Classify reproductive events from their evidence
Use origin and gamete fusion rather than counting visible adults alone.
Section B15.1 · Asexual reproduction
Exam scope and assessment notes
Mapped to the named 0973 section using teaching from the corresponding single-science course. A 0973-specific review of every Core and Supplement objective is still in progress. Written practice is self-checked; it does not demonstrate supervised laboratory competence or award an official Cambridge grade. This qualification reports two grades on the 9–1 scale; confirm the entry route for your zone and exam series.
Before you begin
- Recall cells, DNA, inherited characteristics and the distinction between growth of an organism and production of offspring.
Work on paper. Try each question before revealing help, and explain why your method works.
Quick readiness check
Which supplied record is asexual?
What you will learn
- Identify the mechanism supplied in a record
- Explain why one adult alone is insufficient
Classify reproductive events from their evidence
Supplied fission, cutting and runner copying models are asexual; gamete-nucleus fusion remains sexual within one adult plant. Original teaching model.
| Feature | Meaning |
|---|---|
| Asexual evidence | One-parent copying without gamete fusion |
| Sexual contrast | Fusion of gamete nuclei in the supplied event |
| Adult count | One adult alone is insufficient |
| Appearance | Resemblance alone does not prove a clone |
Identify the mechanism supplied in a record
A reproductive record should supply the offspring origin. A bacterial cell dividing after DNA copying, a rooted stem cutting and a runner daughter are asexual examples in the supplied models. Each develops from one parent without fusion of gamete nuclei and has the expected copied genotype. A plant, animal or fungus label does not classify every reproductive event of that organism.
One adult plant can supply both gametes in a self-fertilisation record. Fusion of their nuclei is still a sexual event, even though only one adult is shown. The one-parent phrase in the asexual definition therefore needs the genetic-copying relationship and mechanism, not merely a count of adults in a picture. Look for the supplied nucleus-fusion information.
Explain why one adult alone is insufficient
A fertilised-seed record differs from a stem cutting or the planting term seed potato. The first explicitly includes gamete-nucleus fusion; the supplied vegetative events do not. Familiar seed examples usually arise sexually, but seed appearance alone is not a universal rule for every plant mechanism. Use the stated fertilisation history rather than assuming every structure called a seed proves the same event.
If a record supplies only two similar-looking individuals, acknowledge the missing origin information. Reproductive mechanism cannot be proved from resemblance alone. A strong explanation names the event, traces the genetic source and identifies whether gamete-nucleus fusion is present. This contrast prepares later sexual reproduction teaching without marking that separate pathway as complete.
Sources for this lesson
Pause and explain
Does one adult in a self-fertilisation drawing prove asexual reproduction?
Worked example
One plant supplies two gametes whose nuclei fuse before a seed develops. Is the event asexual?
Show the worked solution
- Gamete-nucleus fusion is explicitly supplied.
- One adult does not remove that mechanism.
Answer No. The supplied self-fertilisation event is sexual because gamete nuclei fuse.
Try a topic test
Choose Easy, Normal or Difficult. Save your answers and open worked review after finishing.
Test this topic →From guided practice to a new situation
Write your answer and reasoning first. Use a hint only if you are stuck. The model solution is for self-checking; your written work is not automatically marked.
Classify bacterial fission, a rooted cutting and a seed formed after gamete-nucleus fusion.
Give me a hint
Use each supplied origin.
Compare my reasoning
- Fission and cutting use one-parent copying.
- The fusion event is sexual.
Bacterial fission: asexual. Rooted cutting: asexual. Supplied gamete-fusion seed event: sexual.
Look for these in your work
- Classify all three
- Use fusion information
Why is supplied self-fertilisation sexual with one adult plant?
Give me a hint
Focus on the nuclei rather than adult count.
Compare my reasoning
- The plant supplies gametes.
- Their nuclei fuse.
Gamete nuclei fuse, so the supplied self-fertilisation event is sexual despite one adult plant being shown.
Look for these in your work
- Name nucleus fusion
- Reject the adult-count shortcut
Can two similar plants with no origin record be established as clones from appearance?
Give me a hint
Resemblance is not a reproductive history.
Compare my reasoning
- Similar appearance does not establish genotype.
- One-parent copying evidence is missing.
No. Similar appearance establishes neither identical genotype nor a one-parent asexual origin; reproductive or genetic evidence is needed.
Look for these in your work
- Identify missing origin evidence
- Avoid appearance-based genotype proof
Common mistakes
- Classifying self-fertilisation as asexual from adult count.
- Treating resemblance as proof of origin.
What can you explain now?
Does one adult in a self-fertilisation drawing prove asexual reproduction?
Compare with the explanation
No; the supplied gamete-nucleus fusion is sexual
Adult count alone is insufficient.
After trying it yourself, choose your next review. This is your self-assessment.
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Make it stick
Explain why one adult does not make a supplied self-fertilisation event asexual.
If you needed the solution, close it and solve the problem again from a blank page. A correct answer is stronger when you can explain the reason for each step.