Question 1

The chemical structure of prostaglandins is derived from which of the following types of molecules?

Accepted Answer

Prostaglandins are derived from fatty acids, specifically arachidonic acid, through enzymatic reactions involving cyclooxygenases.

Question 2

Fludrocortisone is a steroid hormone used to treat disease. Which of the following most likely occurs when it encounters a target cell?

Accepted Answer

Fludrocortisone, like other steroid hormones, is lipophilic and can easily diffuse through the lipid bilayer of cell membranes. Once inside the cell, it binds to specific intracellular receptors, which can be located in the cytoplasm or the nucleus. This complex then acts as a transcription factor, regulating gene expression.

Question 3

Which of the following statements about growth factors is true?

Accepted Answer

Growth factors are indeed local regulators that play a crucial role in stimulating the division and development of target cells, influencing processes such as wound healing and embryonic development.

Question 4

Which of the following molecules is lipid soluble and acts on target cells at distant locations from where it is released?

Accepted Answer

Cortisol is a lipid-soluble steroid hormone that can pass through cell membranes and acts on target cells at distant locations from where it is released.

Question 5

Which of the following statements is true?

Accepted Answer

Neurohormones are released by neurons into the bloodstream, where they can travel to target distant organs or cells, distinguishing them from neurotransmitters, which typically act across the synaptic gap between neurons.

Question 6

Which of the following types of signal is released into the environment?

Accepted Answer

Pheromones are chemical signals released by an organism into the environment, affecting the behavior or physiology of other members of the same species.

Question 7

Which of the following organs includes endocrine and exocrine tissues?

Accepted Answer

The pancreas has both endocrine functions (releasing hormones like insulin and glucagon into the blood) and exocrine functions (producing digestive enzymes that are delivered to the small intestine via ducts).

Question 8

Testosterone is an example of a chemical signal that affects, variously, the very cells that synthesize it in the testis, the neighboring cells, and distant cells outside the gonads. Thus, testosterone is an example of ________.

Accepted Answer

Testosterone acts as an autocrine signal on the cells that produce it, a paracrine signal on neighboring cells, and an endocrine signal when it affects distant cells through the bloodstream.

Question 9

Which of the following best explains why the steroid hormone aldosterone affects only a small number of target cells in the body?

Accepted Answer

Aldosterone affects only a small number of target cells because only these cells contain specific receptors that can bind to aldosterone, enabling it to exert its effects.

Question 10

Which of the following types of cell-to-cell signaling describes tumor cells that secrete growth factors that induce surrounding cells to grow and divide?

Accepted Answer

Paracrine signaling involves the release of factors by cells that affect nearby target cells, which is the case with tumor cells secreting growth factors that influence the behavior of surrounding cells.

Question 11

Which of the following statements is true about both steroid and polypeptide?

Accepted Answer

Steroid and polypeptide hormones both travel through the bloodstream to reach their target cells.

Question 12

Which of the following correctly describes the target cells in autocrine signaling?

Accepted Answer

In autocrine signaling, the target cells are the same cells that secrete the signaling molecules. This means that the cells both produce and respond to the signals they emit, which is why option D is correct.

Question 13

Which of the following are properties of steroid hormones?

Accepted Answer

Steroid hormones are lipid-soluble and can pass through cell membranes to bind to intracellular receptors, affecting gene transcription. This is in contrast to many other hormone types that are water-soluble and act through membrane-bound receptors.

Question 14

Which of the following statements about aspirin and ibuprofen is true?

Accepted Answer

Aspirin and ibuprofen work by inhibiting the enzyme cyclooxygenase, which is involved in the synthesis of prostaglandins. Prostaglandins are compounds that have several important functions in the body, including mediating inflammation and pain.

Question 15

Molecules that act quickly over short distances are types of ________.

Accepted Answer

The answer of Molecules that act quickly over short distances...

Question 16

Which of the following statements about polypeptides is true?

Accepted Answer

Polypeptides can function as growth factors, which are signaling molecules that stimulate cellular growth, proliferation, healing, and cellular differentiation.

Question 17

A certain hormone activates the cAMP second messenger system in its target cells. Which of the following would yield the greatest response by a target cell?

Accepted Answer

DApplying the hormone to the extracellular fluid allows it to bind to its receptor and initiate the cAMP second messenger pathway, leading to a cellular response. Injecting activated, cAMP-dependent protein kinase directly into the cytoplasm bypasses the earlier steps of the pathway, directly activating the processes downstream of cAMP production, thus also yielding a significant response.

Question 18

Which of the following are the two main systems for communication and control in most animals?

Accepted Answer

The nervous system and endocrine system are the two main systems for communication and control in most animals. The nervous system provides rapid, short-term control through nerve impulses, while the endocrine system offers longer-term control through hormones released into the bloodstream.

Question 19

Tadpoles undergo metamorphosis in their development. The changes include reabsorption of the tail, growth of limbs, and the development of lungs. Amazingly, all of these changes are induced by thyroxine. Which of the following best explains the diverse effects of thyroxine?

Accepted Answer

Different tissues have thyroxine receptors that activate different signal transduction pathways, allowing thyroxine to induce a variety of effects in the body, including the diverse changes seen in tadpole metamorphosis.

Question 20

Which of the following statements about endocrine glands is true?

Accepted Answer

Endocrine glands are ductless glands that release their hormones directly into the bloodstream, which then transports these hormones to target organs or cells.

Quiz 41: Chemical Signals in Animals