Question

section 5: short answer (46-50)
answer the following in complete sentences.

1. explain why cells cannot continue growing indefinitely without dividing.

1. describe the main difference between mitosis and meiosis.

1. what is the importance of apoptosis in preventing cancer?

1. give two examples of asexual reproduction and one advantage of this process.

1. why do chemotherapy drugs cause side effects like hair loss and nausea?

Explanation:

1. As a cell grows, its surface - area - to - volume ratio decreases. A smaller ratio means less efficient transport of nutrients in and waste out. So, cells cannot grow indefinitely without dividing.
2. Mitosis produces two diploid daughter cells that are genetically identical to the parent cell. Meiosis produces four haploid daughter cells that are genetically different from the parent cell (due to crossing - over and independent assortment).
3. Apoptosis is programmed cell death. It eliminates damaged or abnormal cells (such as pre - cancerous cells). If apoptosis fails, these cells can keep dividing and may form tumors.
4. Examples of asexual reproduction: binary fission (e.g., bacteria) and budding (e.g., yeast). Advantage: It is a fast process and can produce many offspring in a short time when conditions are favorable.
5. Chemotherapy drugs target rapidly dividing cells. Hair follicle cells and cells in the digestive tract (which cause nausea as they line the gut) are also rapidly dividing. So, these drugs affect them, causing hair loss and nausea.

Answer:

1. Cells cannot grow indefinitely without dividing because as they grow, the surface - area - to - volume ratio decreases, reducing the efficiency of nutrient uptake and waste removal.
2. The main difference is that mitosis gives two diploid, genetically identical daughter cells, while meiosis gives four haploid, genetically different daughter cells.
3. Apoptosis is important in preventing cancer as it removes damaged or abnormal (pre - cancerous) cells. Without it, these cells may keep dividing and form tumors.
4. Examples: binary fission (bacteria) and budding (yeast). Advantage: A fast process to produce many offspring quickly under favorable conditions.
5. Chemotherapy drugs cause side effects like hair loss and nausea because they target rapidly dividing cells, and hair follicle cells and digestive tract cells (which cause nausea) are also rapidly dividing.