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

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 31–60 of 73.

Who devised the square grid used to predict the outcomes of a genetic cross?Read the answer and worked solution →A Yy pea plant is self-crossed. What genotypic ratio of YY to Yy to yy is expected?Read the answer and worked solution →A Yy pea plant is self-crossed, with yellow dominant to green. What phenotypic ratio is expected in the offspring?Read the answer and worked solution →In a test cross, the plant showing the dominant trait is crossed with which partner?Read the answer and worked solution →Test crosses cannot be used on people. Which method do geneticists use instead to follow a human genetic disease?Read the answer and worked solution →Alkaptonuria is recessive. Neither parent in a family is affected, yet their child is. What must the parents be?Read the answer and worked solution →Inflated pods are dominant to constricted. An F2 generation contains 650 inflated-pod plants. About how many constricted-pod plants are expected?Read the answer and worked solution →A homozygous recessive dwarf pea plant is crossed with a heterozygous tall plant. What phenotypic ratio results?Read the answer and worked solution →Heterozygous individuals who carry a recessive allele without expressing it are usually described as what?Read the answer and worked solution →A snapdragon homozygous for red flowers is crossed with one homozygous for white flowers. What colour are all the offspring?Read the answer and worked solution →Two pink snapdragons are crossed. What phenotypic ratio of red to pink to white is expected?Read the answer and worked solution →True-breeding black mice and true-breeding white mice are mated and all the offspring are grey. Which pattern does that suggest?Read the answer and worked solution →Codominance is defined as which of the following?Read the answer and worked solution →In the human MN blood groups, what does a heterozygote express on its red blood cells?Read the answer and worked solution →Which chromosomes are the autosomes?Read the answer and worked solution →A gene is described as X-linked when it sits where?Read the answer and worked solution →Who mapped eye colour in Drosophila to the X chromosome, and in which year?Read the answer and worked solution →In birds the female carries the non-homologous sex chromosomes. What follows for sex-linked traits in birds?Read the answer and worked solution →A recessive lethal inheritance pattern is one in which the allele has which effect?Read the answer and worked solution →The Curly allele in Drosophila is a recessive lethal. What does it do in a heterozygous fly?Read the answer and worked solution →Huntington's disease is caused by a dominant lethal allele. Why does it persist in human populations?Read the answer and worked solution →What does Mendel's law of segregation state?Read the answer and worked solution →A plant with green wrinkled seeds is crossed with a plant with yellow round seeds, both true breeding. What is the F1 genotype?Read the answer and worked solution →How many different gamete types can a YyRr plant produce, and what are they?Read the answer and worked solution →A YyRr plant is self-crossed. How many equally likely genotypic combinations does the Punnett square contain?Read the answer and worked solution →Yellow is dominant to green and round to wrinkled. What phenotypic ratio does a self-crossed YyRr plant give?Read the answer and worked solution →In the F2 of a YyRr self-cross, what proportion of offspring are expected to be wrinkled and green?Read the answer and worked solution →In the F2 of a YyRr self-cross, what proportion of offspring are expected to be round and green?Read the answer and worked solution →Why is the Punnett square abandoned for crosses involving four genes?Read the answer and worked solution →Two individuals heterozygous at four genes are crossed. What proportion of offspring are homozygous recessive at all four?Read the answer and worked solution →

Worked practice questions

Who devised the square grid used to predict the outcomes of a genetic cross?

  1. Reginald Punnett
  2. Gregor Mendel
  3. Walter Sutton
  4. Theodor Boveri
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Correct answer: A. Reginald Punnett

1. The grid that lists parental gametes along the top and side is the Punnett square. 2. It was devised by the British geneticist Reginald Punnett. 3. Mendel worked out the ratios themselves without using such a grid. 4. Sutton and Boveri are linked with the Chromosomal Theory of Inheritance instead. _Source: OpenStax Biology (1st ed., CC BY 4.0), Ch 12 "Mendel's Experiments and Heredity", section 12.2 Characteristics and Traits_

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A Yy pea plant is self-crossed. What genotypic ratio of YY to Yy to yy is expected?

  1. 3 to 1 to 0
  2. 1 to 1 to 1
  3. 2 to 1 to 1
  4. 1 to 2 to 1
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Correct answer: D. 1 to 2 to 1

1. Each Yy parent makes two kinds of gamete in equal numbers, Y and y. 2. Draw a two by two square with Y and y along the top and Y and y down the side. 3. The four boxes are YY, Yy, yY and yy. 4. The two heterozygous boxes are genetically the same, so they are grouped together. 5. Counting the boxes gives 1 YY, 2 Yy and 1 yy, a ratio of 1 to 2 to 1. _Source: OpenStax Biology (1st ed., CC BY 4.0), Ch 12 "Mendel's Experiments and Heredity", section 12.2 Characteristics and Traits_

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A Yy pea plant is self-crossed, with yellow dominant to green. What phenotypic ratio is expected in the offspring?

  1. 3 yellow to 1 green
  2. 1 yellow to 1 green
  3. 1 yellow to 2 green
  4. 2 yellow to 2 green
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Correct answer: A. 3 yellow to 1 green

1. The two by two square for Yy crossed with Yy gives the boxes YY, Yy, yY and yy. 2. Y is dominant, so YY, Yy and yY all give yellow seeds, which is three boxes. 3. Only yy gives green seeds, which is one box. 4. Applying the sum rule to the yellow classes gives 1/4 plus 1/2, which is 3/4. 5. So the phenotypic ratio is 3 yellow to 1 green. _Source: OpenStax Biology (1st ed., CC BY 4.0), Ch 12 "Mendel's Experiments and Heredity", section 12.2 Characteristics and Traits_

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