10BD 11-2: Punnett Squares and Probability

A tool used to predict the probability of offspring inheriting certain traits is called a ____.

• Punnett square

• karyotype

Cross 2 heterozygous tall pea plants. Tall (T) is dominant to short (t). What fraction of the offspring do you predict to be tall?

• 1/2

• 4/4

• 3/4

• 1/4

In the problem shown, what must the genotype of the missing parent be?

• Bb

• bb

• BB

In humans, freckles (F) on the skin are dominant to no freckles (f). If a heterozygous parent and a recessive parent conceive, what is the chance of having a child with NO FRECKLES?

• 50%

• 0%

• 100%

• 25%

Having freckles is a dominant trait in humans. A girl has freckles, but her brother does not. What do we know for certain about the parents?

• both parents are heterozygous for freckles

• one of the parents does not have freckles

• both parents have a least one recessive allele

Which statement best supports the idea of independent assortment?

• An organism’s alleles from one gene have exactly half the impact on the probability that alleles from other genes will combine in a fertilized egg.

• An organism’s alleles from one gene have no impact on the probability that alleles from other genes will combine in a fertilized egg.

• An organism’s alleles from one gene have some impact on the probability that alleles from other genes will combine in a fertilized egg.

• An organism’s alleles from one gene impact the probability that alleles from other genes will combine in a fertilized egg.

In a population of bees, long wings (L) are dominant of short wings (l). Bees with long wings are ____.

• heterozygous or homozygous dominant (LL or Ll)

• heterozygous only (Ll)

• homozygous dominant only (LL)

In guinea pigs, the allele for rough coat (R) is dominant over the allele for smooth coat (r). A homozygous dominant guinea pig and a homozygous recessive guinea pig are mated. What would be the phenotype of the offspring?

• 100% smooth coat

• 100% rough coat

What ratio best represents the results from a monohybrid cross?

• 9:3:3:1

• 6:4:1

• 10:1

• 3:1

Two parents have three girls and are pregnant with a fourth child. What is the approximate probability that the developing embryo will be a boy?

• 100%

• 75%

• 50%

• 25%