Question

The offspring resulting from a cross between two pure homozygous recessives would be ........

• A. $50\%$ homozygous recessive and $50\%$ homozygous domnant.
• B. $75\%$ homozygous recessive and $25\%$ heterozygous dominant
• C. $75\%$ homozygous recessive and $25\%$ homozygous dominant
• D. $100\%$ homozygous recessive

Answer 1

The correct option is D $100\%$ homozygous recessive

• An organism in which both the alleles of a character at the corresponding loci on homologous chromosomes are identical is said to be homozygous or genetically pure for that character.
• Homozygous individuals produce offsprings with similar genotypes and phenotypes on breeding. They are called pure individuals. For example, the pea plants with 'TT' and 'tt' allele pairs are homozygous for height. The combination of 'TT' alleles is called homozygous dominant and the combination of 'tt' alleles is called homozygous recessive.
• Homozygous individuals because of having identical alleles for one or more traits produce only one type of gametes.
• Therefore, when two pure homozygous recessives will cross, the offsprings produced will be 100% homozygous recessive.
• For example, a cross between a pure dwarf plant with genotype 'tt' and another pure dwarf plant with genotype 'tt' will produce all offsprings with genotype 'tt' and will be dwarf.

Thus, the correct answer is option D.