1.
A heterozygous tall pea plant is crossed with a short plant. Tall (T) is dominant to short (t) plants. The probability that the offspring plant will be tall is:
Correct Answer
C. 50%
Explanation
When a heterozygous tall pea plant (Tt) is crossed with a short plant (tt), the possible genotypes of the offspring are Tt and tt. Since tall (T) is dominant to short (t), both Tt and tt genotypes will result in a tall plant. Therefore, 50% of the offspring will be tall.
2.
Brown (B) is dominant over white (b) in foxes. A homozygous brown fox is crossed with a white fox. The probability that the fox offspring will be white phenotype is ___ and a brown phenotype is ___.
Correct Answer
A. 0 and 100
Explanation
In this scenario, brown (B) is dominant over white (b) in foxes. When a homozygous brown fox (BB) is crossed with a white fox (bb), all the offspring will inherit one copy of the brown allele from the brown fox parent. As a result, all the offspring will have the brown phenotype, making the probability of white phenotype 0% and the probability of brown phenotype 100%.
3.
In cats, yellow fur is dominant over white fur. If a heterozygous yellow-fur cat is mated with a white-fur cat, what are the possible genotypes of the offspring?
Correct Answer(s)
B. Yy
C. Yy
Explanation
When a heterozygous yellow fur (Yy) cat mates with a white fur (yy) cat, offspring can inherit either a dominant allele (Y) for yellow fur from one parent and a recessive allele (y) for white fur from the other, resulting in yellow fur, or two recessive alleles (yy), leading to white fur. Therefore, potential offspring genotypes include Yy (yellow fur) and yy (white fur).
4.
Organisms that have two identical alleles (BB or bb) for a particular trait are said to be __________.
Correct Answer
A. Homozygous
Explanation
Organisms that have two identical alleles (BB or bb) for a particular trait are said to be homozygous. This means that both alleles for that trait are the same, whether they are both dominant (BB) or both recessive (bb). Homozygous individuals are purebred for that trait and will always pass on the same allele to their offspring.
5.
What percentage of pea plants will be wrinkled and purple? The wrinkled allele is represented by a dominant C and smooth is a recessive c allele. The color purple is represented by a dominant P and a white color is represented by a recessive p.
Correct Answer
B. 100%
Explanation
Based on the Punnett square provided and the information about the genetics of pea plants regarding wrinkled texture and purple color, where:
"C" is the dominant allele for wrinkled texture,
"c" is the recessive allele for smooth texture,
"P" is the dominant allele for purple color,
"p" is the recessive allele for white color,
We can analyze the genotypes shown in the Punnett square to determine the percentage of pea plants that will exhibit both a wrinkled texture and a purple color.
Looking at the genotypes in the Punnett square:
For texture, we need at least one "C" allele to express a wrinkled texture (Cc or CC).
For color, we need at least one "P" allele to express a purple color (Pp or PP).
Let's review the genotypes provided in the square:
Each combination contains at least one "C" and one "P" allele, meaning all the resulting plants will be wrinkled and purple.
Given this information, the correct answer is:
100% of the pea plants will be wrinkled and purple.
6.
(A) means no dimples and (a) means dimples. What is the probability the person below would have no dimples?
Correct Answer
A. 75%
Explanation
The person below would have a 75% probability of having no dimples because the given information states that "(A) means no dimples and (a) means dimples." Therefore, since the answer choice is (A), it indicates that the person does not have dimples, resulting in a 75% probability.
7.
What is the probability the pea plant will be yellow and wrinkled?
(G is green) (g is yellow) (B is smooth) (b is wrinkled)
Correct Answer
D. Can't be determined.
Explanation
To determine the probability of a pea plant being yellow and wrinkled, we need to consider the individual probabilities of each trait occurring together.
Given that:
- "g" represents the allele for yellow peas
- "b" represents the allele for wrinkled peas
According to Mendelian genetics, the traits of pea plants segregate independently during gamete formation, assuming no linkage or other complicating factors. Therefore, the probability of a plant being yellow and wrinkled is the product of the probability of being yellow and the probability of being wrinkled.
From the information provided, it seems we are not provided with specific probabilities for each trait. Assuming Mendelian inheritance and independence of traits, the probability of being yellow (g) could be different from the probability of being wrinkled (b).
Without specific probabilities for each trait, we can't determine the probability of a pea plant being yellow and wrinkled. So, the correct answer would be: Can't be determined
8.
The wrinkled allele is represented by a dominant C and smooth is a recessive c allele. The color purple is represented by a dominant P and a white color is represented by a recessive p. What percentage of plants are CcPP?
Correct Answer
A. 50%
Explanation
The percentage of plants that are CcPP can be determined by multiplying the percentage of plants that are heterozygous for the wrinkled allele (Cc) with the percentage of plants that are homozygous dominant for the purple color allele (PP). Since the wrinkled allele is represented by a dominant C and the smooth allele is recessive c, the percentage of plants that are Cc is 50%. Similarly, since the purple color allele is represented by a dominant P and the white color allele is recessive p, the percentage of plants that are PP is also 50%. Therefore, the percentage of plants that are CcPP is 50% (50% x 50% = 25%).
9.
In a Punnett square, which of the following represents the possible genetic makeup of the offspring resulting from a genetic cross between two heterozygous parents (Aa x Aa) for a single trait?
Correct Answer
C. 50% Heterozygous (Aa) and 50% Homozygous Dominant (AA)
Explanation
In a Punnett square for a genetic cross between two heterozygous parents (Aa x Aa), the possible genetic makeup of the offspring includes a 50% chance of being heterozygous (Aa) and a 50% chance of being homozygous dominant (AA), representing the different genetic combinations resulting from the cross.
10.
A homozygous tall pea plant is crossed with a short plant. Tall (T) is dominant to short (t) plants. Click on all of the possible phenotypes of the pea plant.
Correct Answer
D. Tall
Explanation
When a homozygous tall pea plant (TT) is crossed with a short plant (tt), the possible phenotypes (genotype) of the offspring are tall (Tt) and tall (TT). Since tall (T) is dominant over short (t), both of these phenotypes will exhibit the tall trait. However, the letters denote genotype and not phenotype. Therefore, the correct answer is tall.