B8.1 - B8.4 Photosynthesis ✔️ Flashcards
Photosynthesis equation?
Carbon dioxide + water → (light) →glucose + oxygen
What type of reaction is photosynthesis reaction?
Endothermic reaction in which energy (light) is transferred from the environment to the chloroplasts
Leaf adaptions for photosynthesis?
- leaves are thin - short diffusion distances
- leaves contain pigment, called chlorophyll to absorb light
- guard cells open and close the stomata to regulate gas exchange
Light affect on photosynthesis?
More light increases rate of photosynthesis
Temperature affect on photosynthesis?
Temperature rise - photosynthesis increases as reaction speeds up - too high enzymes denature and rate falls
Carbon dioxide affect on photosynthesis?
Increased photosynthesis - often most common limiting factor for plants
Chlorophyll levels affect on plants?
Less chlorophyll results in less photosynthesis
Light intensity and the inverse square law?
Distance of light increases then the light intensity decreases - inverse relationship
method for measuring rate of photosynthesis practical?
1) place pondweed in a tube of water - place test tube in water bath - (keep it at same temperature)
2)setup a light at 10cm from test tube - set a 1 min timer - count number of bubbles rising
3)repeat 3 times for an average - then repeat at different distances eg (20,30 ….)
Photosynthesis practical variables?
Dependent: rate of photosynthesis at different light intensity’s
Independent variable: light intensity - distance of light from pondweed
Control variable: Temperature and pondweed
Uses of glucose?
- converted into insoluble starch for storage
- used for respiration
- used to produce amino acids for protein synthesis
Why can glucose bs stored in large amounts?
Starch is in soluble in water - has no effect on the water balance of the plant - can be stored in large amounts
Where is starch stored?
- Starch is stored in the cells of the leaves - provides and energy store when it is dark
-kept in special storage areas of a plant eg tubers and bulbs - full of starch to help them survive through the winter
What is the test for starch?
using iodine solution - leaves have to be prepared - turns blue-black if starch is present from brown/orange
How do you prepare a leaf for iodine test?
boil the leaf in ethanol - destroys waxy cuticle and then remove the colour - rinse in hot water to soften - now add iodine solution
Why does leaf have to be treated before iodine test?
- waterproof cuticle keeps iodine out
- chlorophyll masks any colours changes
how do plants produced proteins and why are proteins needed in plants?
glucose + sugars and nitrate ions and other mineral ions from the soil make amino acids - which are then built up into proteins and can then be used for respiration or as enzymes
How do plants make lipids?
Use some glucose and energy transferred from respiration to build fats and oils used in the cell as energy stores … ext
Pros of enhancing greenhouses for getting maximum rate of photosynthesis?
- more crops produced
- seed to harvest time is much shorter
- less staff needed
- cleaner crops
Cons of enhancing greenhouses for getting maximum rate of photosynthesis - Give to drawbacks?
- expensive to set up and expensive equipment
- expensive to maintain conditions inside
How is maximum growth achieved in special greenhouses?
by controlling all the factors - light, temperature, carbon levels and amount of mineral ions plant is getting - gives fastest possible rates of photosynthesis
Symbol for glucose?
C6H12O6
What is the limiting factor?
The factor which is in short supply and limits the amount of photosynthesis that can take place
What does glucose provide?
Glucose is broken down using oxygen to provides energy for the cells - carbon dioxide and water are waste products of the reaction
What is energy transferred by respiration used for - Give 3 ways?
- converting glucose into starch
- building smaller molecules into bigger molecules (eg making cellulose from carbohydrates)
- making amino acids which are built up into proteins to make enzymes
What is starch?
Main energy store in plants - and can be found in cells all over the plant (it is insoluble in water)
What are 2 benefits of plants using starch over glucose?
- glucose is soluble in water where as starch is insoluble not affecting water balance
- starch is also a better form of glucose energy wise and is more compact so it can be stored in greater quantity
what is the test for starch?
Use iodine solution test
How to test for starch using iodine solution test?
1) take two leaves from a plant left in the dark for 24 hours and one left in the light for 24 hours
2) boil the leaf’s in ethanol - to destroy waxy cuticle and remove colour
3) rinse in hot water to soften
4) add iodine solution to both - will turn blue/black from orange/brown if starch is present
Why can we not just add iodine solution to leaf’s to test for starch - explain 2 reasons?
- waxy waterproof cuticle keeps the iodine out
- green chlorophyll masks any colour changes
How does algae make amino acids?
Algae makes amino acids through taking nitrate ions and other materials from the water they live in
How to plants make proteins?
Plants use glucose from photosynthesis to make amino acids by combining sugars and nitrate ions which are built up into proteins
Why are limiting factors important?
Limiting factors are important in the economics of enhancing the conditions in greenhouses to gain the maximum rate of photosynthesis while sill maintaining profit
effect of decreased magnesium for plants?
lack of magnesium means leaf cant make chlorophyll - so rate of photosynthesis drops
issues with plants storing glucose?
if stored in a plant it could affect how water moves in and out of cells - affecting the plants water balance
what does starch present on a leave suggest?
Presence of starch on leaf gives evidence that photosynthesis has taken place
what is the light intensity and the inverse square law equation ?
Light intensity = 1/distance ^2
