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IGCSEs > Biology πŸƒ | Biological Molecules | 4 > Flashcards

Biology πŸƒ | Biological Molecules | 4 Flashcards

1
Q

What are the four main chemical elements in our body?

A

Oxygen, carbon, hydrogen, nitrogen.

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2
Q

What are the elements in our body used for?

A

They are used to be synthesized into biological compounds.

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3
Q

What are organic compounds?

A

Compounds found or synthesized in organisms.

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4
Q

What are most organic compounds based around?

A

Most are based around the element of carbon.

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5
Q

Examples of organic compounds:

A

Lipids, carbohydrates, proteins, nucleic acids, alcohol and DNA.

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6
Q

Why is water needed for organisms?

A
  • As a solvent
  • To transport substances around the body
  • To regulate temperature
  • Enables metabolic reactions
  • Photosynthesis in plants
  • Rid of waste products
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7
Q

Why is water being a solvent important to organisms?

A

As water is a solvent, it stops cells from drying.

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8
Q

How does water help substances be transported around the body?

A

Plasma, the liquid part of blood, needs lots of water so that substances like glucose can dissolve in it.

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9
Q

How does water help with digestion?

A

Water dissolves enzymes and nutrients in the alimentary canal.

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10
Q

Why is water needed for metabolic reactions in organisms?

A

Metabolic reactions only take place if the chemicals reacting are dissolved in water.

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11
Q

What three categories do most molecules in living organisms fall into?

A

Carbohydrates, proteins, and lipids.

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12
Q

What are the chemical elements in carbohydrates?

A

Carbon oxygen and hydrogen.

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13
Q

What are the chemical elements found in protein?

A

Carbon oxygen hydrogen nitrogen and small amounts of sulfur.

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14
Q

What are the chemical elements found in lipids?

A

Carbon oxygen and hydrogen.

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15
Q

What ratio of carbon:hydrogen:oxygen do carbohydrates have?

A

1:2:1

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16
Q

Why are carbohydrates important to organisms?

A
  • Energy production
  • Energy storage
  • Structural form of cellulose
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17
Q

How do carbohydrates store energy in animals?

A

Using glycogen.

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18
Q

How do carbohydrates store energy in plants?

A

Using starch GRAINS

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19
Q

Another word for carbohydrate is _

A

Sugars.

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20
Q

What are the three kinds of carbohydrates?

A

Monosaccharides, disaccharides, polysaccharides

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21
Q

What is the structure of a monosaccharide?

A

It has one sugar.

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22
Q

What are examples of monosaccharides?

A
  • Glucose, a key energy source and core of disaccharides and polysaccharides
  • Fructose, found in fruit
  • Galactose, found in yoghurt
  • Ribose
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23
Q

What is the molecular formula of glucose?

A

C₆H₁₂O₆

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24
Q

Another word for monosaccharides is _

A

Simple sugars

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25
Q

What are the characteristics of monosaccharides?

A

They are small, soluble in water, and sweet.

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26
Q

What is the structure of disaccharides?

A

Two chemically bound monosaccharides.

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27
Q

What are examples of disaccharides?

A
  • Sucrose, found in some cereal or hot drinks
  • Maltose, malt sugar
  • Lactose, found in milk
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28
Q

What two monosaccharides joined together is sucrose?

A

Glucose and fructose.

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29
Q

What two monosaccharides joined together is maltose?

A

Two glucose

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30
Q

What two monosaccharides joined together is lactose?

A

Galactose and Glucose

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31
Q

What is the structure of polysaccharides?

A

More than two joined monosaccharides, complex and large.

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32
Q

What are examples of polysaccharides?

A
  • Starch
  • Amylase
  • Glycogen
  • Amylopectin
  • Cellulose
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33
Q

What are the characteristics of polysaccharides?

A

They are not soluble in water or sweet.

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34
Q

What is the structure of glycogen?

A
  • Glucose molecules joined
  • Branching structure
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35
Q

Where is glycogen found?

A

In muscles and the liver.

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36
Q

What is the structure of starch?

A
  • Glucose molecules joined together
  • Branching structure
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37
Q

What is the carbohydrate used for respiration in animals?

A

Glucose.

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38
Q

What is the structure of cellulose?

A
  • Glucose molecules joined together
  • A very strong spiral structure.
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39
Q

What is the carbohydrate used for respiration in plants?

A

Sucrose or starch, changed to glucose in cells.

40
Q

What are fats also known as?

A

Lipids.

41
Q

What are fat molecules made of?

A

3 fatty acid chains and a glycerol backbone.

42
Q

What are fatty acids?

A

Long hydrocarbon chains!

43
Q

How do fatty acids behave in water?

A

They are non polar and non soluble.

44
Q

When liquid at room temperature, the fat is called a __

A

An oil.

45
Q

What is the function of lipids?

A

To give and store energy, almost twice the energy of carbs.

46
Q

What is the difference between saturated and non saturated fats?

A

Unsaturated ones have double bonds that cause bends and are liquid at room temperature, Saturated ones are solid at room temperature with less double bonds.

47
Q

What are proteins made of?

A

Chains of many amino acids folded into different 3D shapes.

48
Q

How many naturally occurring amino acids are there?

A

20.

49
Q

What makes amino acids unique from each other?

A

Slight changes in structure, in the R group.

50
Q

What do all amino acids have in common?

A

The carboxyl group, amino group, an R group, and central carbon atom paired with an oxygen atom.

51
Q

What atoms are in the amino group?

A

NHH

52
Q

What atoms are in the carboxyl group?

A

COOH

53
Q

What atoms are in the R group?

