Topic 2 The World of Plants Standard Grade Biology World of Plants is divided into: A- Introducing plants B- Growing plants (Pollination, Fertilisation, Asexual reproduction) C- Making food Plants- the first link Plants are the link between the energy in the sun being converted into a form which animals can eat and get the energy to survive… Workbook Activity p 54 Food webs and plants The process by which plants do this is called: Photosynthesis All living things respire all the time to release energy from their food in a process called: Respiration Plant survival Plants make their own food, glucose, by photosynthesis. It only happens during the daytime when there is light available. This happens in plant cells containing the chemical chlorophyll (green-coloured) which traps the light energy. The plants have captured light energy and turned it into a store of chemical energy (glucose). Raw materials Products carbon dioxide + water  glucose + oxygen chlorophyll More on the uses for glucose shortly… Is light needed for photosynthesis? 1. Take a de-starched geranium plant (24h in dark). 2. Cover part of a leaf with some tin foil (this prevents light getting through). 3. Leave the plant in sunlight for a few hours. 4. Test the leaf for starch. Is carbon dioxide needed for photosynthesis? 1. Take a de-starched geranium plant 2. Enclose it in a plastic bag with a chemical that absorbs carbon dioxide. (e.g. soda lime or sodium hydroxide pellets). 3. Leave the plant in sunlight for a couple of hours. 4. Test the leaf for starch. Questions: 1. Which parts of the leaf do you think will go blue- black? 2. Why do parts that were not covered contain starch? Is light needed for photosynthesis? Workbook Problem Solving p 81 Making a starch print Is carbon dioxide needed for photosynthesis? Questions: 1. Does the leaf contain starch? Why/ why not? 2. Has the plant carried out photosynthesis? 3. What would be your control plant’s conditions? (Hint: a control plant should have everything it needs for photosynthesis including carbon dioxide). Workbook Problem Solving p 76 Plants and greenhouses CO 2 is converted into glucose by photosynthesis. Mans’ uses of plant glucose Plants’ uses of plant glucose Glucose Used immediately to provide energy source for respiration Energy used to turn sugars, nitrates & other nutrients into amino acids which build up proteins To make cellulose, the main structural material in cell walls Raw material for growth, repair and replacement of damaged parts Energy stored as starch (in leaves, seeds, roots and tubers) To make fats & oils (energy stored in seeds) Energy stored as sucrose (in fruit) [...]... steps, and results, in each one Activity -Testing a leaf for starch 1 2 3 4 5 6 7 Dip a leaf into boiling water for about a minute (to soften it) Turn off the Bunsen burner Put the leaf into a test-tube of ethanol (to remove chlorophyll) Stand the test-tube in a beaker of hot water for about 10 minutes Wash the leaf in cold water Spread the leaf out flat on a petri dish and cover it with iodine solution... life of a leaf http://www.portlandpress.com/pp/books/online/leaf/ alit_eng.pdf Source: http://www.life.uiuc.edu/plantbio/102/links.html Leaves… Leaves are the organs of photosynthesis and make all the food for a plant We will look at:  Outer layers (top & bottom)  Inner structure including veins (its transport system) waxy cuticle Internal structure mesophyll Collect the handout ‘Leaf structure’ and... allow:  Gases to get in and out of the leaves  Water and nutrients to move into the plant from the soil  Glucose made in photosynthesis to be carried to the rest of the plant Workbook Activity p 61 Food transport diagram Giant redwood trees carry water & nutrients over 100m from the soil Roots  Roots have specialised cells called root hair cells, which are long and thin providing a large surface . Introducing plants B- Growing plants (Pollination, Fertilisation, Asexual reproduction) C- Making food Plants- the first link Plants are the link between the energy in the sun being converted. survive… Workbook Activity p 54 Food webs and plants The process by which plants do this is called: Photosynthesis All living things respire all the time to release energy from their food in a process called: Respiration Plant. release energy from their food in a process called: Respiration Plant survival Plants make their own food, glucose, by photosynthesis. It only happens during the daytime when there is light available. This