9700_s23_qp_13
A paper of Biology, 9700
Questions:
40
Year:
2023
Paper:
1
Variant:
3
Login to start this paper & get access to powerful tools
14
Some animals produce antimicrobial proteins which protect them from pathogens. These proteins could be used to kill human pathogens, however when used as a medicine they are broken down by protein-digesting enzymes. Replacing one of the amino acids found in the protein with an amino acid that had been synthesised in the laboratory resulted in a modified protein that was not broken down. What could explain why this modified protein was not broken down by the protein-digesting enzymes?
6. Nucleic acids and protein synthesis  →  6.2. Protein synthesis
Open
15
A student investigated the effect of substrate concentration on the rate of an enzyme-catalysed reaction. A graph was plotted to show the relationship between these two variables. The student was asked to take readings from the graph that could be used to determine the Michaelis–Menten constant, Km, for this enzyme. J, K, L and M show points read from the graphs which the student could use to determine the value of Km. rate of reaction concentration of substrate J rate of reaction concentration of substrate K rate of reaction concentration of substrate L rate of reaction concentration of substrate M Which two readings must the student use to determine the value of Km?
3. Enzymes  →  3.2. Factors that affect enzyme action
13. Photosynthesis  →  13.2. Investigation of limiting factors
Open
16
The end-product of a metabolic pathway can act as a competitive inhibitor. This is called end-product inhibition and allows a cell to control a metabolic pathway. The diagram shows a metabolic pathway where the end-product could act as an inhibitor of enzyme W. substrate intermediate 1 intermediate 2 intermediate 3 end-product inhibition enzyme W enzyme X enzyme Y enzyme Z What would be the effect if enzyme Z was inhibited by the end-product instead of enzyme W?
3. Enzymes  →  3.2. Factors that affect enzyme action
3. Enzymes  →  3.1. Mode of action of enzymes
Open
30
Plants, such as the tobacco plant, retain very little of the water they take in and the volume of water lost during transpiration is very high. This is because these plants can only absorb carbon dioxide through open stomata. Plants use carbon dioxide to synthesise glucose molecules. It is estimated that 400 molecules of water are lost for each carbon dioxide molecule gained. How many water molecules are lost for a plant to synthesise one molecule of glucose?
7. Transport in plants  →  7.2. Transport mechanisms
14. Homeostasis  →  14.2. Homeostasis in plants
Open