Anatomy and Physiology I with Lab (D312)

Correct Answer

A. Anterior pituitary

Explanation

The anterior pituitary gland controls the production of thyroid hormones T3 (triiodothyronine) and T4 (thyroxine). The anterior pituitary releases thyroid-stimulating hormone (TSH) in response to signals from the hypothalamus, which stimulates the thyroid gland to produce T3 and T4. These hormones regulate metabolism, energy production, and growth.

Why other options are wrong

B. Adrenal gland

The adrenal glands are responsible for producing hormones like adrenaline, cortisol, and aldosterone, but they do not control the production of thyroid hormones.

C. Posterior pituitary

The posterior pituitary stores and releases hormones like oxytocin and antidiuretic hormone (ADH) but does not control the production of T3 and T4.

D. Thalamus

The thalamus is involved in sensory processing and does not control the production of thyroid hormones. The hypothalamus plays a more direct role in regulating the release of thyroid-stimulating hormone from the anterior pituitary.

Correct Answer

D. Effector

Explanation

The effector is the component of a feedback system that receives output from the control center and carries out the response to return the system to homeostasis. Effectors can include muscles or glands that perform actions to restore balance, such as producing a hormone or contracting to generate movement.

Why other options are wrong

A. Stimulus

The stimulus is the initial condition that triggers a response, but it does not receive output from the control center. Instead, it initiates the feedback process.

B. Receptor

The receptor detects changes in the environment and sends input to the control center, not the output. It serves as the sensor for the system.

C. Control center

The control center evaluates information received from receptors and sends out instructions to the effector. It does not receive output itself; rather, it processes input from the receptors and sends instructions to the effector.

Correct Answer

D. Allows humans to absorb a large amount of heat before increasing in temperature to help regulate our body temperature.

Explanation

Water has a high heat capacity, meaning it can absorb a large amount of heat before its temperature rises significantly. This property is critical for regulating body temperature in living organisms, including humans. It helps prevent rapid temperature changes and provides stability, which is crucial for maintaining homeostasis.

Why other options are wrong

A. To dissolve other substances, making it the universal solvent.

This is incorrect. While water's ability to dissolve many substances is important, this property is known as its "solvent" function, not its heat capacity. Heat capacity specifically refers to the amount of heat water can absorb without significantly increasing in temperature.

B. Speed up chemical reactions that require the addition of heat in order for the reaction to take place.

This is incorrect. Water's high heat capacity does not directly speed up chemical reactions. While heat can influence reaction rates, water's role is more related to its ability to regulate temperature, rather than specifically accelerating reactions.

C. Allows molecules to move very quickly and produce the heat needed to keep cold-blooded animals warm.

This is incorrect. Water's high heat capacity does not directly influence the movement of molecules to produce heat. Cold-blooded animals regulate their temperature differently, and water's heat capacity primarily helps in temperature regulation rather than generating heat.

Correct Answer

C. Facilitating glucose uptake into cells

Explanation

After a meal, insulin is released by the pancreas in response to increased blood glucose levels. Its primary role is to facilitate the uptake of glucose into cells, particularly muscle and fat cells, where it is either used for energy or stored as glycogen. This process helps lower blood sugar levels back to normal after eating.

Why other options are wrong

A. Stimulating testosterone production. Insulin does not stimulate testosterone production. Testosterone is regulated by the testes in males and ovaries in females, and it is not influenced by insulin in this context.

B. Inhibiting estrogen secretion. Insulin does not have a role in inhibiting estrogen secretion. Estrogen is regulated by the ovaries, and its secretion is influenced by hormonal signals, not by insulin.

D. Increasing blood sugar levels. This is incorrect because insulin actually works to lower blood sugar levels. It facilitates the uptake of glucose into cells, reducing the amount of glucose in the bloodstream.

Correct Answer

C. 20.5 years old

Explanation

The study conducted by Richard and Mulgena found that the average age of the students participating in the study was 20.5 years old. This value represents the mean age of the group under study, which was important for understanding the general demographic profile of the participants.

Why other options are wrong

A. 19.8 years old

This is incorrect because the average age reported in the study was not 19.8 years old. While this could be close to the actual number, it does not accurately reflect the data provided in the study.

B. 25.3 years old

This is incorrect because 25.3 years old is too high compared to the actual reported average age of 20.5 years old. The age was closer to the lower twenties rather than the mid-twenties.

