1.2 Photosynthesis Flashcards
Photosynthesis is an endothermic reaction. What does this mean
Takes in energy (from the sun)
What part of the plant cell is needed for photosynthesis
Chloroplasts
What is the green pigment in chloroplasts called
Chlorophyll
What is the word equation for photosynthesis
Carbon Dioxide + Water ——-> Glucose + Oxygen
What 2 things are needed to allow photosynthesis to happen (what do you write above and below the arrow on the word equation)
Chlorophyll
Light energy
How is a broad leaf a good adaptation for photosynthesis
Gives a large surface area to trap light
Where in the leaf does most photosynthesis occur
Palisade layer
How is the palisade layer a good adaptation for photosynthesis
The cells are packed with chloroplasts to trap light
The layer is near the top of the leaf to catch as much light as possible
The cells sit upright and are long and rectangular - more cells packed into the layer
How do gases enter and leave the leaf
Through the stomata on the lower epidermis
Why does the spongy layer have large air spaces
tTo allow rapid gasous exchange
How do you test for starch and what is the colour change
Add iodine
Turns from yellow brown to blue black
How do you test a leaf for starch
Heat leaf in boiling water
Add leaf to a test tube of ethanol and heat in water bath
Wash leaf in water
Spread leaf and cover with iodine
What is the purpose of boiling the leaf in water
To stop chemical reactions and weaken cell wall
What is the purpose of heating the leaf in a test tube of ethanol
To remove the green chlorophyll
Why do you wash the leaf after it has been in the ethanol
The leaf is brittle so washing it softens the leaf
Another way to test a leaf is to count the number of bubbles produced. What gas is present in the bubbles
Oxygen
How would you measure the rate of photosynthesis using the bubbles produced by the plant
Count number of bubbles over a period of time
Then calculate rate = bubbles per min
What factors can limit the rate of photosynthesis
LIght intensity
Carbon dioxide concentration
Temperature
How do plants use the glucose produced in photosynthesis
Store as starch
use in respiration for energy
Convert glucose to amino acids to make proteins for growth
Convert to cellulose for cell walls
Convert to fats and oils for storage
On a limiting factors graph describe what shape the graph would be and what it means
The line graph will initially rise up and then level out
It rises due to the factor on x axis being the limiting factor - as this factor increases e.g. light intensity the rate of photosynthesis increases.
The graph levels out as the factor on the x axis is no longer a limiting factor but one of the other 2 factors is now.
In an experiment to compare the rate of photosynthesis and the rate of respiration. What is the indicator used
Hydrogen carbonate
What does hydrogen carbonate detect
Changing levels of carbon dioxide
Turns red to purple if carbon dixoide levels decrease
Turns red to yellow if carbon dioxide levels increase
In an experiment of a plant under light the hydrogen carbonate turns from red to purple. What does this mean
This means that the level of Carbon dioxide has decreased.
The rate of photosynthesis (uses carbon dixoide) is greater than the rate of respiration (produces carbon dioxide)
In an experiment of a plant in hydrogen carbonate the hydrogen carbonate stays red. What are the light conditions that cause this and what does it mean
The light conditons - low light intensity eg. sunrise/sunset
stays red as the rate of photosynthesis = rate of respiration
This is called the compensation point
