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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 have no stomata on the lower surface of the leaves because the lower surface is submerged in water, which means it is not in contact with air. As a result, gas exchange cannot occur there because the stomata are designed to facilitate the exchange of gases between the leaf and the atmosphere.
Step 2
Describe how this sugar is transported from the leaves to the flowers of the water lily.
Answer
The sugar, primarily sucrose, is transported from the leaves to the flowers of the water lily through the phloem. This process involves translocation, where the sucrose is dissolved in water and moved through the plant via the phloem tissues, utilizing processes such as active transport and diffusion.
Step 3
Explain why this non-indigenous plant now covers the whole surface of the lake.
Answer
The non-indigenous water lily plant likely covers the lake due to several factors:
- The conditions in the lake, such as light and nutrient availability, are ideal for its growth and photosynthesis.
- The plant may have reproduced rapidly, outcompeting native plants for space and resources.
- There are no natural herbivores in the area to eat or restrict its growth, allowing it to thrive unchecked.
Step 4
Explain how the water lilies will affect the biodiversity of this lake.
Answer
The presence of water lilies can significantly impact the biodiversity of the lake in several ways:
- Biodiversity may be reduced as fewer plant and animal species can survive due to the dense coverage of water lilies, which can overshadow native plants.
- The reduction in plant species can lead to lower oxygen levels in the water, affecting fish and other aquatic life.
- The reduction of available light and space for other organisms can disrupt the food web, ultimately leading to fewer food sources for animals, further diminishing biodiversity.