AP BIOLOGY

Detailed explanation-1: -The dwarf plant will be homozygous (tt), as dwarfness is a recessive character. Thus, the ratio between homozygous tall and homozygous dwarf will be 1 : 1.

Detailed explanation-2: -This is because the heterozygous plant will make two types of gametes, one type having T allele and the other having t allele. Hence, the correct answer is ‘1 tall : 1 dwarf’

Detailed explanation-3: -Correct answer: If the unknown organism is homozygous dominant, then all offspring will show the dominant phenotype. Crossing an homozygous tall plant with a homozygous short plant, and observing all tall offspring, would prove that the tall trait is dominant.

Detailed explanation-4: -When a homozygous tall pea plant and a homozygous short pea plant are crossed, the next generation are all heterozygous and the dominant allele is expressed in all the plants, and the recessive trait seems to disappear.

Detailed explanation-5: -Since a Tt heterozygous, tall plant produce with equal probabilities the gametes T and t, and the tt homozygous, short plant only t gametes, when they are crossed (Tt x tt) the progeny will be 50% tall (all genotypically Tt) and 50% short (all genotypically tt).