<span>Of the 118 elements that have been discovered, 90 of them indisputably occur in nature. There is disagreement over whether four more or eight more occur naturally as a result of radioactive decay of other natural elements. The answer is, therefore, 94 or 98.</span>
<span><span>All cells have a plasma membrane, ribosomes, cytoplasm, and DNA.
</span>Prokaryotic cells lack a nucleus and membrane-bound structures.
<span>Eukaryotic cells have a nucleus and membrane-bound structures called organelles.</span></span>
Answer:
The correct answer is b. must be present in a population before natural selection can act upon the population
Explanation:
Genetic variation can be caused by mutation, recombination between chromosomes during meiosis and by fusion of two genetically different gametes during sexual reproduction.
This genetic variation is necessary for the evolution of any population. Natural selection acts on every individual and it decreases the frequency of those alleles that are not suited for the environment and increase the frequency of those alleles which helps the individual to survive in the changing environment.
Therefore genetic variation must be present in the population before natural selection act on the.
Answer:
i think it might Be B. but im not 100% sure but it seems to be the only logical one
Explanation:
