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A cross is performed between a bird that is homozygous for red feathers and a bird that is homozygous for blue feathers. Purple offspring result due to incomplete dominance. Then, two of the purple offspring are crossed. What proportion of the offspring from the second cross will be purple?

1 in 4

2 in 4

3 in 4

4 in 4

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In roses, red flowers and long stems are dominant traits. A rose plant that is homozygous for both red flowers and long stems is crossed with a rose plant that is heterozygous for red flowers and homozygous for short stems. What percentage of the offspring will exhibit red, long-stemmed flowers?

25 percent

50 percent

75 percent

100 percent

Some flowering plants appear to have offspring that have traits that are intermediate between those of the parents. Which type of dominance is exhibited by the offspring?

complete dominance

blended dominance

codominance

incomplete dominance

Red-green color blindness is an X-linked recessive disorder. What is the probability of the offspring having red-green color blindness for the cross that is represented by the Punnett square?

0 percent

25 percent

50 percent

75 percent

A plant that has round and yellow seeds (RrYy) is crossed with a plant that has round and yellow seeds (RrYy). What is the ratio of the offspring that will have round and yellow seeds?Key: R = round r = wrinkled Y = yellow y = green

1:16

3:16

8:16

9:16

Cystic fibrosis is a genetic disorder. It is a recessive trait that is determined by two alleles. Suppose two parents each carry at least one recessive allele, but neither of them has cystic fibrosis. Which statement reflects the likelihood of a child of these parents having cystic fibrosis?

The child cannot have the disease because only the dominant alleles will be passed on.

The child will have the disease because only recessive alleles will be passed on.

The child may or may not have the disease because a recessive gene from each parent may be passed on.

The child may or may not have the disease because the disease does not depend on the alleles of the parents.

Mendel was able to study seven traits in all the pea plants in each generation. Which of his hypotheses allowed him to analyze each trait separately?

If two different alleles for a gene occur together, one of the alleles may be expressed while the other is hidden.

When gametes are formed, each gamete carries only one allele for the gene.

There are alternate versions of a alleles called genes.

For each inherited trait, there is only one copy of the gene that codes for that trait.

The pedigree traces red-green color blindness. Which family members have red-green color blindness?

Sam, Tim, Bella, and Joshua

Lisa and Monica

Ben, Jenny, Mike, Carol, Katie, and Chris

Sam, Joshua, and Tim

Mendel’s pea plants had either purple or white flowers. This means that the plants

can self-pollinate.

have two recessive traits.

have two alleles for the gene.

have two copies of a gene from one parent.

If Mendel had crossed a true breeding dominant plant with a true breeding recessive plant, in which of the three generations is the recessive trait visible?

F1 generation only

P generation only

F1 generation and F2 generation

P generation and F2 generation

Which scenario breaks the law of segregation?

a gamete contains the father’s allele

the gametes produced each have 1 allele after meiosis II

a gamete produced has 2 of the same alleles after meiosis II

the gamete fertilized has the dominant trait

The Punnett square predicts the ratio of genotypes in the offspring based on the genotypes of the parents. Which Punnett square represents a cross between a mom who is heterozygous for dimples and a dad who is homozygous for no dimples?

A Punnett square is shown. The columns are labeled Upper D and Upper D. The rows are labeled d and d. Clockwise from upper left the boxes contain: Upper D d, Upper D d, Upper D d, Upper D d.

A Punnett square is shown. The columns are labeled Upper D and d. The rows are labeled d and d. Clockwise from upper left the boxes contain: Upper D d, d d, d d, Upper D d.

A Punnett square is shown. The columns are labeled Upper D and d. The rows are labeled Upper D and d. Clockwise from upper left the boxes contain: Upper D Upper D, Upper D d, d d, UpperD d.

A Punnett square is shown. The columns are labeled Upper D and Upper D. The rows are labeled Upper D and Upper D. Clockwise from upper left the boxes contain: Upper D Upper D, Upper D Upper D, Upper D Upper D, Upper D Upper D.

The diagram represents a dihybrid cross between two pea plants heterozygous for both seed color and seed shape.What is the phenotypic ratio of the offspring?

1:1:1:1:2:2:2:2:4

1:3:3:9

1:4

4:12

Pedigrees help geneticists understand how traits are inherited between generations. Red-green color blindness is a sex-linked disorder that is determined by a recessive allele on the X chromosome.If Brian has a son who is color-blind, what is known about the genotype of the son's mother?

She must have at least one allele for color blindness.

She must have two alleles for color blindness.

She cannot be homozygous recessive for the gene for color blindness.

She cannot be a heterozygous carrier of the gene for color blindness.

Which are different forms of the same gene?

genotypes

phenotypes

alleles

traits

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