<span>All cells contain the same key elements, such as carbon, nitrogen, and oxygen. </span>
<span>The cells that most directly attack and lyse cells infected by the virus are T cells. These cells mature in the thymus. T cells are an essential part of a properly functioning immune system. Patients with reduced T cells may end up being in more danger from the flu than those with a healthy immune system.</span>
Answer:
Question: Two requirements for gas exchange which are accomplished by the gills in a fish include:
1. Water flowing in opposite directions across the gill lamellae for gas exchange, in other words, respiration is experienced by the fish.
2. The fish allows water through its mouth, then forces the water to drain through the gills supporting gill lamellae, and enhancing gas exchange.
Question: How does their structure help to satisfy these requirements?
1. The rows of gill filaments with numerous folds through diffusion makes sure oxygen from the water moves from a place of more concentration to the blood of the fish which has less concentration causing the removal of carbon dioxide.
2. The large surface area of the gill means it has to maximize the low percentage of dissolved oxygen in the water compared to the higher percentage of oxygen in the air makes it possible for water to pass through the mouth and empty through the gills after the mouth is closed.
Animals pass down their features to their children when they breed. When you separate a population (or group of animals of the same species), say by building a large wall, they can't interbreed with each other. This means that if an animal on one side of the border gets an adaptation, it won't pass it on to the other animal. Soon, each side will evolve different adaptations, and the two populations will become so different that they become two different species.
It is possible that one-half wouldn't be able to survive, and go extinct, but it doesn't happen all the time (A is incorrect). Similarly, the populations don't ALWAYS evolve into two different species, though they may (B is incorrect). However, if the environments differ enough, they will acquire different adaptations through evolution. C is correct! Keep in mind that D is incorrect: the first part, the populations can't interbreed, is correct, but that doesn't mean they will die off.
