Paper 1: Topic 1 Cell Biology - Transport in cells (IV form) Flashcards Preview

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Flashcards in Paper 1: Topic 1 Cell Biology - Transport in cells (IV form) Deck (48)
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1

Give 3 examples of molecules that diffuse

Some of the substances transported in and out of cells by diffusion are:

oxygen and carbon dioxide in gas exchange

urea from cells into the blood plasma for excretion in the kidney

2

How are the lungs in mammals adapted for exchanging materials?

Alveoli increase the surface area

The alveoli wall is only one cell thick (reduces the diffusion distance)

The lining of the alveoli is moist (to increase the diffusion of oxygen and carbon dioxide across the membrane)

Alveoli are covered in capillaries to ensure gases diffuse in and out of the blood efficiently

3

Why do plants need a supply of potassium ions?

To produce some enzymes and fruits

4

What is a hypotonic solution?

A solution with a lower concentration of solutes dissolved in it

Hence it has a higher water potential

5

Define the term osmosis

The movement (diffusion) of water molecules DOWN a WATER POTENTIAL GRADIENT across a partially permeable membrane from an area of higher water potential to an area of lower water potential

6

Why can single-celled organisms obtain their nutrients and remove their wastes by diffusion?

They have a relatively large surface area to volume ratio.

This allows sufficient transport of molecules into and out of the cell to meet the needs of the organism

7

What happens to plant cells that are placed into a concentrated solution?

Water moves out of the cell

Down the water potential gradient

By osmosis

The cell decreases in size and mass as it loses water

The vacuole shrinks

The cell will eventually become flaccid

8

Give an example of active transport in plants

The absorption of mineral ions from the soil by root hair cells

Mineral ions are in a very dilute solution in the soil and are moved into the concentrated solution of the cell vacuole

9

What happens to red blood cells (or other animal cells) that are placed into pure water or a dilute solution?

Water moves into the cell

Down the water potential gradient

By osmosis

The cell increases in size and mass as it gains water

The cell will eventually rupture (burst)

 

They are described as being cytolysed (or if they are a red blood cell they are described as being haemolysed)

10

What is meant by the term 'haemolysis'

The rupturing of an animal cell as a result of water moving into the cell by osmosis

11

How are leaves in plants adapted for exchanging materials?

Leaves are broad, and thin flat (to increase the surface area)

Leaves are have many stomata on the underside of the leaf (to allow gas exchange to occur by diffusion)

12

How do you calculate the volume of a cube?

volume = height x width x depth

 

remember to include the units e.g mm3 or cm3

13

Is active transport an active or passive process?  Explain your answer.

Active

 

It requires an input of ATP which is produced during respiration

 

ATP is needed to change the shape of the carrier protein to move the molecule against the concentration gradient

14

Give 2 ways in which diffusion and osmosis are different

  1. Diffusion applies to gases and small molecules, osmosis ONLY applies to water molecules 
  2. Diffusion uses a concentration gradient, osmosis uses a water potential gradient
  3. Diffusion occurs until the moelcules are in equilibrium, osmosis occurs until the water potentials are equal

15

Give 3 ways diffusion and osmosis are different from active transport

Diffusion and osmosis are passive processes, active transport is an active process

Diffusion and osmosis move molecules down a gradient, active transport moves molecules against a gradient

Diffusion and osmosis only use kinetic energy, active transport requires an input of energy (ATP)

Diffusion and osmosis do not require protein carriers in the membrane, active transport does

16

What happens to red blood cells (or other animal cells) that are placed into pure water or a dilute solution?

Water moves into the cell

Down the water potential gradient

By osmosis

The cytoplasm increases in volume and mass as it gains water

The cytoplasm will push against the cell surface membrane

The cell ruptures and becomes haemolysed

17

Give 3 examples of molecules that can diffuse across cell membranes

Carbon dioxide

Oxygen

Carbon monoxide

Urea

18

How are gills in fish adapted for exchanging materials?

Gills have many gill filaments (to increase the surface area)

Gills are thin (to reduce the diffusion distance)

Gills have a good blood supply (to maintain a high concentration gradient)

Water continually runs over the surface of the gills (to maintain a high concentration gradient)

19

Give 4 ways in which the effectiveness of an exchange surface can be increased

  1. having a large surface area
  2. having a membrane that is thin,
  3. having a short diffusion path
  4. animals have an good ('rich') blood supply
  5. ventilating their gas exchange surfaces

 

20

What is the name of the apparatus that can be used to study osmosis?

Osmometer

21

Is osmosis an active or passive process?

Passive - it does not require any energy input

Water molecules possess kinetic energy and this enables them to move

22

Why do plants need a supply of magnesium ions?

To produce chlorophyll (the green pigment that is essential for photosynthesis)

23

Give 2 examples of molecules that are absorbed into the blood plasma by active transport

Glucose

Amino acids

Small proteins

 

 

24

Describe the pattern of movement of molecules that are diffusing

Random

25

How do you calculate the surface area of a cube?

Remember a cube has 6 faces!

The surface area of each face = height x width

If all faces are the same then multiply this by 6

If the faces differ in sizes i.e. it is an oblong rather than a cube 2 faces will have one surface area and 4 faces will have a different surface area

 

Remember to add units: e.g. mm2 or cm2

26

What is meant by the term 'crenated'

The shriveling of an animal cell as a result of water moving out of the cell by osmosis

27

Define the term diffusion

The movement of molecules from an area of high concentration to an area of low concentration down a concentration gradient across a partially permeable membrane i.e. from a concentrated to dilute solution.  Diffusion usually occurs until an equilibrium is reached.

28

Give an example of active transport in animals

The absorption of glucose from the small intestine into the blood plasma

The contents of the small intestine have a low glucose concentration and the blood plasma has a high concentration of glucose

29

Give 3 factors that INCREASE the rate of diffusion

LARGER difference in concentrations (STEEPER concentration gradient)

HIGHER temperature

INCREASED surface area of the membrane

DECREASED the diffusion distance

30

Define a solution

A liquid (solvent) in which solids (solutes) are dissolved

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