Biology topic 4 Flashcards
(23 cards)
What is the equation for photosynthesis?
Carbon dioxide + water - glucose + oxygen
What is photosynthesis?
Uses energy to change carbon dioxide and water to glucose and oxygen.
Takes place in chloroplasts in green plant cells (contain chlorophyll).
Energy transferred to chloroplasts by light.
Endothermic process (energy transferred from environment)
What do plants use glucose for? (5 ways)
Respiration - transfers energy from glucose, enables plants to convert glucose into other substances.
Making Cellulose - glucose is converted into centimetres for making strong plant walls.
Amino acids - glucose is combined with nitrate ions (from soil) to make amino acids, made into proteins.
Stored as oils or fats - glucose is turned into lipids for storing in seeds.
Stored as starch - glucose is turned into starch (insoluble) and stored into roots. Better than glucose, as glucose drawers in lots of water and swells up).
What are the limiting factors that affect the rate of photosynthesis?
Light, concentration of carbon dioxide and temperature.
At night light is limiting factor.
In winter, it’s the temperature.
If it’s warm and bright enough carbon dioxide is usually limiting.
Chlorophyll can also be a limiting factor if the plant is affected by the disease, or environmental stress, such a lack of nutrients.
How does light affect the rate of photosynthesis?
Light provides energy, which increases the rate of photosynthesis, as light intensity increases. Only to a certain point , beyond that The rate will no longer increase because it’s either the temperature or CO2 level which is limiting light . In a lab can change the light intensity by moving a lamp closer or further away.
If you just put the rate of photosynthesis against distance of lamp from plant, you get a weird shaped graph.
How does not enough carbon dioxide slow down the rate of photosynthesis?
Carbon dioxide will only increase the rate of photosynthesis up to a point after this, the graph flattens out as the amount of carbon dioxide increases the rate to no longer increases. This shows that carbon dioxide is no longer the limiting factor. As long as lighten CO2, plentyful, then the factor, limiting photosynthesis must be the temperature.
Why does the temperature have to be perfect for photosynthesis?
The enzymes needed for photosynthesis, work, more slowly at low temperatures. If the temperature gets too hot, the enzymes will be damaged. This happens at 45°.
Explain the different graphs for photosynthesis
One graph might show more than one limiting factor on the rate of photosynthesis.
What is the photosynthesis practical?
Using pondweed in a test tube with water measuring the rate at which the pond weed produces oxygen, and if it corresponds to the rate at which it’s photosynthesising.
What is the inverse Square law?
As distance increases, the light intensity decreases in the photosynthesis, practical, meaning that inversely proportional to each other. As light intensity decreases in proportion to the square of distance, this is called the inverse square law. Light intensity is directly proportional to 1/distance squared.
How can you artificially create the ideal conditions for farming?
Grow them in a greenhouse. This traps, the suns heat insuring the temperature doesn’t become limiting. They might use a heater in winter and ventilation in summer.
Light is always needed so commercial farmers often supply artificial light for nighttime.
They may increase levels of carbon dioxide by using a paraffin heater, which produces CO2 as it burns.
Keeping plants enclosed, keeps them free from pests and diseases. The farmer can add fertilisers to the soil to provide minerals as well.
This costs money, however, if the conditions are perfect, the plants will grow much faster and produce a decent crop, it’s important to produce the right conditions, but not overly as this wastes money.
What is respiration?
the process of transferring energy from glucose, which goes on in every cell.
Involves many reactions, creating energy used for all living processes.
It goes on in every cell in your body continuously and happens in plants too, all living things respire, it’s how they transfer energy from food to their cells. It’s exothermic as it transfers energy to the environment.
What things does respiration transfer energy for?
Building larger molecules from smaller ones like proteins from amino acids.
In animals, it’s used to allow the muscles to contract.
In mammals and birds, the energy is used to keep their body temperature study in colder surroundings.
How does metabolism work?
In a cell, there are lots of chemical reactions all the time controlled by enzymes working together to form bigger reactions.
Sometimes larger molecules are made from smaller ones, e.g. glucose is combined with nitrate ions to make amino acids which are made into proteins.
Another reactions, larger molecules are broken down into smaller ones. E.g. excess protein is broken down in a reaction to produce urea, urea is an excreted in urine.
The sum of all the reactions that happen in a cell or body is called metabolism.
What is an aerobic respiration?
Respiration using oxygen, most efficient way to transfer energy from glucose.
Goes on all the time in plants and animals. Most of the reactions in aerobic respiration happen inside the mitochondria.
What is the word equation for an aerobic respiration?
Glucose + oxygen - carbon dioxide + water
When is anaerobic respiration used?
When you do, vigourous exercise, and your body can’t supply enough oxygen to your muscles, they do anaerobic respiration as well as aerobic.
Anaerobic means without oxygen, incomplete breakdown of glucose, making lactic acid.
Doesn’t transfer as much energy as aerobic, glucose isn’t fully oxidised, so only used in emergencies ( allows you to keep using muscles for longer).
What is the word equation for anaerobic respiration?
Glucose turns in to lactic acid
How is anaerobic respiration in plants and yeast different?
Plants and cells can respire without oxygen, but produce ethanol and carbon dioxide instead of lactic acid.
In the cells, this is called fermentation.
In the food and drink industry fermentation, buy yeast is of great value as it used to make bread and alcohol.
In bread, making its the carbon dioxide that makes bread rise. In alcohol making its the fermentation process which produces alcohol.
What is the word equation for anaerobic respiration in plants and yeast?
Glucose - ethanol + carbon dioxide
Why do you respire mean when you do exercise?
Muscles need more energy to contract, needs more respiration, so your cells can get more oxygen in them.
Your breathing and breath volume rates increase to get more oxygen into the blood.
Heart rate increases to get the oxygenated blood around the body faster, removing carbon dioxide more quickly at the same time.
Really vigourous, exercise, like sprinting, means your body can’t supply oxygen so they start respiring anaerobically.
This is not the best way to transfer energy from glucose as lactic acid buildup in the muscle creating pain. Long periods of exercise can also cause muscle fatigue as muscles get tired and stop contracting efficiently.
Why does anaerobic respiration lead to an oxygen debt?
When you stop exercising, you have an oxygen debt, meaning you have an excess of oxygen to react with the buildup of lactic acid, and remove it from the cells to form harmless carbon dioxide and water.
Meaning you have to repay the oxygen because your lungs, heart and blood couldn’t keep up with demand earlier.
Meaning you have to keep breathing hard for a while after you start to get more oxygen into your blood which is transported to muscle cells.
The pulse and breathing rate stay high. Well, they’re levels of lactic acid and carbon dioxide.
Another way with coping with the high level of lactic acid, is that the blood that muscles transports to the lactic acid to the liver, then convert the lactic acid back to glucose.
How can you affect the effective exercise on the body?
You can measure the breathing rate by counting breaths, heart rate and taking a pulse.
E.g. you could take your pulse after gentle, walking, slow jogging and running, then put your results in a bar chart.
The pulse rate will increase the more intense the exercises as your body needs to get more oxygen to the muscles and take more carbon dioxide away. To reduce the effect of any random errors do it as a group and put the average pulse rate for each exercise.
