Ch.12.2

Question 1

What are the six main types of food substances? Put them into two main categories and explain the differences between the food substances in these two categories.

Answer 1

Primary food substances — carbohydrates, lipids, proteins — are essential for supporting life.
Protective food substances — vitamins, minerals, dietary fibre — are important for keeping the body healthy.

Question 2

Carbohydrates are ____________________________. They are made up of ________________________________________ atoms, in which the __________ ratio is ________. Name an example and of carbohydrates and its chemical formula.

Answer 2

organic substances, carbon, hydrogen and oxygen, H:O, 2:1; glucose, C6H12O6.

Question 3

Hydrolysis is a _______________ reaction. It involves ______________________________, which is done so by ______________________________________.

Answer 3

Catabolic, breaking down molecules, adding a water molecule.

Question 4

Condensation is an _______________ reaction. It involves ______________________________, which is done so by ______________________________. In carbohydrates, ____________________________ are formed when condensation is carried out.

Answer 4

anabolic, combining molecules, taking away a water molecule, glycosidic bonds

Question 5

The processes of hydrolysis and condensation are carried out, or ________________, by _____________________.

Answer 5

catalysed, specific enzymes

Question 6

What are the three types of carbohydrates?

Answer 6

Monosaccharides, disaccharides, and polysaccharides.

Question 7

Name the features of monosaccharides and give three examples of this type of carbohydrate along with the food sources in which they can be found.

Answer 7

Monosaccharides are the simplest form of carbohydrates. They taste sweet and are soluble in water.
Glucose and fructose can be found in fruits and honey, while galactose can be found in milk and dairy products.

Question 8

Name the features of disaccharides.

Answer 8

They are formed by the condensation of two monosaccharide molecules. They can be broken down into monosaccharides by enzymes during hydrolysis. They taste sweet and are soluble in water.

Question 9

Give three examples of disaccharides, name the monosaccharides that they are formed by and the food sources in which these disaccharides can be found in.

Answer 9

Maltose is formed by the condensation of two glucose molecules. They can be found in germinating barley.
Sucrose is formed by the condensation of a glucose and fructose molecule. They can be found in sugar cane and sugar beet.
Lactose is formed by the condensation of a glucose and galactose molecule. They can be found in milk and dairy products.

Question 10

Name the features of polysaccharides.

Answer 10

They are long chains of monosaccharides joined by condensation. They do not taste sweet and are insoluble in water.

Question 11

Give three examples of polysaccharides, describe the functions of these polysaccharides, and name the food sources in which these polysaccharides can be found in (except for no. 2)

Answer 11

Starch acts as the storage form and energy reserves of carbohydrates in plants. They can be found in potatoes and cereal products.
Glycogen acts as the storage form and energy reserves of carbohydrates in animals.
Cellulose is an important source of dietary fibre and can be found in plant products.

Question 12

What are the 5 functions of carbohydrates?

Answer 12

It acts as the main energy source in our bodies.
Glucose is directly broken down in respiration to release energy.
Starch is the storage form of carbohydrates in plants.
Glycogen is stored in the liver or muscles as energy reserves.
Cellulose is a source of dietary fibre.

Question 13

Lipids are _______________________ made up of _______________________ atoms, but the _________ ratio is ____________________ 2:1.

Answer 13

organic substances, hydrogen, carbon and oxygen, H:O, much greater than

Question 14

Lipids are insoluble in _____________ but _________________________________ such as _____________ and _____________.

Answer 14

water, soluble in organic solvents, alcohol, acetone

Question 15

What are the most common type of lipids? What are they formed from?

Answer 15

Triglycerides. Three fatty acid chains and one glycerol molecule.

Question 16

Name the chemical formula of the hydrolysis of maltose.

Answer 16

Maltose + water — maltase —> glucose

Question 17

Name the chemical formula of the hydrolysis of sucrose.

Answer 17

Sucrose + water — sucrase —> glucose + fructose

Question 18

Name the chemical formula of the hydrolysis lactose.

Answer 18

Lactose + water — lactase —> glucose + galactose

Question 19

Name the formula of the condensation of triglycerides.

Answer 19

Glycerol + fatty acid — enzyme —> triglyceride + water

Question 20

What are the two main types of fatty acids?

Answer 20

Saturated fatty acids and unsaturated fatty acids.

Question 21

What can triglycerides be classified into? What are the features of the triglycerides in these groups?

