The Leaf / Plant Tissues Flashcards
(24 cards)
what is the order of size for cells?
similar cells - tissues - organs - organ systems
what are the 7 main features of a leaf?
waxy cuticle, upper epidermis, palisade cells (mesophyll), spongy mesophyll, lower epidermis, guard cells, stoma/stomata
what is the function of the waxy cuticle?
waterproof barrier that covers the leaf
what is the function of the upper epidermis?
transparent to allow sunlight to pass through and reach the palisade cells
what is the function of the palisade cells?
tightly packed, no light misses them to hit the chloroplasts and carry out photosynthesis
what is the function of the spongy mesophyll?
irregular shapes, lots of air spaces, allowing gases to diffuse
what is the function of the lower epidermis?
include guards cells (exit or entrance) which also include stoma/stomata allowing gases in and out
what is the vascular bundle?
includes xylem and phloem, carrying water in and taking away glucose once it has been made
why is the palisade layer packed with chloroplasts?
allowing photosynthesis to occur
why does a leaf have a broad shape?
increasing surface area to catch more light
why are leaves thin, have lots of air spaces and have lots of stomata?
allowing rapid diffusion for gas exchanges
why do leaves have guard cells?
to control is the stomata is open or closed
what does the waxy cuticle layer reduce?
water loss by evaporation
what is translocation mainly achieved by? (cells)
phloem cells - arranged end to end to form long tubes
what do pores in the gaps of phloem cells allow?
they enable the movement of cell sap (liquid mixture of water and sugar)
what 2 things can sugars be used for after transported to the specific cells during translocation?
-directly for energy
-stored
that are xylem cells made up of?
dead xylem cells - have no ends between them, forming one long hollow tube
what is the role of the xylem tube?
transport water and mineral ions from the roots up the stem to the leaves from roots to leaves
what is the evaporation of water from the leaves called?
transpiration
what are the 4 factors that affect transpiration?
-light intensity
-temperature
-air flow
-humidity
what happens if there is more light intensity in transpiration?
-more photosynthesis
-more stomata open to let in carbon dioxide
what happens if there is a higher temperature in transpiration?
-higher rate (water particles have more energy)
-water more likely to evaporate
-occurs faster
what happens if air movement in transpiration is high?
-water molecules are quickly going to be blown away
-concentration gradient is kept high
what happens with high levels humidity during transpiration?
-decrease rate
-large amount of moist air would decrease concentration
-less water will diffuse — less evaporation overall
