Movement of substances Flashcards

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1
Q

What is the meaning of concentration gradient?

A

It is the difference between two regions.

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2
Q

Do you agree with this statement?

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

A

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

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3
Q

What is diffusion?

A

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.

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4
Q

What is dynamic equilibrium?

A

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.

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5
Q

What is a permeable membrane?

A

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

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6
Q

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

A

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.

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7
Q

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

A

Diffusion. Because this is a exchange of gas.

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8
Q

Why is the cell surface membrane a partially permeable membrane?

A

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.

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9
Q

What is water potential?

A

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

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10
Q

Does concentrated solution contain more water molecule than saturated solutions?

A

Yes

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11
Q

How is water potential gradient established?

A

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

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12
Q

What is osmosis?

A

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.

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13
Q

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

A

Isotonic

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14
Q

What is another term used for concentrated solutions?

A

Hypertonic

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15
Q

What is another term used for a diluted solution?

A

Hypotonic

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16
Q

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

A

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

17
Q

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

A

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

18
Q

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

A

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.

19
Q

What is plasmolysis?

A

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

20
Q

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

A

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

21
Q

What is crenation?

A

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

22
Q

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

A

The cells in plants lose turgidity and the plants wilts.

23
Q

Why is turgor important in plants?

A

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.

24
Q

Cells become limp or flaccid because of the process ___.

A

Plasmolysis.

25
Q

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

A

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.

26
Q

Describe soil solution?

A

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

27
Q

Define active transport?

A

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.

28
Q

True or false?

Active transport occurs in living and dead cells.

A

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.

29
Q

What are the factors that affects the rate of diffusion?

A

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

30
Q

Root hair cells have a high ion concentration.

Explain how this is maintained and its importance.

A
  • 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.
31
Q

When is a solution hypertonic/ isotonic/ hypotonic?

A

When you are comparing 2/ more solutions.

32
Q

What are examples of osmosis not being able to happen?

A

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