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1. Figure 1 shows the leaves and flowers of water lily plants (Nymphaea odorata) on a lake - Edexcel - GCSE Biology Combined Science - Question 1 - 2020 - Paper 1
Question 1
1. Figure 1 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. Explai... show full transcript
Worked Solution & Example Answer:1. Figure 1 shows the leaves and flowers of water lily plants (Nymphaea odorata) on a lake - Edexcel - GCSE Biology Combined Science - Question 1 - 2020 - Paper 1
Step 1
(a) 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 their leaves primarily because the lower surface is not in contact with air, which limits gas exchange. Since the leaves are submerged or located over water, there is no necessity for gas exchange on this surface. Consequently, water enters through the stomata on the upper surface where it can facilitate photosynthesis without the risk of water loss, as transpiration is minimized.
Step 2
Step 4
(b)(iii) 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. This transport occurs in a dissolved state, facilitated by a process known as translocation. Sucrose can be actively transported or passively diffused through the phloem tubes, thereby ensuring that the flowers receive the necessary nutrients for growth and development.
Step 5
(c) Explain why this non-indigenous plant now covers the whole surface of the lake.
Answer
The water lily from America has proliferated in the lake due to a combination of suitable environmental conditions for growth and reproduction. These conditions likely mirror those of its native habitat, allowing it to adapt successfully. Additionally, the water lily has outcompeted the native plants for resources such as light, nutrients, and space. The absence of natural herbivores in the area to control its population further enables it to spread unchecked, leading to its dominance over the lake's surface.