B6 - Plant Nutrition Flashcards
What is photosynthesis? [2]
process by which plants synthesise carbohydrates from raw materials using energy from light
What is the word equation for photosynthesis? [2]
carbon dioxide + water —> glucose + oxygen
What is in the presence of photosynthesis? [2]
- light
- chlorophyll
What is chlorophyll? [2]
- green pigment
- found in chloroplasts
What is the balanced symbol equation for photosynthesis? [3]
6CO₂ + 6H₂O —> C₆H₁₂O₆ + 6O₂
What does chlorophyll do? [2]
- absorbs light
- transfers light energy into chemical energy
Why does chlorophyll transfer light energy to..? [2]
- chemical energy
- for the synthesis of carbohydrates
Where does the carbon dioxide needed for photosynthesis come from? [1]
air
By which process does carbon dioxide move? [1]
diffusion
How does carbon dioxide get into the leaf? [1]
through the stomata
Where does the light energy needed for photosynthesis come from? [1]
sun
How are leaves adapted to absorb the maximum amount of light? [1]
large surface area
What sort of reaction is photosynthesis? What does this mean? [2]
- endothermic
- it needs energy to keep it going
Why doesn’t photosynthesis happen in the roots? [2]
- no chloroplasts in the roots
- its underground and doesn’t get any light
What is glucose? [1]
a sugar
What does the plant use glucose for? [2]
- respiration
- growth
How is extra glucose stored by the plant? [1]
stored as starch in the leaf
What does biomass mean? [1]
how heavy the plant is
Where is chlorophyll found? [1]
in the chloroplasts
What is cellulose used for? [1]
building cell walls
What is sucrose used for? [1]
transport in the phloem
What is nectar used for? [1]
attract insects for pollination
What are the 2 main minerals plants require? [2]
- nitrate ions
- magnesium ions
What are nitrate ions used for? [2]
- protein synthesis
- making amino acids
What are magnesium ions used for? [1]
production of chlorophyll
How do plants get their minerals? [4]
- soil
- dissolved in water
- enter through the roots via osmosis
- enter through the soil via active transport
How does water needed for photosynthesis enter the plant? [1]
through the roots
Where does the water needed for photosynthesis come from? [1]
the soil
By which process does the water needed for photosynthesis enter? [1]
osmosis
How does the water needed for photosynthesis travel to the leaves? [1]
xylem vessel
Why is it important that plants store some of their glucose as starch? [3]
- provides a store of energy
- used at night when plant can’t photosynthesise
- used for respiration
Why are plants called producers? [1]
they produce their own food
What is a variegated leaf? [2]
- a leaf which has chlorophyll in some parts but doesn’t have chlorophyll in some parts
How can carbon dioxide be removed from the air surrounding the leaf? [4]
- leaf is destarched to get rid of all prior starch
- leaf put into an airtight bag
- bag contains CO₂ remover (limestone or soda lime)
- other gases like oxygen still present
What is destarching and how is it done? [3]
- plant should be in the dark for at least 24hrs
- removes all stores of glucose
- this is done to see if any starch was made during the experiment
How is light removed from the leaf? [4]
- leaf destarched for around 24hrs
- piece of cardboard or dark paper is put on top of a section of the leaf - not allowing light to enter
- whole leaf is not covered - so there is a control and so that we can see the difference
- it is put in the light for 24hrs afterwards
What’s the method for testing a leaf for starch? What is the reason for doing each step? [8]
- boil the leaf in water for 2 minutes
- breaks down the cell walls and stops enzyme action with the leaf - the leaf is then warmed in warm ethanol until it turns colourless
- it takes out chlorophyll as chlorophyll only dissolves in ethanol and not water - the leaf is then dipped into water briefly
- allows penentration by iodine solution and softens the brittle leaf - the leaf is then placed on a white tile where iodine solution is added to it
- iodine shows if there is starch or not and colours can be easily seen on top of a white tile
What are safety precautions to take when testing a leaf for starch and reasons why they are taken? [4]
- safety goggles
- in case ethanol or hot water gets in your eyes - ethanol
- it’s flammable so make sure the bunsen burner is turned off
What are the limiting factors of photosynthesis? [3]
- light intensity
- carbon dioxide concentration
- temperature
What do the graphs for carbon dioxide concentration and light intensity look like? [3]
- rate of photosynthesis gets higher as both factors increase
- then it levels off
- graph = up then mid straight
What does the graph for temperature look like? [3]
- rate of photosynthesis increases the higher the temperature
- if temperature gets too high the enzymes will denature and reaction will stop
- graph = up then down
How do leaves having a large surface area benefit for photosynthesis? [1]
it can absorb lots of sunlight
How do plants being very thin benefit for photosynthesis? [1]
gases do not have to travel very far
What is the function of the waxy cuticle? [2]
- helps in water proofing the leaf
- this prevents water loss
What is the function of the upper epidermis? [3]
- acts as a protective layer
- barrier to disease organisms
- allows sunlight to penetrate
What is the function of the palisade mesophyll layer? [3]
- main region for absorption of light for photosynthesis
- near leaf surface = maximum light intensity
- most chloroplasts for maximum light absorption
How does the palisade mesophyll layer being close to the airspaces and the vascular bundle help? [2]
- air spaces: chloroplasts to receive carbon dioxide and release oxygen (gas exchange)
-vascular bundle: receive water and sending sucrose
What is the function of the spongy mesophyll layer and air spaces? [2]
- air spaces allow gas exchange
- carbon dioxide to the cells and oxygen from the cells during photosynthesis
What is the vascular bundle? [2]
- contains xylem vessels
- contains phloem vessels
What is the function of the xylem vessels? [2]
- transports water and minerals to the leaf
- supports the leaf and stem
What is the function of the phloem vessels? [2]
- transports sucrose sugars and amino acids away from the leaf
What is the function of the lower epidermis? [2]
- acts as a protective layer
- contains the stomata and guard cells
What is the function of the guard cells/stomata? [2]
- guards cells control the opening and closing of the stomata
- maintain the loss of water vapour during transpiration and allows carbon dioxide in
What are 4 factors that make photosynthesis happen efficiently? [4]
- method of exchanging gases
- way of delivering water
- way of absorbing light
- removal of glucose
