B2.3 Photosynthsis Flashcards
What is photosynthesis?
The process that produces ‘food’ in plants and algae
What is the ‘food’ that is produced from photosynthesis?
Glucose
Where does photosynthesis occur?
Inside chloroplasts in plant cells and algae
What is the process of photosynthesis?
Chloroplasts contain a green substance called chlorophyll which absorbs sunlight and uses its energy to convert carbon dioxide and water into glucose, oxygen is also produced as a by-product
What is the word equation for photosynthesis?
Carbon dioxide + water ==light energy==> glucose + oxygen
Where are chloroplasts found?
In the leaves of all green plants
What is the rate of photosynthesis affected by?
The intensity of light, the volume of carbon dioxide and the temperature
What happens when one of the three factors which affect the rate of photosynthesis is too high or too low?
It will become the limiting factor, it’s the factor which is stopping photosynthesis from happening any faster
When will the intensity of light become a limiting factor?
At night
When will the temperature become a limiting factor?
In the winter
When will the levels of carbon dioxide become a limiting factor?
When it is warm and bright enough, the amount of carbon dioxide is usually limiting
How can you investigate the rate of photosynthesis?
Gas syringe - amount produced over a time method
What would the control variables of an investigation on the rate of photosynthesis link to?
The three limiting factors of photosynthesis
When interpreting data on the effect of light intensity and carbon dioxide on the rate of photo’, what does the graph flattening suggest?
That they are no longer the limiting factor, and it is another factor as the rate of photo synthesis is no longer increasing
When interpreting data on the effect of temperature on the rate of photosynthesis, why does the graph decrease rapidly if the plant gets to hot?
Because the enzymes which catalyse the rate of photosynthesis are damaged/destroyed after a certain temperature, which means they can no longer work causing the rate of photo’ to plummet
Where can you create the ideal conditions for photosynthesis?
In greenhouses
How is temperature managed in greenhouses?
They help to trap the sun’s heat, and make sure that the temperature doesn’t become limiting
How can temperature be managed in a greenhouse in the winter when it is too cold, and in the summer when it is too hot?
In the winter heaters can be used to keep temperatures at the ideal level, and in the summer, shades and ventilation can be used to cool things down
How is light managed in greenhouses?
Artificial lights can be used after the sun goes down to give the plants more photosynthesis time
How are carbon dioxide levels managed in greenhouses?
Paraffin heaters can be used to heat the greenhouse, which produces carbon dioxide as a by-product
How is the general health of the plants in greenhouses managed? (2)
Keeping the plants enclosed in a greenhouse keeps them safe from pests and diseases, and farmers can add fertilisers to the plant’s soil to provide the minerals needed for healthy growth
Keeping the conditions in a greenhouse at an optimum can be expensive, but why is it worth it?
Because keeping the conditions just right for photo’ makes the plants grow faster and a decent crop can be harvested much more often, which can then be sold
What is glucose used for in plants? (3)
Respiration, making cell walls and making proteins
How is glucose used for respiration?
The breakdown of glucose produces energy which can then be used to convert the rest of the glucose into other useful substances
How is glucose used for making cell walls?
Glucose is converted into cellulose to make strong cell walls especially in a rapidly growing plant - these cell walls support and strengthen the cells
How is glucose used to make amino acids?
Glucose is combined with nitrate ions absorbed from the soil to make amino acids
How is glucose used for making proteins?
Glucose can be used to make amino acids, which are the building blocks of proteins - they can make a particular protein when joined together in a particular sequence
How can glucose be stored in plants? (2)
In lipids or starch
How can glucose be stored as lipids?
Glucose can converted into lipids, which are then stored in seeds (in plants) and oil droplets in cells (in algae)
Why is glucose stored as starch?
So it can be used for when photosynthesis isn’t happening as much, like in the winter
Where is starch stored in plants? (4)
In the roots, stems, seeds and leaves
Why is it better for plants to store starch rather than glucose?
Because starch is insoluble, and a cell with lots of glucose in would draw in loads of water and swell up
