Sexual and asexual reproduction: what joins?
| English | 中文 | Pinyin |
|---|---|---|
| gamete/ˈɡæmiːt/ | 配子 | pèi zi |
| clone/kləʊn/ | 克隆体 | kè lóng tǐ |
What would explain this observation?
- A strawberry plant can form a runner or produce seeds. Counting visible plants is not enough to decide which reproductive process happened.
- Start with a prediction. State the quantities or features you would compare, then decide what evidence could distinguish two explanations.
Build the model
- Sexual reproduction involves fusion of male and female gametes 配子. In animals these are sperm and egg cells. In flowering plants pollen carries male gametes and the egg is the female gamete. Genetic information from two gametes mixes, producing variation in offspring. Meiosis forms the gametes; fertilisation joins them.
- gamete: A reproductive cell that can fuse with another gamete; clone 克隆体: An organism genetically identical to its source in the stated model.
Which evidence identifies sexual reproduction?
Asexual reproduction uses one parent without fusion of gametes. There is no mixing of information from two parents; mitosis produces genetically identical offspring called clones in the school model. A clone can still grow differently in a different environment. Genetic identity is not a promise of identical height, health or every visible feature.
Match each technical term to its precise meaning.
Use the definitions to distinguish related quantities and processes.
Choose evidence that can test it
- Asexual reproduction uses one parent without fusion of gametes. There is no mixing of information from two parents; mitosis produces genetically identical offspring called clones in the school model. A clone can still grow differently in a different environment. Genetic identity is not a promise of identical height, health or every visible feature.
- Sort supplied life-cycle descriptions by evidence: identify gamete fusion, number of parents and whether genetic information mixes. Draw two separate routes, rather than placing meiosis and mitosis as alternative names for the same division. Use prepared plant examples without treating human family characteristics as class investigation data.
Which two habits make the investigation or model in this case more defensible?
Sort supplied life-cycle descriptions by evidence: identify gamete fusion, number of parents and whether genetic information mixes. Draw two separate routes, rather than placing meiosis and mitosis as alternative names for the same division. Use prepared plant examples without treating human family characteristics as class investigation data.
Work from known quantities
- State the known values and their units. Choose the relation because its assumptions fit this case, then rearrange before substitution.
- Known: a parent produces 12 runner-derived plants and 8 seed-derived plants. Asexual proportion = 12/(12+8) = 0.60, or 60%. This counts reproduction routes, not the proportion of DNA inherited from each parent. Seed-derived plants are not classified as clones simply because their flowers look similar.
A nursery has 18 runner-derived and 12 seed-derived plants. Find the runner-derived percentage. Use the same sequence: known quantities → model → relation → substitution → unit and interpretation.
A nursery has 18 runner-derived and 12 seed-derived plants. Find the runner-derived percentage.
The result is 60 %. Known: a parent produces 12 runner-derived plants and 8 seed-derived plants. Asexual proportion = 12/(12+8) = 0.60, or 60%. This counts reproduction routes, not the proportion of DNA inherited from each parent. Seed-derived plants are not classified as clones simply because their flowers look similar.
Check the conclusion and its limits
- Pollen is not an egg cell. Mitosis also supports growth after sexual reproduction, so finding mitosis alone does not show how an organism originally formed. The key difference between reproductive routes is gamete fusion and genetic mixing.
- Return to the original observation. Explain what the result supports, which conditions it assumes, and one way to test a competing explanation.
All similar-looking offspring must be clones. This claim is false: Pollen is not an egg cell. Mitosis also supports growth after sexual reproduction, so finding mitosis alone does not show how an organism originally formed. The key difference between reproductive routes is gamete fusion and genetic mixing.
Sexual and asexual reproduction: what joins?: Asexual reproduction uses one parent without fusion of gametes. There is no mixing of information from two parents; mitosis produces genetically identical offspring called clones in the school model. A clone can still grow differently in a different environment. Genetic identity is not a promise of identical height, health or every visible feature.
All similar-looking offspring must be clones.
Pollen is not an egg cell. Mitosis also supports growth after sexual reproduction, so finding mitosis alone does not show how an organism originally formed. The key difference between reproductive routes is gamete fusion and genetic mixing.
A reproductive cell that can fuse with another gamete: write the technical term.
gamete means A reproductive cell that can fuse with another gamete.