topic 6 - plant structures and their functions Flashcards
what happens during photosynthesis
photosynthesis occurs when light energy from the sun is used to react carbon dioxide from the atmosphere and water from the soil to produce glucose and oxygen. this means that plants are producers
is photosynthesis an exothermic or endothermic reaction
photosynthesis is an endothermic reaction because it taken in energy from the environment
what is the word equation for photosynthesis
carbon dioxide + water ⟶ glucose + oxygen
arrow - (light and chlorophyll)
what happens to the glucose made by the plant
respiration
storage (as starch)
cellulose (to build cell walls)
minerals (to absorb minerals by active transport)
what 4 things affect the rate of photosynthesis
which are the 3 main ones
- temperature
- light intensity
- carbon dioxide concentration
- (chlorophyll)
how does temperature affect the rate of photosynthesis
- at low temps, the enzymes that drive photosynthesis are lacking in kinetic energy so don’t collide with the substance
- has an optimum temp
- above the optimum temp, the enzymes cannot work, they become denatured and the shape of the acive site changes
how does light intensity/carbon dioxide/chlorophyll affect the rate of photosynthesis
- as the amount of light increases, so does the rate. the limiting factor is light
- after the saturation point, increasing the light has no effect on the rate, the limiting factor is now carbon dioxide or temperature or chlorophyll
what is inverse square law
we can work out light intensity when we change how far away a light source is away from a plant by using inverse square law
what is the equation for inverse square law
intensity = 1 / (distance)2
what is the core practical for light intensity and photosynthesis
how does water get into plants
1 - high concentration of water in soil
2 - low concentration of water in root
3 - water enters the root by osmosis, through the partially permeable membrane
4 - water moves through root by osmosis
5 - water enters vessels called xylem vessels to be carried to the leaves
why do plants need water
- photosynthesis
- carrying dissolved mineral ions around the plant
- keeping cells rigid
- cooling the leaves
how do minerals get into the plant
1 - there is a low concentration of minerals in the soil
2 - there is a higher concentration inside the plant root
3 - minerals enter by active transport against a concentration gradient
4 - root hairs have lots of mitochondria to supply their energy
5 - the mineral ions are dissolved in water and carried in the xylem vessels
how do plants use active transport
- active transport uses energy from respiration to move substances against a concentration gradient ( low to high)
- specific minerals from the soil e.g nitrates to make proteins enter through the root hair cells
- the minerals then travel around the plant in the xylem vessels
how are root hair cells specialised to absorb substances from the soil
- large surface area (long and thin)
- lots of mitochondria to supply energy for active transport
- NO CHLOROPLASTS
what are stomata
the stomata are small openings on the underside of leaves. they allow gas exchange with the atmosphere
how many guard cells are there per stomata
2 guard cells per stomata
what happens when the stomata are open
water vapour evaporates through them as well
what happens to stomata during the morning (how do they open)
water flows into the guard cells by osmosis which causes the guard cells to swell and bend, forming an opening
what happens to stomata during the night (how do they close)
water flows out of the guard cells by osmosis and they shrink, the stomata disappears
what is the function of xylem tissue
transport water and minerals from the roots to the leaves
are the xylem cells alive or dead
dead hollow tubes
how are the xylem vessels adapted to their function
- dead hollow tubes, very little resistance to water flow
- they contain lignin which gives strength to the vessels to prevent them from collapsing
what is the function of phloem tissue
transport the sugars the plant makes in photosynthesis. the sugars are changed into sucrose
