Plant nutrition

© UCLES 2025 5090/11/O/N/25 10 Hydrogencarbonate indicator changes colour according to the concentration of carbon dioxide present. The table shows these changes. colour of hydrogencarbonate indicator concentration of carbon dioxide orange atmospheric carbon dioxide concentration yellow higher than atmospheric carbon dioxide concentration purple lower than atmospheric carbon dioxide concentration Four test-tubes were set up under different conditions. The colour of hydrogencarbonate indicator in each test-tube at the start of the experiment and after one hour is also shown. Which test-tube sho

27 The tips of growing shoots of a plant are cut off and placed on small blocks of jelly which contain no auxin. Small pieces of impermeable clear glass are placed in some of the jelly blocks, as shown in diagram X. Some of the shoot tips are divided by impermeable clear glass pieces, as shown in diagram Y. The tips are left on the small blocks of jelly with light coming from one side only. After 12 hours, the number of arbitrary units of auxin is measured in each of the jelly blocks and the means, shown in the diagrams, are calculated. tip of plant jelly block light impermeable clear glass 14

7 The diagram shows a section through a dicotyledonous leaf. 1 2 3 4 5 Which structures are almost transparent to help increase the rate of photosynthesis in the leaf? A 1 and 2 B 2 and 3 C 3 and 4 D 4 and 5

8 Oxygen is produced in leaf cells during photosynthesis and diffuses out of the leaf. By which pathway does the oxygen diffuse? A through the upper epidermis and through the cuticle B through the airspaces and through the stomata C through the mesophyll and through the phloem D through the mesophyll and through the xylem

10 Which graph shows the effect of light intensity on the rate of transpiration? rate of transpiration light intensity A rate of transpiration light intensity B rate of transpiration light intensity C rate of transpiration light intensity D

5090/21/O/N/25 © UCLES 2025 4 Chlorophyll is found in all organisms that photosynthesise. (a) Complete these sentences about chlorophyll by writing suitable words in the gaps. A chlorophyll molecule contains carbon, hydrogen, oxygen, nitrogen and an atom of ................................................... . Chlorophyll molecules are found in plant cells in structures called ................................................... . The type of leaf cells that contain the most chlorophyll are the ................................................... cells. Chlorophyll molecules trap sunlight energy

Explain how the structure of a leaf is adapted for photosynthesis.