The vitamin that acts as a coenzyme in transamination reactions is:
A. Thiamine
B. Pyridoxine (B₆)
C. Riboflavin
D. Niacin
Answer: Option B
Solution (By JKExamLibrary)
Pyridoxal phosphate (PLP), the active form of vitamin B₆, is a coenzyme for transaminases (ALT, AST), decarboxylases, and other enzymes in amino acid metabolism. Thiamine in decarboxylation of keto acids, riboflavin in redox, niacin in NAD/NADP.
Consider statements about cell biology: 1. The plasma membrane is composed of a phospholipid bilayer. 2. The nucleus contains the cell's genetic material. 3. Mitochondria are the site of photosynthesis. Which are correct?
Explanation:
The plasma membrane (cell membrane) is primarily composed of a phospholipid bilayer with embedded proteins, following the fluid mosaic model, regulating transport in and out of the cell. The nucleus is the membrane-bound organelle that houses the cell's genetic material (DNA) organized into chromosomes. Mitochondria are the site of aerobic cellular respiration and ATP production; chloroplasts are the organelles where photosynthesis occurs in plant cells. Thus, statements 1 and 2 are correct.
Explanation:
The Haldane effect describes how the oxygenation of blood in the lungs displaces carbon dioxide from hemoglobin, increasing the removal of CO2. Conversely, deoxygenated blood in the tissues has an increased capacity to carry CO2. This is complementary to the Bohr effect. Exam tip: Bohr = CO2 affects O2; Haldane = O2 affects CO2.
Explanation:
Bile does not contain digestive enzymes; it contains bile salts that emulsify fats, increasing surface area for lipase action. Thus, A is false, R is true.
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