The substance that makes the plant cell wall rigid and is a major component of wood is: MCQ with Answer and Explanation

Explanation:
A reflex arc is the neural pathway that controls a reflex action. It typically involves: a receptor (detects stimulus), a sensory neuron (carries impulse to CNS), an interneuron (in the spinal cord), a motor neuron (carries impulse away from CNS), and an effector organ (muscle or gland that responds). The motor neuron is responsible for the final output.

Explanation:
The humerus is the upper arm bone. The femur is the thigh bone. So C is incorrect.

Explanation:
Angiotensin II is a powerful octapeptide hormone formed in the blood by the action of angiotensin-converting enzyme (ACE). It has multiple effects to increase blood pressure and volume. It is a potent vasoconstrictor, increasing systemic vascular resistance. Crucially, it also acts on the zona glomerulosa of the adrenal cortex to stimulate the secretion of the mineralocorticoid hormone aldosterone. Aldosterone then acts on the kidneys to increase sodium and water reabsorption, further increasing blood volume and pressure.