Cross selected parents to produce offspring
Crossing chosen parents creates the next generation, but does not make offspring identical.
Mapped to the named 0654 section using teaching from the corresponding single-science course. A 0654-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.
Before you begin
- Use the stated case, sample and assumptions. Diagrams and numerical records in this pathway are original teaching models; written answers are self-checked.
Work on paper. Try each question before revealing help, and explain why your method works.
Quick readiness check
What does crossing selected parents do in selective breeding?
What you will learn
- Describe crossing selected parents
- Allow for variation among their offspring
Original selection schematic. Population counts and scenarios are supplied teaching models; they are not field observations.
| Stage or record | Meaning |
|---|---|
| Before cross | Selected parents with the stated feature |
| Cross | Reproduction produces the next generation |
| After cross | Offspring vary and need assessment |
| Distinction | Breeding is not automatically gene editing |
Describe crossing selected parents
After humans select parents for desirable features, they cross those individuals to produce the next generation. In a crop example, chosen plants may be pollinated under the stated breeding plan. In an animal example, selected parents mate. The essential syllabus link is that the chosen individuals produce offspring.
Offspring inherit information from both parents, so they can differ from one another and from each parent. A parent’s appearance is not a complete description of its alleles. Unless a genetic cross or inheritance rule is supplied, do not predict that every offspring will show the desired phenotype.
Allow for variation among their offspring
Crossing is not the same as selecting offspring. A breeder must inspect or measure the new generation and choose individuals that show the target feature. This keeps the steps distinct: select parents, cross them, then select suitable offspring. The cycle can be repeated over many generations.
Selective breeding uses reproduction of chosen organisms. It does not by itself mean that a gene was directly inserted or edited. That would be genetic modification, a separate biotechnology topic. Use the process actually described in a question and do not add molecular methods that were not supplied.
Sources for this lesson
Pause and explain
After selected parents produce offspring, what comes next?
Worked example
Two bean plants selected for seed mass are crossed. The next generation contains 40 plants. What has crossing achieved, and what must the breeder do next?
Show the worked solution
- The selected parents have produced the next generation.
- Measure the 40 offspring against the stated seed-mass criterion, then select suitable offspring as future parents.
Answer Crossing produced a new generation. The breeder must assess variation among its 40 offspring and select individuals showing the desirable feature.
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.
Selected tomato parents produce 36 offspring. The goal is firm fruit. Describe the next breeding step without assuming every fruit will be firm.
Give me a hint
Assess offspring using the stated feature.
Compare my reasoning
- Measure firmness with the same method for the offspring.
- Choose suitable offspring as parents for the next cross.
Assess the 36 offspring for firmness, then select those that meet the criterion as future parents. Offspring variation means the chosen parents do not guarantee every fruit is firm.
Look for these in your work
- Measure offspring
- Choose for another generation
A student writes, “The parents were crossed, so selective breeding is finished.” Correct the sequence.
Give me a hint
There are three steps in the syllabus description.
Compare my reasoning
- People first choose parents with desired features.
- Crossing makes offspring; those offspring must be assessed and selected.
The sequence is human selection of parents, crossing to produce offspring, and selection of offspring showing the desired features.
Look for these in your work
- All three steps in order
- Offspring selection explicitly included
Two selected animal parents both show long wool. Why can the breeder not conclude that all young will have long wool from appearance alone?
Give me a hint
Separate parental phenotype from offspring inheritance.
Compare my reasoning
- The appearance does not reveal every allele or breeding outcome.
- Offspring receive inherited information from both parents and may vary.
Parent appearance alone does not guarantee every offspring phenotype. Assess the offspring and use any supplied inheritance evidence before making a stronger prediction.
Look for these in your work
- Phenotype limit
- Variation and assessment
Common mistakes
- Saying crossing itself selects offspring
- Assuming all offspring copy a selected parent
- Equating selective breeding with gene editing
What can you explain now?
After selected parents produce offspring, what comes next?
Compare with the explanation
Select offspring that show the desired feature
The third step evaluates the new generation.
After trying it yourself, choose your next review. This is your self-assessment.
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Make it stick
Without your notes, describe crossing selected parents and allow for variation among their offspring. Explain the mechanism, use the given population or breeding records and state what the evidence does not establish.
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.