Igcse Model Questions Vol1 2023 Biology Question 10

Practice essay / theory question 10 from the 2023 Igcse Model Questions Vol1 Biology examination. This question covers Genetics .

Igcse Model Questions Vol1 2023 Biology Essay / Theory
Topic: Genetics
Question 10 IGCSE_MODEL_QUESTIONS_VOL1 • 2023 • BIOLOGY • essay

A plant breeder is developing a new variety of maize that is resistant to a fungal disease. The resistance trait is known to be controlled by a single dominant allele (R). The breeder crosses a homozygous resistant plant (RR) with a susceptible plant (rr) and then self‑pollinates the F1 generation.

Question Parts

( a )
Using appropriate genetic notation, predict the genotypic and phenotypic ratios expected in the F1 generation.
( b )
From the F1 plants, a self‑cross is performed. Determine the expected genotypic and phenotypic ratios in the F2 generation.
( c )
If a sample of 200 F2 plants shows 130 resistant and 70 susceptible individuals, perform a chi‑square test at the 5 % significance level to assess whether the observed segregation fits the expected 3:1 ratio. Show all calculations and state your conclusion.
( d )
Discuss two possible reasons why the observed ratio might deviate from the expected ratio, relating your answer to genetic principles.

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About This Question

This is Igcse Model Questions Vol1 2023 Biology Question 10. It is one of the essay questions from the 2023 Igcse Model Questions Vol1 Biology examination.

The question covers Genetics .

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