Plant structures and functions Flashcards
Protists
Plants and algae (can trap energy transferred by light from the sun_
Glucose
Molecules of sugar
Photosynthesis
Transferring light energy from the sun into glucose and using it for respiration
Biomass
The materials in an organism
Photosynthesis equation
Carbon dioxide + water ——> glucose + oxygen
Where does photosynthesis occur
In the chloroplast, which contains a green substance called chlorophyll that traps energy transferred by light
What type of reaction is photosynthesis
Endothermic reaction
Glucose molecules are linked together to form
Starch (a polymer)-> which is broken down into simpler substances which are moved to the cytoplasm and used to make sucrose
Palisade cells
Near thr top of the leafy, packed with chloroplasts to allow a leaf to absorb more light
Stomata
Microscopic pores that allow carbon dioxide to diffuse into the leaf, to be used for photosynthesis.
Guard cells
The stomata are opened by guard cells which are controlled by water flow. When there is more light, they are more rigid and at night, they lose their water and become less rigid
Concentration of air molecules effect on photosynthesis
Lower rate of photosynthesis in high mountains compared to sea level because of a reduced concentration of air molecules
Temperature effect one photosynthesis
Reactions in photosynthesis are catalysts by enzymes that work better at warmer temperatures. High altitudes are colder (less photosynthesis at top of mounts)
Limiting factor
A factor that prevents a rate increasing (e.g carbon dioxide, temperature, light intensity)
The water absorbed by plant roots is used for:
- Carrying dissolved mineral ions
- Keeping cells rigid
- Cooling the leaves
- Photosynthesis
Hoot hair cells
The outer surfaces of roots are covered by root hair cells.
They are an extension of the cell to prove larger surface area (to dissolve the ions quicker)
They have thin walls so the flow of water is not slowed down
Xylem vessel
Carries water
Phloem tissue
Carries sugars
Transpiration
The flow of water into a root, up the stem and out of the leaves
Xylem vessels
Form continuous pipes leading from a plants roots up into its leaves.
What is inside xylem vessels
An unbroken chain of water. Water is pulled up the xylem vessels in the stem as water evaporates in the leaves.
Xylem
During their development, xylem cells die and their top and bottom cell walls disintegrate. This create long empty vessels through which water can move easily.
Xylem vessels are rigid because they have thick side walls and rings of hard lignin and so water pressure inside the vessels does not burst or collapse them
Phloem
Plants make sucrose from the glucose and starch made by photosynthesis. Sucrose is translocated in the sieve tubes of the phloem tissue.
The large central channel in each sieve cell is connected to its neighbors by holes
Companion cells
Actively pump sucrose into or out of the sieve cells that form the sieve tubes
