Final answer:
Radiation and chemotherapy cause hair loss, fatigue, and nausea due to their effects on rapidly reproducing cells in the body.
Step-by-step explanation:
Radiation and chemotherapy can cause hair loss, fatigue, and nausea due to their effects on rapidly reproducing cells in the body. Radiation damages cells that reproduce quickly, such as those in the stomach lining, hair follicles, bone marrow, and embryos, leading to these side effects. Similarly, chemotherapy drugs interfere with cell division, affecting healthy cells in the skin, hair, gastrointestinal tract, and bone marrow.