B8: Photosynthesis

Question 1

Photosynthesis…

• • equation*
• • what is it*

Answer 1

Where plants make food using carbon dioxide, water and light. It is an endothermic reaction (energy taken from enviroment, temp goes up).

Question 2

The process of Photosynthesis?

Answer 2

• Uses energy to change Carbon Dioxide and Water into Glucose and Oxygen.
• Takes place in chloroplasts
• Energy is transferred to the chloroplasts from the environment by light

Question 3

Producing Oxygen

Answer 3

Question 4

Leaf Adaptations

Answer 4

• Broad leaves (bigger surface area for light to fall on)
• leaves are thin (diffusion distance for gases are short)
• Contain chlorophyll in chloroplasts (absorb light)
• Have veins (bring plenty of water in xylem to cells of leaves, remove products of photosynthesis in the phloem)
• Have air spaces (allow CO₂ to get to the cells and oxygen leave by diffusion)
• Have guard cells that open and close the stomata (regulate gas exchange)

Question 5

Uses of Photosynthesis?

• • other ways that plants use the glucose they produce during photsynthesis?*
• • Plants use some of the glucose they produce to make a substance which strengthen their cell walls. What is it?*

Answer 5

• Respiration
• Making cellulose
• Making amnio acids
• Stored as oils or fats
• Stored as starch

Cellulose is answer to question because it supports the cell and strengthens it.

Question 6

Required Practical…

Investigate the effect of light intensity on the rate of photosynthesis using pondweed.

Answer 6

Youtube: https://www.youtube.com/watch?v=hITp-60mqzg

: Effect of a Varying Light Intensity on Rate of Photosynthesis-Updated

See A4 Booklet

Question 7

How do you measure Light Intensity?

Answer 7

Question 8

Limiting factors

• what is meant by a limiting factor by the rate of photosynthesis?

Answer 8

Limit the rate of reaction, stops photsynthesis from happening any faster, e.g. photosynthesis

Question 9

What factors affect the rate of Photosynthesis?

Answer 9

• Light
• Temperature - too hot, enzymes needed for photsynthesis and its other reactions will be damaged making them denatured causing a rapid decrease in photosynthesis
• Carbon Dioxide concentration

Question 10

Rate of Photosynthesis graphs…

• Light
• Temperature
• Carbon Dioxide Concentration

Answer 10

Light:

• More light, the more photosynthesis that takes place (only to a certain point)
  
  • Because as the light intensity increases, the rate will no longer increase because either the temperature or CO₂ level is now the limiting factor not light
• Provides energy needed for photosynthesis

Temperature:

• Affects the enzymes involved
• If this is the limiting factor, because the temp is too low
  
  • enzymes work a lot slower
• too hot, enzymes can get damaged
• Enzymes get destroyed at roughly 45^oc

Carbon Dioxide:

• Raw material needed for photsynthesis
• More CO₂ there is, will increase the rate of photosynthesis up to a cetain point.
• At flat line, Light or temperature needs to be increased
• Curve, plenty of light and warmth

Question 11

How do plants use glucose?

Answer 11

• During photosynthesis during respiration
• broken down using oxygen to provide energy for the cells
• Carbon dioxide and water are waste product

Lipids:

• Plants and algae use some of the glucose from photosynthesis and energy tansferred to build up fats and oils
  
  • used in the cells as energy store
  • used in cell walls to make them stronger
  • energy store in their seeds
    
    • provide food for the new plant to respore as germinates

Nitrates, Proteins and Carnivorous plants:

• Plants use some of the glucose from photosynthesis to make amio acids
  
  • combining sugars with nitrate ions and other mineral ions from the soi
  • build up to proteins
  • be used in plant cells (enzymes)
• Algae also make amnio acids
  
  • take nitrate ions from water they live in
• Some carnivorous plants i.e. Venus Flytraps, are adapted to live in nitrate-poor soil.
  
  • Nutrients from animals i.e. insects
  • Plants produce enzymes to digest the insects they trap

Cellulose for strength, startch for storage:

• Energy transferred in respiration may be used to build up smaller molecules into bigger ones
• Plants convery some of the glucose they produce in photosynthesis into starch to be stored
  
  • Glucose is insoluble in water
  • Lots of glucose stored in the plant cells could affect the water balance if the whole plant
• Starch is insoluble in water
  
  • no effect on the watter balance of plant making plant be able to store large amounts of starch in cells
  • Starch is stored in the cells of the leaves
  • Starch is kept in special storage areas of a plant

Question 12

higher…

Ideal conditions for photosynthesis

Answer 12

Greenhouse…

• trap suns heat
• Temperature doesn’t become limiting
• Artifical light after sun goes down to maintain photosynthesis
• Can use it all year round
  
  • not depent on the weather
• Increase level of Carbon dioxide
• Keeping them enclosed limits the pests and diseases
• it is very expensive but if done correctly, then it could save them money

Question 13

What does C₆H₁₂O₆ represent?

Answer 13

Glucose