Anatomy and Physiology I with Lab (D312)

Correct Answer

C. Oxytocin

Explanation

Oxytocin is produced by the posterior pituitary, not the anterior pituitary. The anterior pituitary produces hormones such as TSH (thyroid-stimulating hormone), growth hormone, and FSH (follicle-stimulating hormone). Oxytocin, however, is synthesized in the hypothalamus and stored in the posterior pituitary for release.

Why other options are wrong

A. TSH

This is incorrect because TSH (thyroid-stimulating hormone) is produced by the anterior pituitary. It stimulates the thyroid gland to release thyroid hormones.

B. Growth hormone

This is incorrect because growth hormone is produced by the anterior pituitary. It stimulates growth, cell reproduction, and cell regeneration in the body.

D. FSH

This is incorrect because FSH (follicle-stimulating hormone) is produced by the anterior pituitary. It plays a key role in the reproductive system, stimulating the growth of ovarian follicles in women and spermatogenesis in men.

Correct Answer

C. The ability of a living organism to maintain an internal balance of conditions despite constant changes

Explanation

Homeostasis refers to the ability of an organism to maintain a stable internal environment despite external changes. This includes regulating variables such as temperature, pH, and electrolyte balance, which are critical for the survival of cells and overall bodily functions. For example, humans maintain a body temperature around 37°C (98.6°F) through physiological processes like sweating or shivering. Homeostasis allows organisms to adapt to changing conditions while keeping vital functions stable.

Why other options are wrong

A. The ability of the environment to increase conditions in response to a living organism. This option is incorrect because homeostasis refers to an organism's ability to regulate its internal environment, not the environment's ability to respond to the organism.

B. The ability of a living organism to increase conditions in response to an environmental change. This is incorrect because homeostasis focuses on maintaining stable internal conditions, not merely increasing them in response to external changes.

D. The ability of a living organism to decrease conditions in response to an environmental change. This option is also incorrect because homeostasis involves maintaining a stable internal environment, which may involve both increases and decreases in certain conditions, depending on the situation.

Correct Answer

B. Contribute to atomic mass

Explanation

Neutrons are neutral particles located in the nucleus of an atom. They have no charge and contribute to the atomic mass of an element along with protons. The number of neutrons in an atom can vary, leading to different isotopes of an element. Neutrons do not affect the atomic number, which is determined by the number of protons.

Why other options are wrong

A. Revolve around the nucleus

This is incorrect because electrons revolve around the nucleus, not neutrons. Neutrons are located in the nucleus and do not orbit the nucleus.

C. Are positively charged

This is incorrect because neutrons have no charge; they are neutral. It is the protons that are positively charged.

D. Determine atomic number

This is incorrect because the atomic number is determined by the number of protons in the nucleus, not neutrons.

Correct Answer

A. Hormonal

Explanation

The regulation of thyroid hormone secretion by the thyroid gland in response to a stimulating hormone (like TSH from the anterior pituitary) is an example of hormonal regulation. In this case, one hormone (TSH) stimulates the release of another hormone (thyroid hormones), following a hormonal feedback loop.

Why other options are wrong

B. Humoral

This is incorrect because humoral regulation involves changes in the levels of substances in the blood (such as glucose or calcium) that directly influence the secretion of hormones. It does not involve the release of one hormone in response to another.

C. Synthetic

This is incorrect because synthetic regulation is not a recognized classification of hormonal regulation. The correct term for hormone secretion in response to another hormone is hormonal regulation.

D. Neural

This is incorrect because neural regulation involves the nervous system stimulating hormone release (e.g., during stress or fight-or-flight responses). It does not apply to the hormonal stimulation of the thyroid gland.

Correct Answer

B. The left kidney

Explanation

The left kidney is positioned more laterally compared to the urinary bladder. The kidneys are located retroperitoneally, with the left kidney slightly more lateral, being closer to the midline of the body. The urinary bladder is located more medially in the pelvic region.

Why other options are wrong

A. The urinary bladder

This is incorrect. The urinary bladder is more medial compared to the kidneys, which are located laterally on either side of the body.

C. The right kidney

This is incorrect. While the right kidney is positioned laterally as well, the left kidney is slightly more lateral in relation to the midline of the body.

