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1. A level master > A3 Transport Across Membranes > Flashcards

A3 Transport Across Membranes Flashcards

1
Q

Name the molecule shown in the diagram

A

Glycerol

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2
Q

Name the bond formed between a fatty acid and glycerol

A

Ester bond

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3
Q

Name the type of fatty acid shown in the diagram

A

Saturated fatty acid

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4
Q

Name the type of fatty acid shown in the diagram

A

Unsaturated fatty acid

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5
Q

Name the molecule shown in the diagram

A

Phospholipid

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6
Q

Name the structure labelled A on the diagram of a membrane

A

Phospholipid

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7
Q

Define diffusion?

A

The movement of a substance from a high concentration to a lower concentration

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8
Q

Give two differences between active transport and facilitated diffusion.

A

Active transport requires energy/ATP whereas facilitated diffusion is passive.

Active transport moves substances against the concentration gradient whereas facilitated diffusion moves substances down the concentration gradient.

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9
Q

Give a similarity between active transport and facilitated diffusion.

A

Both use carrier proteins.

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10
Q

Which type of molecule can diffuse across the phospholipid bilayer?

A

Non- polar or lipid soluble molecules.

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11
Q

Through what structure do water soluble molecules cross the membrane?

A

Through channel proteins/aquaporins

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12
Q

Name the structure labelled C on the diagram of a membrane

A

Glycoprotein

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13
Q

Name the structure labelled F on the diagram of a membrane

A

Extrinsic protein

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14
Q

Name the structure shown in the diagram

A

Phospholipid bilayer

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15
Q

Name the part of the membrane labelled A

A

Channel protein

Intrinsic protein

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16
Q

Which part of the phospholipid is hydrophobic?

A

Fatty acid tail.

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17
Q

Name the structure labelled E on the diagram of a membrane

A

Cholesterol

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18
Q

Protein molecules found on the surface of the membrane are called …

A

Extrinsic proteins

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19
Q

Give 2 differences between a triglyceride and a phospholipid.

A

Phospholipids contain a phosphate group whereas triglycerides do not.

Phospholipids have 2 fatty acids whereas triglycerides have 3 fatty acids.

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20
Q

What is the function of the carbohydrates found on the outer surface of the membrane?

A

Antigens

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21
Q

Each carrier proteins are specific. What does this mean?

A

Can only transport one type of molecule

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22
Q

Name the two carbohydrate containing chemicals found in cell membranes.

A

Glycoproteins and glycolipid.

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23
Q

What is the function of the microvilli?

A

Increase surface area for absorption of digested food by the small intestine.

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24
Q

What effect does cholesterol have on the fluidity of the membrane?

A

Reduces the fluidity/movement of phospholipids in the membrane.

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25
Q

How can the structure of the membrane be changed to make the diffusion of water soluble molecules more rapid?

A

Increase number of channel proteins
Increase surface area.

26
Q

Give three ways in which the rate of gas exchange can be increased.

A

Increase the surface area.
Increase the concentration gradient.
Decrease the diffusion pathway/distance
Increase the temperature

27
Q

Why is the term fluid mosaic used to describe the model for membrane structure?

A

Fluid - phospholipid move within the membrane.

Mosaic - proteins form blocks on the surface of the membrane.

28
Q

The water potential of the cell cytoplasm is -5.

The cell is place in a solution with water potential of-10.

Which way will the water move?

A

Osmosis will cause water to leave the cell (water moves from high water potential to lower water potential).

29
Q

A cell with a water potential of -5 is placed in a solution with a

water potential of -5.

Which way will the water move?

A

No net movement of water.
Water will still cross the membrane.
Same number of water molecules enter and leave the cell.

30
Q

A cylinder of potato is placed into pure water.
Explain why the mass mass of the potato changes.

A

The cylinder will increase in mass.

Osmosis - water will enter the cylinder.
Water moves from high water potential to lower water potential through selectively permeable membrane.

31
Q

Why should percentage change in mass be calculated when carrying out osmosis experiments.

A

Does not matter if the initial masses of the cylinders are not identical.
Allows comparison of results.
Calculating change in mass per gram of potato.
A proportion is calculated.

32
Q

Give the equation for calculating the percentage change in mass.

A

% change in mass

= change in mass/initial mass X 100

33
Q

Why is it important to dry the potato cylinders before placing them
in solutions of different water potential?

