Genetics

What is a phenotype?

• A description of the alleles for a trait

• The description of the appearance of a trait

• The name of the process of completing a Punnett square

• The name given to a type of inheritance pattern

Answer explanation

The phenotype is how the trait LOOKS or is expressed. Eye color, taster/non-taster, hairline - widows peak/no widows peak.....

What is a genotype?

• A description of the alleles for a trait

• The description of the appearance of a trait

• The name of the process of completing a Punnett square

• The name given to a type of inheritance pattern

Answer explanation

The genotype is the description of the alleles for that trait:

TT, Tt, tt

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Why do genotypes always have two letters?

• Because you get one allele from each parent, meaning two in total

• Because both a dominant and a recessive allele are needed for a trait

• Because it is easier to see what type of trait it is using two letters

• Because you get two alleles from each parent for each trait

Answer explanation

Alleles are found on chromosomes, and you have 23 pairs of chromosomes. Of each pair of chromosomes you got one from your mom and one from your dad. So you get one allele for a trait from your mom and one allele for a trait from your dad.

Brown is dominant to green. What is the probability of these parents having green offspring?

• 25%

• 50%

• 75%

• 100%

Answer explanation

This is simple Mendelian inheritance.

What would go into punnet square 1

• BB

• Bb

• bb

• all choices

Answer explanation

In this example black fur in dominant.

The genotype of this flower is....

• homozygous recessive

• heterozygous

• homozygous dominant

• white

Answer explanation

It's homozygous recessive because of the two lowercase letters.

This type of inheritance pattern is a BLEND of both phenotypes.

• incomplete dominance

• co-dominance

• Mendelian dominance

• complete dominance

Answer explanation

If it's a BLEND then it is incomplete dominance.

Incomplete dominance or co-dominance?

A calico cat shows both the traits for orange fur and black fur.

• Incomplete Dominance

• Co-dominance

• Complete dominance

• Mendelian dominance

Answer explanation

If you can see both phenotypes then it is codominance.

A breed of chicken shows codominance for feather color. One allele codes for black feathers, another codes for white feathers. The feathers of heterozygous chickens of this breed will be....

• all black

• all white

• all gray

• speckled black and white

Answer explanation

Codominance is when you see both phenotypes - it is not a blend.

An individual can be blood group A, B, AB, or O. What type of inheritance is this?

• Incomplete dominance

• Codominance

• Mendelian dominance

• Complete dominance

Answer explanation

If you see both phenotypes and they are not a blend, then it is codominance.