Topic 6 - Plant Structures and Their Functions Flashcards
Define osmosis.
Movement of water molecules from a high concentration to a low concentration through a partially permeable membrane. Requires no energy.
Define diffusion.
Particles moving from a high concentration to a low concentration down a concentration gradient. Requires no energy.
Define active transport.
Movement of particles from low to high concentration up a concentration gradient, requiring energy.
What is the word equation for photosynthesis?
LIGHT
carbon dioxide + water → glucose + oxygen
CHLOROPHYLL
What is the symbol equation for photosynthesis?
LIGHT
6CO2 + 6H2O → C6H1206 + 602
CHLOROPHYLL
What are the limiting factors of photosynthesis?
- light intensity
- concentration of CO2
- temperature
How are mineral ions absorbed by root hair cells?
And why?
Active transport - the concentration of mineral ions is usually higher in the root hair cells rather than the soil.
How is water absorbed by root hair cells?
Osmosis.
How are root hair cells adapted to their function?
- They are covered in millions of microscopic hairs
- Large surface area
- Thin membrane
What does the phloem transport?
Food substances, mainly sucrose.
What is translocation?
It is where the phloem transports food substances made in the leaves to the rest of the plant, requiring energy from respiration.
What is the structure of the phloem?
It is made of columns of elongated living cells with small pores in the end walls to allow things to flow through.
What does the xylem transport?
Water and mineral ions.
What is the structure of the xylem?
It is made of dead cells joined end to end with no end walls between them and a hole down the middle. They are strengthened with lignin.
What is lignin?
A complex organic polymer deposited in the cell walls of plants to strengthen them.
What is transpiration?
The process where water and mineral ions are transported up the xylem against the force of gravity from the roots and out of the pores of leaves.
What factors affect transpiration rate?
- Light
- Wind
- Temperature
- Humidity
How does light affect the rate of transpiration?
The stomata open wider, allowing more CO2 into the leaf for photosynthesis and increasing transpiration rate.
How does temperature affect the rate of transpiration?
Evaporation and diffusion are faster at higher temperatures.
How does humidity affect the rate of transpiration?
Diffusion of water vapour out of the leaf slows down if the leaf is already surrounded by moist air.
How does wind affect the rate of transpiration?
Water vapour is removed quickly by air movement, speeding up diffusion of more water vapour out of the leaf.
What are stomata?
Tiny pores on the surface of a plant.
How are stomata adapted to their function?
- They are surrounded by guard cells, which change shape to control the size of the pore. When turgid, the stomata are open. When flaccid, they are closed.
What is the function of stomata?
Allow carbon dioxide and oxygen to diffuse directly in and out of a leaf. They also allow water vapour to escape during transpiration.