D. Both are equally lateral

This is incorrect. The left kidney is positioned more laterally than the urinary bladder.

Correct Answer

C. Active transport requires energy.

Explanation

Active transport is the movement of molecules across a cell membrane against their concentration gradient, meaning from a lower concentration to a higher concentration. This process requires energy, usually in the form of ATP, to drive transport proteins such as pumps. Examples include the sodium-potassium pump and endocytosis. Active transport is essential for maintaining cellular function, especially in nerve signaling and nutrient absorption.

Why other options are wrong

A. Passive transport moves substances up a concentration gradient.

Passive transport does not move substances up a concentration gradient; it moves them down the gradient (from high to low concentration) without the use of energy. Examples include diffusion and osmosis.

B. Active transport moves substances down a concentration gradient.

This is incorrect because active transport moves substances against their concentration gradient. Movement down the gradient (high to low concentration) occurs in passive transport, not active transport.

D. Passive transport requires energy.

Passive transport does not require energy because it relies on natural diffusion processes. The movement of molecules follows the concentration gradient, making ATP unnecessary. Examples include facilitated diffusion and osmosis.

Correct Answer

B. The development of secondary male characteristics

Explanation

Androgens, primarily testosterone, are responsible for the development of secondary male sexual characteristics during puberty. These include the growth of facial and body hair, deepening of the voice, and increased muscle mass. These hormones are essential for male sexual differentiation and the development of traits distinctively associated with male physiology.

Why other options are wrong

A. The development of secondary female characteristics

This is incorrect. Estrogens, not androgens, are responsible for the development of secondary female sexual characteristics such as breast development, widening of hips, and the regulation of the menstrual cycle.

C. Regulating the menstrual cycle

This is incorrect. The menstrual cycle is regulated by estrogen and progesterone in females, not androgens. Androgens influence male characteristics, not the female reproductive cycle.

D. Stimulating mammary gland development

This is incorrect. Mammary gland development is primarily stimulated by estrogen and progesterone in females, not by androgens.

E. Preparing the uterus for implantation of a fertilized ovum

This is incorrect. Preparing the uterus for implantation is the function of estrogen and progesterone in females, not androgens.

Correct Answer

C. Potassium has a higher reactivity because the valence electron on potassium is farther from the nucleus.

Explanation

Potassium (K) has a higher reactivity than sodium (Na) because its valence electron is farther from the nucleus. This makes the valence electron more easily lost because it is less tightly held by the nucleus due to the increased distance. The atomic radius of potassium is larger than that of sodium, so its outermost electron is more shielded from the attractive force of the nucleus, making it easier to remove.

Why other options are wrong

A. This cannot be determined from the information given.

This is incorrect because the trend in reactivity of alkali metals (like sodium and potassium) is well-known: the reactivity increases as you move down the group in the periodic table, due to the increasing distance of the valence electron from the nucleus.

B. Potassium has a lower reactivity because potassium has more protons than sodium.

This is incorrect because while potassium has more protons, it also has more electron shells, which results in greater shielding and a larger atomic radius, making it more reactive, not less.

D. Both metals have the same reactivity because the potassium and sodium valence electrons experience the same effective nuclear charge.

This is incorrect because the effective nuclear charge felt by the valence electrons decreases as you move down the group, not staying the same. Potassium’s valence electron is less tightly bound to the nucleus compared to sodium’s, making potassium more reactive.

Correct Answer

A. The number of protons and the number of neutrons.

Explanation

Atomic weight (or atomic mass) is primarily determined by the sum of the protons and neutrons in the nucleus of an atom. Protons contribute a mass of 1 amu (atomic mass unit) and neutrons also contribute approximately 1 amu. Electrons have negligible mass and do not significantly affect the atomic weight.

Why other options are wrong

B. The number of protons and the number of electrons.

This is incorrect. While the number of protons determines the element, electrons have an insignificant mass and do not contribute meaningfully to the atomic weight.

C. The number of neutrons and the number of electrons.

This is incorrect. Electrons do not affect the atomic weight because they are much lighter than protons and neutrons. The correct answer involves protons and neutrons.

D. The number of electrons, protons, and neutrons.

This is incorrect. Electrons are not considered when calculating atomic weight, as their mass is so small compared to protons and neutrons. Atomic weight is determined by protons and neutrons only.