Osmosis (T1) Flashcards Preview

Biology > Osmosis (T1) > Flashcards

Flashcards in Osmosis (T1) Deck (7):
0

Water moves across all membranes by osmosis. What two things are crucial for osmosis to take place?

- two solutions with different concentrations
- a partially permeable membrane to separate them

1

Define osmosis...

Osmosis is the movement of water from a less concentrated solution (more dilute) to a more concentrated solution (less dilute)

2

The level of water on the more concentrated side ....... while the level of water on the less concentrated side .......

The level of water on the more concentrated side rises while the level of water on the less concentrated side falls

3

Osmosis is crucial to plants. Why?

- it is the mechanism by which water and nutrients from the roots moves through their cells
- as the plant cells take in more and more water they become turgid and firm and are able to support and hold the plant upright

4

What is 'tugor' and why is it important?

- when plant cells are turgid
- it's very import to plants as the pressure inside the cells pushes the neighbouring cells against each other
- this provides support to the non-woody parts of the plants and helps hold the stems upright to the leaves can carry out photosynthesis
- it is also important in the functioning of stomata; if a plant loses too much water from its cells the cells become flaccid and the plants wilt. This is a protective actions which cuts down water loss by reducing the exposed surface area of the leaves and closing stomata

5

If a plant loses too much water from its cells what happens and why?

The cells become flaccid and the plants wilt. This is a protective action which cuts down water loss by reducing the exposed surface area of the leaves and closing stomata.

6

What experiments can be carried out to investigate osmosis outside the body of an organism?

- construct an artificially permeable membrane using visking tubing
- fill the visking tube with concentrated sucrose solution, attaching it to a capillary tube and placing the visking tube in a beaker of water
- the level of water in the capillary tube rises as water moves from the beaker to the inside of the visking tube

OR..

- place a drop of sucrose solution on one microscope slide and a drop of tap water on another
- transfer two small squares of inner epidermis from the outer layer of an onion onto each one
- out a drop of the correct solution on top of each an then cover slips
- any excess liquid is blotted up with filter paper
- observe through a microscope for several minutes
- the specimen in water will show turgid cells
- the other will gradually plasmolyse (shrink away from the cell wall due to water loss)
- if the cell is placed in a solution with the same concentration as inside the cell, it will become flaccid

Decks in Biology Class (69):