Answer:
The fossil record of the evolution of modern cetaceans.
Explanation:
The fossil record has observable data on morphological development of early cetaceans as well as their bio-geographical distribution.
Answer:
<em>Look below.</em>
Explanation:
This question may have made it seem like natural selection is a harmful process -- be wary of this. To understand this, you have to note something known as heterozygote advantage. All this means is that the heterozygotes, the organism that expresses both the dominant and recessive alleles, rather than the homozygotes, organisms that express both dominant or both recessive alleles, have an advantage. An example is with sickle cell disease. People heterozygous for the sickle cell trait are more resistant to malaria for some reason, whereas the homozygotes are not. Because heterozygotes (which have a harmful allele and normal allele) have the advantage, natural selection selects for this trait and favors it. This leads to the "persistence of harmful or even lethal allele[s]." Again, just because the organism has a lethal allele isn't necessary always a bad thing. :)
Answer:
The roles of the organelles within the cells need to be introduced and relate structure and location of organelles to their function. Cells differ in size, shape and structure and therefore carry out specialized functions.
Frogs lay eggs under water. When they hatch they are called tadpoles. After a time as tadpoles they undergo metamorphosis where they grow legs and lungs and become the little friendly hippidy hoppidy guys you see on your porch every night.
Food is digested, or broken down, so that the nutrients can be extracted for use by the body as it passes through the digestive system. If food wasn't digested you would not have energy required to run vital chemical reactions and eventually resulting death
