UNIT 3: CELL CYCLE, CANCER, DNA STRUCTURE and REPLICATION - PAP

Which phase of the cell cycle is responsible for DNA replication?

• G1 phase

• S phase

• G2 phase

• M phase

Answer explanation

The S phase of the cell cycle is specifically designated for DNA replication, where the cell duplicates its genetic material in preparation for cell division.

Tags

TX.112.42.C.6.A.

What is a common result of a disruption in the cell cycle?

• Increased cell specialization

• Development of diseases such as cancer

• Enhanced DNA replication

• Faster cell aging

Answer explanation

A disruption in the cell cycle can lead to uncontrolled cell growth, which is a hallmark of cancer. This makes 'development of diseases such as cancer' the correct answer, as it directly relates to cell cycle abnormalities.

Tags

TX.112.42.C.6.C.

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

• Ligase

• Helicase

• Polymerase

• Primase

Answer explanation

Helicase is the enzyme that unwinds the DNA double helix during replication, separating the two strands to allow access for other enzymes. Ligase, polymerase, and primase have different roles in DNA replication.

Tags

TX.112.42.C.6.A.

During which stage of the cell cycle does the cell prepare for mitosis by checking for DNA errors?

• G1 phase

• S phase

• G2 phase

• M phase

Answer explanation

The G2 phase is crucial for preparing for mitosis, as it involves checking for DNA errors and ensuring the cell is ready to divide. This quality control step is essential for maintaining genetic integrity.

Tags

TX.112.42.C.6.A.

What is the main function of the cell cycle in multicellular organisms?

• To produce energy

• To allow growth and repair

• To digest nutrients

• To remove waste

Answer explanation

The main function of the cell cycle in multicellular organisms is to allow growth and repair. It facilitates cell division, enabling organisms to grow and replace damaged or dead cells.

Tags

TX.112.42.C.6.A.

What is the role of DNA polymerase in DNA replication?

• Unwinds the DNA

• Adds nucleotides to the new DNA strand

• Joins Okazaki fragments

• Removes primers

Answer explanation

DNA polymerase is essential in DNA replication as it adds nucleotides to the growing new DNA strand, ensuring accurate copying of the genetic material. This is the primary function of DNA polymerase during replication.

Tags

TX.112.42.C.6.A.

How does the process of cell differentiation contribute to the development of tissues in an organism?

• By producing identical cells

• By allowing cells to become specialized for specific functions

• By causing cell death

• By preventing cell division

Answer explanation

Cell differentiation allows cells to develop specialized structures and functions, which is essential for forming various tissues in an organism. This specialization enables efficient performance of specific roles, unlike identical cells.

Tags

TX.112.42.C.6.B.

Why is DNA replication considered a semi-conservative process?

• Each new DNA molecule contains two new strands

• Each new DNA molecule contains one old and one new strand

• Both strands are completely new

• Only one strand is copied

Answer explanation

DNA replication is semi-conservative because each new DNA molecule consists of one old strand and one newly synthesized strand, ensuring that genetic information is accurately preserved and passed on.

Tags

TX.112.42.C.6.A.

What is the significance of checkpoints in the cell cycle?

• They speed up cell division

• They ensure the cell is ready to proceed to the next stage, preventing errors

• They stop DNA replication

• They cause cell differentiation

Answer explanation

Checkpoints in the cell cycle are crucial as they ensure the cell is ready to proceed to the next stage, preventing errors. This helps maintain genetic stability and proper cell function.

Tags

TX.112.42.C.6.A.

Which of the following best explains why cancer cells are able to grow uncontrollably?

• They have more mitochondria

• They ignore cell cycle checkpoints and signals to stop dividing

• They have larger nuclei

• They undergo more differentiation

Answer explanation

Cancer cells grow uncontrollably because they ignore cell cycle checkpoints and signals that normally regulate cell division, allowing them to proliferate without the usual constraints.

Tags

TX.112.42.C.6.C.