Question

NAME SID 25. Usted below are different steps that occur during the excitation and contraction of a muscle fiber. Please select the correct sequence in which these stages occur. 1) Ca2+ binds to Tropomyosin, causing a conformational change that unblocks cross-bridge binding sites. 2) The Sarcoplasmic Reticulum is depolarized, which opens up Voltage-Gated Channels that release Ca2+ into the cytoplasm. 3) The Action Potential then travels along the cell membrane and down transverse tubules that extend into the muscle fiber. 4) Thin Filaments are ratcheted across the Thick Filaments by the myosin heads, in a process that utilizes ATP to induce "power stroke" motions. (5) Action Potential in a motor neuron causes the axon to release acetylcholine, which then crosses the synapse to depolarize the muscle cell. Possible Sequence Options: a. 1,2,3,4,5 2. 1,3,5,4 c. 5,3, 1, 2,4 d. 5,3,4, 1,2 e. 5,3, 2, 1,4 35+ 26. of the following categories of Essential Nutrients that organisms must acquire in their diets. which represents the group that includes inorganic nutrients? a. Essential Amino Acids b. Essential Fatty Acids c. Vitamins d) Minerals e. None of the above. 27. Which of the following is NOT a role performed by the large intestine? Connecting to the rectum and anus, so that wastes can be eliminated from the body. (6) Conducting plant fermentation in a region called the cecum. Playing a primary role in absorbing water. Acting as a site where ducts connect to the pancreas and liver. Housing the appendix, which plays a minor role in Immunity

Answer 1

According to me,

Answer of 25th ques is e.

Explanation: The sequence of events that result in the contraction of an individual muscle fiber

1. Begins with a signal—the neurotransmitter, Acetylcholine—from the motor neuron innervating that fiber. The local membrane of the fiber will depolarize as positively charged sodium ions (Na+) enter, triggering an action potential that spreads to the rest of the membrane will depolarize, including the T-tubules. This triggers the release of calcium ions (Ca++) from storage in the sarcoplasmic reticulum (SR). The Ca++ then initiates contraction, which is sustained by ATP. As long as Ca++ ions remain in the sarcoplasm to bind to troponin, which keeps the actin-binding sites “unshielded,” and as long as ATP is available to drive the cross-bridge cycling and the pulling of actin strands by myosin, the muscle fiber will continue to shorten to an anatomical limit.

26 answer : Minerals as it does not constitute of carbon.

Water and mineral are the two inorganic nutrients.

27 answer :D option ; as small intestine is the site where pancreas and liver duct connects, large intestine absorbs water ,cecum helps in fermenting cellulose present in vegetables and appendix plays a minor role in immunity.

22 answer : C is the correct option

1 - thick ( myosin) filament

2 - M line

3 - thin ( actin) filament

4 - Z line

23 answer : d option is true : thick filament having myosin head form cross bridge with actin active site which then act as motors and now thin filaments push towards the mild line, contraction occurs shortens the sarcomere.

Atp is hydrolysed when myosin head binds with active site .

Each muscle cell have many myofibrils.

Filaments can never change there length by stretching or contracting it's just the sarcomere which shortens when the distance between the filaments reduces.

NOTE: distance btw filaments decreases, Not the filament.

Thick filament do not have only 2 myosin heads it is more in number.

24 answer : True

A motor unit is made up of a motor neuron and the skeletal muscle fibers innervated by that motor neuron's axonal terminals.

28 answer :C

Protein digestion starts in stomach by the action of pepsin enzyme.

29 answer :D

Most of the digestion occurs in upper part of small intestine in duodenum.

30 answer: a option is correct

Arteries carry the oxygenated blood that is purified blood to all the body parts then distribute it through the capillary network and veins carry the deoxygenated blood having CO2 to the ventricle of heart.