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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
The offspring are all tall because the tall allele (A) is dominant over the short allele (a). In this cross, when a tall parent (AA or Aa) is crossed with a short parent (aa), all offspring inherit at least one dominant tall allele, resulting in a 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, allowing them to thrive and produce healthy offspring.
- A closed greenhouse reduces the risk of cross-pollination from outside plants, ensuring that the genetic traits in the experiment are controlled and consistent.
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 parents (Aa x Aa):
A a
---------
A | AA Aa
|
a | Aa aa
From this, we see that 1 out of 4 offspring (aa) will have green-coloured peas. Therefore, the percentage probability is 25%.
Step 4
Explain one advantage to pea plants of using sexual reproduction to produce offspring.
Answer
One advantage of sexual reproduction is increased genetic diversity among the offspring. This genetic variation can enhance the population's ability to adapt to changing environmental conditions and resist diseases, ultimately improving survival chances.
Step 5