Unit Test — Unit test Answers

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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?

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A
She must have at least one allele for color blindness.
B
She must have two alleles for color blindness.
C
She cannot be homozygous recessive for the gene for color blindness.
D
She cannot be a heterozygous carrier of the gene for color blindness.
2
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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?

A
F1 generation only
B
P generation only
C
F1 generation and F2 generation
D
P generation and F2 generation
3

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?

A
The child cannot have the disease because only the dominant alleles will be passed on.
B
The child will have the disease because only recessive alleles will be passed on.
C
The child may or may not have the disease because a recessive gene from each parent may be passed on.
D
The child may or may not have the disease because the disease does not depend on the alleles of the parents.
4

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

A
can self-pollinate.
B
have two recessive traits.
C
have two alleles for the gene.
D
have two copies of a gene from one parent.
5

Which represents the cross between parent plants if one is heterozygous and has yellow-colored pods and the other is homozygous and has green-colored pods?

A
Yy ´ yy
B
YY ´ yy
C
Yy ´ Yy
D
yy ´ yy
6

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?

A
If two different alleles for a gene occur together, one of the alleles may be expressed while the other is hidden.
B
When gametes are formed, each gamete carries only one allele for the gene.
C
There are alternate versions of a alleles called genes.
D
For each inherited trait, there is only one copy of the gene that codes for that trait.
7

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?

Question illustration
A
0 percent
B
25 percent
C
50 percent
D
75 percent
8

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

Question illustration
A
Sam, Tim, Bella, and Joshua
B
Lisa and Monica
C
Ben, Jenny, Mike, Carol, Katie, and Chris
D
Sam, Joshua, and Tim
9

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?

A
25 percent
B
50 percent
C
75 percent
D
100 percent
10

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
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.
Option A
B
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.
Option B
C
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.
Option C
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.
Option D
11

Hemophilia is an X-linked recessive disorder that is passed through generations and can be traced by using a pedigree. Who has hemophilia in the pedigree that is shown?

Question illustration
A
John and Ann
B
Fred and Luke
C
John, Charles, Jack, and Irene
D
Ann and Marie
12

Round seeds and yellow seed color are dominant to wrinkled seeds and green seed color. Which Punnett square represents the correct way to set up the cross RRYy ´ RrYY?

A
A 4-column Punnett square has 4 rows. The columns are labeled Upper R Upper Y, Upper R y, r Upper Y, r y. The rows are labeled Upper R Upper Y, Upper R y, r Upper y, r y.
Option A
B
A 4-column Punnett square has 4 rows. The columns are labeled Upper R Upper Y, Upper R y, r Upper Y, r y. The rows are labeled Upper R Upper Y, Upper R y, Upper R Upper y, Upper R y.
Option B
C
A 4-column Punnett square has 4 rows. The columns are labeled Upper R Upper Y, Upper R Upper Y, r Upper Y, r Upper Y. The rows are labeled Upper R Upper Y, Upper R y, Upper R Upper Y, Upper R y.
Option C
D
A 4-column Punnett square has 4 rows. The columns are labeled Upper R Upper Y, Upper R Upper Y, r Upper Y, r Upper Y. The rows are labeled Upper R Upper Y, Upper R Upper Y, Upper R Upper Y, Upper R Upper y.
Option D

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