Chapter 03 - Biological Molecules

Question 1

Food nutrients contain water, ____, ____ and ____

Answer 1

Food nutrients contain water, carbohydrates, fats and proteins

Question 2

What are carbohydrates?

Answer 2

Carbohydrates are organic molecules made up of carbon, hydrogen and oxygen. The hydrogen to oxygen atoms are present in the ratio 2:1.

Question 3

What are the 3 types of carbohydrates

Answer 3

1) Simple Sugars (monosaccharides)
2) Double Sugars (disaccharides)
3) Complex Carbohydrates (polysaccharides)

Question 4

Name 3 examples of polysaccharides

Answer 4

Starch, Glycogen, Cellulose

Question 5

Name 2 examples of disaccharides

Answer 5

Maltose, Sucrose

Question 6

Name 3 examples of monosaccharides

Answer 6

Glucose, Fructose, Galactose

Question 7

Polysaccharides are ____, ____ and ____

Answer 7

Polysaccharides are large, complex and insoluble

Question 8

Disaccharides are ____, ____ and ____

Answer 8

Disaccharides are small, simple and soluble

Question 9

Monosaccharides are ____ ____ ____

Answer 9

Monosaccharides are one basic unit

Question 10

What are the 3 properties of sugars?

Answer 10

1) Soluble in water
2) Lowers water potential of solutions
3) Provides energy

Question 11

All monosaccharides have the same formula: ____

Answer 11

C6H12O6

Question 12

Even though monosaccharides have the same formula, they differ in ____ of various atoms, resulting in different ____ and ____ properties

Answer 12

Even though monosaccharides have the same formula, they differ in arrangement of various atoms, resulting in different chemical and biological properties

Question 13

Can monosaccharides pass through a partially permeable membrane?

Answer 13

Yes, monosaccharides pass through partially permeable membranes for absorption

Question 14

Where can glucose be found?

Answer 14

In plants and animals

Question 15

Where can fructose be found?

Answer 15

Commonly in plants (fruit sugar), rarely in animals

Question 16

How do double sugars form?

Answer 16

Double sugars are formed when 2 single sugars join together

Question 17

Which 2 monosaccharides make up maltose?

Answer 17

2 glucose molecules

Question 18

Where does maltose occur in?

Answer 18

Maltose occurs in germinating grains

Question 19

Where does sucrose occur in?

Answer 19

Sucrose occurs in fruits

Question 20

What can an enzyme do to a disaccharide?

Answer 20

An enzyme can split a disaccharide into 2 monosaccharides
e.g Maltase splits maltose into 2 glucose moleucles

Question 21

All disaccharides have the same formula: ____

Answer 21

C12H22O11

Question 22

Even though disaccharides have the same formula, they differ in ____ of various atoms, resulting in different ____ and ____ properties

Answer 22

Even though disaccharides have the same formula, they differ in arrangement of various atoms, resulting in different biological and chemical properties

Question 23

How do complex carbohydrates form?

Answer 23

Many similar molecules of single sugars joined together

Question 24

Starch, cellulose and glycogen are formed by many ____ molecules joined together in ____ ways resulting in different ____ and ____ properties

Answer 24

Starch, cellulose and glycogen are formed by many glucose molecules joined together in different ways resulting in different biological and chemical properties

Question 25

What is starch made up of?

Answer 25

Several thousands of glucose molecules

Question 26

What can starch do?

Answer 26

Starch is required for respiration, as it can be digested to provide energy when needed

Question 27

Is starch formed or stored by animals?

Answer 27

No, starch is formed by plants (photosynthesis) and is a storage form of carbohydrates for plants for when they need energy

Question 28

Is starch soluble?

Answer 28

Starch is insoluble, making it ideal for storage

Question 29

Where can starch be found?

Answer 29

In storage organs of plants e.g potato tubers

Question 30

What is cellulose made up of?

Answer 30

Many glucose molecules linked together, bonds between glucose are different from those in starch

Question 31

Cellulose is not easily broken down in the digestive system and also is a major component of ____ ____ for humans to avoid ____

Answer 31

Cellulose is not easily broken down in the digestive system and also is a major component of dietary fibre for humans to avoid constipation

Question 32

Cellulose is a major component in ____ ____ to protect the plant cells from ____ or ____

Answer 32

Cellulose is a major component in cell walls to protect the plant cells from bursting or injury

Question 33

What is glycogen made up of?

