Bioenergetics Flashcards
Is photosynthesis endothermic or exothermic
Endothermic
It requires energy from the sun to happen so takes in light energy
Why is photosynthesis endothermic
Takes in energy from the sun (light)
Top 5 uses of glucose by plants
Cellular respiration (releases energy)
Converted into insoluble starch for storage
Producing cellulose
Producing amino acids
Producing lipids (fat/ oil)
Top 5 uses of glucose by plants
Cellular respiration (releases energy)
Converted into insoluble starch for storage
Producing cellulose
Producing amino acids
Producing lipids (fat/ oil)
Glucose helps produce cellulose. What is the purpose of cellulose
Strengthens cell walls
Glucose helps produce amino acids in plants. What are the amino acids needed for
Protein synthesis
What else is needed as well as glucose from photosynthesis for plants to produce amino acids
Nitrate ions from soil
Glucose can help produce fats in plant. What is the fat used for
Future energy source
What is meant by inverse square law
As distance of light source from plant increases, light intensity decreases
Relationship between light intensity and distance
Light intensity is Inversely proportional to (1 over) the distance squared
E.g if distance doubles then light intensity quarters
What is meant by a limiting factor (of photosynthesis)
Anything that limits the rate of a reaction when in short supply
3 main limiting factors of photosynthesis (if you’re asked for a 4th then number of chlorophyll is also one)
Light intensity
Temperature
Concentration of carbon dioxide
When drawing a graph to show how limiting factors affect the rate of photosynthesis what goes on each axis
Y axis is rate of photosynthesis
X axis is limiting factor (CO2 concentration/ light intensity/ temperature)
Describe how light intensity (limiting factor) affects rate of photosynthesis
As light intensity increases so does the rate of photosynthesis
However once the light intensity reaches a certain point something else becomes the limiting factor
Therefore after this certain point rate of photosynthesis will remain at a steady rate even as light intensity keeps increasing
Which 2 limiting factors of photosynthesis have similar graphs
CO2 concentration and light intensity
As the factor increases so does rate of photosynthesis up to a certain point where something else becomes the limiting factor so rate of photosynthesis remains constant even as the CO2 concentration/ light intensity keeps increasing
Describe how carbon dioxide (limiting factor) affects rate of photosynthesis
As carbon dioxide concentration increases so does rate of photosynthesis up to a certain point where something else becomes the limiting factor
After this point as CO2 concentration keeps increasing the rate of photosynthesis remains constant
Plateaued meaning
Where the rate of photosynthesis reaches a stage of no change after a period of progress (rate increasing)
This is where as the limiting factor increases, the rate of photosynthesis no longer does but remains the same (as it’s now another limiting factor that affects it)
What is Photosynthesis controlled by
Enzymes
Why at first does rate of photosynthesis increase as temperature increases
The enzymes involved can work more quickly and the molecules can move faster
What happens to rate of photosynthesis after enzymes have reach their optimum temperature
Enzymes start to denature
Active site can no longer bind to substrate
Rate of photosynthesis quickly decreases
Describe how temperature affects rate of photosynthesis
As temperature increases so does rate of photosynthesis as the enzymes can work quickly and the molecules can move faster as they have more kinetic energy
Up to the optimum temperature after which the enzymes denature and the active sites can no longer bind to the substrate so rate of photosynthesis quickly decreases
What can farmers to increase rate of photosynthesis
Grow plants in greenhouses (especially in colder climates) as it traps the sun’s heat to increase temperature
Use artificial light so photosynthesis can occur at night
Use a paraffin heater (releases heat and CO2 as it burns)
Fertilisers (ensure plants have enough essential minerals)
Use pesticides to kill unwanted pests
What is the equation linking light intensity and distance
Light intensity = 1/ distance squared
Is respiration exothermic or endothermic and why
Exothermic
Releases energy
