B4 - BIOENERGETICS Flashcards
What is the equation for photosynthesis?
Light
Carbon dioxide + water ———-> glucose + oxygen
CO2 + H2O ———> C6H12O6 + 02
Is photosynthesis an exothermic or endothermic reaction?
Endothermic (takes heat in)
How is energy supplied for photosynthesis?
Sunlight, which is trapped by the green chemical chlorophyll, which is found in chloroplasts
What happens to the energy from sunlight in photosynthesis?
The energy from sunlight is converted from chemical energy in the form of glucose molecules
What is a limiting factor?
The factor that stops the reaction going any faster
What factors affect the rate of photosynthesis?
- carbon dioxide concentration
- temperature
- light intensity
- chlorophyll intensity
How does temperature affect rate of photosynthesis?
- as temp increases, so does rate of photosynthesis, because there is more energy provided for the reaction
- as the temp approaches 45’C, the rate of photosynthesis drops to zero, because the enzymes controlling photosynthesis have been destroyed
How does carbon dioxide concentration affect rate of photosynthesis?
- as the CO2 conc increases, so does the rate of photosynthesis as CO2 is needed in the reaction
- after reaching a certain point, an increase in CO2 will have no further effect, as it is no longer the limiting factor
How does light intensity affect rate of photosynthesis?
- as light intensity increases, so does the rate of photosynthesis as it provides more energy for the reaction
- after reaching a certain point, an increase in light intensity will have no further effect, as it is no longer the limiting factor
How does chlorophyll concentration affect rate of photosynthesis?
- this does not vary in the short term, but may change if plants are grown in soil without enough minerals to make chlorophyll
What is the outcome of the light intensity practical?
Doubling the distance between the lamp and the pondweed will reduce light intensity by a quarter. This is called the inverse square law
What is the glucose in plants used for?
- may be used by the plant during respiration to provide energy
- may be changed into insoluble starch, which is stored in the stem, leaves or roots
- may be changed into fat or oils, which is also stored (e.g. in seeds)
- may be changed into cellulose, to strengthen cell walls
- may be changed into proteins, which are used for growth and for enzymes
What is used as well as glucose to produce proteins?
Plants also use nitrate ions, which are absorbed from the soil. Nitrate ions are needed to make proteins because amino acids contain nitrogen, but glucose does not.
Is respiration an exothermic or endothermic reaction?
Exothermic, as it releases energy from glucose molecules for use by body
What is the energy from glucose molecules used for in organisms?
- for chemical reactions to build larger molecules
- for movement
- to keep warm
Is respiration in cells aerobic or anaerobic?
It can be both
What is the equation for aerobic respiration?
Glucose + oxygen ——-> carbon dioxide + water
C6H1206 + O2 ————> CO2 + H2O
What is aerobic respiration?
Respiration in cells WITH oxygen
What is anaerobic respiration?
Respiration in cells WITHOUT oxygen
Why is there less energy transferred in anaerobic respiration, compared to aerobic respiration?
- the glucose is not completely broken down
- less energy transfer in anaerobic respiration
What is the equation for anaerobic respiration in animals??
Glucose ———-> lactic acid
What is the equation for anaerobic respiration in plants and yeast?
Glucose ———> ethanol + carbon dioxide
What is anaerobic respiration in yeast cells called?
Fermentation
What type of alcohol is made by fermentation?
Ethanol
