Revision…

RAG – Self assessment What I need to know/ be able to do… Understand the process of photosynthesis and its importance in the conversion of light energy to chemical energy The word equation and the balanced chemical symbol equation for photosynthesis Understand how varying carbon dioxide concentration, light intensity and temperature affect the rate of photosynthesis (drawing or explaining graphs) Describe the structure of the leaf and explain how it is adapted for photosynthesis Understand that plants require mineral ions for growth, and that magnesium ions are needed for chlorophyll and nitrate ions are needed for amino acids Describe a practical to investigate photosynthesis by showing the evolution of oxygen from a water plant, Describe a practical to investigate photosynthesis by the production of starch Describe practical’s to investigate the requirements of light, carbon dioxide and chlorophyll for photosynthesis

Q) How are the external shapes and internal structures of a leaf adapted for photosynthesis?

Take a look inside a leaf

Leaf adaptations

Testing a leaf for starch

Testing leaves for starch

Only the green areas of the leaf react with the iodine and turn blue-black. Without chlorophyll, the pale areas have been unable to produce starch and do not turn Is chlorophyll needed for photosynthesis? Variegated leaves have pale parts, which do not contain chlorophyll. The green parts of the leaf contain chlorophyll and are the control. Chlorophyll cannot be removed from a plant without killing the plant. Instead, variegated leaves can be used to show chlorophyll is essential for photosynthesis. Which areas will react with iodine? blue-black.

Testing leaves for starch – activity

Method and Risk assessment Method Risk assessment: Identify the hazard explain the precaution… Hazard/Risk…. (what is dangerous and why?) Precaution…. (How will you stop the risk from harming anyone?) Results/Conclusion: Why are some parts blue/black and some are brown?

Rate of photosynthesis

Section 2: Structures and functions in living organisms Give the word and symbol equation for photosynthesis: Explain how you would carry out experiments to investigate photosynthesis, including the evolution of oxygen from a water plant, the production of starch and the requirements of light, carbon dioxide and chlorophyll: Q) Independent and dependent variable? Q) How will all variables be controlled? How does varying carbon dioxide concentration, light intensity and temperature affect the rate of photosynthesis? Draw a sketch graph to illustrate the effect of each one on the rate of photosynthesis: Can you explain gas exchange (of carbon dioxide and oxygen) in relation to respiration and photosynthesis?

Title? (Which factor will you investigate?) Q) Hypothesis? What do you expect to happen and why? Q) Apparatus? Q) Method… Q) Independent and dependent variable? Q) How will all variables be controlled? Q) Reliable? Range?

Graph to show how the rate of photosynthesis changes as light intensity increases

Light levels are limiting initially. The rate of photosynthesis then levels off. It increases at a higher temperature, so at higher light levels, temperature becomes the limiting factor.

Which mineral?

Plant mineral deficiencies…

Mineral deficiencies and plant growth

Suggest: Q) What are the artificial conditions like in this greenhouse for plant to best grow?

Gas exchange in plants…

Q) How are the external shapes and internal structures of a leaf adapted for photosynthesis?

How do gases enter and leave plants? On the underside of leaves are small holes, or pores, called stomata. A single hole is called a stoma. Each stoma is surrounded by two guard cells. When guard cells gain water, they curve outwards. This opens the stoma, allowing gases in and out. Losing water causes the guard cells to come closer together, closing the stoma. This stops the movement of gases, but also prevents water loss.

Graph to show how the rate of photosynthesis changes as light intensity increases

Light levels are limiting initially. The rate of photosynthesis then levels off. It increases at a higher temperature, so at higher light levels, temperature becomes the limiting factor.

Investigating photosynthesis…

Respiring..