Brainscape's Knowledge GenomeTM

Browse over 1 million classes created by top students, professors, publishers, and experts.


See full index

Biology A-level > Biology Chapter 4 > Flashcards

Biology Chapter 4 Flashcards

You may prefer our related Brainscape-certified flashcards:
AP® Biology flashcards Biology 101 flashcards
1
Q

What is the cell surface membrane also known as?

A

The plasma membrane

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

What are the functions of the cell surface membrane?

A
  1. To form a boundary
  2. Allows different intracellular and extracellular conditions
  3. Controls movement of substances into and out of cell
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

What are the functions of the phospholipids in the membrane?

A
  1. Allow transport of lipid-soluble substances
  2. Prevent water-soluble substances from entering or leaving the cell
  3. Allow flexibility in the membrane
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

Define ‘extrinsic protein’

A

A protein that is either embedded in the cell surface membrane of a cell or on its surface, but does not completely pass through the membrane’s bilayer

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

What are the functions of an extrinsic protein?

A
  1. Mechanical support

2. Receptors

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

Define ‘intrinsic protein’

A

A protein that spans the entire phospholipid bilayer

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

What are the functions of an intrinsic protein?

A
  1. Carriers/channels

2. Enzymes

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

What are the functions of the membrane proteins?

A
  1. Structural support
  2. Carriers for water-soluble substances
  3. Active transport - form ion channels
  4. Recognition sites
  5. Help cells join together
  6. Receptors
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

What is the model of the plasma membrane structure called?

A

The fluid mosaic model

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

Why are the words ‘fluid’ and ‘mosaic’ used in the fluid mosaic model?

A

Fluid = the membrane is flexible as the phospholipid molecules are free to move within the membrane

Mosaic = The proteins in the membrane resemble the pieces of a mosaic, in that they vary in shape, pattern and size

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

Is diffusion passive or active?

A

Passive

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

Where does the energy in this type of diffusion come from?

A

The kinetic energy which all particles possess, rather than an external source

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

How would you describe the motion of particles in their natural state?

A

Random

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

Define diffusion

A

The net movement of molecules or ions from a region of higher concentration to one where the concentration is lower

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

3 factors that affect the rate of diffusion

A
  1. Area over which diffusion takes place
  2. Concentration gradient
  3. Thickness of exchange surface
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

What equation describes the relationship between 3 factors affecting the rate of diffusion?

A

Diffusion is proportional to:

length of diffusion pathway

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

What are 2 limitations of the diffusion equation?

A
  1. Affected by nature of plasma membrane

2. Affected by the nature of the diffusing molecules itself

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
18
Q

Is facilitated diffusion a passive or active process?

A

Passive

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
19
Q

Give 2 ways through which facilitated diffusion can occur

A
  1. Through protein channels

2. Through protein carriers

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
20
Q

Define osmosis

A

The passage of water from a higher water potential to a region of lower water potential, through a partially permeable membrane

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
21
Q

What is the water potential of pure water under standard conditions?

A

0

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
22
Q

Will adding a solute to pure water lower or higher its water potential?

A

Lower

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
23
Q

What is meant by ‘net movement of water’?

A

The overall movement of all the water molecules in the system

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
24
Q

What would be the net movement of water if the cell is placed in a solution of equal water potential to that of the cell solution?

A

None

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
25
Q

What would be the likely consequence of placing an animal cell in pure water?

A

It would burst

26
Q

Define ‘turgid’ in terms of cell wall and protoplast

A

Where the protoplast is pushed against the cell wall

27
Q

Define ‘incipient plasmolysis’ in terms of cell wall and protoplast

A

The protoplast begins to pull away from the cell wall

28
Q

Define ‘plasmolyse’ in terms of cell wall and protoplast

A

The protoplast pulls away from the cell wall completely

29
Q

Why do plant cells not burst when in contact with pure water?

A

Their tough cell wall prevents them from bursting

30
Q

What soluble products are produced from carbohydrate breakdown?

A

Glucose
Fructose
Gallactose

31
Q

What are villi?

A

Finger-like projections on the folded walls of the small intestine

32
Q

How do villi increase the efficiency of absorption from the small intestine?

A
  1. Increase surface area
  2. Reduce diffusion distance
  3. Maintain diffusion gradient
  4. Good blood supply
33
Q

What are microvilli?

A

Finger-like projections of the epithelial cells lining the villi

34
Q

What 2 features help maintain the concentration gradient for glucose?

