2301. A smallest contractile unit of muscle contraction called sarcomere is the area between two:
✅ C. Z- Line
Option A: H- zone Option B: M- Line Option C: Z- Line Option D: A band Correct Answer : Z- Line Read more
Author: Sheeraz Ahmed – Page 116
2302. Which of the following animal has a hydrostatic skeleton?
✅ A. Earthworm
Option A: Earthworm Option B: Round worm Option C: Tape worm Option D: Pin worm Correct Answer : Earthworm Read more
2303. Diameter of thick filament is____________?
✅ C. 16nm
Option A: 7 nm. Option B: 8 nm Option C: 16nm Option D: 10-100 ?m. Correct Answer : 16nm Read more
2304. In an annelids, the contraction of circular muscle results in___________?
✅ D. Thinning of body
Option A: Lengthening of the body. Option B: Shortening of the body. Option C: Widening of body Option D: Thinning of body Correct Answer : Thinning of body Read more
2305. The most important function of troponin is___________?
✅ D. All of these
Option A: To bind with actin Option B: To bind with tropomyosin. Option C: To bind with Ca2+ ions. Option D: All of these Correct Answer : All of these Read more
2306. Which of the following statement is incorrect about Molluscans?
✅ D. They move by tube feet
Option A: They are surrounded by single or double pieces of hard skeleton. Option B: Their shell grows as the animal grows. Option C: They have hydrostatic skeleton. Option D: They move by tube feet Correct Answer : They move by tube feet Read more
2307. If a cross section of a sarcomere is seen, each myosin is surrounded by how many actin molecules:
✅ C. 6
Option A: 9 Option B: 5 Option C: 6 Option D: 7 Correct Answer : 6 Read more
2308. Which one of the following forms the blk of exoskeleton of an arthropod?
✅ B. Procuticle
Option A: Epicuticle Option B: Procuticle Option C: Ectocuticle Option D: None of these Correct Answer : Procuticle Read more
2309. What happens during muscle contraction to the length of each myosin and action filament?
✅ A. Z- lines get closer
Option A: Z- lines get closer Option B: A band becomes short Option C: 1 band elongates Option D: There is no change in sarcomere Correct Answer : Z- lines get closer Read more
2310. Which of the following step occurs immediately after binding of Ca2+ with troponin molecule during muscle contraction.
✅ C. Tropomyosin gets removed from the binding sites of actin filaments.
Option A: Binding sites of actin get attached to the myosin hea Option B: Troponin uncovers the actin binding sites. Option C: Tropomyosin gets removed from the binding sites of actin filaments. Option D: Ca2+ goes back inside sarcoplasmic reticulum. Correct Answer : Tropomyosin gets removed from the binding sites of actin filaments. Read more