Which of the following glands are responsible for producing 70% of semen volume?

A. collecting duct: While the collecting duct plays a critical role in final water reabsorption and urine concentration, it receives drainage from multiple nephrons. It is not considered the basic unit because it is shared among many functional units. Its activity is primarily regulated by antidiuretic hormone.

B. nephron: This is the microscopic structural and functional unit responsible for filtering blood and forming urine. Each kidney contains approximately 1 million nephrons, each consisting of a renal corpuscle and a renal tubule. It performs all primary renal functions including filtration, reabsorption, and secretion.

C. capsular space: This is the physical gap between the visceral and parietal layers of the glomerular capsule. It serves as the initial reservoir for glomerular filtrate before it enters the proximal tubule. It is merely a compartment within a larger structure rather than a complete functional unit.

D. nephron loop: Also known as the loop of Henle, this is a specific U-shaped segment of the renal tubule. It is essential for establishing the medullary osmotic gradient via the countercurrent multiplier system. It represents only one part of the entire nephron's complex tubular system.

E. glomerular capsule: This epithelial structure captures the fluid filtered from the glomerular capillaries. While it is a vital part of the renal corpuscle, it cannot function independently to produce urine without the associated glomerulus and tubules. It is a sub-component of the nephron unit.

A. Meiosis produces genetically unique cells while mitosis produces genetically identical cells. Mitosis is a form of asexual cellular reproduction used for growth and repair, ensuring daughter cells are clones. Meiosis introduces genetic variation through crossing over and independent assortment. This statement accurately reflects the differing biological outcomes of the two types of nuclear division.

B. A cell undergoing meiosis results in 4 cells while a cell undergoing mitosis results in 2 cells. Mitosis involves a single round of division, splitting one parent cell into two. Meiosis consists of two successive divisions, Meiosis 1 and 2, resulting in four haploid daughter cells. This is a fundamental structural difference between the two reproductive processes.

C. Meiosis results in haploid cells while mitosis results in diploid cells. Mitosis maintains the original chromosome count (2n to 2n) to preserve the genetic blueprint in somatic tissues. Meiosis reduces the chromosome number by half (2n to n) to produce gametes. This reduction is essential for maintaining a stable chromosome count across generations.

D. Meiosis occurs only after the onset of puberty while mitosis occurs throughout an entire lifetime. In females, the process of meiosis actually begins during fetal development, with oocytes arrested in prophase 1 until puberty. Mitosis indeed occurs throughout life for tissue maintenance. This choice is false because it ignores the prenatal initiation of oogenesis in the female reproductive cycle.