16. Reproduction
A section of Biology, 0610
Listing 10 of 757 questions
shows part of a classification diagram for plants. Complete . ………………… plants ………………… ferns monocotyledons Describe two identifying features of monocotyledons. shows the life cycle of a fern. The life cycle of a fern has some similarities and some differences compared with the life cycles of other plants. The letters represent processes that occur during the life cycle. The haploid stages of the life cycle are represented by . The diploid stages of the life cycle are represented by (2n). adult sporophyte (2n) spores zygote (2n) gametes adult gametophyte A B C C D not to scale The adult sporophyte has 1200 chromosomes in its body cells. State the number of chromosomes in the body cells of the gametophyte. Identify and describe process A in . State the name of process D in . shows the parts of two flowers from two different plants of the same species. Describe what is meant by the term species. Annotate to show the mechanism of cross-pollination by: • labelling the structures involved • drawing an arrow to show the pathway of pollen. Draw an X on to show where fertilisation occurs. Explain the disadvantages of cross-pollination compared with self-pollination.
0610_m23_qp_42
THEORY
2023
Paper 4, Variant 2
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For Examiner's Use Sorghum bicolor is a cereal crop important in many dry areas of the world. shows some plants of S. bicolor growing in a field in China. S. bicolor is a monocotyledon. State two features that are used to identify plants as monocotyledons. shows the flower heads of sorghum. Pollen is released from the individual flowers when they open. Most sorghum flowers are self-pollinated and then self-fertilised. State the meanings of the terms pollination and fertilisation. pollination fertilisation For Examiner's Use Describe two implications of self-pollination. Describe the events that occur in flowering plants after fertilisation to form a seed. In India, the cultivation of sorghum has decreased because now people prefer foods based on wheat and rice. There are alternative uses of sorghum in the production of new foods, processed foods and as feed for animals. Explain why it is less efficient to feed crops, such as sorghum, to animals rather than to use them for human foods.
0610_s13_qp_32
THEORY
2013
Paper 3, Variant 2
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is a half-flower drawing of pride of Barbados, Caesalpinia pulcherrima. B A E D C F Complete Table 6.1 by stating the letter from that indicates the organ where each function occurs and the name of the organ. Table 6.1 function letter from name of the organ meiosis to produce pollen grains pollination development of seeds protection of flower in the bud is a scanning electron micrograph of some pollen grains from wind-pollinated flowers and insect-pollinated flowers. magnification ×220 H J Write the formula that would be used to calculate the actual diameter of pollen grain H. The actual diameter of pollen grain H is 0.082 mm. Convert this value to micrometres (μm). Space for working. μm Explain how the pollen grain labelled J is adapted for insect pollination. Pollen grains grow tubes, which contain haploid male gamete nuclei. One of these male gamete nuclei fuses with the female gamete. State the part of the flower that contains the female gamete. Define the term haploid nucleus. Explain why it is important for gametes to be haploid.
0610_s18_qp_43
THEORY
2018
Paper 4, Variant 3
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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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Questions Discovered
757