Question 1

Which of the following best explains why offspring produced by sexual reproduction are genetically unique?

Accepted Answer

Because fertilization randomly combines gametes, and processes like independent assortment and crossing over occur during meiosis.

Question 2

A scientist observes a single-celled organism dividing into two genetically identical offspring. Which process is most likely occurring?

Accepted Answer

Binary fission

Question 3

During which phase of the cell cycle does chromosome duplication occur?

Accepted Answer

Interphase

Question 4

Which of the following statements about homologous chromosomes is correct?

Accepted Answer

They carry genes controlling the same inherited characteristics, but may have different alleles.

Question 5

A plant cell is observed forming a structure along its center line during cell division. What is this structure, and what is its function?

Accepted Answer

Cell plate; it separates the cytoplasm into two daughter cells

Question 6

Which process is responsible for producing four genetically unique haploid cells from a single diploid cell?

Accepted Answer

Meiosis

Question 7

A human karyotype shows 47 chromosomes, including three copies of chromosome 21. What condition does this indicate, and what is the most likely cause?

Accepted Answer

Down syndrome; caused by nondisjunction resulting in trisomy 21

Question 8

Which of the following best describes the law of segregation?

Accepted Answer

Each pair of alleles for a character separates during gamete formation, so each gamete receives only one allele.

Question 9

A black Labrador retriever (dominant phenotype) is crossed with a chocolate Lab (recessive phenotype). All offspring are black. What is the most likely genotype of the black Lab parent?

Accepted Answer

Homozygous dominant (BB)

Question 10

In a dihybrid cross between two individuals heterozygous for both coat color (B = black, b = chocolate) and hearing (H = hearing, h = deaf), what is the expected phenotypic ratio among the offspring?

Accepted Answer

$$9:3:3:1$$

Question 11

Which of the following processes increases genetic variation during sexual reproduction by creating hybrid chromosomes?

Accepted Answer

Crossing over

Question 12

A cell with 24 chromosomes undergoes mitosis. How many chromosomes will each daughter cell have after division?

Accepted Answer

$$24$$

Question 13

Which of the following is true about stem cells obtained through therapeutic cloning?

Accepted Answer

They can develop into any cell type in the body.

Question 14

If a cell fails to separate its chromosomes properly during meiosis, what is the most likely result?

Accepted Answer

Some gametes will have abnormal numbers of chromosomes, a condition called nondisjunction.

Question 15

Which of the following best describes the difference between mitosis and meiosis?

Accepted Answer

Mitosis involves one round of division and produces genetically identical diploid cells; meiosis involves two rounds and produces genetically unique haploid cells.

Question 16

A heterozygous pea plant (Yy) is crossed with a homozygous recessive plant (yy). What is the expected genotypic ratio of the offspring?

Accepted Answer

$$1:1 (Yy$$:yy)

Question 17

Which of the following is NOT a source of genetic variation in sexually reproducing organisms?

Accepted Answer

Binary fission

Question 18

A researcher wants to determine if a black-coated dog is homozygous or heterozygous for the coat color gene. Which experimental approach should they use?

Accepted Answer

Perform a testcross with a homozygous recessive (chocolate) dog

Question 19

Which of the following equations correctly represents the number of possible chromosome combinations due to independent assortment in human gametes?

Accepted Answer

$$2^{23}$$

Question 20

A cell in your small intestine is actively producing digestive enzymes and growing in size. In which phase of the cell cycle is this cell most likely to be?

Accepted Answer

Interphase

Cell Division and Genetics: Study Notes for General Biology

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