Osmosis And Transpiration Flashcards
What is osmosis?
Osmosis is:
The movement (diffusion) of water
from a dilute solution to a more concentrated solution
through a selectively permeable membrane
because the sugar molecules are too large to pass across the membrane.
What happens when water moves into a plant cell by osmosis?
Water moves in so that the cytoplasm (and vacuole) increases in volume.
The cell membrane is pushed up against the cell wall.
The pressure inside the cell increases and the cell is turgid.
What happens when water moves out of a plant cell by osmosis?
Plasmolysis occurs. This happens when too much water has left the plant cell and its contents shrink.
The cell membrane pulls away from the cell wall.
The vacuole gets smaller.
How does a plant’s cellulose cell wall help it?
Plant cells have a cellulose cell wall and therefore they are prevented from taking in too much water and bursting. The cell wall limits the entry of water.
What is cell lysis?
Since animal cells don’t have a cell wall to stop more water from entering they burst.
What is transpiration?
Transpiration is the evaporation of water from the spongy mesophyll cells in plant leaves, through the air spaces and subsequent diffusion through the stomata.
What are the 5 factors that affect the rate of transpiration in plants?
Wind- windy conditions increase the rate of transpiration. Water molecules are blown away from the leaf surface, so more diffuse out of the stomata.
Humidity- humid conditions decrease the rate of transpiration as the air contains a lot of water already.
Warmth- warm conditions increase the rate of transpiration.
Light - light causes the stomata to open, so the rate of transpiration will increase.
Leaf Surface area - while not an environmental factor, leaf surface area affects the rate of transpiration. Larger or more leaves will have more stomata through which water can evaporate.
What do plants use water for?
Plants use water for support, transport, transpiration and photosynthesis.
What are the layers of plants from top to bottom?
Waxy cuticle, upper epidermis, palisade mesophyll, spongy mesophyll, lower epidermis.
