Question 1

Which of the following best describes the difference between mitosis and the mitotic phase of the cell cycle?

Accepted Answer

Mitosis refers to the division of the nucleus, while the mitotic phase includes both mitosis and cytokinesis.

Question 2

During which subphase of mitosis do chromosomes align at the metaphase plate, and what is the significance of this arrangement?

Accepted Answer

Metaphase; it ensures that each daughter cell receives an identical set of chromosomes.

Question 3

Which structure is responsible for attaching spindle fibers to chromosomes during mitosis?

Accepted Answer

Kinetochore

Question 4

A researcher observes a cell with a cell plate forming in the center during cytokinesis. What type of cell is this, and why does this process occur?

Accepted Answer

Plant cell; the cell plate forms because the rigid cell wall prevents cleavage furrow formation.

Question 5

Cyclin-dependent kinases (Cdks) are crucial for cell cycle regulation. What is their primary function?

Accepted Answer

They phosphorylate target proteins only when bound to cyclin, controlling progression through cell cycle checkpoints.

Question 6

Which of the following best explains why meiosis results in genetic variation among offspring?

Accepted Answer

Crossing over, independent assortment, and random fertilization all contribute to new combinations of alleles.

Question 7

A human cell with 46 chromosomes undergoes meiosis. How many chromosomes will each resulting gamete contain, and what is this condition called?

Accepted Answer

$$n = 23$$; haploid

Question 8

Which process during meiosis is responsible for Mendel’s law of independent assortment?

Accepted Answer

Random alignment of homologous chromosome pairs during metaphase I

Question 9

A pea plant with genotype $$YyRr is $$crossed with another $$YyRr$$ plant. What is the expected phenotypic ratio in the offspring for a dihybrid cross involving two traits with complete dominance?

Accepted Answer

$$9:3:3:1$$

Question 10

Which of the following best describes codominance?

Accepted Answer

Both alleles are fully expressed in the phenotype of a heterozygote.

Question 11

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 12

Which chromosomal abnormality is characterized by a karyotype with 47 chromosomes, including three copies of chromosome 21?

Accepted Answer

Down’s Syndrome (Trisomy 21)

Question 13

Which scientist’s X-ray diffraction images were critical in revealing the double helix structure of DNA?

Accepted Answer

Rosalind Franklin

Question 14

What is the role of DNA ligase during DNA replication?

Accepted Answer

It joins Okazaki fragments on the lagging strand.

Question 15

If a DNA template strand has the sequence $$5'	ext{-}ATCGGTA-3'$$, what is the sequence of the complementary DNA strand (written $$5' to$$ $$3'$$)?

Accepted Answer

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

Question 16

Why do telomeres shorten with each round of DNA replication in eukaryotic cells?

Accepted Answer

DNA polymerase cannot fully replicate the 5’ ends of linear chromosomes.

Question 17

Which of the following best explains why mutations in somatic cells are generally not passed on to offspring?

Accepted Answer

Somatic cells do not contribute genetic material to gametes.

Question 18

A patient is diagnosed with Klinefelter syndrome. Which karyotype would you expect to find in this individual?

Accepted Answer

$$47,\ XXY$$

Question 19

Which enzyme is responsible for unwinding the DNA double helix during replication?

Accepted Answer

Helicase

Question 20

A geneticist observes a chromosome with a segment that has been reversed end to end. What type of chromosomal mutation is this?

Accepted Answer

Inversion

Core Biology 1 Exam 3 Study Guide – Step-by-Step Guidance

Study Guide - Practice Questions

Study Guide - Flashcards