Brainscape's Knowledge GenomeTM

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


See full index

A-level Biology > 1 - Biological Molecules > Flashcards

1 - Biological Molecules Flashcards

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

What is a polymer?

A

A long chain of repeating monomers or sub-units.

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

What are monosaccharides, disaccharides and polysaccharides?

A

Sugars formed from monomers, saccharides.

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

What is lactose?

A

A disaccharide formed from glucose and galactose.

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

What is sucrose?

A

A disaccharide formed from glucose and fructose.

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

What is maltose?

A

A disaccharide formed from two alpha glucose molecules.

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

What is hydrolysis?

A

The addition of water to break a glycosidic bond, to release the constituent monosaccharides.

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

What are the bonds formed between monosaccharides?

A

Glycosidic bonds.

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

What is a condensation reaction?

A

During the joining of monosaccharides, a molecule of water is removed.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

What is the test for non-reducing sugars?

A

Add 2cm3 of sample to 2cm3 if Benedict’s, in a water bath. If it remains blue, no reducing sugar is present.

Add 2cm3 hydrochloric acid, mix, then add an alkaline to neutralise.

Reheat with Benedict’s, if the reagent turns brick-red, a non-reducing sugar was present in the original sample.

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

What is the test for starch?

A

Place 2cm3 of sample into a test tube or spotting tile.

Add two drops of iodine solution, shake.

If the solution goes blue-black, starch is present.

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

What is the role of starch in the body?

A

Energy storage.

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

What are the properties of starch, and how do these link to its role?

A

Insoluble - doesn’t affect water potential, so water isn’t drawn into cells
Large and insoluble - does not diffuse out of cells
Compact - can be stored in a small place
The branched form has many ends - so each can be acted on simultaneously

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

What is the function of glycogen?

A

Found in animals and bacteria, it is a storage molecule. Animals have very high metabolic requirements.

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

What are the properties of glycogen, and how does this aid its role.

A

Insoluble - does not draw water into cell by osmosis
Insoluble - does not diffuse out of cells
Compact - a lot can be stored in a small space
Very highly branched - rapidly hydrolysed to give glucose which is important as animals have very high metabolic requirements

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

What is the function of cellulose in plants?

A

It is a major component of plant cell walls, and provides structure as well as stopping the cell from bursting.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

How is cellulose adapted to its function?

A

Cellulose is made from beta glucose and so form straight, unbranched chains, these chains run parallel to each other and are connected by hydrogen bonds. These group together to microfibrils which then form fibres.

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

What are the two main groups of lipids?

A

Triglycerides

Phospholipids

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

What are the four roles of lipids?

A

Source of energy
Waterproofing - insoluble in water
Insulation - slow conductors of heat
Protection - around delicate organs

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

What is a triglyceride?

A

A triglyceride is a lipid composed of three fatty acids and a glycerol molecule.

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

What is the difference between saturated and unsaturated fatty acids?

A

If there are no carbon-carbon double bonds in the -COOH group, it is unsaturated. If there is one, it is mono-unsaturated, if there are multiple it is polyunsaturated.

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

What are the properties of triglycerides?

A

High ratio of carbon-hydrogen bonds to carbon atoms. These bonds are good at storing energy.

Low mass to energy ratio, good for storage.

Large and non-polar, so do not affect osmosis or water potential.

High H to O ratio, release water when oxidised, good source of water.

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

What is a phospholipid?

A

2 fatty acids and a phosphate molecule each bonded to a glycerol molecule.

Have a hydrophilic phosphate ‘head’ that attracts to water, and a hydrophobic fatty acid ‘tail’ that orients away from water.

They are polar, so when placed in water, the heads are close as possible to water, and tails as far as possible.

23
Q

What are the properties of phospholipids?

A

Polar, so when in an aqueous environment, form a bilayer within cell-surface membranes. This forms a hydrophobic barrier.

Can form glycolipids by combining with carbohydrates.

24
Q

What is the test for lipids?

A

Add ethanol, shake thoroughly.
Add water, shake gently.
Cloudy-white colour emulsion indicates presence of lipids.
To control, use water instead of sample, solution should remain clear.

25
Q

What are proteins made from?

A

Polypeptides, of which the monomer is an amino acid.

26
Q

What is the structure of an amino acid?

A

A central carbon atom attached to which is:

Amino group -NH2
Carboxyl group -COOH
Hydrogen atom -H
Variable R group

27
Q

How is a peptide bond formed between amino acids?

A

Condensation reaction. Removes the -OH from the COOH and the -H from the amino group. The peptide bond then forms between the C and N atoms.

28
Q

What is the primary structure of a protein?

A

The sequence of amino acids in the polypeptide chain. This determines the protein’s properties and shapes.

