Question

The marathon is a 26.2-mile-long, endurance running race. Successful marathon runners will benefit from having leg muscles with __________.

i. fibers with a high concentration of myoglobin

ii. fibers depending on glycolysis for generation of ATP

iii. fibers with relatively low mitochondria content

	a.	None of the above are correct
	b.	Exactly ONE of the above is correct
	c.	Exactly TWO of the above are correct
	d.	All of the above are correct.

Which of the following is a correct pair telling WHERE and HOW sodium ions are reabsorbed in the loop of Henle?

	a.	Descending limb, active transport
	b.	Descending limb, passive transport
	c.	Thin ascending limb, active transport
	d.	Thick ascending limb, active transport

Answer 1

Answer 1. b. Exactly ONE of the above is correct.

The statements-

i. fibers with a high concentration of myoglobin- True

This is because marathon runners depend on slow-twitch fibres which contain large amount of myoglobin for prolonged activity.

ii. fibers depending on glycolysis for generation of ATP- False

This is because for more efficient production of ATP, muscles of marathon runners rely upon aerobic respiration; when glycolysis is the primary source of ATP, that's is called anaerobic respiration.

iii. fibers with relatively low mitochondria content- False

Marathon runners actually have a larger number of mitochondria, for more energy production through aerobic respiration.

Answer 2. d. Thick ascending limb, active transport

Sodium is selectively reabsorbed in the thick ascending limb of loop of Henle to establish osmotic gradient that's essential for urine concentration; this limb is actually impervious to water.