Answer 21

Fats, which are solids at room temperature, come mainly from animals and are mostly made up of saturated fatty acids; and
Oils, which are liquids at room temperature, come mainly from plants and are mostly made up of unsaturated fatty acids.

Question 22

How are the fatty acids that fats are made up of related to its physical state at room temperature?

Answer 22

They are mostly made up of saturated fatty acid chains, which contain no double bonds. Hence, the straight chains of fatty acids can be packed closely together as a solid.

Question 23

How are the fatty acids that oils are made up of related to its physical state at room temperature?

Answer 23

Oils are mostly made up of unsaturated fatty acids chains, which contain some double bonds. Hence, their tails are not straight and they are not closely packed together as a liquid.

Question 24

Name four examples of foods that are rich in fat.

Answer 24

Meat, lard, butter and cheese.

Question 25

Name three examples of oils.

Answer 25

Peanut oil, corn oil, canola oil.

Question 26

Name the three main functions of lipids.

Answer 26

—They are stored in adipose tissues under the skin as subcutaneous fat or as visceral fat around internal organs, which act as energy reserves (second to carbohydrates), an insulator to reduce heat loss, and a shock absorber to protect the internal organs. —They are involved in transporting and storing lipid-soluble vitamins such as vitamins A and D. —They are involved in making cell membranes (eg phospholipids), which are thin flexible layers that surround and enclose cells and can control what goes in and out of them, and some hormones (eg sex hormones), which regulate our emotions and metabolic activities by stopping or triggering them.

Question 27

When is trans fat produced? Give two examples of trans fat.

Answer 27

It is produced when vegetable oils are processed to make semi-solid or solid fat. Margarine and shortening.

Question 28

Where are trans fat commonly found?

Answer 28

In deep fried foods, bakery products and salad dressings.

Question 29

Trans fat can raise the level of ____________________________ (________________________) — ______________________, and lower the level of ____________________________ (________________________) — ______________________ in the _____________.

Answer 29

LDL cholesterol (low-density lipoprotein), “bad” cholesterol; HDL cholesterol (high-density lipoprotein), “good” cholesterol, blood

Question 30

What may the excessive intake of trans fats lead to?

Answer 30

Trans fats raise the level of LDL cholesterol, increasing the risk of cardiovascular diseases such as heart attacks, strokes or even death by causing the accumulation of trans fats in blood vessels.

Question 31

Proteins are _______________________ made up of ______________________________ atoms. Some proteins also contain _______________.

Answer 31

organic substances, hydrogen, oxygen, carbon, nitrogen; sulphur

Question 32

Amino acids are ________________________________________. They can be joined together in _________________________ to make __________________________________.

Answer 32

the basic building blocks of proteins, different sequences, proteins of different sizes

Question 33

Describe the basic structure of an amino acid.

