B6 Flashcards
What is photosynthesis?
A chemical reaction that tasked place inside a plant converting light energy into chemical energy
Write the word equation for photosynthesis?
Carbon dioxide + water -> Glucose + oxygen
Why is photosynthesis important?
Produces glucose which is used in respiration to release energy.
Converted to starch and stored.
Where does photosynthesis take place ?
Chloroplast
What type of reaction is photosynthesis?
Endothermic reactions
What is chlorophyll?
A pigment found in chloroplasts that absorb light
What factors affect the rate of photosynthesis?
1.temperature
2.light intensity
3.carbon dioxide concentrations
What is a limiting factor ?
A variable that limits the rate of a reaction
How does temperature affect the rate of photosynthesis?
> Higher temperatures can cause enzymes to be denatured and rate of photosynthesis decreases
How does light intensity affect the rate of photosynthesis?
Rate of photosynthesis is directly proportional to light intensity
How can the effect of light intensity on the rate of photosynthesis be measured in the lab ?
> using a light meter
using the inverse square law where:
Light intensity is directly proportional to 1over distance squared
Why does the rate of photosynthesis decrease as the distance from a light source increases?
Light intensity is inversely proportional to the square of the distance from the light source
How does carbon dioxide concentration affect the rate of photosynthesis?
As carbon dioxide concentration increases the rate of photosynthesis increases
Why do plants require water ?
Photosynthesis, maintenance of structure
Why do plants require minerals ions ?
For growth
Which structure in plants is adapted for the uptake of water and minerals?
Root hairs
How is water transported into root hairs ?
Osmosis
How are minerals transported into the root hair ?
Active transport
How are roots adapted for the absorption of water and minerals?
Long hairs that extend from the cell body to increase surface area and absorption
What are the 2 transport tissues?
Xylem and the Phloem
What is the function of the xylem?
Transport water and minerals up the plant from the root to the leaves via the transpiration stream
Describe how the xylem is adapted to its function ?
- Composed of dead cells laid end to end to form a hollow column
- Thick cell wall strengthened with lignin to provide support
What is the function of the phloem ?
Transported sugars up and down the stem from photosynthetic tissues via translocation
What are the 2 cell types that make up the phloem ?
Seine tube Elements and companion cells
How is the phloem adaptation of sieve tube elements good for its function ?
They are long thin tubes with perforated end plates to enable the flow of sugars
How is the phloem adaptation of companion cells good for its function ?
Contain a dense cytoplasm, nucleus and mitochondria.
They provide energy for processes in both cell types
What is transpiration?
The loss of water vapour from the parts of a plant exposed to the air due to evaporation and diffusion
Where does the most transpirtation take pace ?
Leaves
What is the process of transpiration?
- Water evaporates from the mesophyll cell surfaces and diffuses out of the stomata
- Water molecules are drawn up the xylem vessels to replace the water that has been lost
- This causes more water molecules to be absorbed from the soil into the root hair cells
What are stomata ?
They are pores found in the lower epidermis of a leaf which allow gas exchange
What are guard cells ?
Specialised cells surrounding the stoma that change shape to control the size of the pore
How do guard cells open the stomata ?
Water enters the cell and it then swells and becomes turgid meaning the cell bands and draw away from each other opening the stomata
How do guard cells open the stomata ?
Water enters the cell and it then swells and becomes turgid meaning the cell bands and draw away from each other opening the stomata
How do the guard cells close the stomata?
Water leaves the cell they become flaccid which closes the stomata
What factors affect the rate of transpiration?
Light intensity, temperature and air movement
What apparatus is used to measure the rate of transpiration?
Photometer
What equation is used to calculate the rate is transpiration using a Photometer?
Distance moved by bubble /time take
