CB6 Flashcards
All living things need glucose to …
Repairs and release energy to live
All food chains start with ______ or _____ which photosynthesise to make _______ - they are called __________ ….
All food chains start with plants or algae which photosynthesise to make glucose - they are called producers. They store this and when they get eaten, the animals get their source of energy from the stores.
Plants and animals use energy from food to make _____ - all materials in an organisms is known as ________ …
Plants and animals use energy from food to make cells - all materials in an organism is known as biomass. All biomass ultimately comes from producers as the plant biomass is the food for the animals that eat them
Where does photosynthesis happen?
Inside chloroplasts - they contain chlorophyll which absorbs light
Energy is transferred to the chloroplasts by light
Equation for photosynthesis
Carbon dioxide + water —glucose + oxygen
What kind of reaction is photo synthesis?
An endothermic reaction - energy is taken
It uses light energy to react carbon dioxide and water to produce glucose and oxygen
Method to investigating how light intensity effects photosynthesis
Put Canadian pondweed into a conical flask with water and a stopper
Place a source of light at a specific distance
Set time for photosynthesis to happen
Oxygen will be collected in gas syringe
Repeat at different light distances
Volume / time taken
What are the controls of investigating light intensity on photosynthesis?
Temperature - put conical flask in water bath
Carbon dioxide concentration - set amount of sodium hydrogencarbonate to a set volume of water
How does light intensity effect photosynthesis?
Light transfers energy needed for photosynthesis
As the light level increases - the rate of PH increases steadily
At a certain point - it won’t make any difference
Light lamp and photosynthesis
They are inversely proportional
Light intensity decreases in proportion to the square of the distance
How does carbon dioxide effect photosynthesis?
Increasing the carbon dioxide concentration increases the are if photosynthesis up to a point
After the graph flattened out and showing that carbon dioxide is no longer the limiting factor
As long as light and carbon dioxide are in plentiful supply then the factor limiting photosynthesis is temperature
How does temperature effect photosynthesis?
The enzymes needed for photosynthesis work more slowly at low temperatures
If the plants get too hot, the enzymes will be denatured
Happens around 45 degrees
How is the root hair cell adapted to absorb water?
The hairs stick out into the soil - each branch will be covered in millions of these hairs
This gives the plant a large surface area for absorbing water and mineral ions from the soil
The concentration of mineral ions are higher in the root hair cells than in …
In the soil around them so mineral ions are absorbed by active transport
What is the water transported by?
Osmosis
How are the phloem tubes adapted?
Made out of columns of elongated living cells with small pores in the end walls to allow stuff to flow through
Phloem tube - translocation
They transport food substances made in the leaves to the rest of the plant for immediate use or for storage
Translocation requires energy from respiration - goes in both directions
How are xylem tubes adapted?
Made out of dead cell joined end to end with no end walls between them and a hole down the middle - they are strengthened with a material called living
What do xylem do?
They carry water and mineral ions from the roots to the stem and leaves -
What is transpiration steam?
The movement of water from the roots, through the xylem and out of the leaves
What is transpiration caused by?
The evaporation and diffusion of water from a plants surface - most transpiration happens at leaves
What is transpiration?
The loss of water from the plant
How does transpiration happen?
The loss of water creates a slight shortage of water in the leaf and so more water is drawn up from the rest of the plant through the xylem vessels to replace it. This means more water is drawn up from the roots - constant transpiration stream
What does the transpiration stream carry?
Mineral ions that are dissolved in the water along with it
How is sucrose transpired around the plant?
Phloem transports food substances mainly sucrose made in the leaves to the rest of the plant for immediate use or for storage
It requires energy from recitation
Translocation
The structure of stomata
They are tiny pores on the surface of a plant
They allow carbon dioxide and oxygen to diffuse directly in and out of a leaf
They also allow water vapour to escape during transpiration
Why is the stomata needed for gas exchange?
So that the gases can be exchanged easily there is more water inside the plant than in the air outside, the water escapes from the leaves through the stomata by diffusion
How does light intensity affect the transpiration rate?
The brighter the light the greater the transportation rate
Stomata begin to close as it gets darker, photosynthesis can’t happen in the dark so they don’t need to be open to let carbon dioxide in
When the stomata is closed - very little water vapour can escape
How does the temperature affect the transpiration rate?
The warmer it is, the faster the transpiration happens
When it’s warmer the water particles have more energy to evaporate and diffuse out of the stomata
How does air flow affect the transpiration rate?
The better the air flow around a leaf the greater the transpiration rate
If air flow around the leaf is poor, the water vapour just surrounds the leaf and doesn’t move away - this means that there’s a high concentration of water particles outside the leaf as well as inside it so diffusion happens slowly
How do you calculate the rate of transpiration?
Potometer - measures water uptake
Record the distance moved by the bubble per unit time
Calculate the speed of air bubble movement and estimate the transpiration rate
Distance moved/time taken
