Answer:
A.Oxygen
Explanation:
Trees take in Carbon for photosynthesis and as a waste product air.Animals do the exact opposite for cellular respiration.
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Answer: Human population, now over 7 billion, cannot continue to grow indefinitely. There are limits to the life-sustaining resources earth can provide us.
Explanation:
Natural selection lead to different species when the squirrels were separated, some of them acquired traits better suited for their new environment. This allowed them to survive and reproduce better than others. Over time, each group evolved to display unique traits for their different environments until one species evolved into two.
Explanation:
The speciation in the squirrels due to the barrier in canyon occurred due to this. Such speciation is called allopatric speciation.
Speciation leads to formation of new species from the existing species due to change in their habitat or physical structure.
The squirrels on the two different side of canyon adapted to the habitat they are in. Their reproductive cycles, habitat and adaptation mode has become different due to the change in environment.
The species of squirrels became two as they reproduce and passed on the traits for survival in the environment which they had adapted.
The squirrels have become <em>reproductively isolated</em> also.
Genetic divergence takes place due to natural selection as squirrels arenow two different species.
Answer:
There are vitamin A receptors on cancer cells and retinoid chemotherapy drugs bind to them.
Explanation:
In the given question all the statements are true but the false statement is that the cancer cells possess the Vitamin A receptors.
This statement is not correct as the cancer cells do not possess the vitamin A receptor in their membrane and since there are no receptors therefore the retinoid chemotherapy drugs do not bind to them.
But the studies on the cancer cells has shown that there are vitamin D receptors in the cells.
Thus, the selected options are correct.
