16.3. Sexual reproduction in plants
A subsection of Biology, 0610, through 16. Reproduction
Listing 10 of 316 questions
is a photograph of a spider plant, Chlorophytum comosum. Spider plants can reproduce by producing an identical plantlet, which grows away from the single parent plant. parent plant offspring plantlet Identify one feature in that shows that spider plants are monocotyledons. Describe the advantages and disadvantages of asexual reproduction in a population of spider plants in the wild. shows pollen that has been released from the flowers of a hazel tree, Corylus avellana. These flowers are wind‑pollinated. pollen Explain why a hazel tree has to produce very large amounts of pollen. Describe how a stigma from a wind‑pollinated plant is adapted for pollination. The hazel tree uses cross‑pollination rather than self‑pollination. Describe cross‑pollination. Outline the events that occur in the flower after pollination.
0610_s24_qp_43
THEORY
2024
Paper 4, Variant 3
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For Examiner's Use Define the term self-pollination. Snapdragon plants have flowers with three colours: red, pink and white. Some students investigated the inheritance of flower colour in snapdragons. In cross 1 they cross-pollinated plants that were homozygous for red flowers with plants that were homozygous for white flowers. They collected and planted the seeds from cross 1. All of the resulting plants had pink flowers. In cross 2 they self-pollinated all the pink-flowered plants and found that in the next generation there were red-flowered plants, white-flowered plants and pink-flowered plants. Complete the genetic diagrams to show how flower colour is inherited in snapdragon plants. Use the symbol IR for the allele for red flowers and IW for the allele for white flowers. cross 1 parental phenotypes parental genotypes gametes offspring genotypes offspring phenotypes red flowers × × pink flowers white flowers For Examiner's Use cross 2 parental phenotypes parental genotypes gametes pink flowers × × pink flowers offspring genotypes …………………………………………………………………………………………. ratio of offspring phenotypes ……………………………………………………………………………………… Another student cross-pollinated pink-flowered plants with white-flowered plants. Complete the genetic diagram to show the results that the student would expect. phenotypes genotypes gametes pink flowers × × white flowers offspring genotypes …………………………………………………………………………………………. ratio of offspring phenotypes ……………………………………………………………………………………… For Examiner's Use Explain the advantages of sexual reproduction to a species of flowering plant, such as the snapdragon.
0610_w10_qp_32
THEORY
2010
Paper 3, Variant 2
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The flowers of pea plants, Pisum sativum, are produced for sexual reproduction. The flowers are naturally self-pollinating, but they can be cross-pollinated by insects. Explain the difference between self-pollination and cross-pollination. For Examiner's Use Explain the disadvantages for plants, such as P. sativum, of reproducing sexually. Pea seeds develop inside pea pods after fertilisation. They contain starch. A gene controls the production of an enzyme involved in the synthesis of starch grains. The allele, R, codes for an enzyme that produces normal starch grains. This results in seeds that are round. The allele, r, does not code for the enzyme. The starch grains are not formed normally. This results in seeds that are wrinkled. shows round and wrinkled pea seeds. round pea seed wrinkled pea seed Pure bred plants are homozygous for the gene concerned. A plant breeder had some pure bred pea plants that had grown from round seeds and some pure bred plants that had grown from wrinkled seeds. State the genotypes of the pure bred plants that had grown from round and from wrinkled seeds. round wrinkled For Examiner's Use These pure bred plants were cross-pollinated (cross 1) and the seeds collected. All the seeds were round. These round seeds were germinated, grown into adult plants (offspring 1) and self-pollinated (cross 2). The pods on the offspring 1 plants contained both round and wrinkled seeds. Further crosses (3 and 4) were carried out as shown in Table 6.1. Table 6.1 phenotype of seeds in the seed pods cross round seeds wrinkled seeds ratio of round to wrinkled seeds pure bred for round seeds x pure bred for wrinkled seeds   1:0 offspring 1 self-pollinated   offspring 1 x pure bred for round seeds offspring 1 x pure bred for wrinkled seeds Complete Table 6.1 by indicating • the type of seeds present in the pods with a tick () or a cross () • the ratio of round to wrinkled seeds. You may use the space below and on page 22 for any rough working. For Examiner's Use Seed shape in peas is an example of discontinuous variation. Suggest one reason why seed shape is an example of discontinuous variation. Plants have methods to disperse their seeds over a wide area. Explain the advantages of having seeds that are dispersed over a wide area,
