Topic 6- Plant structures and their functions Flashcards
Describe photosynthetic organisms as the main producers of
food and therefore biomass
At the base of almost every food chain is a producer . These are plants or algae , which photosynthesise.This means they convert energy from the sun into glucose during photosynthesis producing biomass. which feeds the rest of the food chain.
Explain how the structure of the root hair cells is adapted to
absorb water and mineral ions.
- has a large surface area to increase rate of absorption
- has lots of mitochondria which releases lots of energy from glucose that can be used for active transport
(concentration of mineral ions is higher in the root hair cell than the soil -active transport)
Describe photosynthesis in plants and algae
reaction that uses light energy
Carbon dioxide + Water –> Oxygen + Glucose
This is an endothermic reaction, and it has chlorophyll (in the chloroplast) to absorb the light energy.
Explain how the structures of xylem and phloem are adapted to their function in the plant.
Phloem : (transports food)
- the tubes are made of columns of elongated living cells
- this process is called translocation and it requires energy from respiration - transport goes both ways
Xylem: (moves water up)
-tubes are made from dead cells which are strengthen by a material called lignin.
- process transpiration
Explain how water and mineral ions are transported through the plant by transpiration , including structure and function of stomata
Water is lost from the plant’s leaves by diffusion and evaporation. This creates a slight storage of water in the leaves , so more water is drawn up from the xylem vessels to replace it. This in turn means there’s more water drawn from the roots, so there is a constant transpiration stem through the plant.
Stomata - tiny pores on the surface of the plant , and allows C02 and oxygen to diffuse directly in and out of the leaf. Also allows water vapour to escape during transpiration.
Describe how sucrose is transported around the plant by translocation
The sucrose is transported around the plant through the phloem vessles. It needs to be able to reach all cells in the plant so the the sucrose can be converted back into glucose through respiration.
How the structure of a leaf is adapted for photosynthesis and gas exchange
- Large surface area to maximise light absorption( means more chloroplast containing chlorophyll)
- Thin structure means a shorter diffusion distance for carbon dioxide to diffuse into leaf cells.
Explain the effect of environmental factors on the rate of water
uptake by a plant, to include light intensity, air movement and temperature.
Light intensity- the brighter the light, the greater the transpiration rate because the stomata would be open to allow wore carbon dioxide into the leaf for photosynthesis.
Temperature- the warmer it is the faster the transpiration rate , when its warm water particles have more energy to evaporate and diffuse out of the stomata.
Air flow- the better the air flow around the leaf the better the transpiration rate, because air removes water vapour , increasing the rate of diffusion of water vapour from the leaf.
How to calculate transpiration rate.
distance moved divide time taken
Explain how plants are adapted to survive in extreme
environments including the effect of leaf size and shape, the
cuticle and stomata
- the leaves are broad , so there’s a large surface area exposed to the light , which is needed for photosynthesis.
- waxy cuticle helps to reduce water loss by evaporation
- lower epidermis has lots of stomata , which lets Co2 to diffuse directly into the leaf
What does the spongy mesophyll tissue do
It contains air spaces which increase the rate of diffusion of gasses in and out the leaf’s cell
Explain how plant hormones control and coordinate plant
growth and development, including the role of auxins in
phototropisms and gravitropisms
Auxins- plant hormone which controls growth at the tip of the shoots and roots
Shoots: positively phototropic , negatively gravitropic
growing towards light away from gravity
Roots: positively gravitropic and negatively phototropic
towards gravity away from light
Explain the action of auxin is different in the roots and shoots of the plant
Roots- inhibits cell elongation
Shoots - promotes cell elongation
Describe the commercial uses of auxins, gibberellins
and ethene in plants, including:
a auxins in weedkillers and rooting powders b
gibberellins in germination, fruit and flower
formation and the production of seedless fruit c
ethene in fruit ripening
Auxin;
- selective weedkillers have been developed from auxins , which only affect broad leave plants, whilst leaving crops and the plants untouched.
-then end of the branch that has been cut off , won’t grow on its own , but by adding rooting powder which contains auxin will produce roots rapidly
Gibberellins;
- can be used to control flower /fruit formation
- can produce seedless fruits , when inserted into unpollinated flowers.
- Can control seed germination
Ethene;
- makes food ripen quicker when on their way to a supermarket
