Igcse Model Questions Vol1 2020 Biology Question 10

Practice essay / theory question 10 from the 2020 Igcse Model Questions Vol1 Biology examination. This question covers Genetics .

Igcse Model Questions Vol1 2020 Biology Essay / Theory
Topic: Genetics
Question 10 IGCSE_MODEL_QUESTIONS_VOL1 • 2020 • BIOLOGY • essay

A genetics teacher is preparing a lesson on inheritance patterns, probability calculations and DNA replication. The class is working with pea plants, a human pedigree for a hereditary hearing disorder and a review of the enzymes involved in DNA synthesis.

Question Parts

( a )
In peas, plant height is controlled by a single gene with alleles T (tall, dominant) and t (dwarf, recessive). A heterozygous tall plant (Tt) is crossed with a dwarf plant (tt).
( b )
Two heterozygous tall F₁ plants (both Tt) are crossed. (i) Determine the probability that a randomly selected offspring from this cross will be dwarf. (ii) Determine the probability that a randomly selected offspring will be both dwarf and homozygous for the recessive allele.
( c )
A pedigree chart shows a hereditary hearing disorder that appears in both males and females, affected individuals have unaffected parents, and the disorder occurs in siblings of affected persons but not in the previous generation. (i) Identify the most likely mode of inheritance. (ii) If two unaffected individuals are known carriers, calculate the risk that their child will be affected.
( d )
During DNA replication, DNA polymerase and DNA ligase play essential roles. Explain the specific function of each enzyme and describe how the proofreading activity of DNA polymerase contributes to the overall fidelity of DNA replication.

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About This Question

This is Igcse Model Questions Vol1 2020 Biology Question 10. It is one of the essay questions from the 2020 Igcse Model Questions Vol1 Biology examination.

The question covers Genetics .

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