, and vasopressin do not have the same chemical structure as cholesterol.

Question 5

Removing which of the following glands would have the most wide-reaching effect on bodily functions of an adult human?

Accepted Answer

The pituitary gland is often referred to as the "master gland" because it produces hormones that control the functions of several other endocrine glands in the body, including the thyroid gland, adrenal glands, and reproductive organs. Therefore, removing the pituitary gland would have the most wide-reaching effect on bodily functions.

Question 6

In experiments where researchers suspect that a hormone may be responsible for a certain physiological effect,they may cut the neurons leading to the organ where the effect being studied occurs.What is the purpose of cutting these neurons?

Accepted Answer

By cutting the neurons leading to the organ, the researchers can eliminate any contribution from the nervous system and ensure that the effect being studied is due to the hormone. This is important because hormones and nervous system signals often work together to produce physiological effects.

Question 7

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?

Accepted Answer

Endocrine signaling involves the secretion of hormones into the bloodstream, which can travel throughout the body and affect distant target cells or organs. In this scenario, the removed portion of the pancreas likely secretes a hormone that regulates appetite, which is now lacking in the rat's body.

Question 8

The regulation of blood sugar levels and our stress responses are controlled in part by a negative feedback loop involving cortisol,ACTH,and CRH.What would likely be the result during times of stress if cortisol receptors in the hypothalamus were nonfunctional?

Accepted Answer

If cortisol receptors in the hypothalamus were nonfunctional, the negative feedback loop would be disrupted. The hypothalamus would not detect cortisol levels, leading to continuous production of CRH and ACTH, resulting in excessive cortisol production and potentially causing blood sugar levels to rise to dangerous levels.

Question 9

When a person drinks alcohol the rate of urination increases.This suggests that antidiuretic hormone (ADH)may be affected by alcohol consumption in some way.Which of the following could account for the increase in urination?

Accepted Answer

Alcohol inhibits the release of ADH, leading to decreased water reabsorption in the kidneys and increased urination.

Question 10

A cluster of tumor cells that produces and secretes growth factors to induce surrounding cells to grow and divide are showing which type of cell-to-cell signaling?

Accepted Answer

Paracrine signaling involves cells secreting signals to nearby cells to induce a response. In this case, the tumor cells are secreting growth factors to nearby cells to induce cell growth and division. Autocrine signaling involves cells secreting signals to themselves and endocrine signaling involves signals being secreted into the bloodstream to travel to distant cells. Neuroendocrine signaling involves signals being released from neurons to affect endocrine cells.

Question 11

If a biochemist discovers a new molecule,which of the following pieces of data would allow her to draw the conclusion that the molecule is a steroid hormone?

Accepted Answer

All of the listed characteristics are indicative of steroid hormones.

Question 12

Which of these glands is located within the abdominal cavity?

Accepted Answer

The pancreas is located within the abdominal cavity, while the thyroid and parathyroid are located in the neck, and the adrenal glands are situated on top of the kidneys. Therefore, option D (pancreas) is the correct choice. Option E (all of the above) is incorrect because not all of the listed glands are located within the abdominal cavity.

Question 13

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 have the greatest effect on calcium levels in the bones?

Accepted Answer

Calcitonin injection would have the greatest effect on increasing calcium levels in the bones because calcitonin helps to lower blood calcium levels by inhibiting osteoclast activity, which breaks down bone, thereby promoting calcium deposition in the bones.

Question 14

All of the following are examples of amplification of a hormone signal except _____.

Accepted Answer

Amplification of a hormone signal involves increasing the effect of a hormone, such as through enzyme cascades or gene transcription. Different cell types having different receptors is about specificity, not amplification.

Question 15

In human embryonic development,which of the following pairs of hormones are released by the developing testes and result in development of the male reproductive tract and inhibition of the female reproductive tract?

Accepted Answer

The developing testes release testosterone and Mullerian inhibitory substance (MIS), which result in the development of the male reproductive tract and the inhibition of the female reproductive tract. Testosterone is responsible for the development of the epididymis, vas deferens, seminal vesicles, and penis. MIS causes regression of the Mullerian ducts, which would otherwise develop into the uterus, fallopian tubes, and upper part of the vagina. Estrogen and progesterone are female hormones, and estradiol is a type of estrogen. While these hormones do play important roles in female reproductive development, they are not involved in the development of the male reproductive tract.

Question 16

Predict the effects of a drug that increases adrenocorticotropic hormone (ACTH)synthesis.

Accepted Answer

ACTH stimulates the adrenal cortex to produce glucocorticoids, so an increase in ACTH synthesis would lead to an increase in glucocorticoid production.

Question 17

When partially digested food enters the small intestine from the stomach,several events must occur to protect the intestine and allow for the continued digestion of the food.One hormone in particular performs two of these functions.What intestinal hormone is responsible for causing the pancreas to release digestive enzymes and the gallbladder to release bile salts into the intestine?

Accepted Answer

Cholecystokinin (CCK) is the intestinal hormone responsible for causing the pancreas to release digestive enzymes and the gallbladder to release bile salts into the small intestine. Secretin also plays a role in digestion by causing the pancreas to release bicarbonate to neutralize acidic chyme from the stomach, but it does not directly stimulate the release of digestive enzymes or bile salts. Insulin, epinephrine, and corticosterone are not involved in the secretion of digestive enzymes or bile salts.

Question 18

You have three strains of mice:
A,B,and C.You experimentally manipulate each strain and find that all three show increased secretion of molecule X.Now you perform a parabiosis experiment with the three combinations of these mice:
AB,AC,and BC.You perform the same experimental manipulation as above on one mouse of each pair without directly affecting the other mouse and look for effects on the other mouse.You find no detectable effect on the unmanipulated partner in any of the combinations.What is the logical conclusion based on these results?

Accepted Answer

The effect on molecule X is not mediated by hormones.The parabiosis experiment shows that the effect on molecule X is not mediated by hormones because the unmanipulated partner in each pair does not show any detectable effect. This means that the effect is not due to a circulating hormone that is produced by the manipulated mouse and then travels to the unmanipulated mouse.

Question 19

What property of the steroid hormones allows them to cross the phospholipid bilayer?

Accepted Answer

Steroid hormones are lipid soluble, which means they can easily dissolve in the hydrophobic interior region of the phospholipid bilayer. This property allows them to pass through the membrane and enter the cytoplasm of cells, where they bind to specific intracellular receptors and initiate gene expression.

Question 20

What is the only type of chemical signal that is not intended to alter the physiology of the animal producing that signal?

Accepted Answer

Pheromones are chemical signals intended to communicate with individuals of the same species, but they are not intended to alter the physiology of the animal producing the signal. Instead, pheromones are used for social or reproductive purposes, such as attracting mates, marking territories, or signaling danger.

Quiz 47: Chemical Signals in Animals