The answer would be the first option; Memory Cells.
Urea s a waste product that normally diffuse across the placenta from the embryo to the mother.
Populations of organisms that exhibit a high degree of variation have a greater chance for survival than populations of organisms that show little variation is described below.
Explanation:
- Allele frequencies in a population may change due to four fundamental forces of evolution: Natural Selection, Genetic Drift, Mutations and Gene Flow. Mutations are the ultimate source of new alleles in a gene pool. Two of the most relevant mechanisms of evolutionary change are: Natural Selection and Genetic Drift.
- The genetic variation in the population is increasing due to selective pressure. The genetic variation in the population is decreasing due to selective pressure. The genetic variation in the population is increasing due to gene flow. The genetic variation in the population is decreasing due to gene flow.
- Genetic drift is a random change in allele frequencies. These random changes in allele frequency can accumulate over time. ... Small samples can vary more markedly from the larger sets from which they are selected than larger samples, so genetic drift is more powerful in smaller populations
- Natural selection can cause microevolution (change in allele frequencies), with fitness-increasing alleles becoming more common in the population.
Fitness is a measure of reproductive success (how many offspring an organism leaves in the next generation, relative to others in the group).
