5.6.1: The interrelationship between photosynthesis and respiration Flashcards
What is photosynthesis?
An important physiological process used in plants, algae and some types of bacteria to convert light energy from sunlight into chemical energy.
How is photosynthesis an example of autotrophic nutrition?
chemical energy is used to synthesise large organic molecules (building blocks of living cells) from simple inorganic molecules such as H2O and CO2.
What are organisms that photosynthesise called?
Photoautotrophs because they use light as the energy source for autotrophic nutrition.
Why are organisms that photosynthesise described as ‘producers’?
Because they are the first trophic level of a food chain and provide energy and organic molecules to other, non-photosynthetic, organisms.
What is the general equation for photosynthesis?
6CO2 + 6H2O → C6H12O6 + 6O2
What is a photon?
a particle of light; each photon contains an amount (a quantum) of energy.
What is the main product of photosynthesis?
A monosaccharide sugar which can be converted into disaccharides for transport and then starch for storage.
photosynthesis is an example of carbon fixation, what is this?
- The process by which carbon dioxide is converted into sugars.
- The carbon for synthesising all types of organic molecules is provided by carbon fixation.
What does carbon fixation need?
- Endothermic so needs energy.
- Electrons; the addition of electrons is reduction.
What is the importance of carbon fixation?
Helps regulate CO2 concentration in atmosphere and
What do plants do when they respire?
-Oxidise organic molecules previously synthesised by photosynthesis and stored releasing chemical energy.
Why are non-photosynthetic organisms described as ‘heterotrophs’?
They obtain energy by digesting complex organic molecules of food to smaller molecules that they can use as respiratory substrates.
-They obtain energy from the products of digestion by respiration.
The overall equation for respiration:
C6H12O6 + 6O2 → 6CO2 + 6H2O
How is respiration exothermic?
-It releases chemical energy that can drive the organism’s metabolism.
When do plants respire?
All the time
When do plants photosynthesise?
During daylight
Plants often compete for light, what does the light intensity have to be sufficient to allow?
A rate of photosynthesis that replenishes the carbohydrate stores used up by respiration.
When is a plant at its compensation point?
When photosynthesis and respiration proceed at the same rate so there is no net gain or loss of carbohydrates.
What is the time taken for a plant to reach its compensation point called?
-The compensation period.
How are shade plants different to sun plants.
shade plants:
-Utilise light of lower intensity
-When exposed to light after bein in dark, they reach compensation point sooner.
-Shorter compensation periods.
Sun plants:
-Require higher light intensity to achieve their optimum rate of photosynthesis.