29
Q

What is the secondary structure of a protein?

A

Hydrogen bonds between the -NH group and -CO form, twisting the polypeptide chain into either an alpha helix or beta pleated sheet.

30
Q

What is the tertiary structure of a protein?

A

Affects the 3-D shape of a protein and hence its function. Contains disulphide bridges, hydrogen bonds, and ionic bonds.

31
Q

What is the quaternary structure of a protein?

A

The linkage of multiple polypeptide chains. Can also include non-protein (prosthetic) groups, such as a haem group in haemoglobin.

32
Q

What is the test for proteins?

A

Biuret test - detects peptide bonds.

Place sample in test tube, add equal volume NaOH.
Add a few drops of dilute Copper (II) sulphate solution.
Mix gently.
Purple colouration indicates peptide bonds and hence a protein, if no peptide bonds are present, remains blue.

33
Q

What is the function of a catalyst?

A

To increase the rate of reaction, while remaining chemically unchanged. Can also lower activation energy.

34
Q

Detail the induced fit model of enzyme action.

A

Each enzyme has a general shape. When the substrate comes into contact with the enzyme, it represents a change in the enzyme’s environment. This leads to a change in shape, which puts strain on the substrate molecule’s bond(s), hence lowering the activation energy.

35
Q

Describe the effect of raising temperature on enzyme action.

A

To begin, the rate increases. However it then decrease slowly as the active site changes shape. At some point (usually 60C) the active site is distorted to the point of inhibiting entirely functionality, and is denatured. Denaturation is permanent.

36
Q

Describe the effect of enzyme concentration on rate of reaction.

A

While there is an excess of substrate, there is proportional increase. If the substrate is however limiting, rate of reaction stabilises, shown by a plateau on a graph.

37
Q

Describe the effect of increasing substrate concentration on rate of reaction.

A

While substrate is the limiting factor, an increase in substrate concentration will increase the rate of reaction. However, when substrate becomes in excess, the rate of reaction stabilises, shown by a plateau on a graph.

38
Q

What are the two types of enzyme inhibitors?

A

Competitive and non-competitive.

39
Q

Explain the role and effect of a competitive inhibitor.

A

Similar molecular shape to the substrate, allowing them to occupy active site. So increasing the substrate concentration reduces the effect of the inhibitor. Competitive inhibitors are temporary as they do not alter the shape of the active site.

40
Q

Explain the role and effect of non-competitive inhibitors.

A

Attach to the enzyme at a binding site, which is not the active site. This alters the tertiary structure of the enzyme and hence the active site. Increasing the concentration of substrate does not reduce effect of the inhibitor.

41
Q

What are the bonds in triglycerides and phospholipids?

A

Ester bonds.

42
Q

Give three examples of monomers.

A

Monosaccharides, amino acids, nucleotides

43
Q

Give three common monosaccharides.

A

Glucose, galactose, fructose

44
Q

Give three disaccharides.

A

Maltose, Sucrose, Lactose

45
Q

What is a monomer? (1)

A

A small repeating unit from which polymers are made.

46
Q

Describe the chemical reaction involved in the conversion of polymers to monomers and monomers to polymers. Give two named examples of polymers and their associated monomers to illustrate your answer. (5)

A
  • Condensation reaction joins monomers and forms a bond and releases water
  • Hydrolysis reaction breaks bond and uses water
  • B-glucose forms cellulose through glycosidic bond
  • a-glucose forms starch through glycosidic bond
47
Q

Give one reason why using a colorimeter makes results repeatable. (1)

A

Quantitative so standardises results

48
Q

Describe and explain two features of starch whivh make it a good storage molecule. (2)

A
  • Large so cannot cross cell membrane
  • Insoluble so does not affect water potential of cell
49
Q

Describe the structure of glycogen. (2)

A

Polymer of a-glucose
Branched

50
Q

Explain how cellulose molecules are adapted for their function in plant cells. (3)

A
  1. Long and straight chains
  2. Linked by many H bonds to form fibrils
  3. Prove strength to cell wall
51
Q

Describe a biochemical test for a non-reducing sugar. (3)

A
  1. Add HCl and neutralise
  2. Add Benedicts solution and heat
  3. Brick-red ppt forms
52
Q

Suggest a method to measure the quantity of reducing sugar in solution.

Not the test

A
  1. Filter and dry
  2. Find mass of precipitate
53
Q

Explain the difference in the strucyure of a starch molecule and cellulose molecule. (2)

A
  • Cellulose made from B-glucose whereas Starch made from a-glucose
  • In cellulose, position of hydrogen and hydorxyl on C1 inverted

A-level Biology (21 decks)

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