Bioenergetics Flashcards
Using glucose in plants - respiration
Transfers energy from glucose which enables the plant to convert the rest of the glucose into various other useful substances
Using glucose in plants - making cellulose
Glucose is converted into cellulose for making strong cell walls
Using glucose in plants - making amino acids
Glucose is combined with nitrate ions to make amino acids
Using glucose in plants - stored as oils or fats
Glucose is turned into lipids for storing in seeds
Using glucose in plants - stored as starch
Glucose is turned into starch and stored in roots
When is light the limiting factor?
Night time
When is temperature the limiting factor?
Winter
When is the carbon dioxide concentration the limiting factor?
When it’s warm and bright enough
Limiting factors - light intensity
As the light intensity increases, the rate of photosynthesis increases steadily
Limiting factors - carbon dioxide concentration
As the concentration of carbon dioxide increases, the rate of photosynthesis increases steadily
Limiting factors - temperature
If the temperature gets too high, the enzymes will denature - 45 degrees
If the temperature is too low, the enzymes will work very slowly
What is light intensity inversely proportional to?
Distance²
Greenhouses - temperature
Help to trap the sun’s heat and ensure the temperature doesn’t become a limiting factor
Heaters are used in winter to maintain a high temperature
Ventilation is used in summer to prevent the temperature increasing too much
Greenhouses - light intensity
Artificial light is used after the sun goes down - gives the plant more quality photosynthesis time
Greenhouses - carbon dioxide concentration
Paraffin heaters help increase the concentration of carbon dioxide - as the paraffin burns, it creates carbon dioxide as a by-product
Other benefits of greenhouses
1) Easier to keep the plants free from pests
2) Fertilisers help provide all the minerals needed for healthy growth
What is respiration?
The process of transferring energy from glucose which goes on in every cell
Is photosynthesis endothermic or exothermic?
Endothermic - energy is transferred from the environment
Is respiration endothermic or exothermic?
Exothermic - transfers energy to the environment
How do organisms use the energy transferred by respiration?
1) To build up larger molecules from smaller ones e.g. proteins from amino acids
2) In animals, it’s used to allow the muscles to contract
3) In mammals and birds, the energy is used to keep their body temperature steady in colder surroundings
Aerobic respiration
Respiration using oxygen
Goes on constantly in plants and animals
Most of the reactions happen inside mitochondria
Aerobic respiration equation
Glucose + oxygen –> carbon dioxide + water
Anaerobic respiration - animals
Respiration without oxygen
Incomplete breakdown of glucose
Happens when your body can’t supply enough oxygen to your muscles during vigorous exercise
Doesn’t transfer as much energy as aerobic respiration - glucose isn’t fully oxidised
Anaerobic respiration equation - animals
Glucose –> lactic acid
Anaerobic respiration - plants & yeasts
In yeasts
Fermentation is used to make bread and alcohol drinks
Anaerobic respiration equation - plants and yeasts
Glucose –> ethanol + carbon dioxide
What three things increase with increased respiration?
1) Breathing rate
2) Breath volume
3) Heart rate
What happens during increased respiration?
More oxygen diffuses into the blood which causes carbon dioxide to be removed more quickly
What does anaerobic respiration lead to?
Oxygen debt - the amount of extra oxygen your body needs to react with the build up of lactic acid and remove it from the cells
What forms when oxygen reacts with lactic acid?
Carbon dioxide and water
How else does the body cope with a high level of lactic acid?
The blood that enters your muscles transports the lactic acid to the liver. Here, the lactic acid is converted back to glucose
Oxygen Production - Method
1) A source of white light is placed at a specific distance from the pondweed
2) The pondweed is left to photosynthesise for a set amount of time. As it photosynthesises, the oxygen released will collect in a capillary tube
3) At the end of the experiment, the syringe is used to draw the gas bubble in the tube up alongside a ruler & the length of the gas bubble is measured. This is proportional to the volume of O2 produced
4) Any variable that could affect the results should be controlled
5) The experiment is repeated twice with the light source at the same distance & the mean volume of O2 produced is calculated
6) Then, the whole experiment is repeated with the light source at different distances from the pondweed
What are lipid molecules made up of?
One molecule of glycerol & three fatty acids
What is metabolism?
The sum of all the reactions that happen in a cell or in the body
What is muscle fatigue?
When over long periods of exercise, the muscles get tired & stop contracting efficiently