Q: If two heterozygous pea plants (Rr) are crossed, what is the probability that an offspring will have wrinkled seeds? Use the product and sum rules as needed.

$$\frac{1}{2} \times \frac{1}{2} = \frac{1}{4}$$

Q: If the probability of rolling a 2 on a single six-sided die is $$\frac{1}{6}$$, what is the probability of rolling a 2 on both of two dice simultaneously?

$$\frac{1}{6} \times \frac{1}{6} = \frac{1}{36}$$

Question 1

In Mendel's pea plant experiments, the gene for seed shape (R) codes for an enzyme that synthesizes amylopectin. What is the molecular consequence of the r allele in homozygous recessive (rr) plants?

Accepted Answer

The r allele produces a non-functional enzyme due to a mutation, resulting in no amylopectin synthesis.

Question 2

If two heterozygous pea plants (Rr) are crossed, what is the probability that an offspring will have wrinkled seeds? Use the product and sum rules as needed.

Accepted Answer

$$\frac{1}{2} 	imes \frac{1}{2} = \frac{1}{4}$$

Question 3

Which of the following best explains why the R allele is dominant over the r allele at the molecular level?

Accepted Answer

The R allele produces a functional enzyme, and 50% of normal enzyme activity is sufficient for the round seed phenotype.

Question 4

A plant with genotype Rr is crossed with a plant with genotype rr. What is the probability that their offspring will have round seeds?

Accepted Answer

$$\frac{1}{2}$$

Question 5

Which statement about alleles and gene expression is correct?

Accepted Answer

A recessive allele may be transcribed and translated, but its effect is not visible in the phenotype if a dominant allele is present.

Question 6

If the probability of rolling a 2 on a single six-sided die is $$\frac{1}{6}$$, what is the probability of rolling a 2 on both of two dice simultaneously?

Accepted Answer

$$\frac{1}{6} 	imes \frac{1}{6} = \frac{1}{36}$$

Question 7

A mutation in the r allele creates an early stop codon in the coding region. What is the most likely result at the protein level?

Accepted Answer

A truncated, non-functional enzyme is produced.

Question 8

In a monohybrid cross between two heterozygotes (Rr x Rr), what is the expected genotypic ratio among the offspring?

Accepted Answer

1 RR : 2 Rr : 1 rr

Question 9

Which of the following best describes the sum rule in probability as applied to genetics?

Accepted Answer

The probability of two or more mutually exclusive events producing the same outcome is the sum of their individual probabilities.

Question 10

A plant with genotype RR is crossed with a plant with genotype rr. What will be the genotype and phenotype of all F1 offspring?

Accepted Answer

All will be Rr (heterozygous) and have round seeds.

Question 11

If a plant has the genotype Rr, what proportion of the enzymes produced will be functional for amylopectin synthesis?

Accepted Answer

$$50\%$$

Question 12

Which of the following is a correct application of the product rule in probability?

Accepted Answer

Calculating the probability of getting RR offspring from two Rr parents by multiplying $$\frac{1}{2} 	imes \frac{1}{2}.$$

Question 13

Why do wrinkled seeds (rr) accumulate more sucrose than round seeds (RR or Rr)?

Accepted Answer

They lack amylopectin, so more disaccharide sucrose remains as solute in the seed.

Question 14

Which of the following statements about genes, alleles, and proteins is correct?

Accepted Answer

Alleles are different DNA sequence versions of a gene that may produce different protein products.

Question 15

A geneticist wants to know the probability of getting a heterozygous (Rr) offspring from two heterozygous parents (Rr x Rr). Which calculation is correct?

Accepted Answer

$$\frac{1}{4} + \frac{1}{4} = \frac{1}{2}$$

Question 16

If the regulatory regions of two alleles are identical, what will happen to their expression in the presence of the correct transcription factors?

Accepted Answer

Both alleles will be expressed.

Question 17

Which of the following best describes a monohybrid cross?

Accepted Answer

A cross involving one gene where both parents have two different alleles.

Question 18

A student rolls two dice. What is the probability of getting a total of 6 in one roll, considering all possible combinations?

Accepted Answer

$$\frac{5}{36}$$

Question 19

Which of the following is NOT a correct statement about the relationship between genotype and phenotype in the context of the R and r alleles?

Accepted Answer

The R allele is only expressed if the r allele is absent.

Genetics: Mendelian Inheritance, Alleles, and Probability in Monohybrid Crosses

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