9700_w14_qp_43
A paper of Biology, 9700
Questions:
10
Year:
2014
Paper:
4
Variant:
3
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1
Phenylketonuria (PKU) is a genetic disease which results in a raised concentration of the amino acid phenylalanine in the blood. If left untreated in a newborn baby, it can lead to brain damage. For this reason, babies may be tested for PKU soon after birth. In people without PKU, excess phenylalanine is converted to the amino acid tyrosine by the enzyme phenylalanine hydroxylase (PAH). One of the mutations that can lead to PKU is caused by a base substitution in the gene coding for PAH. This results in the replacement of the amino acid arginine by the amino acid glutamine. Table 1.1 shows the triplet base codes for arginine and glutamine. Table 1.1 amino acid DNA triplet arginine GCA GCG GCT GCC TCT TCC glutamine GTT GTC Using the information in Table 1.1, explain how a single base substitution can replace arginine with glutamine in PAH. Suggest the consequence to the structure of PAH as a result of a single base substitution in its gene. For some genetic diseases, the proportion of individuals that have the disease can vary in different parts of the world. Sometimes this is due to different environmental conditions. The number of cases of PKU is approximately ten times higher in Europe than in Sub-Saharan Africa. • Individuals who are carriers of the recessive allele for PKU are more resistant to ochratoxin A, produced by a fungus found on contaminated grain products. • Ochratoxin A has been linked to a form of renal cancer. • The fungi that produce ochratoxin A are less common in dry regions such as Sub-Saharan Africa. Suggest and explain the mechanism which has resulted in the different number of cases of PKU in European and Sub-Saharan populations.
16. Inheritance  →  16.2. The roles of genes in determining the phenotype
6. Nucleic acids and protein synthesis  →  6.2. Protein synthesis
14. Homeostasis  →  14.1. Homeostasis in mammals
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2
The endangered Californian condor, Gymnogyps californianus, is the largest flying bird in North America. Condors feed on dead bodies of large mammals, such as cattle and deer. shows the Californian condor. The population of these condors fell to just 22 in 1982 and this led to the California Condor Recovery Program (CCRP), a captive breeding programme, being set up in different zoos in the United States and Mexico. Owing to the success of the captive breeding programme there are now over 300 condors. Many of these have been released as part of the programme. Outline the advantages of captive breeding programmes such as CCRP. Suggest why animals in captive breeding programmes may not always breed successfully. When animals that have been bred in captivity are released, their survival rate is low. Suggest two reasons why many of these animals are unable to survive in the wild. Bullets containing lead are commonly used by hunters. Hunting for pleasure means that hunters often leave the killed animals, such as deer, bears and antelopes, in the area where they have been shot. Suggest why this is a threat, rather than an advantage, to the Californian condor.
18. Classification, biodiversity and conservation  →  18.3. Conservation
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3
The diagram outlines how a gene coding for human insulin is produced by genetic engineering techniques. mRNA for human insulin gene isolated step 1 step 2 X Y step 3 step 4 single strand of complementary DNA (cDNA) produced single-stranded DNA made into double-stranded DNA additional non-coding DNA added Name the enzymes X and Y. X Y Explain why the starting point in this procedure is mRNA. Suggest why some methods of manufacturing genetically engineered insulin use eukaryotic yeast cells rather than prokaryotic bacterial cells. State three advantages of using human insulin produced by genetic engineering.
19. Genetic technology  →  19.2. Genetic technology applied to medicine
19. Genetic technology  →  19.1. Principles of genetic technology
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4
All living organisms require a continuous supply of energy. Outline the need for energy in living organisms. is a diagram of ATP. N NH2 CH2 O P O O P O O O P O N O N A B N O– O– O– Name A and B. A B Describe how the structure of ATP is related to its role as energy currency. Thermus thermophilus is a bacterium found in geothermal environments, such as hot springs. The bacterium respires aerobically, even though at high temperatures the solubility of oxygen in water is low. Explain how aerobic respiration may be affected by a decrease in oxygen availability. One strain of T. thermophilus, HB8, has an enzyme, nitrate reductase, which allows nitrate to be used as the final electron acceptor in the electron transport chain (ETC). Suggest an advantage to the bacterium of this adaptation. A mutant strain of HB8 (HB8 mutant) was made by adding an insertion mutation to the gene that codes for the enzyme nitrate reductase. An investigation was carried out into population growth of HB8 and of HB8 mutant in aerobic and in anaerobic conditions. In each experiment, a flask containing bacterial culture medium was incubated. Table 4.1 shows how the flasks were set up. The number of bacteria of each strain per cm3 was calculated after 20 hours. Table 4.1 flask bacteria conditions HB8 aerobic HB8 mutant aerobic HB8 and HB8 mutant aerobic HB8 anaerobic HB8 mutant anaerobic HB8 and HB8 mutant anaerobic Compare the growth of the two strains of bacteria in aerobic and anaerobic conditions in separate cultures. Compare the growth of the two strains of bacteria in aerobic and anaerobic conditions in mixed cultures. Suggest an explanation for the results shown in flask 6.
