B4- Bioengernetics Flashcards
What is photosynthesis?
Photsynthesis uses energy to change carbon dioxide and water into glucose and oxygen. It takes place in chloroplasts in green plant cells which contain pigments like chlorophyll that absorb light. Energy is transferred to the chloroplasts from the environment by light. Photosynthesis is endothermic which means energy is transferred from the environment in the process.
What is the word equation for photosynthesis?
Light
Carbon dioxide + water——>glucose+oxygen
Light
6CO2+6H2O——>C6H12O6+6O2
How do plants use glucose?
For respiration- This transfers energy from glucose which enables the plants to convert the rest of the glucose into various other useful substances
Making cellulose-glucose is converted into cellulose for making strong plant cell walls
Making amino acids- glucose is combined with nitrate ions absorbed from the soil to make amino acids which are then made into proteins
Stored as oils or fats- glucose has turned into lipids which are fats and oils for storing in seeds
Stored as starch – glucose is turned into starch and stored in roots, stems and leaves, ready for use when photosynthesis isn’t happening, like in the winter. Starch is insoluble, which makes it much better for storing then glucose – a cell with lots of glucose in would draw in loads of water and swell up
List some limiting factors that affect the rate of photosynthesis
The rate of photosynthesis is affected by:
.Intensity of light- at night light is the limiting factor
.Concentration of Co2-if it’s warm enough and bright enough, the amount of Co2 is usually limiting
.Temperature-if it’s winter it’s often the temperature
Any of these three factors can become the limiting factor which means that it’s stopping the rate of photosynthesis from happening any faster
Chlorophyll can also be a limiting factor. The amount of chlorophyll in the plant can be affected by disease or environmental stress such as lack of nutrients. These factors can cause chloroplasts to become damaged or to not make enough chlorophyll. This means the rate of photosynthesis is reduced because they can’t absorb as much light.
Explain how not enough light slows down the rate of diffusion
Light provides the energy needed for photosynthesis. As the light level is raised, the rate of photosynthesis increases steadily but only to a certain point. Beyond that it won’t make any difference as light intensity increases the rate will no longer increase. This is because it’ll be either the temperature or the CO2 level which is now the limiting factor not light. In the lab you can change the light intensity by moving a lot closer to or further away from the plant. A graph would show the rate increasing steadily and then staying constant.
Explain how too little carbon dioxide slows down the rate of photosynthesis
CO2 is one of the raw materials needed for photosynthesis. As with light intensity, the amount of CO2 will only increase the rate of photosynthesis up to point. After this the graph flattens out as the amount of CO2 increases, the rate no longer increases. This shows that CO2 is no longer the limiting factor. As long as light and co2 are in plentiful supply the factor limiting photosynthesis must be temperature. A graph would show the rate increasing steadily and then staying constant.
Explain how temperature affects the rate of photosynthesis
Usually if the temperature is the limiting factor is because it’s too low the enzymes needed for photosynthesis work more slowly at low temperatures. But if the plant gets too hot, the enzymes it needs photosynthesis and it’s all the reactions will be damaged. This happens at around 45° where the enzyme will become denatured. A graph showing the rapid increase and then a rapid decrease.
Explain the Canadian pondweed experiment
Canadian pondweed can be used to measure the effect of light intensity on the rate of photosynthesis. The rate at which the pondweed produces oxygen corresponds to the rate at which is photosynthesising – the faster the rate of oxygen production, the faster the rate of photosynthesis. Here’s how the experiment works:
A source of white light is placed at a specific distance from the pondweed. The ponweed is left to photosynthesise for a set amount of time. As it photosynthesises the oxygen released will collect in the capillary tube. At the end of the experiment, the syringes used to draw the gas bubble in the tube up alongside a ruler and the length of the gas bubble is measured. This is proportional to the volume of O2 produced. For this experiment any variables that could affect the results should be controlled. The experiment is repeated twice with a light source at the same distance and the main volume of O2 produced is calculated. Then the whole experiment is repeated with a light source at different distances from the pondweed. Variables that could affect the results are temperature and time.
What is the measure of light intensity?
d2
How can you artificially create the ideal conditions for farming?
The most common way to artificially create the ideal environment for plants to grow them in the greenhouse. Greenhouses help to track the Suns heat and make sure that the temperatures don’t become limiting. In winter a farmer or garden er might use the heater as well to keep the temperature at the ideal level. In summary could get too hot so they might use shades and ventilation to cool things down.
Light is always needed for photosynthesis so commercial farmers often supply artificial light after the Sun goes down to give their plants more quality photosynthesis time. Farmers and gardeners can also increase the level of carbon dioxide in the greenhouse. Keeping plants in closed in the greenhouse also makes it easier to keep them free from pests and diseases. The farmer can add fertilisers to the soil as well to provide all the minerals needed for healthy growth
What is respiration?
Respiration is the process of transferring energy from glucose which goes on in every cell. Respiration is exothermic as it transfers energy to the environment
How do you organisms use the energy transferred by respiration?
.To build up larger molecules from smaller ones
. In animals its used to allow the muscles to contract
. In mammals and birds the energy is used to keep their body temperature steady in cooler surroundings
What is metabolism and how does it work?
The total of all reactions that happen in the cell or the body is called its metabolism
In a cell there are lots of chemical reactions happening all the time which are controlled by enzymes.
Many of these reactions are linked together to form a bigger reactions. In some of these reactions larger molecules are made from smaller ones for example lipid molecules that are each made from one molecule of glycerol and three fatty acid’s. Glucose is also combined with nitrate ions to make amino acid’s which are then made into proteins
In other reactions larger molecules are broken down into smaller ones. For example glucose is broken down into respiration and respiration transfers energy to power all the reactions in the body that make molecules. Also excess protein is broken down into a reaction to produce urea which is then excreted in urine
What is a aerobic respiration?
Aerobic respiration is respiration using oxygen. It’s the most efficient way to transfer energy from glucose. Aerobic respiration goes on all the time in plants and animals. Most of the reactions that happen in aerobic respiration happen inside mitochondria.
What is the word and symbol equation for aerobic respiration?
Glucose+ oxygen—-> carbon dioxide+Water
C6H1206—->6C02+6H20
