16.3. Sexual reproduction in plants
A subsection of Biology, 0610, through 16. Reproduction
Listing 10 of 316 questions
For Examiner's Use is a section through the fruit of a pea plant showing some of its seeds. sepals seed fruit pod Explain why the cells of the fruit pod, as shown in , are genetically different from the cells of the embryo in the seeds. shows a pea seedling after germination has begun. A B Name the structures labelled A and B. Write your answers on . State three external conditions that are always required for germination. For Examiner's Use Define the terms growth and development. growth development
0610_w13_qp_22
THEORY
2013
Paper 2, Variant 2
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shows a vertical section through a leaf. B A C Name the structures labelled A, B and C. Write your answers in the spaces below. A B C Potato plants produce new potato tubers underground as part of the process of asexual reproduction. shows the amount of carbohydrate stored in the leaves and new tubers of potato plants, grown in a country in the northern hemisphere, between May and September. amount of carbohydrate / arbitrary units May June July date August September new tubers leaves Compare the amount of carbohydrate in the leaves and new tubers in May and September. Give an explanation for the differences. Use data from in your answer. May difference explanation September difference explanation State the form in which carbohydrate is stored in potato plants. State two uses, other than storage, for the carbohydrate made by photosynthesis.
0610_w14_qp_21
THEORY
2014
Paper 2, Variant 1
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shows a dwarf sunflower and a tall sunflower, Helianthus annuus. The height of the dwarf sunflower is 0.45 m and the height of the tall sunflower is 4.5 m. dwarf not to scale tall Dwarf plants like the one in have mutant alleles. Define the term allele. Shoot growth in plants is controlled by auxins. An enzyme in shoot tips converts molecules of an amino acid into auxins as shown in . enzyme amino acid auxin Explain how a mutation in DNA results in an abnormal enzyme which does not catalyse the reaction shown in . Two tall sunflower plants were crossed. 25% of the offspring produced were dwarf. Explain how it is possible for two tall parent plants to have this percentage of dwarf offspring. shows how several strawberry plants can be formed from one parent plant. parent plant offspring Explain the type of reproduction that produces plants by the method shown in . Explain the disadvantages of the type of reproduction shown in .
0610_w18_qp_42
THEORY
2018
Paper 4, Variant 2
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Two tomato plants that produce red fruit were bred together. This cross produced 71 offspring plants with red fruit and 26 offspring plants with yellow fruit. Complete the genetic diagram to show this cross. Select a suitable letter to represent the alleles and decide which allele will need a capital letter and which allele will need a lower case letter. letter representing the allele for red fruit letter representing the allele for yellow fruit parental phenotypes red fruit × red fruit parental genotypes × gametes × , , offspring genotypes expected phenotype ratio red fruit : yellow fruit actual phenotype ratio red fruit : yellow fruit Researchers carried out some experiments on tomato plants that were homozygous for fruit colour. State how the researchers could be sure that the fruit came from homozygous plants. The researchers analysed two pigments, chlorophyll and lycopene, in homozygous red tomato fruit and homozygous yellow tomato fruit. Chlorophyll is found in unripe tomato fruit. Describe the function of chlorophyll. State the name of one mineral required for the synthesis of chlorophyll. The researchers analysed the concentration of the pigments in tomato fruits: • before they were ready to eat • when they were ready to eat . The results of the analysis are shown in Table 2.1. Table 2.1 chlorophyll concentration / mg per g of tomato fruit lycopene concentration / mg per g of tomato fruit unripe red fruit 10.0 0.0 ripe red fruit 1.2 105.7 unripe yellow fruit 6.2 0.0 ripe yellow fruit 0.4 0.7 Use the information in Table 2.1 to compare the changes in pigments in red fruit and yellow fruit as they ripen. A gene is responsible for the production of lycopene in fruits. Geneticists have recently produced genetically modified pink pineapples using the gene associated with the production of lycopene. Genes are found at specific locations on an important biological molecule. State the name of this biological molecule. Describe the disadvantages of genetically modifying crops.
0610_w21_qp_41
THEORY
2021
Paper 4, Variant 1
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A scientist investigated sexual reproduction in flowering plants. shows the procedure for crossing two plants of the same species. anthers are removed from flower 1 paint brush used to pick up pollen from flower 2 pollen transferred to the stigma of flower 1 stigma ready to receive pollen bag placed around flower 1 and tied tightly seeds develop in flower 1 after fertilisation The scientist collected the seeds and germinated them. The leaves and flowers of the offspring plants showed phenotypic variation as they were not all identical to the parent plants. The scientist then investigated the chromosomes of all the offspring plants and found that they had exactly the same number of chromosomes as the parent plants. Define the term chromosome. Suggest why the scientist placed a bag around flower 1. Explain how sexual reproduction results in the variation that the scientist discovered in the offspring plants. The chromosome number of the offspring plants is the same as the chromosome number of the parent plants in this investigation. Explain how the chromosome number is maintained from one generation to the next. The plant Camellia japonica has flowers that can be white, red or a mixture of these two colours. When red-flowered plants are crossed with white-flowered plants, all the offspring plants have flowers with petals that are a mixture of red and white, as shown in . • The gene for petal colour in C. japonica is given the symbol P. • The allele for white petals is given the symbol PW. • The allele for red petals is given the symbol PR. Table 2.1 shows the phenotypes of three different pairs of parent plants. Complete Table 2.1 by giving all the possible genotypes of the offspring plants that could be produced by these parent plants. Space for working. Table 2.1 phenotype of male parent phenotype of female parent all the possible genotypes of offspring plants produced by this cross red petals red petals white petals red petals petals that are both red and white petals that are both red and white State the type of inheritance that is shown by petal colour in C. japonica.
0610_w21_qp_42
THEORY
2021
Paper 4, Variant 2
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Bluebells are plants that can reproduce sexually and asexually. Define the term asexual reproduction. State one example of a structure that is involved in asexual reproduction in a plant. is a drawing of a bluebell plant. On , label the structure that carries out sexual reproduction with a label line and the letter S. Bluebells grow in ancient woodlands. is a graph showing the percentage of land that was covered with woodland in one country from the years 1100 to 2000. 1100 1200 1300 1400 1500 year 1600 1700 1800 1900 2000 percentage of land covered with woodland State the years when the percentage of land covered with woodland was 10% in . and State the percentage of land covered with woodland in 1600 in . % In many countries the percentage of land covered with woodland has decreased because of deforestation. Suggest two reasons why deforestation occurs. Explain the undesirable effects of deforestation.
0610_w23_qp_33
THEORY
2023
Paper 3, Variant 3
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Questions Discovered
316