Chapter 02 - Movement of Substances

Question 1

Define diffusion

Answer 1

Diffusion is the net movement of particles from a region of higher concentration to a region of lower concentration down a concentration gradient

Question 2

What is a concentration gradient?

Answer 2

A concentration gradient is the difference in concentration between two regions over a given distance

Question 3

Can diffusion take place with or without membrane. True or false?

Answer 3

True

Question 4

Diffusion is caused by Brownian Motion which states that all particles are in ____, ____ movement because they possess ____ energy

Answer 4

Diffusion is caused by Brownian Motion which states that all particles are in constant, random movement because they possess kinetic energy

Question 5

Due to the ____ and ____ movement of particles, the particles move ____ the concentration gradient until they are ____ spaced out between all regions

Answer 5

Due to the constant and random movement of particles, the particles move down the concentration gradient until they are evenly spaced out between all regions

Question 6

When concentration of particles are equal in all regions, there will be no more movement of particles. True or false?

Answer 6

False. When concentration of particles are equal between all regions, there will be movement of particles due to Brownian Motion (particles are in constant movement) but there will not be NET movement of particles as the concentration gradient is no longer present.

Question 7

What type of transport is diffusion? (Active/Passive)

Answer 7

Diffusion is a passive transport as it does not require any energy to take place

Question 8

What are the 6 factors that affect the rate of diffusion?

Answer 8

1) Surface area to volume ratio
2) Diffusion distance
3) Concentration gradient
4) Size of particles (atoms, ions, molecules)
5) Temperature
6) Presence of pores

Question 9

Explain how surface area to volume ratio affects the rate of diffusion

Answer 9

The larger the surface area to volume ratio, the faster the rate of diffusion of substances in and out.

Question 10

What is diffusion distance?

Answer 10

Diffusion distance is the distance between 2 regions of different concentration of particles.

Question 11

Explain how diffusion distance affects the rate of diffusion

Answer 11

As diffusion distance decreases, the rate of diffusion increases because the particles take less time to move through the shorter diffusion distance (vice versa)

Question 12

Explain how the surface area to volume ratio affects the rate of diffusion in a root hair cell

Answer 12

The root hair cell has a long and narrow protrusion to increase surface area to volume ratio so that the rate of diffusion of substances in and out is faster

Question 13

Explain the adaptation in an alveolus which reduces diffusion distance

Answer 13

In order to reduce diffusion distance and speed up movement of oxygen and carbon dioxide into and out of the cells, the human blood capillaries and the alveolus in the lungs are only one cell thick

Question 14

Explain how concentration gradient affects rate of diffusion

Answer 14

The greater the difference in concentration between 2 regions, the higher the rate of diffusion

Question 15

You are given a 2 cm by 2 cm cube. Calculate the surface area to volume ratio

Answer 15

Length = 2
Width = 2
Height = 2
Surface area of one side = 2 x 2 = 4
Surface area of the cube (6 sides) = 4 x 6 = 24
Volume = 2 x 2 x 2 = 8
Surface area : Volume ratio
24:8
3:1

Question 16

The ____ the size of an object, the ____ the surface area to volume ratio, the ____ the movement of substances in and out of the object

Answer 16

The smaller the size of an object, the greater the surface area to volume ratio, the faster the movement of substances in and out of the object

Question 17

Define osmosis

Answer 17

Osmosis is the net movement of water molecules from a region of higher water potential to a region of lower water potential down a water potential gradient through a partially permeable membrane

Question 18

What type of transport is osmosis? (Passive/Active)

Answer 18

Osmosis is a passive transport as it does not consume energy

Question 19

What is water potential?

Answer 19

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

Question 20

You are given a beaker with 78% water and 22% sugar solution. Is this solution diluted or concentrated?

Answer 20

The solution is dilute because it contains a significantly higher proportion of water molecules (solvent) compared to sugar molecules (solute).

Question 21

State 2 differences between diffusion and osmosis

Answer 21

1) Diffusion can occur with our without a membrane while osmosis can occur only with a partially permeable membrane

2) Osmosis only involves the movement of water molecules while diffusion involved the movement of any particle

3) Diffusion is driven by a concentration gradient of the solute while osmosis is driven by a water potential gradient.

Question 22

When all the regions have the same water potential, does movement of water molecules stop?

Answer 22

No, movement of water molecules do not stop. However, NET movement of water molecules will stop when all regions are of the same water potential

Question 23

What is the effect of osmosis in a concentrated solution on an animal cell?

Answer 23

In a concentrated solution, there is a lower water potential compared to the higher water potential inside the animal cell. As a result, water molecules move out of the cell by osmosis, from a region of higher water potential to a region of lower water potential. This causes the cell to lose water, leading to crenation, where the cell membrane shrinks and forms spikes. (Over time, this dehydration can cause the cell to become damaged and potentially die)

Question 24

What is the effect of osmosis in a dilute solution on an animal cell?

Answer 24

In a dilute solution, there is a higher water potential compared to the lower water potential inside the animal cell. As a result, water molecules move into the cell by osmosis, from a region of higher water potential to a region of lower water potential. This causes haemolysis to occur where the cell to take in water, leading to swelling. If too much water enters, the cell may burst

Question 25

What is the effect of osmosis in a concentrated solution on a plant cell?

Answer 25

In a concentrated solution, there is a lower water potential compared to the higher water potential inside the plant cell. As a result, water molecules move out of the cell by osmosis, from a region of higher water potential to a region of lower water potential and the cell shrinks. This causes the cell to lose water, leading to plasmolysis, where the cell membrane pulls away from the cell wall. The cell becomes plasmolysed

Question 26

What is the effect of osmosis in a dilute solution on a plant cell?

Answer 26

In a dilute solution, there is a higher water potential compared to the lower water potential inside the plant cell. As a result, water molecules move into the cell by osmosis, from a region of higher water potential to a region of lower water potential. This causes the cell to take in water, leading to turgor pressure. The vacuole increases in size. The cell wall prevents the cell from bursting, keeping the plant cell turgid. When the cell is fully turgid, further entry of water is prevented

Question 27

What crucial role does turgor play?

Answer 27

Turgor plays a crucial role in maintaining the shape of the soft tissues such as leaves and stems

Question 28

When there is turgor pressure in plant cells, they are able to remain ____ and ____

Answer 28

When there is turgor pressure in the cells of plants, they are able to remain firm and erect

Question 29

If the plant cells lose to much water, they lose their ____, and the plants will ____

Answer 29

If the plant cells lose to much water, they lose their turgidity, and the plants will wilt

Question 30

Define active transport

Answer 30

Active transport is the process in which energy from respiration is used to move the particles of a substance across a membrane from a region of lower concentration to a region of higher concentration against its concentration gradient

Question 31

Active transport only occurs in ____ organisms as energy is required

Answer 31

Active transport only occurs in living organisms as energy is required

Question 32

What type of transport is active transport? (Passive/Active)

Answer 32

Diffusion is an active transport as it requires any energy to take place

Question 33

Active transport requires a membrane to take place. True or false?

Answer 33

True