Photo AI
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 the leaves due to a few reasons. Firstly, the lower surface is submerged in water, making contact with air unnecessary for gas exchange. Since there is no need for stomata to facilitate the movement of gases, they are absent on this surface. Additionally, the environment below the water level does not require the regulation of water loss, as transpiration does not occur underwater.
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 primarily through the phloem. This process involves translocation where sucrose is dissolved in water and actively transported within the sieve tubes of the phloem. This allows it to move efficiently from areas of high concentration in the leaves to areas of lower concentration in the flowers.
Step 5
Explain why this non-indigenous plant now covers the whole surface of the lake.
Answer
The non-indigenous water lily plant covers the whole surface of the lake due to several factors. Firstly, the conditions in the lake may be suitable for its growth and photosynthesis, allowing it to thrive. The plant likely outcompeted native species for resources, such as light and nutrients. Furthermore, with no natural herbivores in the lake to eat or restrict its spread, the water lily has proliferated rapidly over time.
Step 6
Explain how the water lilies will affect the biodiversity of this lake.
Answer
The presence of water lilies will likely reduce biodiversity in the lake. As they cover the water surface, they may lead to fewer available plants and animal species due to shading, which reduces light penetration. This can inhibit the growth of other aquatic plants, leading to a decline in plant species. Additionally, the decrease in photosynthesis in submerged plants may alter oxygen levels, negatively impacting fish and other aquatic life, thereby resulting in less food availability for various animals.