Movement of substances

Question 1

What is the meaning of concentration gradient?

Answer 1

It is the difference between two regions.

Question 2

Do you agree with this statement?

Statement: The steeper the concentration gradient, the faster the particles will move.

Answer 2

Yes, agree.
This is equally relevant to diffusion. The steeper the concentration gradient, the faster the rate of diffusion is for that substance.

Question 3

What is diffusion?

Answer 3

Diffusion is the net movement of particles (ions or molecules) from a region where they are of higher concentration to a region where they are of lower concentration, that is, down a concentration gradient.

Question 4

What is dynamic equilibrium?

Answer 4

when the rates of the forward and reverse reactions are equal. The system is dynamic because individual molecules react continuously. It is at equilibrium because no net change occurs.

Question 5

What is a permeable membrane?

Answer 5

A permeable membrane is a membrane that allows both the solvent (water) and the solutes (the dissolved substances) to pass through it.

Question 6

If there are 2 substances being dissolved in the same liquid, will they be dissolved separately?

Answer 6

No. If there is more than one substance dissolved in the same liquid, then the dissolved particles of one substance will diffuse independently of the other.

Question 7

The cell of our lungs exchange oxygen and carbon dioxide through diffusion/ osmosis?

Answer 7

Diffusion. Because this is a exchange of gas.

Question 8

Why is the cell surface membrane a partially permeable membrane?

Answer 8

The cell surface membrane is a partially permeable membrane. This is due to the fact that it allows only certain substances to pass through but not others.

Question 9

What is water potential?

Answer 9

Water potential is a measure of the tendency of water to move from one place to another.

Question 10

Does concentrated solution contain more water molecule than saturated solutions?

Answer 10

Yes

Question 11

How is water potential gradient established?

Answer 11

It is when a partially permeable membrane separates two solutions of a different water potentials.

Question 12

What is osmosis?

Answer 12

Osmosis is the net movement of water molecules from aa solution of higher water potential to a solution of lower water potential, through a partially permeable membrane.

Question 13

What is the term used when 2 solutions are of the same concentration, and have the same water potential?

Answer 13

Isotonic

Question 14

What is another term used for concentrated solutions?

Answer 14

Hypertonic

Question 15

What is another term used for a diluted solution?

Answer 15

Hypotonic

Question 16

Why does plant cell behave differently from an animal cell when placed in solutions with differing water potentials?

Answer 16

This is because of the presence of the cell wall in plant cells.

Question 17

Why will plant cell not burst even when placed in a solution with higher water potential?

Answer 17

This is because the cell is protected by the inelastic cell wall.

Question 18

What happens to a cell in a solution of the same water potential? why?

Answer 18

Cells immersed in a solution with the same water potential as their cytoplasm will not change their size and shape.

This is because there is no water potential gradient established since the concentration of water potential in cytoplasm and the solution is the same.

Question 19

What is plasmolysis?

Answer 19

Plasmolysis is the shrinkage of cytoplasm and cell membrane away from the cell wall.

Question 20

How can you restore original shape in plant cells that are being plasmolysed?

Answer 20

The cell can be restored to its original state by placing it in a water or in a solution with higher water potential.

Question 21

What is crenation?

Answer 21

Crenation is a process whereby animal cells shrinks and little spikes appear on the cell surface membrane due to it being dehydrated.

Question 22

What happens when there is a high rate of evaporation of water from plant cells?

Answer 22

The cells in plants lose turgidity and the plants wilts.

Question 23

Why is turgor important in plants?

Answer 23

Turgor plays an important role in maintaining the shape of soft tissues in plants. This can be seen in most leaves and young stems, especially those of the herbaceous and non-woody plants, are able to remain firm and erect because of the turgor pressure within the cells.

Question 24

Cells become limp or flaccid because of the process ___.

Answer 24

Plasmolysis.

Question 25

Why is it not advisable to add too much fertilizer around the roots of plant?

Answer 25

This is because the soil solution will become very concentrated and water will move out of the roots by osmosis. Inability of the roots to absorb water, together with continued evaporation of water from the leaves, will cause the plant to wilt. The plant would then eventually die.

Question 26

Describe soil solution?

Answer 26

Soil solution is a thin film of water that surrounds individual soil particles. It is usually contains dissolved mineral salts or ions.

Question 27

Define active transport?

Answer 27

Active transport is the process in which energy is used to move the p[articles of a substance across a membrane against its concentration gradient, that is, from a region where the particles are of lower concentration to a region where they are of higher concentrations.

Question 28

True or false?

Active transport occurs in living and dead cells.

Answer 28

False. Active transport occurs in living cells as they are able to respire. This process of respiration allows energy to be set free, using part of this energy during active transport. Dead cell cant as they are not able to respire anymore.

Question 29

What are the factors that affects the rate of diffusion?

Answer 29

1) steepness of concentration gradient
2) Temperature
3) Surface area to volume ratio

Question 30

Root hair cells have a high ion concentration.

Explain how this is maintained and its importance.

Answer 30

• Root hair cells absorb water and mineral salts from the surrounding soil solution for the plant.
• Contain many mitochondria to carry out AR to release energy for the active transport of ions into cell.
• Cell sap in vacuole have high conc of ion concentration.
• Cell membrane prevent cell sap from moving out.
• Root hair cell constantly maintain low water potential relative to the surrounding soil solution, so that water can constantly move into them through osmosis.

Question 31

When is a solution hypertonic/ isotonic/ hypotonic?

Answer 31

When you are comparing 2/ more solutions.

Question 32

What are examples of osmosis not being able to happen?

Answer 32

When it is in the xylem or when the cell/ organism is boiled.