The diagram shows a time sequence from a nature centre. A Venus flytrap is a plant that lives in soil with little nitrate. An insect touching hairs inside t...
Question 1 Report
The diagram shows a time sequence from a nature centre. A Venus flytrap is a plant that lives in soil with little nitrate. An insect touching hairs inside the open leaf causes the two halves of the leaf to close. Digestive juices are then released and substances from the insect enter plant cells. The plant also has green leaves that use light energy.
(a) Name the characteristic of living organisms shown when the leaf closes after the insect touches it. [1]
(b) Describe the stimulus and the response shown in the diagram. [2]
(c) Explain how catching an insect helps this plant to grow in soil with little nitrate. [4]
(d) Use the information about the green leaves to explain how the plant obtains the energy needed for growth. [3]
(e) Complete the sentence. The insect is digested outside the plant's cells, so this is an example of ________ digestion. [1]
(f) Suggest two measurements a scientist could take to compare growth of flytraps with insects and flytraps without insects. [2]
Answer Details
(a) Closing after touch shows sensitivity, also called response to a stimulus. [1]
(b) The stimulus is an insect touching the trigger hairs inside the leaf. The response is that the leaf, or trap, closes. [2]
(c) The insect contains protein or other nitrogen-containing compounds. Digestive enzymes break the insect’s large molecules into small soluble molecules. These products are absorbed into plant cells, and the nitrogen is used to make amino acids and proteins for new cells and growth. This is especially useful where soil nitrate is scarce. [4]
(d) Chlorophyll in the green leaves absorbs light energy. Carbon dioxide and water are used in photosynthesis to make glucose. The glucose is then respired, releasing energy for growth. [3]
(e) This is extracellular digestion because the insect is digested outside plant cells. [1]
(f) Two suitable growth measurements are increase in plant mass and number of leaves. Leaf length, number or size of traps, and rate of new-leaf production are also acceptable. Measurements should be compared over the same time interval. [2]
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