Question

When a heterozygous Aa diploid cell undergoes mitosis, what are the genotypes of the mitotic products?

Group of answer choices

Aa (product 1) and Aa (product 2)

AA (product 1) and aa (product 2)

AA (product 1) and AA (product 2)

aa (product 1) and aa (product 2)

When a heterozygous Aa diploid cell undergoes the 1^st meiotic division (meiosis I), how will the A and a alleles distribute to the two meiosis I products if there is no crossing over?

Group of answer choices

Aa (product 1) and Aa (product 2)

AA (product 1) and aa (product 2)

AA (product 1) and AA (product 2)

aa (product 1) and aa (product 2)

According to Mendel’s principle of segregation, an Aa heterozygous diploid organism produces:

Group of answer choices

Only gametes that are AA

Only gametes that are aa

AA and aa gametes in theoretically equal numbers

A and a gametes in theoretically equal numbers

According to Mendel’s principle of independent assortment, a diploid organism with the genotype Aa Bb (the genes are located on different chromosomes) produces:

Group of answer choices

Only Ab and aB gametes

Only ab and AB gametes

AB, Ab, aB, and ab gametes

If allele A confers the A⁺ phenotype, and allele a is recessive (aa has A^- phenotype), what will the A⁺ : A^- ratio be among the offspring of an Aa X Aa cross?

Group of answer choices

1A⁺ : 1A^-

1A⁺ : 3A^-

3A⁺ : 1A^-

4A⁺ : 0A^-

Answer 1

Answer 1: When a heterozygous Aa diploid cell undergoes mitosis, the genotypes of the mitotic products will be: Aa (product 1) and Aa (product 2)

Explanation: Mitosis is an equational cell division in which two daughter cells will be produced which will have exactly the same number and type of chromosomes as in the mother cell. Hence when a heterozygous diploid cell undergoes mitosis it will produce two cells which will be heterozygous Aa

Answer 2: When a heterozygous Aa diploid cell undergoes the 1st meiotic division (meiosis I), then the A and a alleles distribute to the two meiosis I products if there is no crossing over: AA (product 1) and aa (product 2)

Explanation: Meiosis is a reduction division in which chromosome number is halved. The product of Meiosis I are two haploid cells which will have one of the pairs of sister chromatids of the pair of homologous chromosomes. Hence after Meiosis I two cells produced which will have AA and aa, as there is no crossing over.

In Meiosis II which is mitosis like cell division in which the sister chromatids will separate and four daughter cells will be produced with two of them having A and two will be having a.

Answer 3: According to Mendel’s principle of segregation, an Aa heterozygous diploid organism produces: A and a gametes in theoretically equal numbers

Explanation: Mendel’s principle of segregation says that a pair of alleles of the factors separate during the formation of gamates. Now we call these factors as genes, when a diploid organism produces the gamates, one of the gamates will be with one set of homologous chromosomes and the other pairing set of homologous chromosomes enter into another gamate.

Answer 4: According to Mendel’s principle of independent assortment, a diploid organism with the genotype Aa Bb (the genes are located on different chromosomes) produces: AB, Ab, aB, and ab gametes

Explanation: Mendel’s principle of independent assortment says that out of the two members of the pair of factor, distribution of allele of one factor is independent of the allele of the another factor. That is the genes for two characters belonging to two different chromosomes will enter into the gamates independent of each other giving rise to all possible combinations of the characters. In the above case A and a are the alleles for one character and B and b are the alleles for another character, then A can pair with B or b and a can pair with B or b giving rise to four different types of gamates.

Answer 5: If allele A confers the A+ phenotype, and allele a is recessive (aa has A- phenotype), what will the A+ : A- ratio be among the offspring of an Aa X Aa cross : 3A+ : 1A-

Explanation: If the cross is depicted with the help of Punnett square, it will be as follows:

Parents Aa and Aa will be producing the gamates A and a

gamates	A	a
A	AA A+ phenotype	Aa A+ phenotype
a	Aa A+ phenotype	aa A- phenotype

Since the A allele is dominant it will express itself in homozygous AA as well as heterozygous condition Aa, but a is recessive allele and hence it will be expressed only in homozygous aa condition.