organisation in plants Flashcards
what are all the tissues in leaves?
waxy cuticle, upper epidermis, palisade mesophyll, spongy mesophyll, stomata, guard cells
what is a waxy cuticle?
makes the leaf waterproof
what is the upper epidermis?
single later of cells, protects against water loss, transparent to allow light to pass through
what is the palisade mesophyll?
tightly packed cells, lots of chloroplasts to absorb the light for photosynthesis
what is the spongey mesophyll?
spherical cells, lots of air spaces to allow gases to diffuse quickly, large surface area-to-volume ratio to increase gas exchange
what is the stomata?
tiny opening on the lower surface of the leaf that allow gases to move into and out of the leaf
what is the guard cells?
control the opening and closing of the stomata
what are stomata?
tiny openings in the undersides of leaves, the placement reduces water loss through evaporation
how do they control the gas exchange and water loss in a leaf
allowing diffusion of carbon dioxide into the plant for photosynthesis, allowing diffusion of oxygen out of the plant
what is transpiration?
the constant movement of water up the plant
what is the importance of transpiration?
provides water to cells to keep them turgid, provides water to cells from photosynthesis, transports minerals ions to leave
what is the description of a xylem vessel?
one-way transport only, water and minerals, made of dead cells joined together with no end walls between them, thick walls stiffened with lignin
what is translocation?
the movement of dissolved sugars from the leaves to the rest of the plant through the phloem
what is the importance of translocation?
moves dissolved sugars made in the leaves during photosynthesis to other parts of the plant, this allows for respiration, growth and glucose storage
what is the description of a phloem vessle?
water and dissolved sugars, cells have end walls with small holes to allow substances to flow through, substances transported in both directions
what is the factord effecting transpiration
temperature, humidity, wind speed, light intesity
how does temperature effect transpiration?
high temperatures increase the rate of transpiration
how does humidity effect transpiration?
lower humidity increases the rate of transpiration
how does wind speed effect transpiration?
more wind increases the rate of transpiration
how does light intensity effect transpiration?
higher light intesity increase the rate of transpiration
why does temperature effect transpiration?
water evaporates faster in higher temperatures
why does humidity effect transpiration?
the drier the air, the steeper the concentration gradient of water molecules between the air and leaf
why does wind speed effect transpiration?
wind removes the water vapour quickly, maintaining a steeper concentration gradient
how does light intensity effect transpiration?
stomata open wder to let more carbon dioxide into the leaf for photosynthesis