0610_w12_qp_31
THEORY
2012
Paper 3, Variant 1
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For Examiner's Use Wheat is a type of grass that has been grown by humans for about 9000 years. The earliest variety is called emmer. shows emmer wheat and a modern type of wheat. ear of modern wheat ear of emmer wheat ear ear awn grain Use to describe two ways in which emmer wheat is different from modern wheat. Over hundreds of years farmers improved the yield of wheat crops. They kept grains from the highest yielding ears to grow the next crop. Name this farming practice. For Examiner's Use There is evidence that emmer wheat was pollinated by pollen from other grasses. This produced new varieties. shows a section through a flower of wheat. Suggest the method of pollination in this wheat flower. Give two reasons for your answer. method reasons For Examiner's Use 3000 years ago some farmers stored wheat in pits in the ground. shows a pit full of grain. chalk rock chalk rock waterproof, airtight cap of clay layer of wheat grains that germinate wheat grains that do not germinate or decay ground level Wheat grains near the edge of the pit germinate. The germinating grains use up all of one gas from the air in the pit and produce a different gas. The germinating grains also release heat that causes the temperature in the pit to rise to 80 °C. Name the chemical reaction that uses up and produces the gases. Name the gas used up during this chemical reaction. Name the gas released during this chemical reaction. For Examiner's Use Suggest and explain three reasons why most of the grains in the pit did not germinate or decay.
0610_w13_qp_21
THEORY
2013
Paper 2, Variant 1
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The garden pea, Pisum sativum, is a plant which has flowers that have both male and female parts. P. sativum is naturally self-pollinating. Discuss the advantages and disadvantages of self-pollination. Gregor Mendel studied inheritance in the garden pea, P. sativum. The flowers of P. sativum that he studied were either purple or white. The gene that controls flower colour has two alleles, B and b. When Mendel crossed purple-flowered plants with white-flowered plants all the plants in the next generation had purple flowers. Table 4.1 shows five genetic terms that can be applied to Mendel’s study of the inheritance of flower colour. Complete Table 4.1 by stating an example of each genetic term. The first one has been completed for you. Table 4.1 term example in P. sativum dominant trait purple flowers recessive allele phenotype homozygous genotype heterozygous genotype Test crosses can be used to determine the genotype of a plant with purple flowers. The genetic diagrams show test crosses for purple-flowered plants with two different genotypes. Complete the genetic diagrams for test cross 1 and test cross 2. test cross 1 parental phenotype purple flowers × white flowers parental genotype Bb × genotypes of gametes + offspring genotypes offspring phenotypes test cross 2 purple flowers × white flowers BB × + Pickerel weed, Pontederia cordata, is a plant that grows in shallow water on the edges of ponds and lakes in North America. A few seedlings of these plants are white. The white seedlings cannot make chlorophyll. Researchers carried out several crosses using pickerel weed plants. Their results are shown in Table 4.2. Table 4.2 cross number of offspring green white Select suitable symbols for the alleles and state the possible genotypes of the parents for each cross. cross 1 cross 2 It is not possible to carry out a test cross with pickerel weed plants. Suggest why.
0610_w17_qp_42
THEORY
2017
Paper 4, Variant 2
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Pollination occurs when pollen is transferred from one flower to another. is a diagram of part of a flower. A B C D F E State the letter from that identifies the structure which: attracts insect pollinators produces pollen receives the pollen during pollination Draw a label line and the letter X on the flower in to show where fertilisation occurs. State the name of the part labelled E in . The flower shown in represents an insect-pollinated flower. Describe two ways the pollen from an insect-pollinated flower differs from the pollen from a wind-pollinated flower. A student wrote an incorrect statement about fertilisation in plants. Fertilisation is the fusion of zygote nuclei. Circle the incorrect word. Plants can reproduce asexually or sexually. Table 7.1 compares asexual and sexual reproduction. Place ticks (3) in the boxes to show the correct features of asexual and sexual reproduction. Table 7.1 features of reproduction asexual reproduction sexual reproduction involves gametes makes more of the same kind of organism produces genetically identical offspring involves fertilisation
0610_w20_qp_31
THEORY
2020
Paper 3, Variant 1
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Questions Discovered
316