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A Level Biology OCR > 2.2 Biological Molecules > Flashcards

2.2 Biological Molecules Flashcards

1
Q

Why is water a good habitat?

A

It has a high specific heat capacity due to its hydrogen bonds, and doesn’t experience rapid temperature changes.

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2
Q

What is a benefit of water having a high latent heat of evaporation?

A

Lots of energy is used when water evaporates by breaking hydrogen bonds, so organisms can use water to cool themselves e.g. sweat

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3
Q

What is cohesion/surface tension of water and why is it useful?

A

Water molecules are attracted to eachother, helping them to transport substances e.g. transpiration

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4
Q

Why is water a good solvent?

A

The partial charges are attracted to the charges on ions and surround them, seperating the ion.

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5
Q

Water is less _____ when solid.

A

Dense

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6
Q

Why does ice float on the surface of water?

A

Water molecules are held further apart by hydrogen bonds making a lattice structure which is less dense than liquid water.

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7
Q

What is the difference between a and b glucose?

A

a glucose has the OH level whereas b glucose has the OH reversed.

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8
Q

How is glucose structure suitable for its function?

A

Soluble to be transported, and its chemical bonds contain a lot of energy

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9
Q

Monosaccharides are joined together by _______ bonds.

A

Glycosidic

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10
Q

What is a condensation reaction?

A

When compounds are added together in a reaction to release/eliminate a water molecule.

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11
Q

What is a hydrolysis reaction?

A

When water is added to split a polymer into its monomers.

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12
Q

What is maltose made of?

A

2 a-glucose

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13
Q

What is sucrose made of?

A

a-glucose and fructose

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14
Q

What is lactose made of?

A

Galactose and glucose

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15
Q

What is starch?

A

Plant storage molecule of glucose

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16
Q

What is starch made up of?

A

Amylose and amylopectin

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17
Q

What monomer is starch made of?

A

a-glucose

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18
Q

What is the structure of amylose?

A
  • Unbranched a-glucose chain

- Coiled and compact

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19
Q

What is the structure of amylopectin?

A

-Branched a-glucose chain

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20
Q

What bond connects 2 a-glucose molecules in a straight line?

A

a 1-4 glycosidic bond

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21
Q

What bond connects 2 a-glucose molecules as a branch?

A

a 1-6 glycosidic bond

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22
Q

What is glycogen?

A

Animal glucose storage molecule

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23
Q

What is the structure of glycogen?

A

Branched molecule of a-glucose

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24
Q

What is the benefit of having many branches on a storage molecule?

A

Glucose can be released by hydrolysis quickly, and its more compact.

