Bioenergetics Flashcards
Photosynthesis word equation
carbon dioxide + water ———-> oxygen + glucose
Photosynthesis symbol equation
6CO₂ + 6H₂O ————> C₆H₁₂O₆+ 6O₂
Photosynthesis
Endothermic reaction where energy is transferred from environment to chloroplasts by light
Plant uses of glucose
- respiration
- making cellulose to strengthen cell walls
- making amino acids for protein synthesis
- storing as oils or fats
- storing as insoluble starch
How do plants make proteins
- glucose combined with nitrate ions absorbed from soil
- amino acids made into proteins
How do plants store oils and fats
Glucose turned into lipids and stored in seeds
Where is starch stored in plants
- roots
- stems
- leaves
How do plants use stored starch
Used when photosynthesis isn’t happening
How is starch better for plant storage than glucose
- insoluble
- plant with lots of glucose would draw up lots of water and swell up
Photosynthesis limiting factors
- light intensity
- CO₂ concentration
- temperature
- chlorophyll concentration
Photosynthesis limiting factor at night
Light intensity
Photosynthesis limiting factor in winter
Temperature
Photosynthesis limiting factor when warm and bright
CO₂ concentration
What can affect amount of chlorophyll in plant
- disease (TMV)
- lack of nutrients
How can chlorophyll limit photosynthesis
When chloroplasts are damaged, not enough chlorophyll is made to absorb light for photosynthesis
How does light affect rate of photosynthesis
As light intensity increases, rate of photosynthesis increases to a certain point where it then makes no difference
How does carbon dioxide affect photosynthesis
As amount of CO₂ increases, rate of photosynthesis increases to a point then it makes no difference
How does temperature affect photosynthesis
- as temperature increases, rate of photosynthesis increases to a point where it decreases and stops working
- enzymes for photosynthesis work slower and lower temperatures but are destroyed at around 45°C
Photosynthesis practical
- place LED bulb (doesn’t produce heat) at specific distance from pondweed in water in test tube
- as pondweed photosynthesises, count oxygen bubbles produced for 1 minute
- repeat with light at different distances away to see how that affects rate of photosynthesis (number of bubbles produced)
Inverse square law
Light intensity ∝ 1/distance²
How do greenhouses optimise conditions
- trap heat so temperature doesn’t become limiting
- use shade and ventilation in summer to cool down
- can use artificial light to photosynthesise at night
- paraffin heater burns with CO₂ biproduct
- protect from pests/disease
Respiration
Process of transferring energy from glucose which goes on in every cell through an exothermic reaction, happening continuously
Uses of energy transferred from respiration
- chemical reactions for building up larger molecules from smaller ones
- allow muscles to contract and relax
- mammals keep body temperature steady in colder surroundings
Metabolism
Sum of all reactions that happen in a cell or body, continual enzyme controlled process
