Question

1. In an experiment, a plant in a clear, sealed container was exposed to radioactive carbon dioxide 14CO2 for one hour. Following this, a thin cross-section of the stem of the plant was made and placed against photographic film. This radioactive carbon, which exposed the film (visible as black grains), occurred only in the phloem sieve tubes of the stem. Explain these results, using your knowledge of photosynthesis and how gases enter and exit plants. (4 Marks)

Answer 1

sorry I don't know this question