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25
What is cellulose?
Makes up plant cell walls
26
What monomer is cellulose made of?
b-glucose
27
What is the structure of cellulose?
Straight chains of alternating b-glucose, which are hydrogen bonded together to form microfibrils and macrofibrils
28
What bond connects b-glucose monomers?
b 1-4 glycosidic bonds
29
What are the properties of cellulose?
High tensile strength, fully permeable, difficult to digest
30
What are triglycerides composed of?
3 fatty acids ester bonded to a glycerol
31
By which process are triglycerides made?
Esterification
32
What is the difference between saturated and unsaturated fatty acids?
Saturated have no C=C double bond but unsaturated do
33
What are phospholipids comprised of?
2 fatty acds, a glycerol and a fatty acid
34
The phosphate group on a phospholipid is ________.
Hydrophilic
35
Why are triglycerides good for energy storage?
They're insoluble, and their bonds contain a lot of chemical energy
36
What are the main uses of triglycerides?
Energy source, Insulation, Buoyancy, Shock absorption
37
What is the main use of phospholipids?
Comprise the cell surface membranes of cells- phospholipid bilayer
38
What is cholesterol?
A steroid
39
What is the function of cholesterol?
To bind to fatty acid tails in the phospholipid bilayer and make the membrane more rigid
40
Amino acids are joined by _______(amide) bonds.
Peptide
41
What is primary protein structure?
Sequence of amino acids
42
What is secondary protein structure?
The initial folding due to hydrogen bonds, causing a-helix and b-pleated sheets
43
What is tertiary protein structure?
The final 3D structure of a single polypeptide due to different bonds
44
What is quaternary protein structure?
Multiple polypeptide chains joining together to form one protein e.g. haemoglobin
45
What can be used to study protein structure?
Computer modelling
46
What are hydrophobic and hydrophilic interactions?
Hydrophobic groups clump together, pushing hydrophilic groups to the outside of the molecule
47
Globular proteins are ______ in water due to ______ _______.
Soluble due to hydrophobic and hydrophilic interactions
48
What is a conjugated protein?
A protein that contains a non-protein prosthetic group attached
49
What type of functions do globular proteins normally have?
Hormones and enzymes
50
What type of functions do fibrous proteins normally have?
Structural such as collagen
51
What are some properties of fibrous proteins?
Structurally strong, insoluble, metabolically unreactive
52
What is the function of collagen?
To provide mechanical strength to connective tissue such as bones, tendons and arteries
53
What is the structure of insulin?
2 polypeptide chains held together by disulfide bridges
54
What is the function of amylase?
Enzyme that calalyses the breakdown of starch into glucose
55
What is the function of keratin and why does its structure make it suitable for this?
Function is to make things hard and waterproof. It is rich in cysteine so contains a lot of disulfide bridges
56
What are the properties of elastin?
Strong and extensible, able to recoil back to its original shape after being stretched.
57
What is the use of Ca2+ ?
Involved in transmission of nerve impulses and insulin secretion, also a cofactor for many enzymes
58
What is the use of Na+ ?
Involved in nerve impulses, muscle contraction and osmoregulation
59
What is the use of K+ ?
Involved in nerve impulses, muscle contraction and osmoregulation.
60
What is the use of H+ ?
Acidity, and photosynthesis
61
What is the use of (NH4)+ ?
Nitrogen source for plants
62
What is the use of (NO3)- ?
Nitrogen source for plants
63
What is the use of (HCO3)- ?
Maintains blood pH
64
What is the use of Cl- ?
Involved in CO2 transport, action potentials, cofactor for amylase
65
What is the use of (PO4)3- ?
Involved in photosynthesis and respiration, and for making P biological molecules.
66
What is the use of OH- ?
pH regulation
67
What does Benedicts reagent test for?
Sugars
68
How do you modify the tests for sugars to account for non-reducing sugars?
Add dilute HCl then heat in water bath, then neutralise with sodium carbonate
69
What colour shows for a low concentration of glucose in the benedicts test?
Green/yellow
70
What colour shows for a medium/high concentration of glucose in the benedicts test?
Orange/ brick red
71
Other than the benedicts test, what else can test for glucose?
Test strips coated in reagent which have a colour change with glucose which you compare to a chart
72
What can be used to test for starch?
Adding iodine solution, and will change to blue-black if starch is present
73
What tests for proteins?
The biuret test
74
How do you carry out biurets test?
Add NaOH, then CuSO4 - goes from blue to purple if protein is present.
75
What does the Emulsion test test for?
Lipids presence
76
How do you carry out the emulsion test for lipids?
Shake substance with ethanol, then pour into water. Milky layer appears if lipid is present.
77
What is a colorimeter?
A device that measures the strength of a coloured solution by shining a light through it and seeing how much light is absorbed by the solution.
78
What is a biosensor?
A device that uses a biological molecule to e.g. an enzyme to detect a chemical. The enzyme produces a signal which is converted to an electrical signal via a transducer
79
What is chromatography?
A method used to seperate a mixture, to then identify the components.
80
What are the 2 types of chromatography?
Paper chromatography and Thin-layer chromatography
81
What is the mobile phase?
The liquid solvent, e.g. water or ethanol
82
What is the stationary phase?
Where the molecules cant move, so the chromatography paper or the TLC plate
83
How do you calculate the Rf value?
Rf= spot distance/solvent distance

A Level Biology OCR (28 decks)

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