A
  1. Good blood supply, constant flow of blood

2. Smooth muscle contraction mixes contents

35
Q

Why is active transport also necessary?

A

So that all glucose can be absorbed

36
Q

Glucose is co-transported with:

A

Sodium ions

37
Q

Do the sodium ions move up or down the concentration gradient?

A

Down

38
Q

Do glucose molecules move up or down the concentration gradient?

A

Up

39
Q

Is this type of active transport direct of indirect?

A

Indirect

40
Q

Why?

A

Glucose movement is powered by the sodium concentration gradient, not ATP directly

41
Q

Define active transport

A

The movement of molecules or ions into or out of a cell from a region of lower concentration to a region of higher concentration using energy and carrier molecules

42
Q

How does active transport differ from passive transport?

A
  1. It requires ATP
  2. Materials are moved against a concentration gradient
  3. Carrier protein molecules act as pumps
  4. It is selective
43
Q

How is ATP used?

A
  1. Moves molecules

2. Through co-transport

44
Q

Where do the ions or molecules bind on the carrier protein?

A

Receptors on the channel

45
Q

Does ATP bind to the channel inside or outside the cell?

A

Inside

46
Q

What happens when ATP splits?

A

A shape change occurs in the carrier, and opens to the other side of the membrane

47
Q

What happens to the phosphate molecule and ADP after the shape change?

A

They are released and recombine

48
Q

Give an example of a pump that can transport 2 ions at the sample time:

A

Sodium-potassium pump

49
Q

Explain how you could use a students results to find water potential of a potato tissue

A
  1. Plot a graph with concentration on the x-axis and the % change on the y-axis
  2. Find the concentration where the curve crosses the x-axis (where % change is 0)
  3. Use another resource to find water potential of sucrose concentration
50
Q

Why can data in a table be described as processed results?

A

Calculations are made from raw data/ raw data would have recorded initial and final masses

51
Q

Why would a student calculate the percentage change in mass instead of using results from the table when calculating the change in mass?

A

Results from the table have initial and final masses

52
Q

As glucose and sodium ions enter the epithelial cell, water enters the cell from the lumen. Explain why

A
  1. Sodium ions and glucose lower water potential of cell

2. Water enters the cell by osmosis

53
Q

Give a function of cholesterol in cell membranes

A

Stabilises the phospholipid membrane/bilayer

54
Q

Is the head of the phospholipid hydrophilic or hydrophobic?

A

Hydrophilic (water-attracting)

55
Q

Is the tail of the phospholipid hydrophilic or hydrophobic?

A

Hydrophobic (water-repelling)

56
Q

Explain the effect of temperature on membrane permeability

A

Below 0 = phospholipids don’t have much energy, so they can’t move very much. Channel proteins and carrier proteins denature

Between 0 and 45 = phospholipids can move around and aren’t packed as closely together (partially permeable membrane)

Above 45 = phospholipid bilayer starts to melt (break down) and the membrane becomes more permeable. Channel proteins and carrier proteins denature

57
Q

Describe the absorption of glucose into the bloodstream

A
  1. Sodium ions are actively transported out of the epithelial cells in the ileum, into the blood, by the sodium-potassium pump. This creates a concentration gradient- there’s now a higher concentration of sodium ions in the lumen of the ileum than inside the cell
  2. This causes sodium ions to diffuse from the lumen of the ileum into the epithelial cell, down their concentration gradient. They do this via the sodium-glucose co-transporter proteins. The co-transporter carries glucose into the cell wall with the sodium. As a result the concentration of glucose inside the cell increases
  3. Glucose diffuses out of the blood, down its concentration gradient through a protein channel, by facilitated diffusion
58
Q

What are the 3 factors affecting the rate of active transport

A
  1. The speed of individual carrier proteins
  2. The number of carrier proteins present
  3. The rate of respiration in the cell and the availability of ATP
59
Q

Define ‘isotonic’

A

If 2 solutions have the same water potential (they won’t lose or gain water)

60
Q

Define ‘hypertonic’

A

Solutions with a lower water potential than the cell

61
Q

Define ‘hypotonic’

A

Solutions with a higher water potential compared with the inside of the cell

62
Q

What are the 3 steps to investigating water potential?

A
  1. Make serial dilutions
  2. Measure change in mass
  3. Produce a calibration curve

Biology A-level (14 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2024 Bold Learning Solutions. Terms and Conditions