B4 Bioenergetics Flashcards
Photosynthesis word equation
Carbon dioxide + water >(light)> glucose + oxygen
6CO^2 + 6H^2O >(light)> C^6H^12O^6 + 6O^2
Photosynthesis uses…
Energy to change carbon dioxide and water into glucose and oxygen
Photosynthesis takes place in
Chloroplasts in green plant cells. They contain chlorophyll that absorb light. Energy is transferred to the chloroplasts from the environment by light
Photosynthesis is e….
Endothermic, meaning energy is transferred from the environment in the process
Plants use glucose in five ways….
Respiration to transfer energy from glucose which enables the plant to convert the rest of the glucose to other useful substances
Making cellulose as glucose is converted to cellulose for making strong plant cell walls
Making amino acids - glucose is combined with nitrate ions (absorbed from soil) to make amino acids for proteins
Stored as oils or fats - glucose turned into lipids for storing in seeds
Stored as starch - glucose is turned into starch and stored in the roots, stems and leaves ready to use during winter when photosynthesis doesn’t Happen. Starch is insoluble so it’s better for storing.
Limiting factors of photosynthesis
Light, temperature, carbon dioxide and chlorophyll
Chlorophyll as a limiting factor
Chlorophyll amount can be affected by disease or environmental stress like lack of nutrients. This can cause damages chloroplasts so they don’t make enough chlorophyll so photosynthesis rate is reduced as not enough light is absorbed
Light as a limiting factor
Light provides energy for photosynthesis.
As light increases, the rate of photosynthesis increases steadily but only up to a certain point.
It stop here, and the limiting factor I
Is now carbon dioxide or temperature
Limiting factors
These factors have a combined effect on photosynthesis , but which factor is limiting at a particular time depends on environmental conditions
Carbon dioxide as a limited factor
Carbon dioxide is a raw material needed for photosynthesis.
The amount of carbon dioxide will increase the rate of photosynthesis up until a certain point.
If light and carbon dioxide are plentiful then temperature is the limiting factor
Temperature as a limiting factor
If temperature is a limiting factor, it’s because it’s too low. Enzymes needed for photosynthesis work slower at a lower temperature.
If the plant gets too hot the enzymes will become damaged > happens about 45 degrees
As the distance from the light increases, photosynthesis decreases. This means they are…
Inversely proportional to each other
What is the inverse square law
It means that the light intensity decreases in proportion to the square of the distance.
Written as
Light intensity is proportional to 1 / distance squared
Or if you half the distance, the light intensity will be four times greater. Etc
Why is a greenhouse the ideal condition for farming
Greenhouses help trap the suns heat, and make sure the temperature isn’t too limiting. In winter a farmer might use a heater. In winter they might use shades or ventilation’s
They can use artificial light to increase light and paraffin heaters to increase the amount of carbon dioxide.
Easier to keep plants pest and diseases free.
What is respiration
Respiration transfers the energy that the cells need to do everything. This is energy used for all living processes.
It is the process of transferring energy from the breakdown of glucose and goes to every cell continuously
It is exothermic as it transfers energy to the environment
Examples of how organisms use the energy transferred by respiration
To build up larger molecules from smaller ones. E.g proteins from amino acids
In animals it is used to allow muscles to contract
In mammals and birds the energy is used to regulate their body temperature in colder surroundings
Metabolism is all…
The chemical reactions in an organism
What is aerobic respiration
Respiration using oxygen and is the most EFFICIENT way to transfer energy from glucose.
Goes on all the time in plants and animals.
Most of aerobic respiration happen inside mitochondria
Equation for aerobic respiration
Glucose + oxygen > carbon dioxide + water
What is anaerobic respiration
Respiration without oxygen. It’s the incomplete breakdown of glucose, making lactic acid
Happens during vigorous exercise and your body can’t supply enough oxygen to your muscles
Anaerobic respiration equation
Glucose > lactic acid
Anaerobic respiration does not transfer….
As much energy as aerobic because the glucose isn’t fully oxidised
Anaerobic respiration in plants and yeast
Plants and yeast cells can respire without oxygen, but they produce ethanol and carbon dioxide rather than lactic acid.
In yeast it’s called FERMENTATION
Fermentation is used to make bread and alcoholic drinks.
Word equation for anaerobic respiration in plants and yeast cells
Glucose > ethanol + carbon dioxide
When you exercise you
Respire more
Why do you respire more during exercise
Muscles need energy from respiration to contract. During exercise some muscles contract more so you need more energy. This energy comes from increased respiration.
Breathing rate and breath volume increase so more oxygen can come into the blood. Heart rate increases to get oxygenated blood around body faster.
What happens during vigorous exercise
Body can’t supply enough oxygen to your muscles so you start respiring anaerobically.
Lactic acid builds up and causes cramps.
Long periods of exercise can cause..l
Muscle fatigue - the muscles get tired and stop contracting efficiently.
Anaerobic respiration leads to….
Oxygen debt.
What is oxygen debt
Is the extra amount of oxygen your body needs to react with the build up of lactic acid and remove it from cells. Oxygen reacts with lactic acid to form harmless carbon dioxide and water.
Pulse and breathing rate stay high whilst there are high levels of lactic acid and carbon dioxide.
Another way your body deals with lactic acid
Blood that enters your muscles transports the lactic acid to the liver where it is converted back to glucose.
You can measure the breathing rate by
Counting breaths, heart rate ans taking the pulse.
For example take your pulse after 5 mins of walking
5 mins of running
5 mins of sitting down
Put in bar chart and see the different. Pulse rate increase the more intense the exercise is, as your body needs to get more oxygen to muscles so blood pumps faster.
