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WJEC AS Biology > Chemical Elements & Biological Compounds Unit 1.1 > Flashcards

Chemical Elements & Biological Compounds Unit 1.1 Flashcards

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1
Q

What are micronutrients?

A

Minerals needed in minute concentrations. (copper/zinc)

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2
Q

What are macronutrients?

A

Minerals needed in small concentrations. (magnesium/iron)

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3
Q

What is the biological role of magnesium?

A

Constituent of chlorophyll and therefore essential for photosynthesis.

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4
Q

What is the biological role of iron?

A

Constituent of haemoglobin, transporting oxygen in red blood cells.

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5
Q

What is the biological role of nitrogen?

A

Needed to make nucleotides. (ATP, DNA, RNA)

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6
Q

What is an organic molecule?

A

Molecules which have a high proportion of carbon and hydrogen atoms.

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7
Q

What is an inorganic molecule?

A

A molecule/ion that has no more than one carbon atom.

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8
Q

What is a dipole?

A

A polar molecule which has a positive and negative charge, separated by a small distance.

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9
Q

What type of bond would two water molecules form?

A

Hydrogen bond.

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10
Q

What is the attraction between water molecules called?

A

Cohesion

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11
Q

Describe water as a solvent.

A

Ions and polar molecules dissolve in water (glucose) but non-polar molecules (lipids) cannot.

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12
Q

Describe water as a transport medium. (humans & plants)

A
  • Blood is mainly water and transports many dissolved substances around the body.
  • Minerals dissolve in water and are transported from the root to leaves via xylem.
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13
Q

Describe water as a place where chemical reactions take place.

A

Transport of polar molecules and ions allow chemical reactions when particles meet.

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14
Q

Describe water’s high specific heat capacity.

A

A large amount of heat energy is required to raise the temperature, preventing large fluctuations which keeps the temperature of aquatic environments stable so organisms do not have to endure extremes of temperature. (also for cell enzymes)

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15
Q

Water has a high latent heat of vaporisation. Explain.

A

Due to cohesion, a large amount of heat energy is needed to change from liquid to gas. This process of evaporation transfers heat energy and is an effective way to cool down the body.

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16
Q

Explain cohesion in water. (xylem)

A

The attraction between water molecules allows water to be transported through the xylem.

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17
Q

Explain surface tension in water.

A

Ordinary temperatures- highest surface tension of any liquid. (except mercury)

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18
Q

Explain the density of water.

A

Maximum density at 4°C. Ice is LESS dense so it floats to surface and insulates water beneath.

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19
Q

Name 8 properties of water.

A
  1. Is a solvent
  2. A transport medium
  3. Allows chemical reactions
  4. High specific heat capacity
  5. High latent heat of vaporisation
  6. Cohesive
  7. High surface tension
  8. Is dense
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20
Q

What are carbohydrates? What do they contain?

A

Organic compounds containing carbon, hydrogen and oxygen. The basic unit is a monosaccharide.

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21
Q

What would two monosaccharides create?

A

A disaccharide

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22
Q

What would many monosaccharides create?

A

A polysaccharide (type of polymer)

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23
Q

What are the 3 types of monosaccharides and how many carbon atoms do they have?

A
  • Triose - 3
  • Pentose - 5
  • Hexose - 6
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24
Q

Function of a triose:

A
  • Important in metabolism.

* Used in reactions of respiration and photosynthesis.

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25
Q

What is the function of a pentose sugar?

A

Constituents of nucleotides.

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26
Q

Function of hexose:

A

E.g- Glucose.

Source of energy in respiration. Carbon-hydrogen and carbon-carbon bonds break to release energy to make ATP.

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27
Q

Describe an isomer and an isotope.

A
  1. Two molecules that have the same molecular formula and number of atoms. They are just arranged differently. (alpha glucose & beta glucose have OH and H switched)
  2. Molecules with different number of neutrons of the same element.
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28
Q

What bond and reaction does a disaccharide have?

A

Glycosidic bond.

Condensation reaction.

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29
Q

What does a condensation reaction produce?

A

Water is removed from original two molecules. (e.g alpha glucose)
(H20 removed, leaving an O bonded between them- glycosidic)
WATER IS PRODUCED AS AN END PRODUCT.
(2 a glucose —> maltose + water)

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30
Q

How could a glycosidic bond be broken?

maltose & water

A

Hydrolysis:
Water chemically added to break bond.
(maltose + water—> 2 a glucose)

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31
Q

Name 3 disaccharides.

