Photosynthesis Flashcards
What is photosynthesis?
The process in which plants and algae make their own food
What can the food made by plants and algae be used for? (2 points?
- used in RESPIRATION for energy
- turned into other compounds such as PROTEINS and FATS for GROWTH
What provides energy for the photosynthesis reaction?
Light waves from the sun transfer energy to the chloroplast for the reaction
Where does photosynthesis occur in a plant?
Occurs in the chloroplasts of green plant cells
What is the written formula for photosynthesis?
light
Carbon dioxide + water ———> glucose + oxygen
What is the chemical formula for photosynthesis?
light
6CO2 + 6H2O ———> C6 H12 O6 + 6O2
What does the energy transferred cause a reaction between in photosynthesis?
The energy transferred causes a reaction between carbon dioxide and water and produces glucose and oxygen
What type of reaction is photosynthesis and why?
An endothermic reaction+ it requires energy
What are the five main ways plants use glucose?
- respiration
- produce cellulose
- produce amino acids
- produce lipids
- converted into insoluble starch
Why is glucose that is produced in photosynthesis used for respiration?
Transfers energy from some of the glucose to enable plants to convert the rest of the glucose into other useful substances
Why is glucose that is produced from photosynthesis used to produce cellulose?
For making strong plant cell walls
Why is glucose that is produced from photosynthesis used to produce amino acids?
For protein synthesis by combining glucose with nitrate ions absorbed from the soil
Why is glucose that is produced from photosynthesis used in producing lipids?
produces fats and oils for storing in seeds
Why is glucose that is produced in photosynthesis converted into insoluble starch?
For storage in roots+stems+ leaves ready for use when photosynthesis isn’t happening
By what process would nitrate ions be taken from the soil into the root?
Active transport
Why is it useful for the plant to store sugar in the cells in the roots?
It provides a concentration gradient to ensure water moves into the roots by osmosis
Compare the timings of photosynthesis with respiration
Photosynthesis only happens during the day and respiration can happy in the day and at night (all time)
What is much of the glucose made from photosynthesis turned into?
Turned into starch for storage
What can the presence of starch tell us? (2 points)
-Tells us that the plant has been photosynthesising
-glucose made has been turned into starch
Why do we first need to remove the green chlorophyll?
- to avoid interference from the chlorophyll So that the colour change is visible
What is a variegated leaf?
A leaf that has white edges around it
What is a hazard in the testing a leaf for starch experiment and what safety protocol must we take? (2 points)
- ethanol is highly flammable
- Bunsen burner must be switched off before collecting ethanol
What are three safety protocols needed in testing a leaf for starch experiment?
- stools under bench
- hair tied back
- goggles on
Which parts of a variegated leaf contain chlorophyll and which parts don’t? (2 points)
1- green parts contain chlorophyll
2- pale parts don’t contain chlorophyll
Why do only the green parts of the leaf test positive for starch and how would we recognise the presence of starch ?
- some of the glucose from photosynthesis is converted into starch for storage there
- the iodine turns blue/black to show presence of starch
Why do the pale areas not test positive for starch?
Without chlorophyll pale areas don’t photosynthesis and so there is no glucose to convert to starch
Describe the conclusion of the results from the testing the lead for starch (4 points)
- only the parts of the leaf containing chlorophyll contain starch
- only the parts of the leaf containing chlorophyll caused iodine to change from orange/brown to a black/blue colour
- this is because photosynthesis only happens in the parts of a leaf containing chlorophyll
-where some of the glucose produced is converted into starch
In the Experiment if the chemical reactions in the leaf were not stopped the amount of starch in the leaf would decrease, why is this?
The starch begins to be broken down for respiration
How does the presence of starch show that photosynthesis has been taken place?
Glucose has been converted into starch
