2.2. Carbohydrates and lipids
A subsection of Biology, 9700, through 2. Biological molecules
Listing 10 of 368 questions
Candida albicans is a yeast-like fungus that lives in human lungs. It is the causative agent of one of the opportunistic infections that may develop during AIDS. C. albicans is eukaryotic. shows its structure. L K J H Name H to L. H J K L State two ways in which the structure of a prokaryotic cell differs from that shown in . C. albicans uses a transport protein, TMP1, to absorb sugar molecules from the inside of the mouth. TMP1 is encoded by a gene within the nucleus and is produced when sugars are present in the surroundings. Explain how the structures within the cell shown in , are involved with the production of functioning TMP1.
9700_w09_qp_22
THEORY
2009
Paper 2, Variant 2
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is an electron micrograph of three cells of the same species of bacterium, Erwinia carotovora. 0.5 μm Calculate the magnification of the electron micrograph in . Show your working and give your answer to the nearest 10 000. magnification × Name three structures, present in animal cells, which are not present in the cells shown in . 1. 2. 3. E. carotovora is a rod-shaped bacterium. Explain why two of the bacterial cells in do not appear rod-shaped. E. carotovora causes a disease in carrot and potato plants. The bacteria release an enzyme called pectinase which hydrolyses the polysaccharide pectin. Pectin helps plant cells to attach to each other. Name the type of chemical bond which will be hydrolysed by pectinase. Suggest what effect this disease will have on vegetables, such as carrots and potatoes.
9700_w11_qp_23
THEORY
2011
Paper 2, Variant 3
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is a drawing made from an electron micrograph of a mammalian liver cell. F E D C B G glycogen granules A Complete the table by naming the structures B to G and stating one function of each. The first one (A) has been completed for you. name of organelle function A cell surface membrane controls movement of substances into and out of the cell B C D E F G As shown in , liver cells contain many storage granules of glycogen. Describe the molecular structure of glycogen and explain how this structure makes it suitable for storage.
9700_w12_qp_21
THEORY
2012
Paper 2, Variant 1
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Keratin and chitin are two important biological molecules. Keratin is found in hair, fur and skin. Chitin is a modified polysaccharide found in a number of different organisms, for example in fungal cell walls and the hard outer skeletons of insects. Features of chitin and keratin are shown in the boxes in . example: Keratin and chitin are insoluble in water cellulose triglyceride amylopectin collagen Keratin and chitin have structural functions Keratin is a fibrous protein The monomers of chitin are β-1,4 linked Keratin and chitin contain nitrogen Write, in each box, the biological molecules from the list below that have the same feature. Each box may contain one, or more than one, biological molecule. The first box has been completed as an example. amylopectin cellulose collagen haemoglobin mRNA triglyceride Chitin and the products of chitin hydrolysis have many useful medical and environmental applications. Chitinase enzymes can be used commercially to hydrolyse chitin. Enzyme stability and activity are important considerations in technological applications of chitinase. is a graph showing the effects of temperature on chitinase extracted from a soil bacterium. The relative activity of the enzyme was measured at different temperatures, with 100% representing maximum enzyme activity. relative activity / % temperature / °C With reference to , state the optimum temperature for the chitinase enzyme. is a graph showing how temperature affects the stability of chitinase. The activity of the enzyme was measured over a time period of 72 hours at each of five different temperatures. relative activity / % time / h 28 °C 37 °C 40 °C 50 °C 60 °C With reference to and , describe and discuss the effect of temperature on chitinase activity and stability.
9700_w13_qp_22
THEORY
2013
Paper 2, Variant 2
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Questions Discovered
368