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Wjec Biology As Unit 1 > 1.1 > Flashcards

1.1 Flashcards

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1
Q

Role of Mg2+

A

Constituent of chlorophyll

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2
Q

Role of Fe2+

A

Constituent of haemoglobin

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3
Q

Role of Ca2+

A

Structural component of bones and teeth and cell walls

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4
Q

Role of PO4 3-

A

Needed for making nucleotides

Constituent of phospholipids

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5
Q

What is a condensation reaction

A

Removal of a water molecule to form a covalent bond

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6
Q

What is hydrolysis

A

Addition of a water molecule to break a covalent bond as

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7
Q

What is meant by water being dipolar

A

Its a polar molecule with a positive and negative charge

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8
Q

What is the biological importance of water being a solvent

A
  • involved in many biochemical reactions

* dissolves polar molecules

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9
Q

Biological importance of water’s high specific heat capacity?

A
  • need a lot of energy to increase it’s temperature

* stable aquatic environments

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10
Q

Biological importance of water’s high latent heat of vaporisation

A
  • large amounts of heat needed to vaporise water

* used as cooling mechanism eg sweating in mammals

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11
Q

Biological importance of water being a metabolite

A

• involved in many biochemical reactions

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12
Q

Biological importance of water’s cohesive properties

A
  • water molecules attract each other

* water can be drawn up the xylem vessels of trees

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13
Q

Biological importance of water’s high surface tension

A

• supports insects on surface of water eg pond skaters

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14
Q

Biological importance of water’s high density

A
  • ice is less dense than water

* ice floats and acts as an insulator preventing the water freezing which protects the aquatic habitat

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15
Q

Biological importance of water’s transparency

A
  • allows light to pass through

* enables aquatic plants to photosynthesise

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16
Q

Functions of carbohydrates in general

A
  • building blocks for complex molecules
  • source of energy
  • energy storage molecules
  • structural support
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17
Q

Formula of monosaccharides

A

(CH2O)n

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18
Q

Trioses

A

n=3

Important in respiration pathways

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19
Q

Pentoses

A

n=5
eg ribose and deoxyribose
constituent of ribonucleic acid and deoxyribonucleic acid

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20
Q

Hexose

A

n=6

Glucose, galactose and fructose

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21
Q

What are isomers

A

Molecules with same chemical formula but different arrangements of atoms

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22
Q

How do alpha and beta glucose differ

A

OH is interchanged on C1

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23
Q

What is a disaccharide and how is it formed

A

Two monosaccharides joined together by a glycosidic bond

Involves the loss of a molecule of water via a condensation reaction

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24
Q

Maltose

A

Glucose and glucose

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25
Q

Sucrose

A

Glucose and fructose

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26
Q

Lactose

A

Glucose and galactose

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27
Q

What are the reducing sugars

A

All monosaccharides
Maltose
Lactose

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28
Q

Test for presence of reducing sugars

A

Benedict’s reagent + heat

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29
Q

Describe the test for reducing sugars

A
  1. Add equal volume of Benedict’s reagent to the solution being tested and strongly heat in a boiling water bath
  2. A positive test would gradually turn from blue to green, yellow, orange and finally brick-red
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30
Q

Test for non-reducing sugar

A

Hydrochloric acid then Benedict’s and heat

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31
Q

Describe test for non-reducing sugar

A
  1. Hydrolyse and heat with HCl, then neutralise by adding alkali slowly until the fizzing stops
  2. Add Benedict’s reagent and strongly heat. If solution turns blue to red then it is present
32
Q

What is a polymer

A

Large molecule made up of many repeating units bonded together

33
Q

Why are polysaccharides good energy storage molecules?

A
  • unable to diffuse out of the cell
  • compact - can store a lot in a cell
  • insoluble in water - no osmotic effect
  • easily hydrolysed - used in respiration
34
Q

Describe startch

A
  • main energy store in plants
  • alpha glucose
  • consists of 2 polymers - amylose and amylopectin
35
Q

Describe amylose

A
  • linear
  • 1-4 glycosidic bonds
  • forms a straight chain which coils into a single helix
36
Q

Describe amylopectin

A
  • branched
  • fits inside amylose
  • 1-4 and 1-6 glycosidic bonds
  • more exposed ends that can be hydrolysed - rapid release of glucose
37
Q

Test for the presence of starch

A

Iodine solution

Orange-brown to blue-black

38
Q

Glycogen

A
  • main storage product in animals

* branched - more than amylopectin

39
Q

Describe cellulose

A
  • structural polysaccharide
  • beta glucose
  • adjacent glucose molecules rotated by 180 degrees forming long straight parallel chains that are cross-linked by hydrogen bonds
  • called microfibrils
  • contribute to strength of cell wall
40
Q

Describe chitin

A
  • structural polysaccharide
  • beta glucose
  • exoskeleton of insects and fungi cell walls
  • strong, lightweight and waterproof
  • parallel chains of beta glucose with added acetyl amine group
  • chains cross-linked by hydrogen bonds forming microfibrils as adjacent glucose molecules rotated 180 degrees
41
Q

