5090_w19_qp_22
A paper of Biology, 5090
Questions:
9
Year:
2019
Paper:
2
Variant:
2
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1
A species of flowering plant has flowers of two types. Some of the plants of this species have flowers called pin and some of the plants have flowers called thrum. The diagrams show sections through parts of these two types of flower. pin flower thrum flower Describe how the structure of the pin type of flower differs from that of the thrum type of flower. Pollination in this species of plant is not always successful in leading to fertilisation. Examples of successful pollination and of unsuccessful pollination are shown in the diagram below. pin flower thrum flower key successful pollination unsuccessful pollination Use information from the diagram to name the type of pollination that is successful and suggest the advantage to the species of this type of pollination. type of pollination advantage The gene responsible for the production of the different types of flower has two alleles. One allele (T) is dominant to the other allele . A plant with flowers of the pin type has a homozygous recessive genotype. A plant with flowers of the thrum type has a heterozygous genotype. Use the letters T and t to show the genotype of each of the following: a plant with flowers of the pin type a plant with flowers of the thrum type A plant with flowers of the pin type was successfully pollinated by a plant with flowers of the thrum type. Complete the genetic diagram shown below and state the likely ratio of new plants being produced with flowers of the pin and thrum types. gametes plant with flowers of the thrum type plant with flowers of the pin type ratio of new plants with flowers of the pin and thrum types:
16. Development of organisms and continuity of life  →  16.3. Sexual reproduction in plants
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2
Plants absorb light energy to use in the process of photosynthesis. Name the part of a plant cell where photosynthesis takes place. State the equation, in words or symbols, for photosynthesis. Photosynthesis also takes place in some bacteria. Suggest and explain the colour of these bacteria. These bacteria are able to absorb more light than plants because they have additional chemicals that absorb light. Scientists have suggested that it may be possible to transfer a gene that codes for one of these additional chemicals into the DNA of plants used to produce crops that humans eat. Name the process that scientists would use to transfer the gene from these bacteria into the DNA of a plant. Suggest and explain the possible advantages of transferring this gene into the DNA of a plant used to produce crops that humans eat.
6. Plant nutrition  →  6.1. Photosynthesis
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3
Syphilis is an infectious disease transmitted by sexual contact. It is possible to test the blood of a person for the presence of antibodies produced after infection with the pathogen that causes syphilis. State each of the following: the type of pathogen that causes syphilis the component of an infected person’s blood that produces antibodies the component of an infected person’s blood that transports these antibodies. The diagram shows part of a kit for testing a sample of blood for the presence of antibodies for syphilis. coloured lines appear here drop of blood added here S C T If antibodies for syphilis are in the drop of blood added at S, a coloured line will form at the test region, T. The presence of a coloured line at the control region, C, indicates that sufficient blood has been added and that the result at the test region, T, is valid. If a person believes that they may have been infected with syphilis, a doctor may suggest that they have a blood test. Suggest why it is advisable for a person to wait until some time after their last sexual contact has taken place before the test is carried out. Three possible outcomes of the test are shown below. coloured line C T S C T S C T S outcome X outcome Y outcome Z Complete the table below by entering either the word yes or the word no in each box to summarise the significance of each outcome. outcome is the result of the test valid? can it be concluded that the person is infected with syphilis? X Y Z State one first symptom shown by a person with primary stage syphilis. State the type of drug that should be given to a person with primary stage syphilis to prevent the disease from progressing to the secondary stage. The graph shows the number of reported cases of syphilis in men in a country between 1995 and 2012. 1995 1996 1997 1998 1999 2000 2001 2002 2003 year number of reported cases of syphilis per 100 000 population 2004 2005 2006 2007 2008 2009 2010 2011 2012 Calculate the percentage increase in the number of reported cases of syphilis in men between 2004 and 2012. Show your working. % Suggest why the actual increase in the number of cases of syphilis in men may have been higher than shown in the graph. Suggest two recommendations that may be made to men in order to reduce the number of new cases of infection with syphilis.
12. Disease and immunity  →  12.1. Disease
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4
Proteins are an important component of the human diet. Protein molecules are digested and the products of digestion are absorbed into the blood. State one principal source of protein in the diet. Describe the chemical digestion of proteins in named parts of the alimentary canal. State where in the alimentary canal the products of digestion are absorbed into the blood. In a disease that affects a small number of people, the surface through which the products of digestion are absorbed into the blood changes. This change is shown in the diagrams below. Both diagrams are drawn to the same scale. absorption surface in a person not affected by the disease absorption surface in a person affected by the disease Describe the change in the absorption surface in a person affected by the disease and suggest ways in which the person may be affected by this change. change in absorption surface ways in which person may be affected
8. Human nutrition  →  8.2. Human digestive system
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5
The statements E to L relate to the process of cell division. E is used in the repair of damaged tissues F results in the production of diploid cells G results in the production of gametes H results in the chromosome number being halved J gives rise to genetically identical cells K takes place in both animals and plants L is used in the process of asexual reproduction Complete the table by writing each statement letter in the correct box to show whether the statement relates to mitosis only, meiosis only, or to both. The first letter has been written in the correct box for you. mitosis only meiosis only both mitosis and meiosis E
16. Development of organisms and continuity of life  →  16.1. Nuclear division
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7
Respiration in the muscle cells of a human may take place when oxygen is available and when oxygen is not available. Name the type of respiration that takes place when oxygen is available. A person is running in a race. Outline the advantages to the person of the type of respiration in compared with the type of respiration that takes place when oxygen is not available. The oxygen required for the type of respiration in is provided to the muscle cells from the air. Describe the events that must take place in a person’s body so that a muscle cell can be provided with molecules of oxygen from the air.
10. Respiration  →  10.3. Anaerobic respiration
10. Respiration  →  10.2. Aerobic respiration
10. Respiration  →  10.1. Respiration
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8
Describe the possible harmful effects of human activity on the ecosystem of a tropical rainforest. The Sun is the principal source of energy in an ecosystem such as a tropical rainforest. Outline the flow of energy through an ecosystem such as a tropical rainforest. In your answer you should make reference to named levels in food webs.
19. Relationships of organisms with one another and with the environment  →  19.4. Effects of humans on ecosystems
19. Relationships of organisms with one another and with the environment  →  19.1. Energy flow
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