In spermatogenesis, the spermatogonia produce(s) ____ sperm and in oogenesis, the oogonia produce(s) ____ ovum(s).
4; 1
4; 2
2:4
4; 4
1; 4
The Correct Answer is A
A. 4; 1: During spermatogenesis, a single primary spermatocyte undergoes two meiotic divisions to produce four functional, haploid spermatozoa. In contrast, oogenesis involves asymmetrical cytokinesis, where one primary oocyte yields only one functional secondary oocyte and three non-functional polar bodies. This allows the single ovum to retain the cytoplasm necessary for early embryonic life.
B. 4; 2: Oogenesis does not result in two functional ova under normal physiological conditions. While two polar bodies may be visible at different stages, only one cell matures into the gamete capable of being fertilized. Producing two functional eggs would be the result of a double ovulation event rather than the standard meiotic process.
C. 2:4: This ratio is the reverse of biological reality. Males produce significantly more gametes per meiotic event than females to ensure a higher probability of fertilization. Females prioritize the quality and nutrient content of a single cell over the quantity of gametes produced. This ensures the zygote has an adequate supply of organelles.
D. 4; 4: If oogenesis produced four functional ova, human multiple births would be the standard rather than the exception. The energy cost of producing four nutrient-rich eggs is too high for the female reproductive strategy. Asymmetrical division is a specific evolutionary adaptation to ensure the survival of a single fertilized zygote.
E. 1; 4: This choice suggests males produce fewer gametes than females per meiotic cycle, which is incorrect. A single spermatogonium eventually leads to the production of four spermatids through the process of meiosis. Oogenesis is the pathway that results in a single functional gamete due to the formation of polar bodies.
Nursing Test Bank
Naxlex Comprehensive Predictor Exams
Related Questions
Correct Answer is B
Explanation
A. osmosis. Water moves passively across the renal tubular epithelium following osmotic gradients established by the active transport of solutes like sodium. This process, often referred to as obligatory water reabsorption in the proximal tubule, allows water to diffuse through aquaporins. It does not require direct ATP consumption for the water molecules themselves.
B. filtration. Filtration is the process that occurs exclusively in the renal corpuscle where blood is processed into filtrate. Once the fluid enters the renal tubules, the movement of substances back into the blood is classified as reabsorption. Filtration is driven by hydrostatic pressure, whereas tubular water movement is driven by osmotic concentration differences.
C. active transport. There are no known biological pumps that directly use ATP to move water molecules against a concentration gradient. Biological systems move water by actively transporting solutes and allowing water to follow passively. All water movement in the kidney is a response to osmotic or hydrostatic forces rather than direct active pumping.
D. cotransport with sodium ions. While many solutes like glucose and amino acids use secondary active transport (cotransport) with sodium, water moves through separate channel proteins called aquaporins. Sodium reabsorption creates the osmotic drive, but the water molecules do not bind to the carrier proteins alongside sodium. Water movement is the result of the sodium transport, not a shared transport mechanism.
Correct Answer is B
Explanation
A. protein-regulated diffusion. Large plasma proteins like albumin are too big to pass through the filtration membrane and remain in the capillaries. They actually create a colloid osmotic pressure that pulls water back into the blood, opposing filtration. Diffusion is a passive movement of solutes, not the primary mechanical force driving the high-volume ultrafiltration of plasma.
B. glomerular hydrostatic pressure (glomerular blood pressure). This is the blood pressure within the glomerular capillaries, which is typically much higher than in other capillary beds due to the high-resistance efferent arteriole. It serves as the dominant outward force that physically pushes water and small solutes through the filtration slits. It is the fundamental driver of the glomerular filtration rate.
C. the size of the pores in the basement membrane of the capillaries. The fenestrations and filtration slits determine the permeability and selectivity of the filter, essentially acting as a sieve. While these pores permit the passage of substances, they do not provide the energy or force to move them. They represent a physical constraint on what can pass rather than a driving force.
D. the ionic electrochemical gradient. Electrochemical gradients primarily drive the movement of specific ions across tubular epithelial cells during reabsorption and secretion. Glomerular filtration is a non-selective, bulk-flow process driven by mechanical pressure rather than individual ion concentrations. The process is governed by hydrostatic and osmotic pressures according to Starling's law.
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