What is a triglyceride

A

Lipid

1 glycerol 3 fatty acids

42
Q

How is a triglyceride formed

A

Condensation reaction where three water molecules are removed to form three ester bonds

43
Q

Saturated fatty acid tail

A 
No C=C
Each C linked to maximum number of H atoms
Saturated with H atoms
Semi-solid at rtp
Storage of fats in mammals
44
Q

Unsaturated fatty acid

A 
At least 1C=C
1 C=C monounsaturated 
Many C=C polyunsaturated 
Plants eg oil
Kinks where the C=C is
45
Q

Describe waxes

A

Lipid that melt at temperatures above 45 degrees

Waterproofing eg leaf cuticle

46
Q

Roles of lipids

A
  • electrical insulation eg around the myelin sheath
  • energy reserve
  • thermal insulation
  • protection
  • metabolic water
  • waterproofing
47
Q

Lipids role of being a major component of the myelin sheath

A

Increases the speed at which nerve impulses propagate along the neuron

48
Q

Role of lipids as energy reserves

A

Contain more C-H bonds than carbohydrates so yields more energy when oxidised

49
Q

Role of lipids as thermal insulation

A

Stored under the skin

Insulates against heat loss

50
Q

Role of lipids as protection

A

Stored around delicate internal organs eg kidneys

Against physical damage

51
Q

Role of lipids as metabolic water

A

Triglycerides produce lots of metabolic water when oxidised

52
Q

Lipids role in waterproofing

A

Insoluble in water

53
Q

What is a phospholipid

A

Glycerol, phosphate group and 2 fatty acid taisl

54
Q

Fatty acid end of a phospholipid

A

Non-polar
Hydrophobic
Insoluble in water

55
Q

Phosphate head in phospholipid

A

Polar
Hydrophilic
Dissolves in water

56
Q

What is hydrophobic

A

Water hating

Cannot interact with water due to lack of charge

57
Q

What is hydrophilic

A

Water loving

Can interact with water due to charge

58
Q

Test used for fats and oil and describe what is done

A

Lipid Emulsion Test
• sample is mixed with ethanol to dissolve the lipids
• sample is shaken with an equal volume of water
• the lipids will fall out of the solution and will give the sample a cloudy white emulsion appearance

59
Q

What is atherosclerosis

A

Build up of fatty deposits or plaques called atheromas within the artery walls
Causes narrowing of the artieries

60
Q

What causes atherosclerosis

A

Diet high in saturated fats which results in low-density lipoproteins

61
Q

What is the effect of atherosclerosis

A

Restricts blood flow which limits oxygen delivery to the heart
Can lead to angina and eventually a heart attack

62
Q

What do high-density lipoproteins do

A

Carry harmful fats to the liver for disposal

63
Q

What kind of lifestyle causes the body to manufacture more HDL

A
  • diet with a higher proportion of unsaturated fats

* exercise

64
Q

What does a high ratio of HDL:LDL mean

A

Low risk of cardiovascular disease

65
Q

What groups are in an amino acid

A
  • variable R group
  • amino group
  • carboxyl group
66
Q

How is a dipeptide formed

A

A condensation reaction between amino group of one and the carboxyl of
A peptide bond is formed

67
Q

What is a polypeptide

A

Very large molecule that consists of long chains of many amino acids joined together

68
Q

Describe primary structure

A
  • order of amino acids in a polypeptide chain

* determined by the DNA sequence of one strand of the DNA molecule

69
Q

Describe secondary structure

A
  • folding of the primary structure into a 3D shape
  • held by hydrogen bonds between =O on the -COOH group and the H on the NH2
  • alpha helix and beta pleated sheet
70
Q

Describe tertiary structure

A
  • folding of the alpha helix into a more complex shape

* maintained by disulphide, ionic and hydrogen bonds and hydrophobic interactions

71
Q

Describe quaternary protein

A
  • combination of two or more tertiary proteins

* eg haemoglobin

72
Q

Describe fibrous proteins

A
  • structural functions
  • polypeptides in parallel chains or sheets with many cross-links to form long fibres
  • insoluble in water
  • strong, tough
  • eg collagen and ketatin
73
Q

Describe collagen

A
  • one fibre has 3 polypeptide chains twisted around each other
  • cross-bridges make it very stable
74
Q

Describe globular proteins

A
  • metabolic functions - enzymes, antibodies, plasma proteins, hormones
  • compact and spherical molecules
  • water soluble
75
Q

Describe haemoglobin

A
  • four folded polypeptide chains
  • haem at the centre of each
  • unique and specific shape
76
Q

Test for protein name

A

The Biuret test

77
Q

Describe Biuret test

A
  1. Add few drops of Biuret reagent to sample

2. Positive turns from blue to purple

Wjec Biology As Unit 1 (7 decks)

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