Biology - Topic 4 - Bioenergetics
Biology - Topic 4 - Bioenergetics
3) In some of these reactions larger molecules are made from smaller ones e.g. glucose molecules joined to from starch, glycogen and cellulose.
4) In some reactions larger molecules are broken down into smaller ones e.g. excess protein broken down to urea.
2) Reactant -(enzyme)-> product -(enzyme)-> product -(enzyme)-> product
5) The sum of all reactions that happen in a cell or the body is called its metabolism.
1) Lots of chemical reactions controlled by enzymes.
The rate of Photosynthesis
The temperature has to be right. If its too low enzymes need a high temp to work effectively however is pants get to hot the enzymes denature.
Inverse square law links light intensity and distance - light intensity = 1/distance(d^2)
Too little Carbon Dioxide slows it down. If the graph flattens out CO2 is no longer the limiting factor
Can create artificial ideal conditions for farming such as a green house.
Not enough light slows the rate. As the light level is raised the rate of photosynthesis increases only up to a certain point.
Glucose --> Lactic Acid
C6H12O6 --> C2H5OH + CO2
In plants Glucose --> Ethanol + Carbon dioxide
2)In animals used to muscles to contract.
3)In mammals and birds its to keep body temps steady.
1) To build up larger molecules from smaller ones.
Glucose + Oxygen --> Water + Carbon Dioxide
C6H12O6 + 6O2 --> 6H2O + 6CO2
Respiration is a reaction in which glucose is reacted to release energy.
It takes place in the mitochondria
(a type of sub-cellular structure).
Photosynthesis and limiting factors
Carbon dioxide + water --light--> glucose + oxygen 6CO2+6H2O--light--> C6H12O6+6O2
Plants use glucose in 5 main ways
Making amino acids
Used to produce fats and oils for storage
Converted into insoluble starch as storage
For respiration- This transfers energy from glucose which enables the plant to convert the rest of the glucose into various other useful substances.
Photosynthesis produces glucose using light
1) Photosynthesis uses energy to change CO2 and water into glucose and oxygen.
3)Energy is transferred to the chloroplasts from the environment by light
2) It takes place in chloroplasts in green plant cells- they contain pigments like chlorophyll that absorb light.
4) Photosynthesis is endothermic- this means energy is transferred from the environment in the process.
Limiting factors affect the rate of photosynthesis
These factors have a combined effect. At night it is light that is the limiting factor. In winter its often temperature.
If its warm and bright enough the amount of CO2 is the limiting factor.
1) Intensity of light, concentration of CO2 and temperature.
Chlorophyll can also be a limiting factor. This can be affecting by disease e.g TMV. Or environmental stress such as lack of nutrients.
c maximise photosynthesis to improve yields - green houses have heating and extra carbon dioxide to ensure photosynthesis is at its maximum
When you exercise you respire more
Breathing rate, breathing volume and heart rate increase to get the blood oxygenated.
Vigorous exercise means you respire anaerobically.
Need more oxygen.
Makes lactic acid build up.
As muscles need energy to contract..
Long periods of exercise cause muscle fatigue.
Anaerobic respiration leads to oxygen debt.
As you have to repay the oxygen you start heavy breathing.
The pulse and breathing rate star high whilst there are high levels of lactic acid.
You need oxygen reacts with lactic acid to from harmless CO2 and water.
Your body can also transport lactic acid to your liver to be converted back to glucose.
After anaerobic respiration when you stop exercising you have oxygen debt.
Measuring the effect of exercise on the body
As your body needs more oxygen to the muscles and take more CO2 away from the muscles.
Measure breathing rate and heart rate.