Question 1

Which of the following best describes the structural relationship between DNA, histone proteins, and chromosomes in a human cell?

Accepted Answer

DNA is wrapped around histone proteins to form nucleosomes, which further coil and condense to form chromosomes.

Question 2

A DNA double helix contains a segment with 20% adenine. According to base pairing rules, what percentage of guanine would you expect in this DNA?

Accepted Answer

$$30\%$$

Question 3

Which of the following statements about hydrogen bonding in DNA is correct?

Accepted Answer

Adenine and thymine are connected by two hydrogen bonds, while cytosine and guanine are connected by three.

Question 4

A woman with blood type AB and a man with blood type O have a child. Which blood types are possible for their child?

Accepted Answer

Type A or type B

Question 5

In a dihybrid cross between two individuals heterozygous for both traits ($$RrYy 	imes RrYy$$), what is the expected phenotypic ratio among the offspring?

Accepted Answer

$$9:3:3:1$$

Question 6

A geneticist observes a trait in cattle where red and white coat colors produce offspring with both red and white patches. Which inheritance pattern does this represent?

Accepted Answer

Co-dominance

Question 7

A male inherits a recessive allele for colorblindness (an X-linked trait) from his mother. What is the probability that he will express colorblindness?

Accepted Answer

$$100\%$$

Question 8

Which of the following best describes a chromosomal inversion?

Accepted Answer

A segment of a chromosome is reversed end to end.

Question 9

A test cross is performed between a plant with an unknown genotype for a dominant trait and a homozygous recessive plant. If all offspring display the dominant phenotype, what is the genotype of the unknown parent?

Accepted Answer

Homozygous dominant

Question 10

Which of the following is a purine base found in DNA?

Accepted Answer

Adenine

Question 11

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 12

Which of the following best explains why harmful recessive alleles persist in a population?

Accepted Answer

They are masked in heterozygous carriers and not subject to selection.

Question 13

A restriction enzyme recognizes the sequence $$5'	ext{-}GAATTC	ext{-}3'$$ and cuts between G and A. What type of ends are produced?

Accepted Answer

Sticky ends

Question 14

If a parent has the genotype $$AaBb$$, how many different types of gametes can they produce, assuming independent assortment?

Accepted Answer

$$4$$

Question 15

A point mutation changes a single base in a gene. Which of the following is a possible consequence?

Accepted Answer

A single amino acid in the protein is changed.

Question 16

A woman who is a carrier for hemophilia (an X-linked recessive disorder) and a man without hemophilia have a son. What is the probability that their son will have hemophilia?

Accepted Answer

$$50\%$$

Question 17

Which of the following best describes the difference between chromatin and chromatids?

Accepted Answer

Chromatin is the relaxed form of DNA and proteins, while chromatids are condensed, duplicated chromosomes during cell division.

Question 18

During meiosis, non-disjunction occurs. Which of the following is a likely result in the gametes?

Accepted Answer

Some gametes have an extra chromosome, while others are missing one.

Question 19

A child is born with Down syndrome, which is caused by trisomy 21. Which chromosomal event most likely led to this condition?

Accepted Answer

Non-disjunction during meiosis

Question 20

In a monohybrid cross between two heterozygous individuals ($$Aa 	imes Aa$$), what is the expected genotypic ratio among the offspring?

Accepted Answer

$$1:2:1$$

Genetics Unit Study Guide: Key Concepts and Applications

Guida di studio - Domande di pratica

Study guide - Flashcard