Photosynthesis Flashcards
How are leaves adapted for photosynthesis
They are green bc they contain lots chlorophyll to absorb sunlight
They have a large surface area to maximise the amount of sunlight they can absorb
They are thin ,allowing easy diffusion of gases into and out of the leaf
They have veins (xylem and phloem) to allow the transport of water,mineral ions and glucose(food)
Definition of Controlled Variable
Constant and unchanged throughout the course of the investigation
Definition of Independent Variable
Something that is changed throughout the experiment
Definition of Dependant Variable
Something that is being measured in the experiment
5 Ways Plants can use Glucose
Respiration
Making Cellulose
Making amino acids
Stores as oil or fats
Stored as starch
How can you investigate the effect of light intensity
By using and aquatic plant like pondweed
Aquatic meaning
Lives in water
Explain how to investigate the effect of light intensity with a pond weed
Change the distance between the lamp and the pondweed and count the number of bubbles produce per unit Tim e.g. Five per minute
Explain what it means by Respiration
Respiration transfers energy from glucose which enables the plants to convert the rest of the glucose into various other useful substances
Explain what it means by ` Making Cellulose`
Glucose is converted into cellulose for making strong plant cell walls
Explain what it means by Making amino acids
Glucose is combined with nitrate ions (absorbed from the soil) to make amino acids, which are then made into proteins
Explain what it means by ` Stored as oil or fats
Glucose is turned into lipids (fats and oils) for storing in seeds
Explain what it means by `Stored as starch and where exactly is it stored
Glucose is turned into starch and is 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 than glucose- a cell with lots of glucose in would draw in loads of water and swell up.
“Photosynthesis is endothermic”
What does this mean?
Energy is transferred from the environment in the process
What are exothermic reactions?
Exothermic reactions are reactions or processes that release energy
Name the 3 factors that can reduce the rate of photosynthesis/ become the limiting factor:
intensity of light
Temperature
The concentration of CO2
What does a plant immediately do when it receives glucose?
Converts the glucose into starch
Name the 6 steps for the Starch Test:
1) Put the plant in the dark for 1 day to get rid of the starch from the leaves
2) Put the plant in the light for 1 day with 1 leaf in a flask with no CO2 and Part of another Leaf covered with black tape BUT NOT THE WHOLE LEAF
3) After that Boil the leaves in water for a few minutes
4) Soak the leaves in warm alcohol to make them go colourless
5) Dip the leaves in water to soften them
6) Dip brown iodine solution onto each leaf
Where do plants get minerals/water from
The soil
What’s transfers energy from the Sun to a plant
Light
How can u investigate the effect of light intensity on the rate of photosynthesis
U use an aquatic plant e.g. Pondweed.
To do this change the distance between the lamp and the pondweed and count the number of bubbles produced per unit time
What is the independent variable in the pondweed test
Light intensity ( how close the light is )
What is the dependent variable in the pondweed test
The number of oxygen bubbles given off
What is the Controlled variable in the pondweed test
The size of the pondweed
The volume of water used
The waters temperature
What is the deficiency symptom if there is not enough nitrates
A small plant with yellow older leaves
What is the deficiency symptom if there is not enough Phosphates
Poor root growth and purple younger leaves
What is the Deficiency symptom if there is not enough Potassium
Yellow leaves with dead bits
The 3 minerals needed for plants
Nitrates
Phosphates
Potassium
Give an eg of when the Concentration of CO2 is a limiting factor
If it’s warm enough and bright enough the amount of CO2 is usually limiting
What is the idea of the starch test
The idea is to deprive part of either light or CO2 for about a day and test for starch
What is the purpose of a thermometer in the Pondweed Test
Ensuring temperature stays the same
Explain how having lots of chloroplasts near the upper surface is helpful for photosynthesis
Means that as much light as possible reaches the chloroplasts
Explain how having lots of veins is helpful for Photosynthesis
The veins deliver water to the leaf and take away glucose
How can the temperature increase and decrease the rate of Photosynthesis
As the temperature rises,The rate of photosynthesis increases but Photosynthesis is controlled by Enzymes and most Enzymes denature once the temperature get to 40-50 C . If the Enzymes are denatured, The rate of Photosynthesis will fall
Denature meaning
Take away or alter the natural qualities of.
What is the stomata
In the underside of the leaf there are little holes called stomata that allow CO2 to diffuse into the leaf and O2 to diffuse out of the leaf
Why does the Spongy layer have loose fitting cells?
These let carbon dioxide reach the other cells in the leaf, and also let the oxygen produced in photosynthesis leave the leaf easily
Why are leaves important
They provide food for the plants and plants provide the food for all living organisms
True or False
There is more Carbon dioxide around plants at night because it is not being used up in photosynthesis but driven out by respiration
True
4 factors that affect photosynthesis
Water
CO2 levels
Temperature
Light
What are the 5 steps for testing for starch in a leaf
- Boil a beaker of water and the leaf in the boiling water for 2 min
- Remove the leaf from the water and place in a boiling tube containing ethanol
- Place the boiling tube in a beaker of hot water and leave until the thank has turned green meaning that the chlorophyll has been removed
- Wash the leaf, place on a white tile and add a drop of iodine
- If starch is present the iodine turns black
Why is nitrates needed
Healthy growth
Why is phosphates needed
Healthy roots
Why is potassium needed
Healthy leaves and flowers
Why is Magnesium needed
Production of Chlorophyll
