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Wjec Biology As Unit 1 > 1.1 > Flashcards

1.1 Flashcards

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
Sucrose
Glucose and fructose
26
Lactose
Glucose and galactose
27
What are the reducing sugars
All monosaccharides Maltose Lactose
28
Test for presence of reducing sugars
Benedict's reagent + heat
29
Describe the test for reducing sugars
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
30
Test for non-reducing sugar
Hydrochloric acid then Benedict's and heat
31
Describe test for non-reducing sugar
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
What is a polymer
Large molecule made up of many repeating units bonded together
33
Why are polysaccharides good energy storage molecules?
* 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
Describe startch
* main energy store in plants * alpha glucose * consists of 2 polymers - amylose and amylopectin
35
Describe amylose
* linear * 1-4 glycosidic bonds * forms a straight chain which coils into a single helix
36
Describe amylopectin
* branched * fits inside amylose * 1-4 and 1-6 glycosidic bonds * more exposed ends that can be hydrolysed - rapid release of glucose
37
Test for the presence of starch
Iodine solution | Orange-brown to blue-black
38
Glycogen
* main storage product in animals | * branched - more than amylopectin
39
Describe cellulose
* 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
Describe chitin
* 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
What is a triglyceride
Lipid | 1 glycerol 3 fatty acids
42
How is a triglyceride formed
Condensation reaction where three water molecules are removed to form three ester bonds
43
Saturated fatty acid tail
``` 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
Unsaturated fatty acid
``` At least 1C=C 1 C=C monounsaturated Many C=C polyunsaturated Plants eg oil Kinks where the C=C is ```
45
Describe waxes
Lipid that melt at temperatures above 45 degrees | Waterproofing eg leaf cuticle
46
Roles of lipids
* electrical insulation eg around the myelin sheath * energy reserve * thermal insulation * protection * metabolic water * waterproofing
47
Lipids role of being a major component of the myelin sheath
Increases the speed at which nerve impulses propagate along the neuron
48
Role of lipids as energy reserves
Contain more C-H bonds than carbohydrates so yields more energy when oxidised
49
Role of lipids as thermal insulation
Stored under the skin | Insulates against heat loss
50
Role of lipids as protection
Stored around delicate internal organs eg kidneys | Against physical damage
51
Role of lipids as metabolic water
Triglycerides produce lots of metabolic water when oxidised
52
Lipids role in waterproofing
Insoluble in water
53
What is a phospholipid
Glycerol, phosphate group and 2 fatty acid taisl
54
Fatty acid end of a phospholipid
Non-polar Hydrophobic Insoluble in water
55
Phosphate head in phospholipid
Polar Hydrophilic Dissolves in water
56
What is hydrophobic
Water hating | Cannot interact with water due to lack of charge
57
What is hydrophilic
Water loving | Can interact with water due to charge
58
Test used for fats and oil and describe what is done
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
What is atherosclerosis
Build up of fatty deposits or plaques called atheromas within the artery walls Causes narrowing of the artieries
60
What causes atherosclerosis
Diet high in saturated fats which results in low-density lipoproteins
61
What is the effect of atherosclerosis
Restricts blood flow which limits oxygen delivery to the heart Can lead to angina and eventually a heart attack
62
What do high-density lipoproteins do
Carry harmful fats to the liver for disposal
63
What kind of lifestyle causes the body to manufacture more HDL
* diet with a higher proportion of unsaturated fats | * exercise
64
What does a high ratio of HDL:LDL mean
Low risk of cardiovascular disease
65
What groups are in an amino acid
* variable R group * amino group * carboxyl group
66
How is a dipeptide formed
A condensation reaction between amino group of one and the carboxyl of A peptide bond is formed
67
What is a polypeptide
Very large molecule that consists of long chains of many amino acids joined together
68
Describe primary structure
* order of amino acids in a polypeptide chain | * determined by the DNA sequence of one strand of the DNA molecule
69
Describe secondary structure
* 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
Describe tertiary structure
* folding of the alpha helix into a more complex shape | * maintained by disulphide, ionic and hydrogen bonds and hydrophobic interactions
71
Describe quaternary protein
* combination of two or more tertiary proteins | * eg haemoglobin
72
Describe fibrous proteins
* 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
Describe collagen
* one fibre has 3 polypeptide chains twisted around each other * cross-bridges make it very stable
74
Describe globular proteins
* metabolic functions - enzymes, antibodies, plasma proteins, hormones * compact and spherical molecules * water soluble
75
Describe haemoglobin
* four folded polypeptide chains * haem at the centre of each * unique and specific shape
76
Test for protein name
The Biuret test
77
Describe Biuret test
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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