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NCEA Level 2 Mendel's Experiments and Heredity — practice questions — page 3

Explore 73 free Mendel's Experiments and Heredity questions in NCEA Level 2 Biology. Open each question or exercise to read its content, reference answers and available explanation.

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Mendel's Experiments and Heredity questions and exercises with answers

Showing questions 61–73 of 73.

Assuming no linkage, in what ratio does an AaBb heterozygote produce the gametes AB, aB, Ab and ab?Read the answer and worked solution →How many chromosomes does the garden pea have, a number that has fuelled debate about Mendel's choice of characteristics?Read the answer and worked solution →An F2 count gives 2706 tall inflated, 930 tall constricted, 888 dwarf inflated and 300 dwarf constricted. Which ratio is that closest to?Read the answer and worked solution →Epistasis describes which kind of interaction between two genes?Read the answer and worked solution →In an epistatic pair of genes, what are the alleles being masked called?Read the answer and worked solution →Agouti coat colour needs a dominant A allele, but pigment of any kind needs a dominant C allele. What is a mouse of genotype Aacc?Read the answer and worked solution →Two mice heterozygous at both the A and C genes are crossed. What phenotypic ratio of agouti to solid to albino results?Read the answer and worked solution →In shepherd's purse, seeds are ovoid only when both genes are homozygous recessive. What ratio comes from crossing AaBb with AaBb?Read the answer and worked solution →A single characteristic gives a phenotypic ratio whose parts total 16. What does that usually indicate?Read the answer and worked solution →How many genes contribute to eye colour in humans, at minimum?Read the answer and worked solution →Knock out the false allele claimsRead the answer and worked solution →Order the steps of crossing overRead the answer and worked solution →Sort each clue by its dominance patternRead the answer and worked solution →

Worked practice questions

Assuming no linkage, in what ratio does an AaBb heterozygote produce the gametes AB, aB, Ab and ab?

  1. 1 to 3 to 3 to 1
  2. 1 to 1 to 1 to 1
  3. 1 to 2 to 2 to 1
  4. 4 to 3 to 2 to 1
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Correct answer: B. 1 to 1 to 1 to 1

1. Segregation gives each gamete either A or a, with equal chance, so each is 1/2. 2. Segregation likewise gives each gamete either B or b, each at 1/2. 3. Independent assortment means the two choices do not affect each other, so multiply. 4. Every one of the four combinations therefore has a chance of 1/2 times 1/2, which is 1/4. 5. Four equal quarters is a ratio of 1 to 1 to 1 to 1. 6. A 1 to 3 to 3 to 1 or 1 to 2 to 2 to 1 answer would require some gamete combinations to be favoured, which independent assortment forbids. _Source: OpenStax Biology (1st ed., CC BY 4.0), Ch 12 "Mendel's Experiments and Heredity", review questions_

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How many chromosomes does the garden pea have, a number that has fuelled debate about Mendel's choice of characteristics?

  1. Five chromosomes
  2. Seven chromosomes
  3. Fourteen chromosomes
  4. Twenty chromosomes
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Correct answer: B. Seven chromosomes

1. Mendel reported on seven characteristics and never mentioned linkage. 2. The garden pea has seven chromosomes, the same number. 3. Some have suggested his choice of seven characteristics was not a coincidence. 4. Others note that recombination shuffles alleles so extensively that he may simply never have seen linkage. _Source: OpenStax Biology (1st ed., CC BY 4.0), Ch 12 "Mendel's Experiments and Heredity", section 12.3 Laws of Inheritance_

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An F2 count gives 2706 tall inflated, 930 tall constricted, 888 dwarf inflated and 300 dwarf constricted. Which ratio is that closest to?

  1. 1 to 1 to 1 to 1
  2. 12 to 3 to 3 to 1
  3. 3 to 3 to 3 to 1
  4. 9 to 3 to 3 to 1
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Correct answer: D. 9 to 3 to 3 to 1

1. Take the smallest class, 300 dwarf constricted, as one part. 2. Divide the largest class by it: 2706 divided by 300 is about 9.0. 3. Divide the second class: 930 divided by 300 is about 3.1. 4. Divide the third class: 888 divided by 300 is about 3.0. 5. The four classes are therefore close to 9 to 3 to 3 to 1. 6. That is exactly what a dihybrid self-cross predicts when both trait pairs assort independently. 7. A 12 to 3 to 1 pattern has only three classes, so it cannot describe these four counts. 8. A 1 to 1 to 1 to 1 result would need roughly 1206 plants in every class. _Source: OpenStax Biology (1st ed., CC BY 4.0), Ch 12 "Mendel's Experiments and Heredity", section 12.3 Laws of Inheritance_

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