Mendelian Genetics | MCQs

Explanation

The number of different types of gametes is calculated using the formula 2ⁿ, where n is the number of heterozygous gene pairs.

In genotype AaBb, there are 2 heterozygous pairs (A/a and B/b), so 2² = 4 types of gametes: AB, Ab, aB, ab.

Explanation

Explanation

When crossing an organism with genotype Aa (heterozygous) with one that has genotype aa (homozygous recessive), the offspring can inherit either the A or a allele from the Aa parent and only the a allele from the aa parent.

This results in a 1:1 ratio of genotypes, with half of the offspring being Aa (heterozygous) and the other half being aa (homozygous recessive).

The incorrect ratio of "1/2 Az & 1/2 aa" mentioned in the question is likely a typo.

Explanation

The law of independent assortment states that genes for different traits are distributed to gametes independently of one another, leading to a variety of genetic combinations in the offspring.

Explanation

When crossing CC (homozygous dominant) with Cc (heterozygous), the possible genotypes of the offspring are:

CC (from C and C)

Cc (from C and c)

The genotype distribution is:

CC: 50% (or 1/2)

Cc: 50% (or 1/2)

So, the proportion of homozygous dominant (CC) offspring is 1/2.

Explanation

The P generation refers to the parental generation in a genetic cross.

These individuals are considered "pure-breeding," meaning they have homozygous genotypes for a particular trait, and therefore exhibit that trait without any variation. 

Explanation

 The sex of a baby is determined by the sperm that fertilizes the egg.

If the sperm carries a Y chromosome, the baby will be a son.

If the sperm carries an X chromosome, the baby will be a daughter.

Since the chances of receiving a Y or an X chromosome are roughly equal, the probability of having a son or a daughter is approximately 50/50, or 1:1. 

Explanation

• T = dominant allele (e.g., tall)
• t = recessive allele (e.g., short)

Explanation

In incomplete dominance, the heterozygous phenotype is intermediate between the two homozygous phenotypes.

The F2 generation from a cross between two heterozygotes will show a 1:2:1 phenotypic ratio, where one part shows the dominant trait, two parts show the intermediate trait, and one part shows the recessive trait.