Answer:
4,3,1,5,2
4. Vesicles full of acetylcholine are stored at the axon terminal.
3. Action potential arrives at the neuromuscular junction.
1. Action potential is propagated in the sarcolemma.
5. Acetylcholine is released into the synaptic cleft.
2. Acetylcholine binds to ligand gated sodium channels.
Explanation:
Nerve impulse is generated from somatic motor neurons and reaches neuromuscular junction. The nerve impulse specifically reaches a region named 'synaptic end bulbs' at axon terminal. These synaptic end bulbs are in turn connected to the motor end plate region of a sarcolemma.
As soon as the nerve impulse reaches neuromuscular junction, it triggers the opening of voltage gated ion channels which in turn facilitate the influx of Ca²⁺ from the extracellular fluid to the inside of neuron where synaptic vesicles containing neurotransmitter acetylcholine are already stored.
The Ca²⁺ causes the exocytosis of synaptic vesicles which fuse with the plasma membrane of motor neuron as a result of which acetylcholine is released in the synaptic cleft.
The acetylcholine further binds with the acetylcholine receptor which is present at the motor end plate of a skeletal muscle fibre. These receptors are ligand gated ion channels.
Binding of acetylcholine with its receptor causes the ion channels to open and cations like Na⁺ enter the muscle fibre so as to make the electric potential inside the muscle positive.
Answer:
The water soluble hormones affect the target cells with least amount of interaction.
Explanation:
Hormones are the chemical messengers. These are the substances secreted by the endocrine glands. The hormones are secreted directly into the bloodstream and are carried to the target cells within the blood only.
Based on their structure, hormones are water-soluble or lipid-soluble. The lipid-soluble hormones are steroid hormones and thyroid hormones. These hormones can easily pass through the lipid bilayer of the cell membrane of the target cell. Therefore, the lipid-soluble hormones have intracellular receptors that are present in either cytoplasm or the nucleus of the target cells.
On the other hand, the water-soluble hormones can not pass through the lipid bilayer of the target cells. Therefore, these hormones have extracellular receptors on the surface of the target cells. Binding of the water-soluble hormones to their cell surface receptors triggers the production of the intracellular second messengers that finally carry the signal to the target protein or any other target molecule.
<u>Therefore, a water-soluble hormone exhibits the least amount of interaction with the target cell. Amine hormones such as epinephrine and melatonin, peptide hormones such as oxytocin are some examples of the water-soluble hormones. </u>
Stars are formed in clouds of dust and gas (nebulae.) Nuclear reactions at the center (core) of stars gives enough energy to make them shine brightly for many, many years. The exact l<span>ifetime of a star depends on its size.</span>
Answer:
C. There is a 75% probability that an offspring will have brown eyes and a 25% probability that an offspring will have blue eyes.
Explanation:
Note that the brown eyes is the dominant trait, denoted by B, while blue eyes is the recessive trait, denoted by b. In all cases of the Punnett square, if there is a dominant and recessive trait, the dominant trait will always come out on top.
The given Punnett square:
![\left[\begin{array}{ccc}&B&b\\B&BB&Bb\\b&Bb&bb\end{array}\right]](https://tex.z-dn.net/?f=%5Cleft%5B%5Cbegin%7Barray%7D%7Bccc%7D%26B%26b%5C%5CB%26BB%26Bb%5C%5Cb%26Bb%26bb%5Cend%7Barray%7D%5Cright%5D)
Note that there are 3 options (BB, Bb, Bb) respectively, in which there is the dominant trait B (brown eyes). Only in one case is there only the recessive trait b (blue eyes), or a 1/4 chance of obtaining blue eyes. Therefore, there is a 3/4 chance of obtaining a brown eye:
C. There is a 75% probability that an offspring will have brown eyes and a 25% probability that an offspring will have blue eyes.
