L5: Osmosis Flashcards
What is osmosis?
‘The google definition’ is “Osmosis is the net movement of water across a selectively permeable membrane from a high concentration to a low concentration.” It is also a special case of diffusion involving water.
What is a selectively permeable membrane?
This is a membrane which chooses and allows small molecules to pass through, but not larger ones.
What is a partially permeable membrane?
This is a membrane which has tiny holes in it and allows small molecules to pass through but not large molecules (by size).
What is the difference between a selectively permeable membrane and a partially permeable membrane?
A selectively permeable membrane selectively chooses what molecules can pass through whereas partially permeable membranes don’t, they allow molecules to pass through based on the size of the holes in the membrane.
How do plants rely on osmosis?
Plants rely on the movement of water through them. Root hairs take in water from the soil by osmosis.
What happens if too much water goes into the plant?
The plant cell wall stops the cell from bursting, this is known as a turgid cell. The vacuole fills all the space in the cell with water and pushes against the cell wall and turns the cell into a hexagonal shape. The plant will eventually die and can’t take in any more water.
What happens if too little water goes into the plant
The plant cell wall will also prolong (extend the duration of) the whole cell from shrinking, this is known as a plasmolysed cell. The vacuole will be much smaller and will take up less space in the cell. The plant will eventually die.
What is a brief definition of a turgid cell?
When there is a high water concentration outside the cell and osmosis occurs and gives the plant cell too much water making the vacuole’s size increases with water and pushes against the cell wall-the cell will become a hexagonal shape.
What is a brief definition of a flaccid cell?
When there are equal water concentrations inside and outside of the cell.
What is a brief definition of a plasmolysed cell?
When there is a low concentration of water outside the cell and osmosis occurs and the plant cell gives too much water to the outside of the cell, the things inside of the cell wall shrink and there is barely any water within the vacuole/cell.
How does osmosis work in animal cells and what would happen depending on the water concentrations occurring in osmosis?
Animal cells don’t have a cell wall - this means that animal cells can either swell and burst if water moves inside or shrink if too much water leaves.
What happens if cells replaced in distilled water?
The cell would swell and burst.
What happens cells are placed concentrated salt solution?
The cell would shrink and shrivel.
What are two examples of hypertonic solutions?
On the outside, there is a high solute and low water or on the outside, there is a low solute and high water.
Where does water move in osmosis?
To a hypertonic area.
