Answer: a). AA
Explanation: Every trait is controlled by at least a pair of gene. Genes have different forms known as alleles. Alleles can be dominant or recessive. A dominant allele expresses itself in the presence of a recessive allele and masks the effect of a recessive allele. A recessive allele cannot express itself in the presence of a dominant allele and it's effect is masked by a dominant allele. Dominant alleles are usually written in upper cases such as A, T, while recessive alleles are usually written in lower cases such as a, t. The two alleles that determines a trait is called a genotype. A genotype can be homozygous if the two alleles are identical such as in AA or aa
and can be heterozygous if the two alleles are not identical such as in Aa, Tt.
<span>The principal components of the plasma membrane are lipids (phospholipids and cholesterol), proteins, and carbohydrate groups that are attached to some of the lipidsand proteins. A phospholipid is a lipid made of glycerol, two fatty acid tails, and aphosphate-linked head group.
</span>
First comes fertilization, when two gametes combine to form a zygote.
