Genetics Biology Worksheet ANSWERS

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(c) Individuals A and B, as shown on the pedigree diagram, decide to have another child. They draw a Punnett square to find what type of chin their child might have. Explain why the result predicted by the Punnett square may not accurately tell them what type of chin their child will have. In your answer, you should: draw a Punnett square to show the cross between individual A and individual B determine the probabilities of the child having a cleft chin and having a smooth chin explain why the ratio of children born into the family with cleft and smooth chins may not match the probabilities. For Excellence you need to have at least ONE Merit explanation from a) and b) and for c) your answer needs to link the theoretical probabilities derived from the correctly completed Punnett Square for with the explanation of why the actual outcomes for families will not necessarily match the predicted outcomes, especially when dealing with small population samples. Explanation of discrepancy: Random fertilisation of eggs by sperm means that number of offspring showing a particular variation will not always match the probability predicted by a Punnett square, unless the number of offspring is quite large. Each child is a unique and random genetic event.
QUESTION FOUR: SURVIVAL Mutations can occur in DNA during cell division. Explain whether a mutation could be inherited if it occurred in a skin cell of an individual. In your answer, you should: describe what a mutation is explain what determines whether a mutation is able to be inherited or not. ANSWER FOUR: SURVIVAL For Achievement you need ONE statement E.g. Correctly defines or describes a mutation: A mutation is a change to the base sequence of a gene along the DNA of an organism or a change in the genetic code. States that a skin cell mutation is not inheritable (or similar) For Merit you need ONE explanation E.g. If the mutation occurs in a gamete (or a cell that undergoes meiosis), then it would be inherited. As a skin cell is not a gamete, a mutation in a skin cell cannot be inherited. QUESTION FIVE: GENETICS Explain how two parents who don’t show a particular characteristic can have a child who does show that feature. In your answer include: The nature of the characteristic What causes a feature to be expressed (shown) What is different (genetically) between the parents and the child ANSWER FIVE: GENETICS For Achievement your answer should talk about 2 – 3 points from: The characteristic must be recessive For a recessive feature to show a person must have two alleles for that feature For a dominant feature to be shown (or a recessive feature to be hidden) the person must have at least one allele for that feature The parents must be heterozygous The child is homozygous recessive for that feature The parents must have at least one allele each for the (recessive) characteristic in order to pass it on to the child The child must have both alleles for the (recessive) feature for it to be shown For Merit a reasonable explanation covering all the bullet points must be given The feature is linked to a recessive allele. Recessive alleles are only expressed if a dominant allele is not present. Both parents would have to be heterozygous for that characteristic. This means that they would have the dominant allele and the recessive one and only show the characteristic represented by the dominant allele. The child inherits one allele from each parent and if they inherit the two recessive alleles then they will exhibit the recessive characteristic.
Page 1 and 2: QUESTION ONE: DNA AND VARIATION Gen
Page 3: QUESTION THREE: MONOHYBRID CROSSES
Page 7 and 8: QUESTION SEVEN: GENETICS Cloning in
Page 9: For Merit you should give a reason

Genetics Biology Worksheet ANSWERS

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