Apple trees show genetic variation: (i) State one possible cause of genetic variation in apple trees - Edexcel - GCSE Biology - Question 8 - 2023 - Paper 1

D phenotype

Asexual reproduction

An advantage of growing genetically identical apple trees is the uniformity in fruit quality and characteristics, which can be beneficial for marketability. A disadvantage is that a lack of genetic diversity can make the plants more susceptible to diseases and pests.

1. Prepare a series of buffers with varying pH levels (e.g., from pH 4 to pH 10).
2. Add an equal amount of starch solution to each buffer.
3. Introduce a fixed amount of the enzyme solution to each mixture.
4. Incubate the mixtures at room temperature for the same duration.
5. Use iodine solution to test each mixture for the presence of starch. The buffer solution that shows the least color change (indicating starch breakdown) indicates the optimum pH of the enzyme.

Enzymes are sensitive to pH levels, and each enzyme has an optimum pH at which it functions best. At pH 10, the enzyme's structure may become denatured, altering its active site, and preventing substrate binding, which results in a loss of enzymatic activity.