Which component of blood plays a crucial role in blood clotting? MCQ with Answer and Explanation

Explanation:
Sickle cell anemia is an autosomal recessive disorder caused by a single nucleotide substitution (GAG → GTG) in the β-globin gene, resulting in glutamic acid replaced by valine, producing abnormal hemoglobin S. Under low oxygen, HbS polymerizes, distorting RBCs into sickle shape, causing pain and organ damage.

Explanation:
Cortisol, from the adrenal cortex, is a glucocorticoid that increases blood glucose, suppresses inflammation, and aids the body's adaptation to prolonged stress. Adrenaline is for acute stress, thyroxine metabolism, insulin glucose.

Explanation:
A food chain shows the flow of energy from producer to consumers. Grass (producer) → Grasshopper (primary consumer/herbivore) → Frog (secondary consumer/carnivore) → Snake (tertiary consumer). Arrows point in the direction of energy flow. Option A has incorrect order, C and D start with consumer. Typically, energy decreases at each trophic level. This illustrates the correct trophic sequence.