Answer 33

``` H H O \ | // N — C — C / | \ H R OH ``` Left: amino group; Top: hydrogen; Right: carboxylic acid group; Bottom: variable size chain

Question 34

A __________(a)__________ is formed from condensation of ______________________________. A bond is formed between the ______________________ and _______________________. It can be broken down into amino acids by ____________________, in which ________________ must be added. The combination of a (a) with other amino acids forms a ____________________.

Answer 34

dipeptide, two amino acids; amino group, carboxylic acid group; hydrolysis, water; polypeptide

Question 35

A protein may consist of ______________________________. Describe and give an example, and name the deficiency disease caused by the lack of this protein.

Answer 35

One or more polypeptides; haemoglobin, a red protein that is responsible for transporting oxygen in red blood cells; anaemia.

Question 36

The _______________________ of proteins are related to their purpose. When they are destroyed in ways such as ________________, their functions are lost.

Answer 36

specific, unique structures; heating

Question 37

Our body needs ______ types of amino acids to _______________________________. The amino acids can be classified into _______________________, which _______________________, and _______________________, which _______________________.

Answer 37

20, build up various proteins; non-essential amino acids, can be produced by our body; essential amino acids, have to be obtained from out diet

Question 38

Name the three functions of proteins.

Answer 38

—They are used for the growth and repair of body tissues such as muscles, bones, skin, hair and blood —They are used to form enzymes and antibodies; some hormones are protein in nature —Amino acids are broken down to release energy if the carbohydrates and lipids stored in the body are used up

Question 39

What happens when excess protein is taken in?

Answer 39

The excess amino acids are broken down in the liver by deamination to form carbohydrates and ammonia (which are combined with CO2 to form urea or uric acid as they are too toxic to the human system on their own; however this is not part of deamination), during which the nitrogen-containing amino group is removed from the amino acid. The waste products are passed out of the body in urea.

Question 40

What may a deficiency in protein lead to? What are the symptoms of this deficiency disease? Where is this disease most commonly found?

Answer 40

Kwashiorkor. Patients have weak muscles and a swollen abdomen due toe accumulation of tissue fluid. They are usually found in developing countries where milk, meat and eggs are limited in diets.

Question 41

What are some foods that are rich in protein?

Answer 41

Fish, meat, eggs, milk, cheese, nuts and beans.

Question 42

Vitamins have no _____________________, but are essential for _____________________________________________________________. Only ________________ amounts of vitamins are needed.

Answer 42

energy value, maintaining the normal functions of cells and organs in our bodies, small

Question 43

Vitamins help __________________________________, __________________________________ and ___________________________________.

Answer 43

growth and development, regulate metabolism, strengthen immunity

Question 44

Each vitamin has _________________________. The lack of any vitamin to of the __________ types of vitamins in our diet may ________________________________.

Answer 44

important functions, >10, lead to deficiency diseases

Question 45

Describe the solubility of vitamin A.

Answer 45

Lipid-soluble.

Question 46

What are the functions of vitamin A?

Answer 46

They are important for vision in dim light as they form cone and rod cells in the retina and keep the cornea healthy, and strengthening immunity.

Question 47

Name some foods that are rich in vitamin A.

Answer 47

Dairy products, carrots, fish liver oil and dark green vegetables.

Question 48

Name and describe the deficiency disease of vitamin A.

Answer 48

Night blindness — poor vision in dim light.

Question 49

Describe the solubility of vitamin C.

Answer 49

It is water-soluble.

Question 50

What are the functions of vitamin C?

Answer 50

Vitamin C is used for maintaining healthy skin and gums, healing of wounds, and improving iron absorption.

Question 51

Name some foods that are rich in vitamin C.

Answer 51

Fresh fruits and vegetables.

Question 52

Name and describe the deficiency disease of vitamin C.

Answer 52

Scurvy — gums bleed and wounds heal poorly.

Question 53

How is vitamin C lost or destroyed?

Answer 53

Oxidation and heating.

Question 54

What are the pros and cons of heating food?

Answer 54

Pros: kill microorganisms present Cons: destroy vitamin C and other nutrients

Question 55

Describe the solubility of vitamin D.

Answer 55

It is lipid-soluble.

Question 56

What are the functions of vitamin D?

Answer 56

It helps us maintain strong bones and teeth by promoting the absorption of calcium and phosphate ions in our small intestines when they absorb nutrients.

Question 57

How can we obtain vitamin D?

Answer 57

— Consuming foods that are rich in vitamin D — milk, fish liver oil, egg yolk, and fatty fish such as tuna and salmon — Can be produced by our skin when we stand under sunlight

Question 58

Why does milk contain vitamin D?

Answer 58

Milk is not a natural source of vitamin D; they are because it is added into milk manually.

Question 59

Why can’t we obtain vitamin D solely from standing under sunlight?

Answer 59

This is because if we stand too long under the sun, we may get sunburns and an increased risk of skin cancer.

Question 60

Name and describe the deficiency diseases of vitamin D.

Answer 60

Rickets — bones become soft and bent; osteoporosis — bone density decreases and become fragile and brittle.

Question 61

Most water-soluble vitamins are found in _________________________________ while fat-soluble ones are usually found in _____________. These two types of vitamins are _________________________________________ in different methods.

Answer 61

fruits and vegetables, fats, transported around the body

Question 62

Are vitamin supplements essential to us? Why? What may the excess intake of supplements result in?

Answer 62

No. This is because a balanced diet can provide us with sufficient vitamins under normal circumstances; Health problems such as diarrhoea and vomiting.

Question 63

Minerals have no ________________ ________________. We need small amounts of minerals to _____________________________________.

Answer 63

energy value, maintain a healthy body

Question 64

Minerals are used to ________________________________. Some of them are used to ________________________. For example, ________________________________________________.

Answer 64

regulate metabolism, form body tissues, calcium is used for building bones and teeth

Question 65

The lack of minerals in our diet may lead to ________________________________.

Answer 65

various deficiency diseases

Question 66

What are the functions of calcium?

Answer 66

