Practice mode / Biology What is ecdysone? A Option A: An enzyme that digests the endocuticle during arthropod ecdysis B Option B: A hormone that regulates moulting in arthropods C Option C: A process that involves moulting D Option D: A newly formed exoskeleton in arthropods Correct answer B. A hormone that regulates moulting in arthropods Explanation Ecdysone is a steroid hormone produced by the prothoracic glands that triggers moulting (ecdysis), allowing arthropods to shed and replace their rigid exoskeleton. Show answer Report a problem Answer checked 11 October 2026 · How we write and check questions
Question 01 / Biology Which statement about the arthropod exoskeleton is incorrect? A Option A: It contains joints for the same purpose as those in the human skeletal system B Option B: Like all other types of exoskeleton, it lacks sensation C Option C: It permits gaseous exchange D Option D: It provides muscle attachment Correct answer A. It contains joints for the same purpose as those in the human skeletal system Show answer Open question
Question 02 / Biology What causes rigor mortis, the stiffening of the body after death? A Option A: Decrease in body temperature after death B Option B: Death of tissue due to unavailability of O2 C Option C: Unavailability of ATP, which is necessary to break the link between actin and myosin D Option D: Accumulation of rigid protein molecules in the sarcoplasm Correct answer C. Unavailability of ATP, which is necessary to break the link between actin and myosin Show answer Open question
Question 03 / Biology What is the exoskeleton (shell) of a marine snail mainly made of? A Option A: SiO2 B Option B: CaPO4 C Option C: CaCO3 D Option D: CaSO4 Correct answer C. CaCO3 Show answer Open question
Question 04 / Biology During muscle contraction, which step follows immediately after Ca2+ binds to troponin? A Option A: Troponin uncovers the actin binding sites B Option B: Ca2+ goes back inside sarcoplasmic reticulum C Option C: Tropomyosin gets removed from the binding sites of actin filaments D Option D: Binding sites of actin get attached to the myosin head Correct answer C. Tropomyosin gets removed from the binding sites of actin filaments Show answer Open question
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