BS Zoology Semester Exam MCQs

Rising osmolarity stimulates ADH release, leading to increased kidney water reabsorption and more concentrated urine.

Photoperiod can influence melatonin and reproductive hormone pathways. Many animals use seasonal cues to time reproduction.

Arteries receive blood directly from heart contractions and have elastic muscular walls that withstand high pressure.

Prolactin stimulates milk production in mammary glands. Oxytocin causes milk ejection, so the two hormones have related but different functions.

Gonads produce sex steroids that regulate reproductive organs, secondary sexual traits, cycles, and behavior.

Hormones such as glucocorticoids can alter immune responses. This shows endocrine regulation interacts with defense and homeostasis.

Venous pressure is relatively low, especially in limbs. Valves help maintain one-way flow back to the heart.

Melatonin from the pineal gland is associated with circadian rhythms and responses to darkness. It helps coordinate daily physiological cycles.

Growth hormone promotes body growth through effects on tissues and growth factors. Deficiency during development can reduce normal growth.

Across invertebrates, chemical messengers coordinate development, reproduction, metabolism, and behavior, although glands and molecules differ among groups.

Capillaries have very thin walls that permit diffusion and exchange between blood and tissues. Their structure fits exchange function.

Negative feedback counteracts deviations from a normal range. It is a central principle in homeostasis, including glucose, calcium, temperature, and hormone regulation.