Answer 33

Many glucose molecules into a highly branched molecule

Question 34

Like starch, glycogen is also a ____ ____ of carbohydrates but for ____

Answer 34

Like starch, glycogen is also a storage form of carbohydrates but for mammals

Question 35

What can glycogen be converted to, to provide what when needed?

Answer 35

Glycogen can be digested into glucose to provide energy when needed

Question 36

Where can glycogen be found?

Answer 36

In the liver and muscles

Question 37

Why are glycogen and starch ideal for storage? (4 reasons)

Answer 37

1) Insoluble in water - doesn't change water potentials in cell 2) Cannot pass through cell membrane - won't be lost from cells 3) Can be broken down easily to glucose when needed 4) Highly compact - less space needed than individual glucose molecules

Question 38

Which enzymes breaks down starch and into what?

Answer 38

Amylase breaks down starch molecules into maltose molecules

Question 39

Which enzyme breaks down maltose and into what?

Answer 39

Maltase breaks down maltose molecules into glucose molecules

Question 40

What are the 6 functions of carbohydrates?

Answer 40

1) Substrate for respiration, to provide energy for cell activities 2) Forms supporting structures (e.g cell wall) 3) Converted to other organic compounds (e.g amino acids + fats) 4) Forms nucleic acid (e.g DNA) 5) Synthesises lubricants (e.g mucus) 6) Synthesises nectar in flowers

Question 41

Describe the test for starch

Answer 41

1) Add a few drops of iodine solution to the sample +: If starch is present, brown iodine turns blue-back -: If starch is absent, brown iodine remains brown

Question 42

Describe the test for reducing sugars

Answer 42

1) Add 2cm3 of test sample into a test tube 2) Add 2cm3 of Benedict's solution to the test tube. Shake 3) Place in a hot water bath for 5 minutes If reducing sugars are present, blue solution turns green/orange/yellow/brick-red preicpitate If absent, blue solution remains blue

Question 43

What are fats?

Answer 43

Fats are organic molecules made up of carbon, hydrogen and oxygen. Does not contain as much oxygen as carbohydrates. Proportions of elements are not fixed , hence no general formula

Question 44

Fats are only in humans. True or false?

Answer 44

False, fats can be animal or plant fats

Question 45

Enzymes speed up the break down of fats into ____ and 3 ____ ____ ____

Answer 45

Enzymes speed up the break down of fats into glycerol and 3 fatty acid molecule

Question 46

What are the 5 functions of fats?

Answer 46

1) Long term storage in the body, higher energy value than carbs 2) Natural insulating material to prevent excessive heat loss 3) Solvent for fat soluble vitamins and hormones 4) Main part of cell membrane 5) Oil substance secreted to form a thin layer over skin surface to reduce rate of evaporation of water and reduces heat loss

Question 47

Describe the test for fats

Answer 47

1) To a dry test tube, add 2cm^3 of ethanol to a test sample. Shake. 2) Add 2cm^3 of distilled water +: If fats are present, a white emulsion forms -: If fats are absent, solution remains colourless

Question 48

What are proteins?

Answer 48

Proteins are organic molecules made up of carbon, hydrogen, oxygen and nitrogen. Sulfur may be present

Question 49

Proteins are present in all cells and is the ____ and most ____ of all the food substances

Answer 49

Proteins are present in all cells and is the largest and most complex of all the food substances

Question 50

What are the building blocks of proteins?

Answer 50

Amino acids

Question 51

What do different amino acids join together to form?

Answer 51

Different amino acids join together through peptide bonds in a linear sequence to form a polypeptide

Question 52

What do different polypeptides join together to form?

Answer 52

Different polypeptides join together to form a longer chain of amino acids

Question 53

What forms when one or more longer chains of amino acids interact and combine?

Answer 53

A protein molecule, folded into a more complex, 3D shape

Question 54

What are the 3 functions of proteins?

Answer 54

1) Synthesis of new cytoplasm for growth and repair of worn out cells 2) Synthesis of enzymes and some hormones 3) Formation of antibodies to fight diseases

Question 55

Describe the test for protein

Answer 55

1) Add equal amounts of 1% copper (II) sulfate to teh test sample 2) Add sodium hydroxide drop by drop and shake after each drop +: If protein is present, a violet colouration forms -: If protein is absent, solution remains blue

Question 56

Name 2 foods with carbohydrates

Answer 56

Brown rice, Sweet potato, Bread, Oats, Lentils

Question 57

Name 2 foods with fats

Answer 57

Oil, Nuts, Chia seeds, Butter, Egg

Question 58

Name 2 foods with proteins

Answer 58

Chicken, Milk, Cottage cheese, Fish, Beans