Some animals live in cold places. They sometimes huddle together as shown in Fig. 1.1. A student investigated the effect of huddling on heat loss from model animals. Test-tubes containing hot water represented the animals. The student used the method described in step 1 to step 10. Step 1 Place a test-tube in an empty beaker and put a thermometer into the test-tube. Step 2 Approximately half-fill the test-tube with hot water and start the stop-clock. Step 3 After one minute record the temperature of the hot water in the test-tube. Fig. 1.2 is a diagram of part of the thermometer from step 3. In mammals, respiration releases heat energy to maintain an optimum temperature for enzyme activity in the body. Amylase is an enzyme that catalyses the breakdown of starch into reducing sugars. Plan an investigation to identify the temperature at which the enzyme amylase is most active.

Biology

IGCSE&ALevel

CAIE

Exam No：0610_s23_qp_62 Year：2023 Question No：1(b)

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12.2.1 Define aerobic respiration as the chemical reactions in cells that use oxygen to break down nutrient molecules to release energy

12.2.2 State the word equation for aerobic respiration as glucose + oxygen → carbon dioxide + water

12.2.3 Investigate the uptake of oxygen by respiring organisms, such as arthropods and germinating seeds

12.2.4 State the balanced chemical equation for aerobic respiration as

12.2.5 Investigate the effect of temperature on the rate of respiration of germinating seeds

5.1.1 Define the term catalyst as a substance that increases the rate of a chemical reaction and is not changed by the reaction

5.1.10 Explain the effect of changes in temperature on enzyme activity in terms of kinetic energy, shape and fit, frequency of effective collisions and denaturation

5.1.11 Explain the effect of changes in pH on enzyme activity in terms of shape and fit and denaturation

5.1.2 Define enzymes as proteins that function as biological catalysts

5.1.3 Describe why enzymes are important in all living organisms in terms of reaction speed necessary to sustain life

5.1.4 Describe enzyme action with reference to the complementary shape of an enzyme and its substrate and the formation of a product (knowledge of the term active site is not required)

5.1.5 Investigate and describe the effect of changes in temperature and pH on enzyme activity

5.1.6 Investigate and describe the effect of changes in temperature and pH on enzyme activity

5.1.7 Investigate and describe the effect of changes in temperature and pH on enzyme activity

5.1.8 Explain enzyme action with reference to the active site, enzyme-substrate complex, substrate and product

5.1.9 Explain the specificity of enzymes in terms of the complementary shape and fit of the active site with the substrate

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