Movemnt Of Substances Into And Out Of Cells

Question 1

Explain the effect of the different SA:V ratios on the rate of osmosis into the potato.

Answer 1

• Larger SA:V ratio of small cubes
• More osmosis

Question 2

Explain why the mass of each cube increased (in terms of osmosis).

Answer 2

• Water enters (by osmosis)
• Water molecules move from an area of low conc. to an area of high conc.
• Across a partially permeable membrane

Question 3

Why did he convert ‘change in mass’ to ‘percentage change in mass’?

Answer 3

Different masses

Question 4

Explain how this experiment can be used to understand the need for transport systems in larger organisms such as humans.

Answer 4

• Humans have a smaller SA: V ratio
• Diffusion is too slow therefore, there is less relative penetration

Question 5

Explain how the red molecules entered the jelly.

Answer 5

• Diffusion
• Red dye molecules went from a high conc. to a low conc,

Question 6

If red blood cells are placed in distilled water and examined under a microscope no cells can be seen. Why is this?

Answer 6

• There was a lot of water in the blood cells, and so they burst as they did not have a cell wall to protect/ support them

Question 7

Explain why the cells in distilled water looks different when compared to the cells in salt solution.

Answer 7

(In distilled water)

• Water enters cells by osmosis
• Distilled water is low concentrated
• Cell membrane is against the cell wall
• Cell becomes turgid

Question 8

Why are red onions used to spot cells under a microscope?

Answer 8

They are easier to see

Question 9

What is meant by the term diffusion?

Answer 9

• Movement of particles from an area of high conc. to an area of low conc

Question 10

Suggest two reasons why the volume of solution measured by the student may not be accurate.

Answer 10

• Water left in chip
• Water left in cup

Question 11

Explain the difference in the rate of diffusion between the experiments using 1 drop of ammonia and the experiment using 3 drops of ammonia.

Answer 11

• 3 drops are more concentrated

Question 12

How could lily modify her experiment to investigate the effect of temperature on the rate of diffusion?

Answer 12

• Same number of drops
• Different temperatures

Question 13

Describe the changes in the global production of farmed fish and beef cattle since 1950.

Answer 13

• Production of Beef increases
• Production of fish is constant and then increases rapidly
• More beef produced than fish at the start

Question 14

Describe the differences in the appearance of the cells in concentrated salt solution compared with the cells in distilled water.

Answer 14

The cells in concentrated salt solution:

• Shrunk due to osmosis
• Cytoplasm does not fill cell

Question 15

Explain what happens to cells in concentrated salt solution to change their appearance.

Answer 15

• Water leaves the cell across the partially permeable membrane by osmosis
• Cells become flaccid (cell membrane peels away from the cell wall)
• There is a high solute concentration outside the cell

Question 16

The plant swells up.

Explain why, as fully as you can

Answer 16

• water enters by osmosis through a partially permeable membrane