They are used for buildings bones and teeth, blood clotting as the fibrous tissue found in blood vessels to stop blood cells from leaving requires calcium, and muscle contraction as the nerve impulses sent by the brain when we want to do a voluntary action requires calcium.

Question 67

What are some foods that are rich in calcium?

Answer 67

Dairy products, dark green vegetables and soy beans.

Question 68

Name and describe the deficiency diseases of calcium.

Answer 68

Rickets in children and osteoporosis — bones become weak in adults, as their bone density of adults decrease due to the gradual loss of calcium as they age

Question 69

What are the symptoms of osteoporosis?

Answer 69

The long bones of arms and legs are more brittle, a slight loss in height, stiffer joints and a curved and compressed spinal column.

Question 70

How can we prevent osteoporosis?

Answer 70

Taking supplements, consuming a sufficient amount of calcium, and exercising regularly to maintain bone density.

Question 71

What are the functions of iron?

Answer 71

They used for making haemoglobin in red blood cells.

Question 72

What is a haemoglobin?

Answer 72

It is the pigment in red blood cells that carries oxygen.

Question 73

Name some foods that are rich in iron.

Answer 73

Red meat, liver, nuts, beans and dark green vegetables.

Question 74

Name and describe the symptoms of the deficiency of iron.

Answer 74

Anaemia — the number of red blood cells is lower than normal, leading to pale skin, tiredness and fainting

Question 75

Why do patients of anaemia experience a lack of energy or even fainting?

Answer 75

These symptoms are caused by the decreased or insufficient amount of oxygen that they receive as there are less haemoglobin to transport oxygen around the body.

Question 76

What is the function of iodine?

Answer 76

It helps us maintain the functions of the thyroid gland.

Question 77

Name three minerals.

Answer 77

Calcium, iron, iodine.

Question 78

What are some foods that are rich in iodine?

Answer 78

Seafood and seaweed.

Question 79

Name and describe the deficiency disease of iodine. What can it be caused by?

Answer 79

Goitre — the thyroid gland becomes swollen. It can be caused by both the lack of and excessive intake of iodine.

Question 80

What are the main sources of dietary fibre?

Answer 80

Plant foods, such as fruits, vegetables and whole grain cereals.

Question 81

Dietary fibre is a substance found in ________________________________.

Answer 81

the rigid cell wall of plant cells

Question 82

Dietary fibre does not _________________________. It cannot be ____________________ or ____________________ by our bodies.

Answer 82

provide us with energy, digested, absorbed

Question 83

Define digest. What does no digestion lead to and why?

Answer 83

Chemically or physically breaking down food. Absorption; this is because our body can only absorb small simple bits of food, which cannot be obtained without digestion.

Question 84

How is the food in the intestine pushed forwards?

Answer 84

Peristalsis; they are pushed forwards by the contraction of muscles in the intestinal wall.

Question 85

What is the function of dietary fibre?

Answer 85

As dietary fibre cannot be digested, it adds bulk to food and stimulates peristalsis. They also hold water which keeps faeces soft so that they can be passed out of the body easily.

Question 86

What does consuming more dietary fibre helps prevent?

Answer 86

Constipation and colorectal cancer.

Question 87

In addition to the six types of food substances, we must also take in ________________. It has no __________________ and can be obtained from ________________, ________________ and ________________, making up about ______% of our body mass.

Answer 87

water, energy value, food, drinks, respiration, 70

Question 88

What are the 5 functions of water in our body?

Answer 88

— It is the main component of the cytoplasm of cells providing a medium for chemical reactions to take place in body cells and allowing the movement of substances into and out of cells. — Water is the main component of blood, which transports substances around the body — Water is a solvent for wastes which leave the body in solution form, such as urine and sweat — Water makes up body secretions, eg digestive juices and saliva — Water helps regulate our body temperature through the evaporation of sweat

Question 89

When and where is sweat secreted from?

Answer 89

Sweat is secreted from our sweat glands and triggered by an increase in skin (environmental factors) or blood (metabolic factors) temperature.

Question 90

Our body loses water through ________________, ________________ and ______________________.

Answer 90

sweating, urination, breathing out

Question 91

The water loss from our body must be replaced by drinking _____________________________________ (one glass = ______cm3) of water every day. We can also obtain water from ________________________________________________________________.

Answer 91

six to eight glasses of water, 250; other drinks such as milk, juice, tea or soup

Question 92

We may suffer from _________________ and ________________ if we do not drink enough water.

Answer 92

poor digestion, constipation

Question 93

Why might we suffer from poor digestion if we do not drink enough water?

Answer 93

This is because water is needed in the hydrolysis of carbohydrates.

Question 94

Describe the food test for glucose. What will the test results be like if the food substance is present?

Answer 94

Add sample to a well on a spot plate. Dip clinistix/ diastix paper into the sample and observe the colour change. The test paper will change from pink to purple or blue to green/ brown for clinistix and diastix paper respectively.

Question 95

Describe the food test for starch. What will the test results be like if the food substance is present?

Answer 95

Add sample to a well on a spot plate. Iodine test — iodine solution is added to the sample and observe the colour change. The solution changes from brown to blue-black.

Question 96

Describe the food test for lipids. What will the test results be like if the food substance is present?

Answer 96

Grease spot test — add the sample to filter paper and wait for 20 minutes; after that, immerse the filter paper into an organic solvent. A translucent spot is left on the filter paper; however after being immersed in an organic solvent, the spot will disappear.

Question 97

Describe the food test for proteins. What will the test results be like if the food substance is present?

Answer 97

Add the sample to a well on a spot plate. Dip albustix test paper into the sample observe the colour change. The albustix test paper changes from yellow to green.

Question 98

Describe the food test for vitamin C. What will the test results be like if the food substance is present?

Answer 98

Add the sample to DCPIP solution in a test tube, transferring both solutions with a dropper and observe the colour change. The solution changes from blue to colourless / decolourises.

Question 99

Compare the ratio of the energy value of carbohydrates, lipids and proteins.

Answer 99

Around 1:2:1.

Question 100

