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Gregor Mendel used pea plants in plant breeding experiments - Edexcel - GCSE Biology - Question 4 - 2020 - Paper 1
Question 4
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 plants... show full transcript
Worked Solution & Example Answer:Gregor Mendel used pea plants in plant breeding experiments - Edexcel - GCSE Biology - Question 4 - 2020 - Paper 1
Step 1
Step 2
Give two reasons why the parent pea plants were grown in a warm, closed greenhouse.
Answer
- Growing in a warm, closed greenhouse provides optimal growth conditions, which help the plants achieve maximum health and yield.
- A controlled environment reduces the chances of disease or pests affecting the plants, leading to more reliable breeding results.
Step 3
Predict, using the Punnett square, the percentage probability that this cross will have offspring that produce green-coloured peas.
Answer
In a Punnett square for two heterozygous parent plants (Aa x Aa), the possible gamete combinations are:
A a
--------
A | AA | Aa |
--------
a | Aa | aa |
--------
The combinations yield:
- 1 AA (Yellow)
- 2 Aa (Yellow)
- 1 aa (Green)
Thus, the percentage of offspring producing green-coloured peas (aa) is:
rac{1}{4} imes 100 = 25 ext{ %}
Step 4