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>D.It has affected the fates of a space probe and a commercial airline flight.</span>
The probability of transmitting both traits to his son is Zero. This is because the son has one X chromosome and one Y chromosome (XX), therefore since the traits are linked to the X chromosomes, it means the son will only be a carrier but will not show the trait phenotypically.
<span>Among all choices, mobility is not a characteristic of a plant. Plants are multicellular organisms. They have organelles inside their cells and thus they are eukaryotes. Chloroplasts are organelles that are found in plant cells and they have an important role in the process of photosynthesis. However, plants cannot move from place from place like animals.</span>