12. Energy and respiration  →  12.2. Respiration
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5
The pollutants in waste water from the textile industry may include azo-dyes, which give colour to textiles. Azo-dyes are organic pollutants that can be carcinogenic. White-rot fungi are useful for the treatment of environmental pollution as they produce extracellular enzymes that are able to break down a number of organic pollutants, such as azo-dyes. The extracellular enzymes produced by white-rot fungi are primary metabolites that are mass produced by continuous culture. Outline the main operating conditions of continuous culture. State three advantages of using continuous culture and not batch culture, for the mass production of these enzymes. The ability of the white-rot fungi to break down azo-dyes was investigated. A suspension of the intact fungal cells was added to water contaminated with various concentrations of an azo-dye. The results are shown in Table 5.1. Table 5.1 percentage breakdown of azo-dye azo-dye concentration / mg dm–3 after 7 days after 10 days 21.9 100.0 53.1 93.7 61.7 89.6 51.0 87.3 Describe the results shown in Table 5.1. When a similar experiment was performed using the free enzymes from the white-rot fungal cells, all concentrations of azo-dye shown in Table 5.1 were broken down within 12 hours. Suggest why free enzymes break down the azo-dye more quickly than intact white-rot fungal cells. These extracellular enzymes may be immobilised on an inert support. Outline the advantages of using immobilised enzymes in the treatment of textile waste water.
3. Enzymes  →  3.1. Mode of action of enzymes
3. Enzymes  →  3.2. Factors that affect enzyme action
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6
Asparagus, Asparagus officinalis, is a green vegetable plant grown in many parts of the world. shows some asparagus shoots. The shoots are usually cooked and then eaten hot or cold. Asparagus contains many mineral ions which have important roles in the bodies of mammals. Complete Table 6.1 to summarise some of these roles. Table 6.1 ion role type of cell Fe2+ red blood cell Na+ co-transport in the kidney Ca+ neurone When asparagus is digested, some of the compounds produced pass quickly into the urine to give a characteristic odour that only 22% of people can detect. The compounds bind to specific chemoreceptors in the nasal cavities of these people. Complete the sentence below by using the most appropriate scientific term. The chemoreceptors will send impulses to the brain only if the potential is reached. Outline how molecules, such as the compounds from the digestion of asparagus, pass from the blood to become part of the glomerular filtrate.
7. Transport in plants  →  7.2. Transport mechanisms
14. Homeostasis  →  14.2. Homeostasis in plants
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7
The ABO blood grouping system in humans is determined by a single gene with three alleles: IA, IB and Io. Distinguish between the terms gene and allele. gene allele shows a pedigree diagram of the inheritance of the ABO blood group system. The blood group of some of the individuals is given in the pedigree. A O AB B O A Use the information in and the genetic symbols IA, IB and Io, to complete the table. individual phenotype genotype
16. Inheritance  →  16.2. The roles of genes in determining the phenotype
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8
is a diagram of a palisade cell from a leaf. Using label lines and the letters X, Y and Z, identify a structure in that: • contains RuBP – X • is fully permeable – Y • is made mainly of phospholipids – Z An experiment was carried out to investigate the effect of light intensity on the rate of photosynthesis in an aquatic plant using the apparatus shown in . aquatic plant capillary tube test tube scale board plastic tube barrel of syringe plunger of syringe lamp d As photosynthesis took place, the oxygen produced formed a bubble of gas which moved along the scale in the capillary tube. The distance moved by the bubble in a fixed period of time was used to calculate the rate of photosynthesis. The light intensity was varied by altering the distance, d, between the lamp and the photosynthesising plant. The results are shown in Table 8.1. Table 8.1 light intensity / arbitrary units rate of photosynthesis / arbitrary units Using the data in Table 8.1, draw a graph to show the relationship between light intensity and the rate of photosynthesis. Explain the shape of the graph you have drawn, with reference to limiting factors. shows the absorption spectra of the photosynthetic pigments of a flowering plant. wavelength of light / nm absorbance chlorophyll a chlorophyll b carotenoids Name the accessory pigmentshown in . Outline the role of the accessory pigments in photosynthesis. Very little light of wavelength 550 nm is absorbed by the photosynthetic pigments. State what happens to most of this light. A graph can also be drawn to show the relationship between the wavelength of light and the rate of photosynthesis. State the name of this type of graph.
13. Photosynthesis  →  13.1. Photosynthesis as an energy transfer process
13. Photosynthesis  →  13.2. Investigation of limiting factors
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