photosynthesis

1. photosynthesis

4. cuticle Upper epidermis chloroplasts Palisade mesophyll xylem Spongy mesophyll phloem Lower epidermis Air spaces stoma Guard cell

5. Structure of a Leaf

6. Epidermis Single layer of cells around the leaf: Upper and lower epidermis Flat, no chloroplasts to allow light to pass through

7. Cuticle Waxy layer covering the upper epidermis Prevents water loss

8. Palisade mesophyll Layer of rectangular shaped cells found below the upper epidermis Cells arranged side by side, no spaces – traps as much sunlight as possible Many chloroplasts – lots of photosynthesis

9. Spongy mesophyll Layer of round cells below palisade cells Fewer chloroplasts, less photosynthesis Air spaces

10. Intercellular spaces Spaces between the spongy mesophyll cells Allows diffusion of oxygen, carbon dioxide and water between inside the leaf and the air outside

11. Guard cell Stoma Guard cells and Stomata A stoma is a small pore found between the cells of the lower epidermis Two guard cells surround each stoma They allow the stoma to open and close, controlling movement of gases in and out of the leaf

12. Midrib and Veins Contain vascular bundles made up of xylem and phloem Xylemcarries water to the leaf cells from the roots Phloemcarries sucrose sugar made in the leaf cells to other parts of the plant

13. ADAPTATIONS OF A LEAF FOR PHOTOSYNTHESIS COMPLETE THE TABLE USING PAGE 10 & 11

14. stomata investigation When stomata are open, water evaporates from the leaf. There are fewer stomata on the surface of a leaf than underneath because it is cooler under the leaf (less sunlight), so less water is lost.

17. QUESTION 5aend of booklet

18. Read page 18/19 • Complete the notes on the worksheet PHOTOSYNTHESIS • Raw materials • Word equation • Balanced chemical equation • Products of photosynthesis

19. 10605 Sc Eye BBC - Learning Zone Class Clips - Photosynthesis in plant leaves - Science Video

20. SUNLIGHT

21. How the materials for photosynthesis get to a palisade cell • Water travels from the roots up the xylem to the leaves • Carbon dioxide enters the leaf through the stomata • Light enters through the clear epidermis

22. LIGHT worksheet How the materials for photosynthesis get to a palisade cell chloroplast xylem WATER CARBON DIOXIDE

23. USING THE PRODUCTS OF PHOTOSYNTHESIS Glucose is the main product of photosynthesis. It is used in respiration to release energy. Glucose is also converted into other substances. Read page 22 and then complete the worksheet making notes on how the following are used by the plant. amino acids starch cellulose lipids

24. Testing a leaf for starch TAKE NOTES FROM PAGE 19 ON TESTING A LEAF FOR STARCH

29. Leaf before testing Leaf after boiling in ethanol results blue/black: contains starch orange: no starch

30. LIGHT stencil soda lime soda lime carbon dioxide variegated chlorophyll experiments to show factors needed for photosynthesis destarch

31. In these experiments it is necessary to destarch the plant. Leave in dark for 48 hours. This removes any starch in the leaves and shows that if the starch test is positive, starch must have been made during the experiment. PHOTOSYNTHESIS experiments Worksheet

32. 1613 testing for Oxygen BBC - Learning Zone Class Clips - Testing for oxygen produced by underwater plants - Science Video

33. VOLUME OF oxygen CARBON DIOXIDE DISSOLVED IN WATER Oxygen bubbles LIGHT Measuring the rate of photosynthesis

34. pond weed produces bubbles of oxygen during photosynthesis. we can measure the rate at which PS occurs by counting the number oxygen bubbles produced per minute or by measuring the volume of oxygen produced per hour

35. experiments can be used to measure the rate of photosynthesis under different conditions light intensity: a lamp is placed at different distances from the pondweed the closer the lamp the more light is available for PS and the faster the rate of PS

36. to make this experiment a FAIR TEST only the light intensity should be changed; the carbon dioxide concentration, temperature, and pondweed must remain the same

37. CO2 concentration: sodium bicarbonate releases carbon dioxide the pondweed is set up with different concentrations of sodium bicarbonate the higher the concentration of sodium bicarbonate the more carbon dioxide is available for PS so the rate of PS increases

38. to make this experiment a FAIR TEST only the carbon dioxide concentration should be changed; the light intensity, temperature, and pondweed must remain the same

39. temperature: the temperature of the water is increased by placing the beaker in a water bath at higher temperatures there is more energy available for chemical reactions to occur so the rate of PS increases BUT very high temperature kill the plant, so PS slows and stops

40. to make this experiment a FAIR TEST only the temperature should be changed; the light intensity, carbon dioxide concentration, and pondweed must remain the same

41. 6021 Raw materials & products BBC - Learning Zone Class Clips - Plants and photosynthesis - Science Video

42. light limiting factor light no further affect rate of photo light intensity

43. limiting factors • Photosynthesis occurs at a maximum rate if all of the raw materials are readily available (light, carbon dioxide, water). Temperature also affects the rate of any chemical reaction. • If any of these is in short supply it will limit the rate at which photosynthesis can occur. • The substance limiting photosynthesis is called a limiting factor.

44. At the start of the graph increasing the light intensity increases the rate of photosynthesis. This shows that light is limiting the reaction and is the limiting factor. • At the end of the graph the rate is constant. It does not increase any further, even though more light is available. This means that light intensity is no longer limiting the reaction and some thing else , such as temperature or carbon dioxide concentration, must be limiting the rate of photosynthesis.

45. light no further affect light limiting factor high temperature low temperature rate of photo light intensity

46. By increasing the temperature the materials have more energy to react. At the start this has no effect on the rate of photosynthesis compared to the lower temperature. • The rate of photosynthesis is still limited by light intensity. • In the middle of the graph the higher temperature provides more kinetic energy and therefore reactions can occur more quickly, more of the light can be used. • At the end of the graph, even at higher temperatures, the rate of photosynthesis will level out. At this point another factor must be limiting the rate of photosynthesis e.g. carbon dioxide concentration.

47. Questions 5+6 worksheet

48. video in the greenhouse B68

49. Crop Production In crop production it may be possible and profitable to control the environmental conditions to increase productivity.

50. Increase CO2 • Burn fossil fuels e.g. paraffin • Pipe in from canisters HUMIDITY Open/close windows to control humidity LIGHT Artificial lights used to increase light intensity, daylength AND season length • FERTILISERS • Organic e.g. manure • Inorganic e.g. NPK • HEAT • Use electric heaters • Burn fossil fuels • GREENHOUSE • More photosynthesis • More growth • Bigger yield