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Figure 18 shows the leaves and flowers of water lily plants (Nymphaea odorata) on a lake - Edexcel - GCSE Biology - Question 8 - 2020 - Paper 1
Question 8
Figure 18 shows the leaves and flowers of water lily plants (Nymphaea odorata) on a lake. (a) Water lilies have stomata on the upper surface of the leaves. Explain ... show full transcript
Worked Solution & Example Answer:Figure 18 shows the leaves and flowers of water lily plants (Nymphaea odorata) on a lake - Edexcel - GCSE Biology - Question 8 - 2020 - Paper 1
Step 1
Explain why water lilies have no stomata on the lower surface of the leaves.
Answer
Water lilies do not have stomata on the lower surface of their leaves because the lower surface is submerged in water. This means it is not in contact with air, which is necessary for gas exchange to occur. Since the leaf is in water, gas exchange for respiration and photosynthesis does not take place at this lower surface.
Step 2
Step 3
Step 4
Describe how this sugar is transported from the leaves to the flowers of the water lily.
Answer
The sugar, sucrose, is transported from the leaves to the flowers of the water lily through the phloem. It is dissolved in water and moves by translocation, which is an active process that requires energy.
Step 5
Explain why this non-indigenous plant now covers the whole surface of the lake.
Answer
The non-indigenous water lily plant now covers the entire surface of the lake because the conditions in the lake are suitable for its growth and photosynthesis. Over time, it has outcompeted native plants for resources and has reproduced rapidly. Additionally, since there are no natural herbivores in the area to control its spread, it has thrived unchecked.
Step 6
Explain how the water lilies will affect the biodiversity of this lake.
Answer
The presence of water lilies will reduce biodiversity in the lake by decreasing the number of other plant species and thereby reducing the number of animal species that rely on those plants. As the water lilies cover the surface, they will limit sunlight penetration, which inhibits the growth of other aquatic plants. This can lead to lower oxygen levels in the water, affecting the entire ecosystem and reducing the number of fish and other animals.