Question

21 Which of the following statements about the cell cycle is TRUE?

	a.	A cell has more DNA during G1 than it does in G2
	b.	Cytokinesis is the phase of the cell cycle where DNA is replicated.
	c.	Cells in the G0 state are actively dividing.
	d.	Normal cells do not enter S phase unless there are sufficient nutrients and resources to complete an entire cell cycle.

23 Cancers that arise due to proto-oncogenes turning into oncogenes require that:

	a.	neither allele of the proto-oncogene undergoes mutation.
	b.	a different gene be substituted in place of the tumor suppressor gene.
	c.	one allele of the proto-oncogene undergoes mutation.
	d.	both alleles of the proto-oncogene undergo mutation.

Answer 1

Answer - d. Normal cells do not enter S phase unless there are sufficient nutrients and resources to complete an entire cell cycle.

Explanation - For the replication nutrition is required and this preparation are made in G1 phase.

Correct statement of Other options i.e a) - A cell has more DNA during G2 than it does in G1.

b.) CyCytokinesis is the phase of the cell cycle where cytoplasm is divided.

c.) Cells in the G0 state are at rest i.e non dividing.

Answer 23-c) one allele of the proto-oncogene undergoes mutation.

A proto-oncogene is a normal gene found in the cell. There are many proto-oncogenes. Each one is responsible for making a protein involved in cell growth, division, and other processes in the cell. Most of the time, these genes work the way they are supposed to, but sometimes things go wrong.

If an error (mutation) occurs in a proto-oncogene, the gene can become turned on when isn’t supposed to be turned on. If this happens, the proto-oncogene can turn into a malfunctioning gene called an oncogene. Cells will start to grow out of control. Uncontrollable cell growth leads to cancer.