Bio Chapter 3 - Biological Molecules Flashcards

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1
Q

Why do all lining organisms need food and water?

A

Contains nutrients essential for us

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2
Q

What are the 6 functions of water

A

Dissolves substances for chemical reactions that take place in living things. Essential for photosynthesis. Keeps cells turgid and firm. Transport mineral salts.regulate body. Transport dissolved substances within the body.

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3
Q

Describe sugars

A

Sweet. Soluble in water → lower water potential of the solution.

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4
Q

Give the three classifications of carbohydrates

A

Single sugars, double sugars and complex carbohydrates

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5
Q

What are the two single sugars?

A

Glucose and fructose

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6
Q

What are the two double sugars?

A

Maltose and sucrose

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7
Q

What are the three complex carbs?

A

Starch, cellulose, glycogen

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8
Q

Describe single sugars

A

Basic unit of carbs, can pass through cell membranes and can be absorbed into cells

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9
Q

Describe double sugars

A

Formed when two single sugars are joined together

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10
Q

What’s the structure of maltose?

A

Glucose + glucose

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11
Q

What is the structure of sucrose?

A

Glucose + fructose

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12
Q

What is the structure of starch

A

Made up of several thousand glucose molecules joined together

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13
Q

What is the role of starch?

A

Stores carbohydrates in plants. in humans, it is digested into glucose to provide energy for cell activity

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14
Q

Where is starch found?

A

Storage organs of plants

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15
Q

What is the structure of cellulose?

A

Made up of many glucose molecules joined together bonded differently from starch

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16
Q

What is the role of cellulose?

A

Protects plants cells from bursting or damage
Cannot be digested so it acts as dietary fibre that aids in digestion/ prevents constipation in humans

17
Q

Where is cellulose found?

A

Cell walls of plants

18
Q

What is the structure of glycogen?

A

A branched molecule made up of many glows molecules joined together

19
Q

What is the role of glycogen?

A

Stores carbohydrates in mammals. Digested into glucose to provide energy for cell activity

20
Q

Where is glycogen found?

A

Liver and muscles

21
Q

What are the 5 functions of carbohydrates

A

Source and store of energy,
supporting structures such as cellulose in plants,
formation of nucleic acids such as DNA,
to make lubricants such as mucus,
covering the inner surface of the trachea and traps dust particles preventing dust from entering the lungs
To make nectar in some flowers

22
Q

Give 3 examples of reducing sugars

A

Glucose, fructose and maltose

23
Q

How to test for reducing sugars?

A

Benedict’s solution
Add 2cm3 of each food sample into a test tube
Add 2cm3 of Benedicts solution to food sample
Shake mixture and place test tube in boiling water bath for 2 to 3 minutes
Observe colour of solution

24
Q

What are the results of the Benedict’s test?

A

Blue → none
Blue to green → traces
Blue to yellow / orange precipitate → moderate amount
Blue to brick-red precipitate → large amount

25
Q

How to test for starch?

A

Iodine solution
Add a few drops of iodine in potassium iodide solution to a food sample
Record observations

26
Q

What are the results of starch test?

A

Brown → negative
Blue-black → positive

27
Q

What is the structure of fats?

A

Fat molecule → One glycerol + 3 fatty acid molecules

28
Q

Name 4 sources of fats

A

Butter, cheese, fatty meat and salmon

29
Q

What are the 5 functions of fats

A

Source and storage of energy
Insulating material that prevents excessive heat loss
Solvent for fat soluble vitamins and hormones
Essential part of cells
Way to reduce water loss from skin surface

30
Q

Why are fats a better energy source than carbohydrates?

A

Higher energy value compared to carbohydrates which makes it a suitable long-term storage material

31
Q

How does fats reduce water loss on skin surface?

A

Glands in skin secrete a thin layer of an oily substance over skin surface called sebum that reduces rate of evaporation of water → reducing rate of heat loss from the skin

32
Q

How to test for fats in the liquid state?

A

Ethanol emulsion test
Add 2cm3 of ethanol to a drop of liquid sample in a tent tube and shake mixture thoroughly
Add 2cm3 of water into the mixture and shake
Record observations

33
Q

How to test for fats in the solidstate?

A

Crush solid using mortar and pestle and place pieces in test tube
Add 2cm3 of ethanol into test tube and shake thoroughly
Allow solid particles to settle
Pour ethanol into another test tube containing 2cm3 of water and shake
Record observations

34
Q

What are the results of ethanol emulsion test?

A

White emulsion → positive
Solution remained colourless → negative

35
Q

What is the structure of polypeptides?

A

Many amino acid molecules joined together in a linear manner

36
Q

what are some sources of protein?

A

Milk, eggs, seafood, meat
Soya beans, nuts

37
Q

What are the three functions of proteins

A

Synthesis of new cytoplasm for growth and repair of worn out body cells
Synthesis of enzymes and some hormones
Formation of antibodies to combat diseases

38
Q

How to test for protein?

A

Biuret solution
To2cm3 of liquid food sample, add 2cm3 of biuret solution
Shake well and allow mixture to stand for five minutes
Record observation

39
Q

What are the results of the biuret test?

A

Violet -> has proteins
Blue -> no proteins