A

They are unique to all amino acids.

54
Q

What is a polypeptide?

A

A chain of less than 100 amino acids.

55
Q

How many amino acids do proteins have?

A

Over 100.

56
Q

Can proteins be soluble in water?

A

Some, such as haemoglobin are, but others like keratin in hair and nails are insoluble.

57
Q

How do proteins help us in transport?

A

Hemoglobin in red blood cells transport nutrients throughout the body, and others store them.

58
Q

How do proteins help us with chemical reactions?

A

Enzymes such as amylase are proteins that allow key chemical reactions to take place in our body.

59
Q

How do proteins help us defend our systems?

A

Proteins from antibodies protect our bodies from foreign invaders such as disease-causing bacteria and viruses

60
Q

How do proteins help us transmit information?

A

Amino acid chains of various lengths form protein and peptides which make up our body’s hormones and transmit information between cells tissues, and organs. (insulin)

61
Q

How do proteins provide us structure?

A

A class of proteins called fibrous proteins give parts of our body strength, structure, and elasticity. (keratin in skin, hair, and nails.)

62
Q

What happens if the shape of a protein changes?

A

If there is a change in shape (denaturation) then the protein can’t work anymore. This results usually in diseases.

63
Q

Define DNA.

A

DNA is the chemical that makes up our genes and chromosones. It is the material we inherit from our parents, which gives us many of our characteristics.

64
Q

What is the function of DNA?

A

There is DNA in thenucleusof every cell. DNA carries genetic information. The information contains instructions for making proteins, which have various functions.

65
Q

What does DNA stand for?

A

Deoxyribonucleic acid.

66
Q

What is a DNA molecule made of?

A

Two long strand, with a series of β€œbases” coiled to form a double helix.

67
Q

Where is DNA found?

A

In the cell nucleus, DNA is organised into coiled strands called chromosomes.

68
Q

How many chromosomes does a human have per cell?

A

46.

69
Q

How many chromosomes do we have from each parent?

A

23

70
Q

How are the bases on the two strands held together?

A

Bonds.

71
Q

What are the 4 bases in a DNA molecule?

A

A,C,G,T

72
Q

What does the sequence of bases in DNA provide?

A

A code that determines the kind of proteins that are made in our cells, determining how our cells, tissues, and organs develop.

73
Q

What does T pair with?

A

A

74
Q

What does A pair with?

A

T

75
Q

What does G pair with?

A

C

76
Q

What does C pair with?

A

G

77
Q

Why is a chromosome called a helix?

A

The two stands twist together.

78
Q

What is the test for starch called?

A

Iodine test for starch.

79
Q

How is starch tested for?

A
  1. Place one spatula of the food sample on a dish or 1 cm3if the sample is liquid.
  2. Using a dropper, place a few drops of iodine solution onto the food.
  3. Record any change in the colour of the solution.
    If the iodine turns blue-black there is starch
80
Q

What is the positive result of the test for starch?

A

The sample turns blue-black

81
Q

What is the test for reducing sugars called?

A

Benedict’s test for reducing sugars.

82
Q

How are reducing sugars tested for?

A
  1. Place two spatulas of the food sample into a test tube or 1 cm3if the sample is liquid. Add about 1 cm3depth of water to the tube and stir to mix.
  2. Add an equal volume of Benedict’s solution and mix.
  3. Place the tube in a water bath at about 95Β°C for a few minutes.
  4. Record the colour of the solution.
83
Q

What is the positive result of the test for reducing sugars?

A

If orange or brick red, there is reducing sugars.

84
Q

What is the colour gradient of the test result of benedict solution

A

Blue-green-yellow-orange-brick red

85
Q

What are reducing sugars?

A

monosaccharides – such asglucoseandfructose, disaccharides – such as maltose

86
Q

What is the test for proteins called?

A

Protein biruet test

87
Q

How are proteins tested for?

A
  1. Place one-two spatulas of the food sample into a test tube or 1 cm3if the sample is liquid. Add about 1 cm3depth of water to the tube and stir to mix.
  2. Add an equal volume of potassium hydroxide solution to the tube and stir.
  3. Add two drops of copper sulfate solution and stir for two minutes.
  4. Record the colour of the solution.
88
Q

How are proteins detected?

A

Proteins are detected usingBiuret reagent. This turns amauve or purplecolour when mixed with protein.

89
Q

What is the positive result of the test for proteins?

A

The solution turns mauve or purple when positive, blue when negative.

90
Q

What is the test for lipids called?

A

Emulsion test for lipids

91
Q

How are lipids tested for?

A
  1. Place two spatulas of the food sample into a test tube or 1 cm3if the sample is liquid.
  2. Add 2 cm3of ethanol to the tube. Cover the end of the tube and shake the tube vigorously.
  3. Allow the contents to settle.
  4. Pour the liquid from the top of the mixture into a test tube half-filled with water.
  5. Record the level of the food and whether the water is white cloudy or clear.
92
Q

What is the positive result of the test for lipids?

A

Amilky-white emulsionforms if the test substance contains lipids.

93
Q

What is the test for vitamin C called?

A

Vitamin C test with DCPIP

94
Q

How is vitamin C tested for?

A
  1. Pipette 2 cm3of food sample into a test tube.
  2. Add 1% DCPIP drop by drop to the vitamin C solution.
  3. Shake the tube gently after adding each drop
  4. Add DCPIP solution until the blue colour of the final drop does not disappear.
  5. Record the exact amount of DCPIP solution that was added.
  6. Repeat the procedure and calculate an average result.
95
Q

What is the positive result of the DCPIP test for vitamin C?

A

The solution turns colourless.

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