A

Removes the cytoplasm that has leaked out of the cut cells.
Only measuring the mass of the water inside the cells.

34
Q

Why is it important to dry the potato cylinders when they have been removed from the different concentrations of salt solution?

A

Removes the salt solution on the outside of the cells/cylinder.
Only measure the mass of water that has entered the cylinder.
Ensure the experiment is valid.

35
Q

Name the structure labelled G on the diagram of a membrane

A

Channel protein

Intrinsic protein

36
Q

Define osmosis

A

Net movement of water from a high water potential to a lower water potential through a selectively/partially permeable membrane.

37
Q

Name the two main chemicals found in the chloroplast
membranes.

A

Phospholipids and proteins (all membranes have the same structure)

38
Q

Name a chemical that moves by osmosis into cells.

A

Water

39
Q

Name 2 molecules that move into cells and are used in respiration.

A

Oxygen and glucose

40
Q

What happens to ATP during active transport?

A

It is hydrolysed.
A phosphate group is removed.
Allowing the release of a small amount of energy.

41
Q

What is formed when ATP is hydrolysed?

A

ADP and inorganic phosphate (Pi).

42
Q

Describe how an ion is transported across a membrane by active transport.

A

Ion binds to a receptor site on the carrier protein on outside of membrane.
ATP in the cell binds to a receptor site on carrier protein.
ATP is hydrolysed
Causes carrier protein to change shape/open inside the membrane.
ADP is released
Ion released into cell.
Removal of Pi from carrier protein causes protein to revert to original shape.

43
Q

Name the type of transport used to absorb glucose or amino acids into the epithelium cells lining the ileum.

A

Co-transport.

44
Q

All membranes around and within cells (including those surrounding organelles) are called …

A

Plasma membrane

45
Q

Describe how to carry out a biochemical test for a lipid

A

Add ethanol and shake gently

Pour into cold water

Positive result - white emulsion

46
Q

Name the components of a cell surface membrane

A

Phospholipids
Proteins (extrinsic and intrinsic)
Glycoproteins
Glycolipids
Cholesterol

47
Q

Name the type of reaction used to make a monoglyceride

A

Condensation reaction

48
Q

Name the three molecules that make up a phospholipid

A

Phosphate
Glycerol
2 x Fatty acids

49
Q

What are the functions of the phospholipids in the cell membrane?

A

Allow non-polar molecules cross the membrane
Prevent polar molecules crossing the membrane
Makes membrane flexible and self healing

50
Q

What are the functions of proteins in the cell membrane?

A

Provide structural support
Act as channels to transport polar molecules/facilitated diffusion

51
Q

What is the function of cholesterol in the cell surface membrane?

A

Reduces lateral movement of molecules in the membrane
Acts as a buffer against temperature changes
Prevent leakage of water and dissolved ions from the cell

52
Q

What are the functions of glycoproteins in the cell surface membrane?

A

Act as recognition sites for hormones and neurotransmitters
Help cells attach and form tissues

53
Q

In an investigation about diffusion diffusion and plasma membranes (beetroot discs) why would you ensure the temperature remained constant?

A

Maintain a constant rate of diffusion
Maintain constant fluidity of phospholipids
Prevent the denaturation of membrane proteins

54
Q

How can you determine the water potential of plant material

A

Cut identical pieces of plant material
Measure the mass
Place in solutions of known concentration
Leave for 1 hour
Measure the mass of the plant material
Calculate % change in mass
Plot a graph (x axis concentration y-axis % change in mass)
Read off concentration resulting zero change in mass#
Convert to a water potential using a data table

55
Q

What happens to red blood cells if placed in pure water?

A

Swell and burst/undergo lysis

56
Q

What happens to a red blood cell placed in a strong sugar solution?

A

Shrinks

Becomes crenated

57
Q

What happens to a plant cell when placed in pure water?

A

Swells and becomes turgid

58
Q

What happens to a plant cells when placed in strong salt solution?

A

Plasmolysed

59
Q

Define active transport

A

The movement of molecules or ions against a concentration gradient using ATP and carrier proteins.

60
Q

What is the role of ATP in active transport?

A

Provide the energy needed to transplant a molecule against its concentration gradient.
ATP binds to carrier protein, ATP is hydrolysed causing the protein to change shape, allowing the entry of the molecule/ion

1. A level master (39 decks)

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