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10 Gregor Mendel used pea plants in plant breeding experiments - Edexcel - GCSE Biology - Question 10 - 2020 - Paper 1
Question 10
10 Gregor Mendel used pea plants in plant breeding experiments. He discovered the basis of genetic inheritance. (a) He cross-bred tall pea plants with short pea pla... show full transcript
Worked Solution & Example Answer:10 Gregor Mendel used pea plants in plant breeding experiments - Edexcel - GCSE Biology - Question 10 - 2020 - Paper 1
Step 1
Explain why the offspring are all tall.
Answer
All offspring are tall because the tall phenotype is dominant over the short phenotype. This means that even if the parent plants carry a recessive allele for shortness, the presence of a dominant allele for tallness (from the tall parent) ensures that all offspring exhibit the tall phenotype.
Step 2
Give two reasons why the parent pea plants were grown in a warm, closed greenhouse.
Answer
- A warm environment promotes optimal growth conditions for the pea plants, ensuring they thrive and produce healthy offspring.
- A closed greenhouse minimizes external environmental factors such as pests and weather fluctuations, providing a controlled setting that enhances breeding success.
Step 3
Predict, using the Punnett square, the percentage probability that this cross will have offspring that produce green-coloured peas.
Answer
Using a Punnett square for two heterozygous parent plants (Aa x Aa), the potential genotypes are AA, Aa, Aa, and aa. This means:
- 75% (3 out of 4) will produce yellow-coloured peas (AA or Aa)
- 25% (1 out of 4) will produce green-coloured peas (aa) Thus, the percentage probability of green-coloured peas is 25%.
Step 4
Explain one advantage to pea plants of using sexual reproduction to produce offspring.
Answer
One advantage of sexual reproduction in pea plants is genetic diversity. This variation allows for better adaptation to changing environments and increases resilience against diseases, enhancing the overall survival and success of the population.
Step 5