Question

Reading Passage: Haploid and Diploid Cells
All living things have cells, and inside those cells are structures called chromosomes.
Chromosomes carry your DNA, which is the set of instructions that tells your body how to
grow, look, and function. A diploid cell has two sets of chromosomes. Most of the cells in
your body, like skin, muscle, and blood cells, are diploid. A haploid cell has only one set of
chromosomes. Haploid cells are used in sexual reproduction, such as sperm and egg cells.
During fertilization, the haploid sperm and haploid egg join together to form a diploid cell,
restoring the normal chromosome number. If gametes were not haploid, the chromosome
number would double each generation, causing major problems. Diploid cells also help
organisms grow, repair injuries, and replace old cells.
Open-Ended Questions
1. Explain in your own words how haploid cells and diploid cells are different. Why
does this difference matter in living organisms?
2. Describe what happens during fertilization and explain why haploid cells are
needed for this process to work correctly.
3. Why would it be a problem if gametes contained two sets of chromosomes instead
of one? Use information from the passage to support your answer.
4. How do diploid cells help your body grow and repair itself? Give an example of a
situation where diploid cell division is important.
5. Based on what you read, explain why keeping the correct chromosome number in
each generation is important for the survival of a species

Answer 1

1. Haploid cells have one complete set of chromosomes (one copy of each chromosome); diploid cells have two sets (two copies of each). Haploid cells are the sex cells (sperm and eggs) while most body cells (skin, muscle, blood) are diploid. This difference matters because it keeps the chromosome number stable across generations and lets body tissues have two copies of genes for normal growth and function.

2. During fertilization a haploid sperm and a haploid egg fuse to make a single diploid cell (a zygote). Haploid gametes are needed so the zygote ends up with the correct, species-specific number of chromosomes; if both gametes had two sets, the chromosome number would increase each generation.

3. If gametes contained two sets of chromosomes instead of one, the chromosome number would double each generation. That accumulation of extra chromosome sets would cause major problems for development and function (gene imbalance and likely nonviable offspring), so haploid gametes prevent that from happening.

4. Diploid cells divide to make more diploid cells for growth, to replace worn-out cells, and to repair injuries. For example, when you cut your skin, nearby diploid skin cells divide (by mitosis) to produce new skin cells that close the wound and restore the tissue.

5. Keeping the correct chromosome number each generation is important because it preserves the right amount and balance of genetic information needed for normal development and survival. If chromosome numbers changed every generation, genes would be duplicated or lost over time, disrupting bodily functions and reducing a species’ ability to survive and reproduce.