AP Biology : Understanding Hormones

Study concepts, example questions & explanations for AP Biology

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Example Questions

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Example Question #1 : Endocrine System

How do steroid hormones elicit a response from their target cells?

Possible Answers:

Steroid hormones enter the nucleus of the target cell and increase the creation of ribosomes by the nucleolus. This results in more proteins being made by the target cell.

Steroid hormones attach to a membrane-bound receptor on the cell. This creates an intracellular second messenger which leads to a reaction cascade.

Steroid hormones enter the target cell and alter the products of the cell at the transcription level.

Steroid hormones move freely throughout the bloodstream and attach to their target cells. This interaction increases ion permeability in the cell.

Correct answer:

Steroid hormones enter the target cell and alter the products of the cell at the transcription level.

Explanation:

Steroids are nonpolar, which means that they are able to pass easily through cell membranes, but require a transport protein through the hydrophilic blood in order to do so. The steroid hormone then enters the nucleus and attaches to the DNA in order to increase the desired product at the level of transcription.

Example Question #11 : Endocrine System

Which of these hormones is responsible for the secretion of testosterone in males?

Possible Answers:

Human growth hormone (hGH)

Oxytocin

Luteinizing hormone (LH)

Follicle stimulating hormone (FSH)

Correct answer:

Luteinizing hormone (LH)

Explanation:

Luteinizing hormone is responsible for the secretion of testosterone from leydig cells in the testes.

FSH is responsible for the proliferation of sertoli cells, which nurture sperm cell precursors. hGH is responsible for body growth, and is not responsible for testosterone formation. Oxytocin is responsible for increasing uterine contractions during pregnancy.

Example Question #12 : Endocrine System

__________ is released in response to low blood sugar levels, while __________ is released in response to high blood sugar levels.

Possible Answers:

glucagon . . . insulin

insulin . . . thyroid hormones

thyroid hormones . . . glucagon

insulin . . . glucagon

Correct answer:

glucagon . . . insulin

Explanation:

Insulin is responsible for lowering blood sugar levels, and is therefore released when the body's blood sugar levels are too high. Glucagon is released in response to low blood sugar levels, and acts to increase sugar concentrations.

Thyroid hormones (T3 and T4) are released to increase the body's metabolic rate, but are not directly influenced by blood sugar levels.

Example Question #13 : Endocrine System

Obesity can sometimes be caused by the slowing of the thyroid gland's production of thyroid hormones III and IV (T3 and T4), a condition known as hypothyroidism. Conversely, hyperthyroidism occurs when the thyroid overproduces T3 and T4. If T3 and T4 receptors became insensitive to the hormones, what effect would this have on the body?

Possible Answers:

Faster metabolism and weight gain

Faster metabolism and weight loss

Slower metabolism and weight gain

Slower metabolism and weight loss

Correct answer:

Slower metabolism and weight gain

Explanation:

The question tells us that slowed output of thyroid hormones can lead to obesity. One can safely assume that receptor insensitivity will have a similar effect. In either scenario, the T3 and T4 hormones are unable to elicit the proper response form the body. Similar to individuals with hypothyroidism, individuals with insensitive receptors would show slowed metabolism and increased weight gain.

Example Question #14 : Endocrine System

__________, released from the __________, is the hormone responsible for controlling lactation in nursing women, as well as triggering labor in pregnant women.

Possible Answers:

Luteinizing hormone . . . posterior pituitary

Vasopressin . . . posterior pituitary

Oxytocin . . . posterior pituitary

Follicle-stimulating hormone . . . hypothalamus

Correct answer:

Oxytocin . . . posterior pituitary

Explanation:

Oxytocin is responsible for lactation in nursing women. When the nipple is stimulated, oxytocin is released from the posterior pituitary to cause lactation. During labor, release of oxytocin causes positive feedback on the hypothalamus, which causes further oxytocin release.

Luteinizing hormone and follicle-stimulating hormone are released from the anterior pituitary and function to regulate the menstrual cycle. Vasopressin is released from the posterior pituitary and helps to regulate blood pressure and water balance.

Example Question #15 : Endocrine System

Which steroid hormone is responsible for development of the secondary sexual characteristics in males, such as facial hair and deepening of the voice?

Possible Answers:

Estrogen

Progesterone

Cortisol

Testosterone

Correct answer:

Testosterone

Explanation:

Testosterone is well known to be responsible for male secondary sexual characteristics. It also plays a key role in behavior, such as aggression. For example, during mating season in gorillas the testosterone levels in males raise significantly and lead to confrontations between males.

Progesterone and estrogen are responsible for female secondary sexual characteristics, while cortisol plays a role in the body's response to long-term stress.

Example Question #6 : Understanding Hormones

The corpus luteum releases progesterone to prevent menstruation from occurring; if an ovum is not fertilized, then menstruation occurs. What happens to progesterone levels if the ovum is not fertilized?

Possible Answers:

Decrease

Progesterone levels stay the same

Progesterone levels will depend on relative estrogen levels

Increase

Correct answer:

Decrease

Explanation:

In order for menstruation to occur, progesterone levels must decrease. When fertilization does not occur, the corpus luteum ceases progesterone production, initiating menstruation. The corpus luteum then transitions into the corpus albicans and removed from the ovary in preparation for the new menstrual cycle.

Example Question #7 : Understanding Hormones

__________ is a critical hormone that controls heart rate and constriction of blood vessels. It is crucial in the fight-or-flight response.

Possible Answers:

Glucagon

Epinephrine

Insulin

Cortisol

Correct answer:

Epinephrine

Explanation:

Epinephrine, released from the adrenal gland, is important for the fight-or-flight response. During moments of stress, heart rate increases, pupils dilate, and blood vessels constrict in order to prepare for danger. All of this is controlled by epinephrine and norepinephrine, and is part of the sympathetic nervous system.

Example Question #16 : Endocrine System

A certain molecule is known to signal through an autocrine mechanism. What does this tell us about the hormone's behavior?

Possible Answers:

The molecule is released by a certain cell, travels through the bloodstream, and acts on receptors on distant cells

The molecule is released by a certain cell and acts on receptors on that same cell

The molecule is released by a certain cell and acts on receptors on nearby cells

The molecule is released by a certain cell, travels through the bloodstream, and acts on receptors in the hypothalamus

The molecule is released by a certain cell and acts to mediate release of more of the same hormone

Correct answer:

The molecule is released by a certain cell and acts on receptors on that same cell

Explanation:

To answer this question, you must have an understanding of the differences between endocrine, paracrine, and autocrine functioning. This example, in which a molecule exhibits autocrine behavior, means that a cell releases a hormone that acts on itself. In paracrine signaling, the molecule does not act on the same cell, but does diffuse through tissue to reach nearby target cells. Finally, endocrine signaling refers to hormone molecules that are released and transported through the bloodstream to act on more faraway target cells in distant regions.

Example Question #15 : Endocrine System

Which hormone is most likely to be produced in order to decrease plasma calcium levels?

Possible Answers:

Antidiuretic hormone

Parathyroid hormone

Calcitonin

Melatonin

Oxytocin

Correct answer:

Calcitonin

Explanation:

The two hormones known for their effect on plasma calcium levels are calcitonin and parathyroid hormone (PTH). When calcium levels are high, calcitonin is released by the thyroid gland to stimulate the uptake of serum calcium into bone. This effectively decreases calcium levels in the blood. PTH has the opposite effect and is released by the parathyroid gland.

The three remaining answer choices are not known for their effect on calcium levels in the blood.

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