D. 22.9 years old

This is incorrect because the reported average age was 20.5 years old, not 22.9. This value does not match the average age found in the study.

Correct Answer

D. Filter blood in the kidneys.

Explanation

Dialysis tubing is often used to model the function of the kidneys, specifically the filtration of blood. In the kidney, blood is filtered to remove waste, excess substances, and toxins, similar to how the dialysis tubing selectively allows substances to pass through. This process is crucial in maintaining the body's fluid balance and removing harmful substances.

Why other options are wrong

A. Digest food in the stomach. The stomach is responsible for digesting food, not for filtering blood. The dialysis tubing does not represent this function.

B. Transport urine to the bladder. Transporting urine to the bladder is the role of the ureters, not the dialysis tubing, which represents the filtering process in the kidneys.

C. Produce hormones for metabolism. While the kidneys do produce hormones (like erythropoietin), the dialysis tubing represents the filtration function, not hormone production.

Correct Answer

B. Loss of three-dimensional structure

Explanation

Denaturation refers to the process by which a protein loses its three-dimensional structure, often due to environmental factors like heat, pH changes, or chemicals. This disruption in the protein's shape typically leads to a loss of its function because the active sites of enzymes or the structural integrity needed for specific biological functions are affected.

Why other options are wrong

A. Formation of hydrogen bonds. This is incorrect. Denaturation disrupts the existing hydrogen bonds within the protein structure, leading to the loss of its functional shape.

C. Removal of R groups from amino acids. This is incorrect. Denaturation does not remove R groups from amino acids; it alters the protein's structure, affecting how the amino acids interact.

D. No change in enzyme activity. This is incorrect. Denaturation typically leads to a loss of enzyme activity because the protein's shape (and active site) is altered, preventing it from functioning properly.

E. Formation of covalent bonds. This is incorrect. Denaturation does not involve the formation of covalent bonds. Instead, it disrupts the non-covalent interactions like hydrogen bonds and ionic bonds that maintain the protein's structure.

Correct Answer

A. It allows organisms to withstand rapid temperature fluctuations.

Explanation

Water's high heat capacity means that it can absorb or release large amounts of heat without experiencing significant changes in temperature. This property helps maintain stable internal conditions, allowing organisms to withstand rapid temperature fluctuations, which is crucial for maintaining homeostasis. This stability is important for proper enzyme function and overall cellular activities.

Why other options are wrong

B. It increases the rate of chemical reactions within cells.

This is incorrect. While water plays an essential role in chemical reactions, its high heat capacity doesn't directly increase reaction rates. Instead, temperature regulation through heat capacity helps maintain optimal conditions for reactions.

C. It facilitates the transport of nutrients across cell membranes.

This is incorrect. While water is important in the transport of nutrients, its high heat capacity is not directly responsible for this function. Transport is more related to osmotic and diffusion processes.

D. It decreases the solubility of gases in bodily fluids.

This is incorrect. Water's high heat capacity does not decrease the solubility of gases; in fact, gases like oxygen tend to be more soluble in colder water. This option does not relate to the role of heat capacity in homeostasis.

Correct Answer

B. It uses the energy from the electrochemical gradient established by primary active transport, such as the sodium-glucose cotransporter.

Explanation

Secondary active transport does not directly use ATP to move substances across a membrane. Instead, it relies on the electrochemical gradient created by primary active transport. A classic example is the sodium-glucose cotransporter (SGLT), which moves glucose into a cell using the energy from sodium ions moving down their concentration gradient. This gradient is initially established by the sodium-potassium pump, which uses ATP to maintain sodium concentration differences across the membrane.

Why other options are wrong

A. It relies on ATP directly to move substances, such as in the sodium-potassium pump. This is incorrect because direct ATP usage is characteristic of primary active transport, not secondary active transport. The sodium-potassium pump (Na⁺/K⁺ ATPase) actively moves sodium and potassium ions using ATP, but secondary active transport depends on the gradients created by such pumps rather than directly using ATP.

C. It functions solely through passive diffusion of molecules across the membrane. This is incorrect because secondary active transport involves moving substances against their concentration gradient, which requires an indirect energy source. Passive diffusion, on the other hand, occurs without energy input and moves molecules down their concentration gradient.

D. It involves the direct coupling of two ATP molecules to transport ions. This is incorrect because secondary active transport does not involve direct ATP hydrolysis. Instead, it harnesses the potential energy from ion gradients created by primary active transport mechanisms.