Question

scientists studied the cell cycle and exposed some cells to environmental factors that damage dna. the gene that is damaged codes for proteins to keep the cell cycle moving at a normal rate. why do certain environmental factors cause cancer growth?
a. environmental factor damage genes and then cell cannot regulate the cell cycle, therefore the cells can grow uncontrollably causing a cancerous tumor
b. environmental factors can cause genes to get damaged, and the cell continues with the mutated tumor suppressor gene and continues with normal cell growth
c. environmental factors can promote the accumulation of damaged dna and thus halting the development of cancer cells.
d. environmental factors can accelerate the cell cycle, allowing damaged cells to be eliminated efficiently and reducing the risk of cancer development

Explanation:

To determine the answer, we analyze each option:

• Option A: Environmental factors (like those damaging DNA) can harm genes that regulate the cell cycle. If the cell can't regulate its cycle, it grows uncontrollably, leading to cancer. This matches the concept of tumor - suppressor genes (damaged genes can't control cell growth).
• Option B: A mutated tumor - suppressor gene would not lead to normal cell growth. Tumor - suppressor genes are for regulating cell growth, so a mutation would disrupt this, making this option incorrect.
• Option C: Accumulation of damaged DNA would promote, not halt, cancer development. So this option's reasoning is wrong.
• Option D: Environmental factors that damage DNA don't accelerate the cell cycle to eliminate damaged cells; instead, they disrupt regulation, so this option is incorrect.

Answer:

A. environmental factor damage genes and then cell cannot regulate the cell cycle, therefore the cells can grow uncontrollably causing a cancerous tumor