9700_w14_qp_22
A paper of Biology, 9700
Questions:
6
Year:
2014
Paper:
2
Variant:
2
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2
shows one section of the nitrogen (N) cycle. Some details of the water cycle are also included. water and nitrate ions in roots water and nitrogen-containing organic compounds in leaves water vapour in atmosphere X Y transport in xylem uptake death death decomposition and ammonification water and nitrate ions in soil nitrogen-containing organic compounds in soil ammonium ions Name processes X and Y. X Y Name one organism involved in process Y. Explain why process X occurs, even if it is a disadvantage to a plant. State two examples of how the leaves of xerophytic plants are adapted to reduce the loss of water vapour to the atmosphere. 1. 2. Nitrate ions are taken up by root hair cells. Outline the role of the cell surface membrane of root hair cells in the uptake of nitrate ions. Describe and explain how water and nitrate ions are transported in the xylem from roots to leaves. One use of the nitrogen in the nitrate ions is for the synthesis of organic molecules such as RNA. State where nitrogen is found within an RNA molecule.
7. Transport in plants  →  7.2. Transport mechanisms
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3
I n mammals, oxygen is transported by red blood cells in a system that is described as a closed double circulation. The majority of oxygen molecules are transported as oxyhaemoglobin. At the respiring tissues, oxygen dissociates from haemoglobin and diffuses to the surrounding cells. Explain what is meant by a closed double circulation. is a diagram that highlights the tertiary and quaternary structure of a haemoglobin molecule. haem groups At high altitudes, the partial pressure of inspired oxygen is considerably lower than at sea level. This means that the partial pressure of oxygen in the blood is also much lower at high altitudes than at sea level. is an oxygen dissociation curve of adult oxyhaemoglobin. partial pressure of oxygen / kPa percentage saturation of haemoglobin With reference to , calculate the difference in percentage saturation of haemoglobin at sea level, where the partial pressure of oxygen is 13.0 kPa, and at a higher altitude, where the partial pressure of oxygen is 6.2 kPa. Show your working. answer % After spending time at altitude, a person can become acclimatised. One feature of acclimatisation is an increase in the red blood cell count. Explain the importance of the increase in the red blood cell count. Before acclimatisation can occur, some people develop a condition known as acute mountain sickness when they travel to high altitude areas. Acetazolamide is a non-competitive enzyme inhibitor that is used as a drug to prevent and treat acute mountain sickness. Explain the effects of a non-competitive inhibitor on the rate of enzyme activity. Tobacco smoking can have an effect on the transport of oxygen by haemoglobin. shows oxygen dissociation curves with and without the presence of carbon monoxide (CO). partial pressure of oxygen / kPa percentage saturation of haemoglobin no CO (non-smoker) 20% CO (heavy smoker) With reference to , describe the effect of carbon monoxide on the cardiovascular system.
8. Transport in mammals  →  8.2. Transport of oxygen and carbon dioxide
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4
Cholera is an infectious disease that can affect children and adults. Symptoms of the disease can occur very quickly, from a few hours to a few days. Table 4.1 shows: • the economic status of each of five countries • the number of cases of cholera reported to the World Health Organization (WHO) over a five year period for each country • the population in 2006 and in 2010 of each country. Table 4.1 country economic status number of cholera cases reported population / millions Zimbabwe low 12.5297 12.5715 Uganda low 29.3703 33.4247 Angola middle 17.0104 19.0819 Cameroon middle 17.9484 19.5989 Canada high 32.6490 34.1088 Table 4.1 shows that there are differences in the number of cholera cases reported between the high economic status country and the low economic status countries. Suggest three reasons to explain these differences. 1. . 2. 3. With reference to Table 4.1, suggest reasons for the differences in the number of cases of cholera reported over the five year period for Angola and Cameroon. Vaccination helps to prevent the spread of infectious diseases by stimulating an immune response in individuals against specific pathogens, such as Morbillivirus, the virus that causes measles. Suggest two reasons why measles vaccination programmes may fail to prevent epidemics. 1. 2. Outline the response produced by B-lymphocytes on exposure to Morbillivirus in an individual who already has immunity to measles.
10. Infectious diseases  →  10.1. Infectious diseases
11. Immunity  →  11.2. Antibodies and vaccination
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5
Complete Table 5.1 by numbering each event to show the sequence occurring in the initiation and control of one heart beat. Use 1 as the first event in the sequence. Table 5.1 event sequence impulses pass down septum through conducting fibres known as the bundle of His atrioventricular node sends out impulses impulses travel across atrial walls impulses reach base of ventricles (apex of heart) impulses pass up through Purkyne fibres in ventricle walls sinoatrial node sends out impulses Explain the circumstances that cause the closing of the semi-lunar valves during the cardiac cycle. At the arterial end of a capillary bed in muscle tissue, the hydrostatic pressure is high enough to cause the formation of tissue fluid. Explain the differences between the composition of blood and the composition of tissue fluid at the arterial end of a capillary bed.
8. Transport in mammals  →  8.1. The circulatory system
8. Transport in mammals  →  8.3. The heart
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6
Agrobacterium tumefaciens is a bacterium that can enter plants through wounds and cause a disease known as crown gall disease. The bacterium attaches to the surface of cells and inserts a small circular DNA molecule, known as a plasmid, into the cell. Some of the genes on the plasmid code for proteins that cause changes in the plant cell and result in the formation of a plant tumour, or gall. Outline the changes that occur during tumour formation. Bacteria that enter the stem through a wound can reach the root of the plant to cause damage. Suggest how the bacteria are able to reach the root of the plant. shows A. tumefaciens on the surface of cells of a tobacco plant, Nicotiana plumbaginifolia. The cells X and Y are newly formed cells. X Y magnification ×11500 Calculate the actual length of cell X in micrometres. Show your working. answer μm
1. Cell structure  →  1.2. Cells as the basic units of living organisms
4. Cell membranes and transport  →  4.2. Movement into and out of cells
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