Cancer & Stem Cells

Question 1

A 14‑year‑old student has a small skin growth removed. Genetic testing of the cells finds two DNA changes: (1) a loss‑of‑function mutation in the tumor‑suppressor gene TP53, and (2) a gain‑of-function mutation that makes the oncogene KRAS permanently active. Which statement best explains how these mutations cause the growth to become cancerous?

Accepted Answer

The TP53 mutation removes a brake on the cell‑cycle checkpoints, and the constantly active KRAS sends continuous growth signals, so the cell divides without proper control.

Answer

The TP53 mutation causes the cell to produce extra DNA‑repair enzymes, and the KRAS mutation stops the cell from receiving growth signals.

Answer

The TP53 mutation makes the cell die quickly, and the KRAS mutation repairs the DNA damage, preventing cancer.

Answer

The TP53 mutation speeds up cell death, and the KRAS mutation slows metabolism, leading to tumor shrinkage.

Question 2

A biotech lab wants to create a tissue patch to repair a teenager’s damaged heart after a sports injury. They have two possible starting cells: 1. Small pieces of the teen’s own heart muscle, which are already heart‑muscle cells. 2. Skin cells taken from the teen that can become any type of cell in the body. Which approach is most likely to produce enough functional heart tissue, and why?

Accepted Answer

Use the skin cells because they are unspecialized, can be directed to become heart‑muscle cells, and can be grown in large numbers.

Answer

Use the heart‑muscle pieces because the cells are already specialized for heart function.

Answer

Use the heart‑muscle pieces because specialized cells multiply faster than unspecialized cells.

Answer

Use the skin cells because skin cells never trigger an immune response.

Question 3

A researcher is trying to grow new tissue to repair a teenager's damaged knee cartilage. Which statement best explains why using stem cells would be a better choice than using already‑differentiated cartilage cells?

Accepted Answer

Stem cells are unspecialized and can be multiplied, then directed to become cartilage cells for the repair.

Answer

Because specialized cartilage cells already do the job, they can be placed directly into the knee and fix the damage instantly.

Answer

Stem cells are already fully formed cartilage, so they can be implanted without any further steps.

Answer

Specialized cells can change into any type of cell, making them the most versatile option for tissue repair.

Try three questions

A researcher is trying to grow new tissue to repair a teenager's damaged knee cartilage. Which statement best explains why using stem cells would be a better choice than using already‑differentiated cartilage cells?

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