- Created by: abbiedye
- Created on: 20-06-18 19:18
What is photosynthesis?
carbon dioxide + water -----> glucose + oxygen
- It takes place in chloroplasts in green plant cells - they contain pigments like chlorophyll that absorbs light
- Photosynthesis is endothermic
What do plants use glucose for?
For respiration - plants can convert the rest of the glucose into useful substances
Making cellulose - for making strong plant cell walls
Making amino acids - combined with nitrate ions to make amino acids, then made into proteins
Stored as oils or fats - turned into lipids for storing in seeds
Stored as starch - stored in roots, stems and leaves - ready for when photosynthesis isn't happening
What are the limiting factors of photosynthesis?
- Light intensity, concentration of carbon dioxide and temperature
Depends on environmental conditions: - night - light intensity - - winter - temperature - warm and bright enough - carbon dioxide
Chlorophyll - affected by disease and lack of nutrients
How do es light, temperature and CO2 effect photos
- Not enough light slows down the rate of photosynthesis
- Too little carbon dioxide also slows it down
- The temperature has to be just right - too high = enzymes denatured
What is respiration?
Respiration is the process of transferring energy from glucose, which goes on in every cell
- breakdown of glucose
- Respiration is exothermic - energy going to the environment
examples: to build larger molecules from smaller ones, allows muscles to contract and to keep the body temperature of birds and mammals steady
What is metabolism?
- all the chemical reactions in an organism controlled by enzymes
reactant ---> product ---> product ---> product --->
- larger molecules are made into smaller ones
glucose --> starch, glucose and cellulos
- larger molecules are broken down into smaller ones
glucose --> respiration
- excess protein - urea
What is aerobic respiration?
- Respiration using oxygen - most efficient way to transfer energy from glucose
- most reactions happen inside mitochondria
glucose + oxygen ---> carbon dioxide + water
What is anaerobic respiration?
'Anaerobic' - 'without oxygen'
Incomplete breakdown of glucose, making lactic acid
glucose ---> latic acid
does not transfer nearly as much energy - glucose isn't fully oxidised
used in emergencies
How is anaerobic respiration in plants/yeast diffe
Plants produce ethanol and carbon dioxide instead of lactic acid
glucose ---> ethanol + carbon dioxide
anaerobic respiration in yeast cells - fermentation (food and drink)
bread-making = carbon dioxide ----> bread rise
beer and wine making - fermentation produces alcohol
Why do you respire more during exercise?
- During exercise, muscles contract more - needing more energy - from increased respiration
- Increase in respiration - needs more oxygen
- Breathing rate and breath volume increase - heart rate increases to get oxygenated blood around the body
- vigorous exercise - muscles start to respire anaerobically
How does anaerobic respiration lead to an oxygen d
- After resorting to anaerobic respiration, an 'oxygen debt' will occur (amount of oxygen needed to remove lactic acid)
- Pulse and breathing rate stay high - high levels of lactic acid and carbon dioxide
- Lactic acid is converted back to glucose in the liver