The protein-digesting enzyme in the small intestine that is activated by enterokinase is:
A. Trypsin
B. Pepsin
C. Rennin
D. Amylase
Answer: Option A
Solution (By JKSSB Mock Tests)
Trypsinogen, secreted by the pancreas, is activated to trypsin by enterokinase (intestinal enzyme). Trypsin then activates other zymogens. Pepsin is active in the stomach, rennin in infants, amylase digests starch. This cascade prevents premature protein digestion in the pancreas.
In the process of urine formation, the step that involves selective reabsorption of glucose, amino acids, and water from the filtrate back into the blood is:
Explanation:
Tubular reabsorption occurs mainly in the proximal convoluted tubule, where essential substances like glucose, amino acids, and most water are reabsorbed into peritubular capillaries via active and passive transport. Glomerular filtration/ultrafiltration is the initial passive filtration of blood. Tubular secretion adds substances like H⁺ and K⁺ to filtrate.
Explanation:
Vitamin B₁₂ contains a cobalt ion at the center of its corrin ring structure, hence the name cobalamin. It is essential for DNA synthesis and nervous system function. Iron is in heme, magnesium in chlorophyll, zinc in many enzymes. B₁₂ is unique in having a metal-carbon bond.
Explanation:
Phagocytosis is receptor-mediated or non-specific engulfment of large particles, forming a phagosome that fuses with lysosomes. Key in immune defense.
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