Question 1

In Mendel's classic pea plant experiments, crossing a true-breeding plant with yellow seeds (dominant) and a true-breeding plant with green seeds (recessive) produces all yellow seeds in the F1 generation. If two F1 plants are crossed, what is the expected phenotypic ratio in the F2 generation?

Accepted Answer

3 yellow : 1 green

Question 2

A woman who is heterozygous for a sex-linked recessive disorder (such as color blindness) marries a man who does not have the disorder. What is the probability that their son will have the disorder?

Accepted Answer

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

Question 3

Which of the following best describes the difference between codominance and incomplete dominance?

Accepted Answer

Incomplete dominance results in a blending of traits, while codominance shows both traits equally.

Question 4

A fruit fly with genotype $$X^wY ($$where $$X^w is $$the white-eye allele and $$Y is $$the Y chromosome) is crossed with a female with genotype $$X^+X^w ($$where $$X^+ is $$the wild-type red-eye allele). What proportion of male offspring will have white eyes?

Accepted Answer

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

Question 5

Which enzyme is responsible for synthesizing short RNA primers during DNA replication in eukaryotes?

Accepted Answer

Primase

Question 6

A pedigree shows a trait that appears in every generation and affects both males and females equally. What is the most likely mode of inheritance?

Accepted Answer

Autosomal dominant

Question 7

During DNA replication, which enzyme is responsible for joining Okazaki fragments on the lagging strand?

Accepted Answer

DNA ligase

Question 8

Which of the following statements about the central dogma of molecular biology is correct?

Accepted Answer

Information flows from DNA to RNA to protein.

Question 9

A point mutation changes the codon $$UAC ($$tyrosine) to $$UAA. $$What type of mutation is this?

Accepted Answer

Nonsense mutation

Question 10

Which of the following best explains why mitochondrial disorders are only inherited from the mother?

Accepted Answer

Mitochondria in the zygote come exclusively from the egg cell.

Question 11

A man with a balanced translocation between chromosomes 14 and 21 has a child with a normal woman. What is the risk for their child to have Down syndrome due to translocation?

Accepted Answer

Increased risk due to possible unbalanced gametes

Question 12

Which of the following is true about DNA replication in prokaryotes compared to eukaryotes?

Accepted Answer

Eukaryotes have multiple origins of replication, while prokaryotes typically have one.

Question 13

A woman with blood type AB and a man with blood type O have a child. What are the possible blood types of their child?

Accepted Answer

A or B

Question 14

If a DNA template strand has the sequence $$5'	ext{-}ATGCGT-3'$$, what is the sequence of the mRNA transcribed from this region?

Accepted Answer

$$5'	ext{-}UACGCA-3'$$

Question 15

Which of the following best describes the function of topoisomerase during DNA replication?

Accepted Answer

Relieves tension ahead of the replication fork

Question 16

A couple has a child with cystic fibrosis, an autosomal recessive disorder. Both parents are healthy. What is the probability that their next child will also have cystic fibrosis?

Accepted Answer

$$\frac{1}{4}$$

Question 17

During translation, which molecule brings amino acids to the ribosome?

Accepted Answer

tRNA

Question 18

A gene is located close to another gene on the same chromosome. Which of the following is most likely true about their inheritance?

Accepted Answer

They are likely to be inherited together due to genetic linkage.

Question 19

Which of the following is a consequence of semi-conservative DNA replication?

Accepted Answer

Each new DNA molecule consists of one parental and one new strand.

Question 20

A mutation causes a single nucleotide insertion in the coding region of a gene. What is the most likely effect on the resulting protein?

Accepted Answer

A frameshift mutation, altering all downstream amino acids

Mendelian Genetics, Chromosomal Inheritance, Molecular Basis of Inheritance, and Protein Synthesis

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