A
  • Maltose
  • Sucrose
  • Lactose
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32
Q

What is maltose made from and what is it’s role?

A

Two alpha glucoses- germinates seeds

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33
Q

What is sucrose made of and where is it produced?

A

Alpha glucose + fructose:

A product of photosynthesis transported into phloem.

34
Q

What is lactose made of and where is it found?

A

Beta glucose + galactose:

Mammalian milk.

35
Q

Sucrose is a non-reducing sugar. What does this mean and why does the Benedict’s test have to be altered?

A

It does not reduce copper ll sulphate.

  1. Benedict’s will remain blue as the sucrose must be hydrolysed first by boiling in hydrochloric acid.
  2. Glucose + fructose form and acid is neutralised by sodium hydroxide before testing with Benedict’s reagent.
  3. This shows positive result.
36
Q

What is starch made from?

A

Multiple a glucose monomers added by a condensation reaction.

37
Q

What are the two types of polysaccharides in starch?

A

Amylose and amylopectin

38
Q

Describe amylose.

A

A polysaccharide component of starch which is unbranched and coiled.

39
Q

Describe amylopectin.

A

A polysaccharide component of starch which is branched. Each branch point is formed by a C1-C6 glycosidic bond.

40
Q

What is glycogen? (3)

A
  • Main storage product in animals.
  • Has similar structure to amylopectin but has more branches.
  • Shorter C1-C4 a glucose chains than amylopectin.
41
Q

What is cellulose and where is it found? (5)

A
  • Structural polysaccharide found in plant cell walls.
  • Consists of many long, parallel chains of b glucose units.
  • 60-70 cellulose molecules become tightly cross-linked to form microfibrils, these form fibres.
  • Is unreactive and stable as it is unbranched.
  • Has a high tension strength.
42
Q

What is chitin? (5)

A
  • Structural polysaccharide found in exoskeleton of insects and fungal cell walls.
  • Composed of long b glucose chains which have glycosidic bonds.
  • Strong
  • Waterproof
  • Lightweight
43
Q

What is the most common type of lipid?

A

Triglycerides (fats & oils)

44
Q

What are the properties of triglycerides? (6)

A
  • Glycerol bonded with 3 fatty acids
  • Contain carbon, hydrogen & oxygen
  • Insoluble in water
  • Non-polar
  • Soluble in other solvents such as ethanol & chloroform
  • No phosphate group
45
Q

How are triglycerides formed?

A

Condensation reaction between glycerol and fatty acids.

46
Q

Describe glycerol and fatty acids.

A

Glycerol- type of alcohol

Fatty acids- Organic molecules that have a -COOH group attached to a long hydro-carbon tail.

47
Q

What bond is made in triglycerides?

A

Ester bond (triglyceride has 3)

48
Q

What breaks an ester bond?

A

Hydrolysis

49
Q

Describe unsaturated fatty acids. (3)

A
  • Double bonds between carbon atoms. (e.g: C=C-C-C-)
  • Do NOT contain max possible number of hydrogen atoms.
  • Double bond make fatty acids and lipids melt easier.
50
Q

Describe saturated fats. (4)

A
  • No double bonds. (e.g: C-C-C-C)
  • Carries max possible number of hydrogen atoms.
  • Solid
  • Possible link between consumption and heart disease.
51
Q

Three main causes of heart disease:

A
  1. Fatty deposits in coronary arteries (atherosclerosis)
  2. High blood pressure (hypertension)
  3. Diet high in saturated fatty acids, smoking, lack of exercise and ageing
52
Q

What happens if someone’s diet is high in saturated fats? (LDL’s)

A

Low-density lipoproteins build up and fatty material (atheroma) is deposited in coronary arteries which restricts blood flow and oxygen delivery to the heart. This can cause angina or a heart attack.

53
Q

What happens if a diet is high in unsaturated fats? (HDL’s)

A

More high-density lipoproteins are made which carry harmful fats to the liver for disposal.

54
Q

The higher the ratio of HDL:LDL in blood, the…

A

Lower the risk of cardio-vascular and coronary heart disease.

