B8. Photosynthesis Flashcards
What is the word equation for photosynthesis?
Carbon dioxide + Water —-> Glucose + Oxygen
Note: Sunlight and chlorophyll are also needed.
What type of reaction is photosynthesis?
It is an ENDOthermic reaction. This means is requires an input of energy from the environment.
What is the energy transfer in photoysnthesis?
Light energy is converted to chemical energy (in glucose).
What is the chemical equation for photosynthesis?
6CO2 + 6H20 —–> C6H12O6 + 6O2
What is the name of the (food) chemical made in photosynthesis?
Glucose
What is the chemical formula for glucose?
C6H12O6
What do plants use glucose for?
- Used for respiration to release energy
- Converted into insoluble starch for storage until it is needed
- Used to produce fat, or oil for storage
- Used to make other carbohydrates e.g. cellulose which strengthens the cell wall
- Used to produce amino acids for protein synthesis.
In photosynthesis, what is a limiting factor?
When a process (e.g. photosynthesis) depends on two or more factors (/substances), the rate of that process is limited by the factor which is in shortest supply.
Which factors could limit the rate of photosynthesis?
- Light intensity
- Availability of water
- Temperature
- Carbon dioxide concentration
- Amount of chlorophyll in the leaves
In what layer of the leaf does photosynthesis take place?
The palisade layer
Which organelle in plant cells produce chlorophyll?
Chloroplast
What is the function of chlorophyll?
It is a green chemical that traps sunlight energy.
How are water levels controlled in the plant?
The volume of water is controlled by the guard cells that open and close the stomata.
Why are leaves very thin?
This allows for a short diffusion pathway for the exchange of gases.
Which substances does the plant tissue xylem transport?
Water molecules and dissolved minerals
Why are there air spaces in the spongy mesophyll layer?
For faster exchange of gases
What do plants store excess glucose as?
Starch
What is the chemical test for starch?
Add 2-3 drops of iodine to the sample, if the colour changes from red/orange to blue-black starch is present.
What is meant by the ‘rate of photosynthesis’?
The rate of photosynthesis is how quickly photosynthesis takes place (or how quickly a plant converts water and carbon dioxide to glucose and oxygen)
What is a limiting factor?
When are process relies on two or more factors, if one or more of these factors are in limited supply the rate will not increase. These are called limiting factors.
What could be limiting factors of photosynthesis?
- Carbon dioxide concentration
- Water availability
- Light intensity
- Chlorophyll
- Temperature
Name 3 ways a student could measure the rate of photosynthesis?
Measure:
1) the rate ofoxygenoutput
2) the rate ofcarbon dioxideuptake
3) the rate ofcarbohydrateproduction
What is meant by an ‘inverse relationship’ between two variables.
As one variable increases the other decreases.
For e.g. in the photosynthesis experiment as the distance of the light source from the plant increases, the light intensity decreases.
Which variable gets plotted on the x axis?
The independent variable
Which variable gets plotted on the y axis?
The dependent variable
How might farmers increase the carbon dioxide concentration in a greenhouse?
- Use paraffin heaters on a small scale.
- On a larger scale, use carbon dioxide wastes from industrial processes that has been cleaned up before use.
- Can use liquid carbon dioxide, applied through pipes, though this can be expensive.
Which type of microorganism can be used to increase CO2 concentrations in greenhouses?
Fungi can be used, grown as amyceliumin bags around the greenhouse, that add carbon dioxide through their respiration.
Explain 2 ways water volume could be increased in commercial plant greenhouses.
- Irrigation systems.
- Plants are sometimes grown in liquid systems called hydroponics.
Compare the normal concentration of atmospheric carbon dioxide to carbon dioxide in a greenhouse.
- The normal concentration for atmospheric carbon dioxide varies between 0.03 % and 0.04 %.
- The concentration of carbon dioxide in greenhouses is often kept at around 0.1 per cent
In a plant cell, when the rate of respiration = the rate of photosynthesis this is called the ___________ point.
Compensation point
Give an advantage of growing crops in a commercial greenhouse.
- Much higher yields of crops can be obtained.
- Plants can be grown all year round.
Give an disadvantage of growing crops in a commercial greenhouse.
- Manipulating the conditions can be very expensive.
- Very time consuming and workers need to be trained.
