17. Inheritance
A section of Biology, 0610
Listing 10 of 531 questions
The zebra fish, Brachydanio rerio, is a small tropical fish which lives in freshwater streams. In zebra fish, the allele for dark eye colour, D, is dominant to the allele for light eye colour, d. shows a dark-eyed fish and a light-eyed fish. Two dark-eyed fish were allowed to breed together. They produced 32 offspring. 24 of these offspring were dark-eyed. Calculate the ratio of dark-eyed to light-eyed offspring. Show your working. Complete this genetic diagram for the original cross between the two dark-eyed parent fish. parental phenotypes: gametes: offspring genotypes: offspring phenotypes: dark-eyed dark-eyed parental genotypes: Sometimes zebra fish have one dark eye and one light eye. This is very unusual. Name the genetic change which could produce this unusual appearance. Suggest two environmental factors that can increase the rate of this process.
0610_s14_qp_22
THEORY
2014
Paper 2, Variant 2
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shows a wild pig and a Saddleback pig. The drawings are to the same scale. Saddleback pig wild pig The Saddleback pig has been produced from the wild pig by artificial selection (selective breeding). Suggest two useful characteristics, visible in , which the farmers selected when breeding the Saddleback pig. Explain how the Saddleback pig could have been produced by artificial selection. There are different varieties of sheep. Some of these varieties have white wool and some have brown wool. The allele for white wool colour, N, is dominant to the allele for brown wool colour, n. A genetic diagram for the result of crossing a white-coloured sheep with a brown-coloured sheep is shown in . Complete the genetic diagram to show how wool colour is inherited in this cross. white wool SDUHQWDOSKHQRW\SH SDUHQWDOJHQRW\SH JDPHWHV RIIVSULQJJHQRW\SH RIIVSULQJSKHQRW\SH brown brown wool nn
0610_m15_qp_22
THEORY
2015
Paper 2, Variant 2
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Use Two pea plants with red flowers were crossed and produced 177 seeds. 44 of these seeds grew into white flowered pea plants and 133 seeds grew into red flowered pea plants. Which flower colour is controlled by the recessive allele? Using the symbols R and r to represent the alleles, state the genotype of the parent pea plants. By means of a labelled genetic diagram explain the inheritance of flower colour in this cross. A red flowered pea plant, genetically identical to the original parent, was crossed with a white flowered plant. Predict the ratio of red flowered to white flowered plants expected from this cross. You may use this space for any working. red flowered plants : white flowered plants Examiner's Use Germination is the first stage of development of pea plants. List three environmental conditions needed for seeds to germinate.
0610_s06_qp_2
THEORY
2006
Paper 2, Variant 0
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For Examiner's Use shows six members of the cat family, Felidae. A B C D E F For Examiner's Use Use the key to identify the cats, A to F, shown in . Tick () the boxes in Table 1.1 to show how you identify each cat. Write the name of each cat in the correct box in Table 1.1. Cat A has been completed for you as an example. Key name of cat 1 Ears pointed Ears rounded 2 Fur with no stripes or spots Fur with stripes or spots 3 Fur with stripes, but no spots Fur with spots 4 Fur with spots, but no stripes Fur with spots and stripes 5 Fur with spots Fur with no spots go to 5 go to 2 P. leo go to 3 P. tigris go to 4 A. jubatus N. nebulosa L. rufus L. caracal Table 1.1 cat name of cat A ✓ ✓ L. caracal B …………………………………. C ……………………………… D ……………………………….… E ……………………………….… F …………………………………
0610_s11_qp_21
THEORY
2011
Paper 2, Variant 1
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shows the results of crossing a plant with red flowers with a plant with white flowers. offspring parents Key: red flowers white flowers Both of the parent plants were homozygous for flower colour. All of their offspring had red flowers. State what is meant by the term homozygous. The gene controlling flower colour in this plant species has two alleles: • R is dominant and represents the allele for red flowers • r is recessive and represents the allele for white flowers. Describe the evidence shown in that supports the fact that R is the dominant allele for flower colour in this species of plant. Another plant with red flowers was crossed with a plant with white flowers. Some of the offspring plants from this cross had red flowers and some of the offspring plants had white flowers. Complete the genetic diagram to show the results of this cross. red-flowered X white-flowered plant plant parental genotypes X parental gametes offspring genotypes offspring phenotypes
0610_s21_qp_33
THEORY
2021
Paper 3, Variant 3
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The eye is adapted for focusing on near and distant objects. shows the parts of the eye involved in focusing. The eye is focused on a distant object. cornea State the term used to describe what happens to light as it passes from the air into the cornea. Describe and explain the changes that occur in the eye when adjusting focus from a distant object to a near object. Rods and cones are the receptors in the retina of the eye. Describe the functions of rods and cones in the eye. is a photograph showing regions of a human retina, as viewed through the pupil at the front of the eye. fovea peripheral retina blind spot blood vessel Complete Table 3.1 to show the distribution of rods and cones across the retina. Use these words to complete the table, each word may be used once, more than once or not at all: many few none Table 3.1 receptor distribution across the retina peripheral retina blind spot fovea rods cones Colour blindness can be caused by a mutation in a gene. The gene is located on the X chromosome. is a pedigree diagram of a family which has several people who are colour‑blind. female with normal colour vision Key: male with normal colour vision male with colour blindness Colour blindness is sex‑linked. State the evidence from that supports the idea that colour blindness is sex‑linked. State the genotype of person 5. Use the symbols X and Y for the sex chromosomes and A for the dominant allele and a for the recessive allele of the gene for colour blindness. Use the information in to complete the genetic diagram to show the probability of person 3 and person 4 having another child with colour blindness. person 3 person 4 parental female with normal male with normal phenotypes colour vision colour vision parental genotypes gametes + offspring genotypes offspring phenotypes probability of a child having colour blindness
0610_s22_qp_42
THEORY
2022
Paper 4, Variant 2
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