Answer is A
Firstly axon must reach the threshold level and then depolarisation occurs. Depolarisation phrase means sodium enters and potassium leaves the axon . Choice C can't be because main idea is the entering of sodium ions.
Answer:
Kelp is eaten by sea otters. Kelp is a large, brown plant that grows in the sea and is used in some foods and medicines
Answer: a close evolutionary connection between humans and many other mammals
Explanation:
They reproduce over the years making it less frog to survive
Answer:
Four conditions are needed for natural selection to occur: reproduction, heredity, variation in fitness or organisms, variation in individual characters among members of the population. If they are met, natural selection automatically results.
Explanation:
Evolution, in genetic terms, involves a change in the frequency of alleles in a population over time. What are the sources of genetic variation? Three sources of genetic variation are mutation, genetic recombination during sexual reproduction and lateral gene transfer.