Why skeletal muscles are called striated muscles?
(A) They appear darker than smooth muscles by naked eye.
(B) Alternating dark and light bands appear on their surface when visualized by naked eye.
(C) Alternating dark and light bands appear on their surface when visualized via a microscope.
(D) All of these
Roots of a plant show______________?
(A) Positive phototropism and negative geotropism
(B) Negative phototropism and positive geotropism
(C) Negative tactic movement and positive tropic movement
(D) Positive geotropism of stem and roots
The contraction of which of the following muscle fibers, is controlled by hormones?
(A) A smooth muscle
(B) A cardiac muscle
(C) A skeletal muscle.
(D) All of these
Ecdysone is_________________?
(A) An enzyme that digest endocuticle during an arthropodal ecdysis
(B) A newly formed exoskeleton in authropods
(C) A hormone that regulates moulting in arthropods
(D) A process that involves moulting
Which of the following statement about an arthropod exoskeleton is incorrect?
(A) It permits gaseous exchange
(B) It contains joints, for the same purpose as present in human skeletal system
(C) It provides muscle attachment
(D) Like all the other types of exoskeleton, they lack sensation
Rigor mortis i.e, stiffening of body after death results from__________?
(A) Accunulation of rigid proteins molecules in sarcoplam.
(B) Unavailability of ATP, which is necessary to break the link between actin and myosin.
(C) Decrease in body temperature after death.
(D) Death of tissue due to unavailability of O2.
Exoskeleton of a marine snail is composed of________________?
(A) CaPO4
(B) CaCO3
(C) CaSO4
(D) SiO2
Which of the following step occurs immediately after binding of Ca2+ with troponin molecule during muscle contraction.
(A) Binding sites of actin get attached to the myosin head.
(B) Troponin uncovers the actin binding sites.
(C) Tropomyosin gets removed from the binding sites of actin filaments.
(D) Ca2+ goes back inside sarcoplasmic reticulum.
What happens during muscle contraction to the length of each myosin and action filament?
(A) Z- lines get closer
(B) A band becomes short
(C) 1 band elongates
(D) There is no change in sarcomere
Which one of the following forms the blk of exoskeleton of an arthropod?
(A) Epicuticle
(B) Procuticle
(C) Ectocuticle
(D) None of these