Figure 12 shows some characteristics of pea plants - Edexcel - GCSE Biology - Question 6 - 2023 - Paper 1
Question 6
Figure 12 shows some characteristics of pea plants.
| flower colour | seed shape |
|---------------|------------|
| purple | round |
| white | w... show full transcript
Worked Solution & Example Answer:Figure 12 shows some characteristics of pea plants - Edexcel - GCSE Biology - Question 6 - 2023 - Paper 1
Step 1
Which term describes the allele for white flowers?
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Answer
The term that describes the allele for white flowers is "recessive" (D). The recessive allele requires two copies to express the trait, which in this case is the white flower color.
Step 2
Complete the Punnett square.
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Answer
R
r
R
RR
Rr
r
Rr
rr
Step 3
State the percentage of the offspring that will produce round seeds.
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Answer
From the completed Punnett square, 3 out of 4 offspring will produce round seeds. Therefore, the percentage of offspring that will produce round seeds is 75%.
Step 4
Calculate the ratio of offspring with purple flowers to offspring with white flowers.
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Answer
The ratio is calculated by dividing the number of purple flower plants by the number of white flower plants:
Ratio=46133≈3:1
Step 5
Explain why it was possible for this cross to produce some offspring with white flowers.
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Answer
It was possible for this cross to produce some offspring with white flowers because both parent plants were heterozygous (Pp). Each parent carries an allele for white flowers, which can combine to form homozygous recessive offspring (pp), resulting in white flowers.
Step 6
Explain why pea plant gametes have only seven chromosomes.
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Answer
Pea plant cells are diploid, meaning they contain two sets of chromosomes, or 14 chromosomes in total. Gametes are produced through meiosis, which reduces the chromosome number by half, resulting in haploid gametes. Thus, pea plant gametes contain 7 chromosomes.
Step 7
Describe what happens at fertilisation.
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Answer
During fertilisation, two gametes (one from each parent) fuse to form a zygote. This union restores the diploid chromosome number, as the genetic material from both gametes combines. The zygote then undergoes cell division and develops into a new organism.
