Chapter 11 Bio Study Guide

Each pea-plant gamete has how many alleles for the height gene?

1

What is the probability that a cross between parents who are both homozygous recessive for trait will have offspring that are homozygous recessive for that trait?

100%

How many different allele combinations would be found in the gametes produced by a pea plant whose genotype was RrYY?

2

A tall pea plant with yellow seeds is heterozygous for height and seed color (TtYy). This plant is crossed with a pea plant heterozygous for height but homozygous recessive for seed color (Ttyy). If 80 offspring are produced, how many are expected to be tall and have yellow seeds?

30 of the offspring are expected to be tall and have yellow seeds.

A heterozygous tall pea plant is crossed with a short plant. The probability that an F1 plant will be tall is

50%

In the Punnett squares shown in figure 11-1, which of the following is true about the offspring resulting from the cross?

All are expected to be tall

Gregor Mendel's principles of genetics apply to

All organisms

The different forms of a gene are called

Alleles

If a pea plant's alleles for height are tt, what is true of its parents?

Both parents contributed a recessive allele

If two speckled chickens are mated, according to the principle of codominance, 25% of the offspring are expected to be speckled.

False, 50%

True-breeding plants that produced axial flowers were crossed with true-breeding plants that produced terminal flowers. The resulting offspring all produced terminal flowers because the allele for terminal flowers is RECESSIVE.

False, dominant

If a pea plant has a recessive allele for green peas, it will produce

Green peas if it does not also have a dominant allele for yellow peas

Organisms that have 2 identical alleles for a particular trait are said to be

Homozygous

Situations in which one allele for a gene is not completely dominant over another allele for that gene are called

Incomplete dominance

Could the red snapdragons shown in the P generation of Figure 11-7 ever have white offspring? Explain your answer.

It is not possible for the red snapdragon to have white offspring. They are homozygous (RR) and therefore do not carry any white alleles. The red snapdragons in Figure 11-7 will always pass the R allele on to offspring and therefore the offspring can only be red or pink.

Roan cattle show codominance for the color of their hair. There are alleles for red hair and white hair. What would you expect a heterozygous roan bull to look like if the trait showed incomplete dominance instead?

It would be pink

__________'s principles can be used to study heredity in dogs, cats, and sheep.

Mendel

The plants that Gregor Mendel crossed to produce the F1 generation made up the _______ generation.

P

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

Speckled

In the P generation, a tall plant was crossed with a short plant. Short plants reappeared in the F2 generation because

The alleles for both heights segregated when the F1 plants made gametes

A tall plant (TT) is crossed with a short plant (tt). If the tall F1 pea plants are allowed to self-pollinate,

The offspring can be tall or short

What is the phenotype ratio of the offspring of the plants in the Punnett square in Figure 11-2?

The phenotype ratio is 9 round, yellow seeds; 3 round, green seeds; 3 wrinkled, yellow seeds; 1 wrinkled, green seed.

In Figure 11-6, what are the different phenotypes of the offspring?

The phenotypes of the offspring are black, rough hair; black, smooth hair; white, rough hair; and white smooth hair.

A trait in an unidentified plant is controlled by one gene that has two alleles. One allele is dominant over the other. According to Mendel's principles, one fourth of the offspring made from a cross between two HETEROZYGOUS plants will show the recessive trait.

True

If pea plants that are homozygous for round, yellow seeds (RRYY) were crossed with pea plants that are heterozygous for round, yellow seeds (RrYy), the expected phenotype(s) of the offspring would be ________.

round, yellow seeds only