``` Identify this molecule. CH2OH | H C ————— O OH | /╰ H \ | C〈 OH H 〉C | \ | | / | HO C ————— C H | | H OH ```

Answer 100

Glucose; C6H12O6.

Question 101

Describe what should we do when we want to test for food substances in a solid food sample.

Answer 101

(If it is a fruit that has a hard fruit wall, remove it. Cut it into small pieces.) Add distilled water to the sample and grind it using a pestle and mortar. After that, we should filter the mixture with a piece of cloth into a funnel set on top of a test tube and use the filtrate for carrying out food tests.

Question 102

Name two safety precautions we should keep in mind of while testing for food substances in food samples.

Answer 102

Wear safety goggles and avoid contact of iodine with skin as it is corrosive.

Question 103

Why shouldn’t we shake the test tube vigorously when mixing the food sample with DCPIP solution to test for vitamin C?

Answer 103

To prevent the DCPIP solution from reacting with oxygen in the air.

Question 104

Do the amounts of the samples used in testing for food substances in different food samples need to be measured very accurately? Explain.

Answer 104

No. This is because we are only testing for the presence of food substances; therefore, these food tests are qualitative tests and the amount of the food samples used wouldn’t affect the test results.

Question 105

Why should we use a new piece of cloth for creating each food sample from a solid in testing for food substances in different food samples?

Answer 105

This is to avoid contaminating the other food samples and affecting the results of their food tests.

Question 106

In the experiment of comparing the amount of vitamin C in different fruits and vegetables, what type of test is this experiment? Explain.

Answer 106

It is a quantitative test. This is because we are comparing the amount of vitamin C in different fruits and vegetables by recording the number of drops of their sample needed to turn the DCPIP solution colourless.

Question 107

Read below reminder on question type of what food to eat to reduce problem of / prevent deficiency disease.

Answer 107

- Structure of answer - 1-2 pts: name food + food substance it contains - 1 pt: relating disease + symptoms to food substance / “deficiency disease” - 1 pt: relating food to food substance to disease - Example - Lauren has rickets. Suggest one food for her to include in her diet to reduce this problem. Lauren can eat more dark green vegetables, which are rich in calcium. Rickets is a deficiency disease of calcium, in which the bones of a person become soft and bent due to the lack of this mineral. Therefore, if Lauren eats more dark green vegetables, which is rich in calcium, she will no longer lack calcium and her problem of rickets will be improved.

Question 108

Read below the reminders of answering the question type: carrying out food tests for a food substance.

Answer 108

``` Remember to state: — name of test — apparatus required — expected observation — step of observing the results, eg “and observe the colour change” ```

Question 109

Name the formula of hydrolysis of lipids.

Answer 109

lipids + water —lipase—> fatty acids + glycerol