Plant Structures Flashcards
All living things need g______ to respire and release energy to live
Glucose
All food chains start with plants which photosynthesise to make glucose. These are p______
Producers
What is biomass?
All the material in an organism
Where does all biomass come from?
The producers
What is the photosynthesis equation?
Carbon dioxide+water—>glucose+oxygen
How is sunlight absorbed for photosynthesis?
The chlorophyll found in the leaves
What else can glucose be stored as?
Starch
What is an endothermic reaction?
A chemical reaction where the products have more energy than the reactants
Why is photosynthesis endothermic?
Because glucose and oxygen have more energy than carbon dioxide and water
How do root hair cell take in minerals and water?
- water enters via osmosis
- minerals taken up by active transport
How are root hair cells adapted to their function?
‘Hairs’ provide a large surface are for the water and mineral intake
Thin cell wall for a short path for water and minerals
Many mitochondria, providing energy for active transport
What is the difference in concentration of mineral ions in the cell than the soil?
Concentration of mineral ions is usually higher in the cells than the soil around them
What is a ‘limiting factor’?
Something that affects the rate of photosynthesis
What are the 3 limiting factors?
Light intensity
Carbon dioxide concentration
Temperature
What does the waxy cuticle of the leaf cell do?
Reduces water loss
What do palisade cells do?
Many chloroplasts for maximum photosynthesis
What does the spongy layer do?
Air gaps for carbon dioxide and oxygen to diffuse through the leaf
What do guard cells do?
Open and close the stomata
What does the stomata do?
Pores to allow gas exchange
- open in the day for CO2 for photosynthesis (water leaves)
- close at night to prevent water loss and wilting
What is transpiration?
Water moves up a plant in the xylem vessels and evaporates out through the stomata
What are the 5 steps of transpiration?
- Water enters root hair cells via osmosis
- Water enters bottom of xylem vessels from the root by osmosis
- Water is pulled up the xylem vessels
- Water enters the leaf cells by osmosis
- Water evaporates through stomata
What can be used to estimate the rate of transpiration?
Potometer
What is the equation for transpiration?
Distance bubble moves/time
mm/min
How and why does light affect the rate of transpiration?
In bright light, transpiration increases
Because more stomata open (more CO2 in)
How and why does temperature affect the rate of transpiration?
Transpiration is faster in higher temperatures
Evaporation and diffusion take place at a faster rate
How and why does wind affect the rate of transpiration?
Transpiration is faster in windy conditions
Water vapour is removed faster keeping concentration gradient steep
Why are xylem vessels long tubes with no ends?
Because ends would slow the water down
Why do xylem vessels contain lignin?
Makes walls strong
prevents collapse of xylem under pressure
Why are xylem vessels dead cells with no nucleus and little cytoplasm?
Dead cells - no energy is wasted
No nucleus + little cytoplasm - space for water to flow
Why do xylem vessels have tiny pores in the walls?
Allows water to move in and out
What is translocation?
When glucose is converted into sucrose an moves up and down the plant in the phloem tissue
What are the 2 parts of the phloem tissue and what do they do?
Companion cells - actively load sucrose into the sieve tubes
Sieve tubes - translocate sucrose up and down the stem
Why does the phloem tissue contain living cells?
So the cell can have active processes
Why do companion cells contain lots of mitochondria?
Cells can respire and release energy to actively load sucrose into sieve tubes
Why are there pores between the companion cells and the sieve tubes?
Allows sucrose to be actively loaded
