Which of the following statements is correct in describing the terms monohybrid cross and dihybrid cross?
a) a monohybrid cross is performed for one generation, whereas a dihybrid cross is performed for two generations.
b) a monohybrid cross results in a 9: 3: 3: 1 ratio, whereas a dihybrid cross gives a 3: 1 ratio.
c) a monohybrid cross involves a single parent, whereas a dihybrid cross involves two parents.
d) a dihybrid cross involves organisms that are heterozygous for two characters that are being studied, and a monohybrid cross involves organisms that are heterozygous for only one character being studied.

D) A dihybrid cross involves organisms that are heterozygous for two characters that are being studied, and a monohybrid cross involves organisms that are heterozygous for only one character being studied.

Explanation:

When we do a monohybrid cross, we look at one characteristic at a time. When you do dihybrid cross, you are looking at characteristics.

Monohybrid cross example:

If black fur (B) is dominant over white fur (b) what is the probability of black fur in an offspring between two dogs heterozygous for the trait?

Bb x Bb

     B      b

B   BB    Bb

b   Bb    bb

So the probability of black fur is 75%.

Dihybrid example:

If black fur (B) is dominant over white fur (b) and short hair (S) is dominant over long hair (s) what is the probability of white fur and long hair in an offspring between two dogs heterozygous for both traits?

BbSs x BbSs

         BS       bS      Bs      bs

BS  BBSS    BbSS  BBSs  BbSs

bS  BbSS    bbSS   BbSs  bbSs

Bs  BBSs    BbSs   BBss   Bbss

bs  BbSs    bbSs   Bbss    bbss

The answer would be 1:16 = 6.25%