2. Biological molecules
A section of Biology, 9700
Listing 10 of 748 questions
Table 1.1 shows some features of four biological molecules that are all polymers. Complete Table 1.1 by using a tick (3) to indicate the features that apply to each polymer. Table 1.1 feature amylopectin cellulose RNA polypeptide synthesised from amino acid monomers contains glycosidic bonds polymer is branched contains nitrogen can be found in both animal and plant cells is a simple diagram of a phospholipid molecule. Explain how the structure of a phospholipid molecule makes it suitable for its function in cell membranes. You may label and annotate as part of your answer. State two components of a cell surface membrane other than phospholipid molecules and describe their function. component 1 function component 2 function
9700_w16_qp_23
THEORY
2016
Paper 2, Variant 3
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is a transmission electron micrograph showing two adjacent cells in a leaf. cell wall Cellulose is the main polysaccharide in cell walls of plants. Describe the structure of cellulose. State one feature visible in , other than the cell wall, that identifies the cells as plant cells. Outline the role of ATP in a leaf cell. Water is a main component of plant cells. shows two water molecules linked by a hydrogen bond. O H H O H H hydrogen bond Explain how hydrogen bonding occurs between water molecules. Suggest why water is an excellent solvent for ions.
9700_w18_qp_21
THEORY
2018
Paper 2, Variant 1
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A molecule of collagen consists of three identical polypeptides that form a triple helix. The amino acid glycine forms one third of the amino acids in a collagen molecule. A shows a polypeptide molecule during protein synthesis. A molecule of glycine is shown just before it is added to the polypeptide. A rest of polypeptide C N H H C C H H C H H C H H C H H N H H OH O C N + H H H H C OH O B rest of polypeptide C N H H C C H H C H H C H H C H H N H H Complete B to show the molecule of glycine added to the end of the polypeptide. State the type of reaction that occurs when glycine is added to the end of the polypeptide. Explain the importance of glycine in a collagen molecule. Collagen is a fibrous protein. Explain how the structure of collagen is related to its functions within the mammalian body. The enzyme collagenase catalyses the breakdown of collagen molecules. This enzyme acts by using an induced fit mechanism. Describe the mode of action of collagenase. Students investigated the effect of pH on the activity of collagenase extracted from the bacterium Bacillus licheniformis at 50 °C. The results are shown in . relative activity / percentage of maximum pH With reference to , describe and explain the effect of pH on the activity of collagenase.
9700_w20_qp_23
THEORY
2020
Paper 2, Variant 3
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Fibroblasts are one of the cell types of connective tissue. The cells synthesise and secrete collagen, which forms part of the supporting external cellular environment, known as the extracellular matrix. shows the primary structure of a section of a polypeptide chain of collagen. gly pro ala gly pro ser gly ala pro gly pro ile Explain how the primary structure shown in indicates that the structure of the polypeptide is suited to be a component of a collagen molecule. After final processing in the Golgi body, collagen is released to the outer surface of the cell by exocytosis. Complete the passage to describe the process of exocytosis. After final processing in the Golgi body, Hydrolytic enzymes, known as collagenases, are secreted by cells in an inactive form. Cells also secrete inhibitors of collagenases. The activity of the enzymes and inhibitors is regulated so that the development and maintenance of the extracellular matrix is controlled. State and explain what the outcome will be for the composition of the extracellular matrix if collagenase inhibitor activity is needed. Synthetic inhibitors have been trialled as potential treatment for diseases caused by a lack of regulation of collagenase activity. Research involves investigating the mechanism of action of an inhibitor. State the effect that a non-competitive inhibitor will have on the maximum rate of reaction, Vmax, and the Michaelis–Menten constant, Km, of collagenase. Vmax Km
9700_w22_qp_22
THEORY
2022
Paper 2, Variant 2
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Questions Discovered
748