55
Q

What is a phospholipid? Structure? (4)

A
  • Special type of lipid.
  • 2 fatty acid tails with a phosphate group.
  • Phosphate group polar so is soluble in water.
  • Hydrophilic head & hydrophobic fatty acid tails.
56
Q

What do phospholipids do in water?

A

Hydrophobic tails turn inwards to avoid water, forming a micelle. (fatty droplet)
If enough phospholipids present, a bilayer is formed as heads point outward to water. This is the basis of all cell membranes.

57
Q

How do you determine whether a substance contains lipids?

A

•Mix with ethanol.
-Lipid will dissolve.
•Water added & shaken.
-Emulsion occurs and sample turns cloudy white if present.

58
Q

Name 6 functions of lipids.

A
  1. Energy store
  2. Thermal insulator
  3. Protection
  4. Metabolic water source
  5. Waterproofing
  6. Low density
59
Q

Describe lipids as energy stores.

A

They have twice as much energy than carbohydrates when oxidised.

60
Q

Where are lipids stored as a thermal insulator?

A

Under the skin to reduce heat loss.

61
Q

How are lipids used as protection?

A

Fat is often stored around delicate organs (kidneys)

62
Q

How are lipids a metabolic water source?

A

They produce metabolic water, essential for desert animals.

63
Q

Explain lipid waterproofing.

A

Reduce water loss as they are insoluble in water.

64
Q

How are lipids having a low density an advantage?

A

Helps animals, like polar bears, be able to float.

65
Q

What atoms do proteins always contain?

A

Nitrogen

66
Q

What are proteins?

A

Polymers made of monomers called amino acids.

67
Q

What is a chain of amino acids called?

A

Polypeptide.

68
Q

What is an essential and non-essential amino acid?

A

Essential- One that cannot be synthesised by our bodies. Must be provided though diet.

Non-essential- Can be synthesised by our bodies.

69
Q

All amino acids contain the same basic structure. What 4 things do they consist of?

A
  1. Amino group (basic/alkaline)
  2. Carboxyl group (acidic)
  3. Hydrogen atom
  4. The R-group (variable group of atoms)
70
Q

How do amino acids react?

A

With the carboxyl group of another via condensation reaction (water eliminated)
PEPTIDE BOND resulting in dipeptide

71
Q

What are the four levels of protein structure?

A
  • Primary
  • Secondary
  • Tertiary
  • Quaternary
72
Q

Describe a primary structure of protein.

A

The sequence of amino acids in polypeptide chain.
Determined by DNA.
Peptide bond.

73
Q

Describe a secondary protein structure.

A

The shape that polypeptide forms due to hydrogen bonding (twist & fold) forming an alpha helix.

74
Q

Describe a tertiary structure of protein. (2)

A
  • Alpha helix of secondary protein further folds and twist to give more complex & compact 3D structure.
  • Shape maintained by ionic, covalent, disulphide and hydrogen bonds.
  • Enzymes have this structure.
75
Q

Describe a quaternary structure of proteins. (3)

A
  • Arises from combination of 2+ polypeptide chains in tertiary form.
  • Associated with non-protein groups.
  • Form large, complex molecules (e.g haemoglobin)
76
Q

Describe globular proteins. (3)

A

•Compact
•Folded into 3D spherical molecules
•Soluble in water
(e.g haemoglobin)

77
Q

What is a fibrous protein? (5)

A

•Perform structural functions
•Long polypeptide chains in parallel chain/sheets
•Numerous cross linkages to form long fibres
•Insoluble in water
•Strong & tough
(e.g collagen)

78
Q

Compare a globular protein (haemoglobin) and a fibrous protein.(collagen)

A 
G
-4 polypeptide molecules
-Each one is different
-Associated with non-protein groups
-Highest level of protein structure is quaternary
C
-3 polypeptide molecules
-Each is the same
-Not associated with non-protein groups
•Highest level is secondary
79
Q

What is the Biuret test used for?

A

Chemical test for detecting peptide bonds between amino acids. Copper ll ion turns blue colour to violet when present.

80
Q

What are macromolecules and micro molecules?

A
  1. Giant molecule made from smaller unit such as micro molecules. (smaller)
81
Q

What is deoxyribose?

A

A key building block for DNA. (5 carbon sugar)

82
Q

What is the test for starch?

A

Iodine- originally red/brown will go blue black if positive.

WJEC AS Biology (9 decks)

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