Answers:
a local fresh market ( second choice)
a business working with trained animals ( third choice)
a person buying large quanities of wheat ( fourth choice)
Lunar phases are basically the different positions of the moon that we see throughout its whole cycle, from new moon to full moon, back to new moon. Eclipses, though are more rare phenomena. These occur when the sun, moon, and earth line up at a specific position.
Asteroids are usually dense bodies, with many different formations on their surface. They are also believed to be the largest source of precious metals on our planet.
Comets are bright clouds of gas surrounding a center nucleus that speed toward the sun and heat up at the same time. They contain dust, ice, carbon dioxide, and other gases. As the comet soars toward the sun, the radiation pushes dust particles back, forming the tail they are known for.
Answer:
A. Botulinum toxin possesses a heavy chain and a light chain, each of which takes part in the toxicity. The binding of the protein and its invasion within a nerve cell is permitted by the heavy chain. After the entry is permitted, the light chain functions like a protease and chops proteins, which would usually permit neurotransmitters to discharge out from the cell. This is basically a commotion of exocytosis or the discharging of neurotransmitters.
The acetylcholine, that is, the obstructed neurotransmitter generally conducts a nerve impulse to a muscle, allowing the muscle to contract. By inhibiting the neurotransmitter, the botulinum toxin results in its distinctive flaccid paralysis.
B. The small doses of the sterile, purified botulinum toxin when used in a medical setting as an injectable form prevent the release of a chemical known as acetylcholine by the nerve cells, which signal contraction of the muscles. By selectively interfering with the underlying tendency of the muscles to contract, the prevailing frown lines are smoothed out, and in the majority of the cases are almost invisible for a week.
Explanation:
1. they are convenient to use 2. it helps the international tade 3. it eases the exchange of material
