BIO

In garden peas, the allele for tall plants is dominant over the allele for short plants. Imagine that a true-breeding tall plant is crossed with a short plant. Then one of their offspring is test crossed. Out of 20 offspring resulting from the test cross, about how many should be tall?

10

In a test cross, what percentage of the offspring will have the same phenotype as the tested parent if the parent to be tested is homozygous?

100%

In Mendel's experiments, if the gene for tall (T1) plants was incompletely dominant over the gene for short (T2) plants, what would be the result of crossing two T1T2 plants?

25% tall, 50% intermediate, and 25% short

In pea plants, tall plants are dominant over short, and green pods are dominant over yellow. If you crossed true-breeding tall, green-podded plants with true-breeding short, yellow-podded plants, and then crossed the F1 individuals among themselves, what proportion of the F2 offspring would you expect to be tall and yellow-podded?

3/16

If an individual who is homozygous for type B blood marries a heterozygous type A individual, what is the chance that their first child will have type AB blood?

50%

In crossing a homozygous recessive with a heterozygote, what is the chance of getting a homozygous recessive phenotype in the F1 generation?

50%

Albinism results from a recessive allele. Which of the following describes the expected offspring from a normally pigmented male with an albino father and an albino wife?

50% normal; 50% albino

If we cross two pea plants, each heterozygous for yellow seed color genes, the expected ratio of yellow:green among the offspring will be:

75% yellow:25% green.

When Mendel used true-breeding white flowers and true-breeding purple flowers as the parental generation, what were the results? (Purple flower is dominant over white.)

All the offspring had purple flowers.

Imagine that a newly discovered species of fish normally has three eyes (E), but the rare mutation (e) causes "diopthalmic" fish with two eyes to be born. In addition, eye color in these fish is inherited similarly to humans, with black eyes (B) being dominant to blue (b). Assuming these two genes are carried on separate chromosomes, what must the genotypes of two black-eyed, three-eyed parents be if they have a blue-eyed, diopthalmic son?

Both EeBb

What is the genotype of a dominant individual if some of its offspring show the recessive phenotype?

Dd

Sickle-cell anemia is caused by a recessive mutation in the hemoglobin gene. However, heterozygote individuals also show a small percentage of sickled red blood cells. What type of inheritance pattern is this an example of?

Incomplete dominance

Which of the following statements about genotypes and phenotypes is true?

Individuals with the same phenotype might have different genotypes.

A woman with AB blood type and a man with blood type O have three children, one of whom is adopted. The blood types of the children are A, B, and O. What is the blood type of the adopted child?

O

What is the difference between phenotype and genotype?

Phenotype is the physical expression of a trait and genotype is the combination of alleles carried by the organism.

What type of allele produces its effects in only homozygous individuals?

Recessive

A pea plant with red flowers is test crossed; half of the resulting progeny have red flowers whereas the other half have white flowers. The genotype of the test-crossed parent was:

Rr

Round pea shape is dominant over wrinkled pea shape. If a round pea has a wrinkled parent, the round pea is:

Rr

Which of the following is true of genes that are found near each other on the same chromosome?

They are linked and tend to be inherited together.

Suppose you cross a pea plant with yellow, smooth seeds with one that has wrinkled, green seeds. You examine the seeds of 967 offspring and find that some have yellow, smooth seeds and some have yellow, wrinkled seeds, but no green seeds of either type show up. What is the genotype of the yellow-seeded parent? (Y = yellow, y = green; S = smooth, s = wrinkled)

YYSs

All of the following combinations are possible in the gametes of an organism that is AaBb EXCEPT:

aa

A Mendelian test cross is used to determine whether:

an individual is homozygous or heterozygous.

Codominance occurs when:

both of the alleles in a heterozygote are expressed phenotypically in an individual.

If, in a heterozygous individual, only one allele is expressed in the phenotype, that allele is:

dominant

Gregor Mendel concluded that each pea has two units for each trait, and each gamete contains one unit. Mendel's "units" are now called:

genes.

The genetic makeup of an individual is the:

genotype.

Based on this figure, what would be the genotype of an individual pea plant that is homozygous for green pod and constricted pod and is 6 feet tall? (Assume that green and yellow pods are indicated by g and G, inflated and constricted pods by I and i, and height by T and t.)

ggiiTT

According to the law of segregation, in an organism with the genotype Aa:

half the gametes have A and half have a.

If the allele for inflated pea pods (I) is dominant to the allele for constricted pods (i), then the cross Ii x ii is expected to produce:

half with inflated and half with constricted pods.

Peas were a good organism of choice for Mendel because:

he could study one trait at a time.

When the two gametes that fuse to form a zygote contain different alleles of a given gene, the offspring is:

heterozygous.

The results of a test cross reveal that all the offspring resemble the parent being tested. This parent must be:

homozygous.

Mendel's law of segregation states that:

members of a pair of alleles move away from each other during gamete formation.

The physical manifestation of an organism's genes is its:

phenotype.

Human eye color is the result of:

polygenic inheritance

Human skin color is the result of:

polygenic inheritance.

When the expression of a trait is influenced by the action of many genes, the pattern of inheritance is called:

polygenic inheritance.

Crossing spherical-seeded pea plants with dented-seeded pea plants resulted in progeny that all had spherical seeds. This indicates that the dented-seed trait is:

recessive only.

Yellow-seeded pea plants may be homozygous or heterozygous. To find out which, we can cross the plants with:

true-breeding green-seeded plants.

A recessive allele is one:

whose effect is masked by a dominant allele.