Ch.3 - Food

Question 1

Why are nutrients necessary?

Answer 1

Nutrients are necessary as a source of energy, to make chemicals required for metabolic reactions and as the raw materials for the growth and repair of structures in the organism.

Question 2

What is nutrition?

Answer 2

Nutrition is the way in which an organism obtains and uses food.

Question 3

What are the elements present in food?

Answer 3

The 6 common elements are carbon, hydrogen, oxygen, nitrogen, phosphorus and sulfur. The 5 elements that are present as dissolved salts are sodium, magnesium, chlorine, potassium and calcium. The 4 trace elements are iodine, iron, copper and zinc.

Question 4

What are biomolecules?

Answer 4

Biomolecules are chemicals that are made inside an organism. They contain carbon.

Question 5

What biomolecules are found in food?

Answer 5

Carbohydrates, lipids, vitamins and proteins are biomolecules found in food.

Question 6

What is the chemical carbohydrate formula?

Answer 6

Cx(H2O)y, where x=y

Question 7

What are the types of carbohydrates? Define.

Answer 7

Monosaccharides are carbohydrates composed of a single sugar unit. Disaccharides are carbohydrates composed of 2 sugar units joined together and polysaccharides are carbohydrates composed of many sugar units.

Question 8

What are the physical properties of monosaccharides and give examples of them.

Answer 8

Monosaccharides taste sweet and are soluble in water. Glucose is a monosaccharide, it is made by plants in photosynthesis, commonly found in sweets and fruit. Fructose has the same formula as glucose (with atoms arranged differently) and is sweeter than glucose. Fructose is found in fruits

Question 9

What are the physical properties of disaccharides and give examples.

Answer 9

Disaccharides taste sweet dissolve in water. Maltose is a disaccharide, it is found in germinating seeds. As is sucrose (or table sugar).

Question 10

What are the physical properties of polysaccharides? Give examples.

Answer 10

Polysaccharides are insoluble or only slightly soluble in water and are not sweet-tasting. They consist of thousands of monosaccharides. Starch is a polysaccharide stored in plants. Cellulose is also a polysaccharide that is very strong and difficult to digest. Glycogen is a complex polysaccharide that is stored in the liver and muscles.

Question 11

What is the structural role of carbohydrates?

Answer 11

Cellulose is used to form plant cell walls.

Question 12

What is the metabolic role of carbohydrates?

Answer 12

Glucose is broken down in respiration to release energy. Glucose is made in photosynthesis.

Question 13

What elements do lipids contain?

Answer 13

Lipids contain carbon, hydrogen and oxygen.

Question 14

What are phospholipids?

Answer 14

Phospholipids are fat-like substances in which one of the fatty acids is replaced by a phosphate group or has a phosphate group added onto it.

Question 15

What is the structural role of lipids?

Answer 15

Lipids are important as energy stores in plants and animals. 1 gram of lipids contains twice as much energy as the same amount of carbohydrates. In animals, lipids provide heat insulation (fat under skin) and they protect organs.

Question 16

What is the metabolic role of lipids?

Answer 16

Lipids can be broken down in respiration to release energy.

Question 17

What are the elements found in protein?

Answer 17

Proteins contain carbon, oxygen, hydrogen and nitrogen. They contain smaller amounts of sulphur and phosphorus.

Question 18

What happens to surplus proteins (amino acids)?

Answer 18

Amino acids are not stored in the body. Surplus amino acids are taken to the liver and converted into urea (a toxic waste product). This process is called deamination. The urea is taken to the kidneys and becomes part of urine. Which is then excreted.

Question 19

What is the structural role of proteins?

Answer 19

Fibrous protein such as keratin is found in skin and hair. Myosin is found in muscle.

Question 20

What are the metabolic roles of protein?

Answer 20

Proteins are used as enzymes to control reactions. They also form antibodies to fight infection. Some hormones are protein-based and are used to regulate body reactions.

Question 21

What are vitamins?

Answer 21

Vitamins are complex, carbon-based structures which the body cannot make. They are only needed in trace amounts.

Question 22

What is vitamin C?

Answer 22

Vitamin C is called ascorbic acid and it is water-soluble.

Question 23

What are the metabolic roles of vitamin C?

Answer 23

Vitamin C is necessary for the formation of connective tissue such as skin. The growth and maintenance of bones and teeth, helping wounds to heal and helping the proper function the immune system.

Question 24

What disease results from a vitamin C deficiency? What are its symptoms?

Answer 24

Scurvy is caused by a vitamin C deficiency. Its symptoms are the poor healing of skin, bleeding under the skin (bruising) and bleeding gums with loose teeth.

Question 25

What is vitamin D?

Answer 25

The most common form of vitamin D is calciferol. Vitamin D is soluble in fat.

Question 26

What are sources of vitamin D?

Answer 26

Liver, milk, egg yolk and the action of ultraviolet rays on chemicals in the skin are sources of vitamin D.

Question 27

What is the metabolic role of vitamin D?

Answer 27

Vitamin D helps absorb calcium from food in the intestine. Therefore, it is needed for healthy bone and tooth formation.

Question 28

What disease results from a vitamin D deficiency?

Answer 28

A vitamin D deficiency causes rickets (children) and osteomalacia (adults). The symptoms are weak, deformed bones that tend to break easily.

Question 29

What is metabolism?

Answer 29

All the reactions taking place in an organism are referred to as its metabolism. They can be divided into anabolic and catabolic reactions.

Question 30

What are anabolic reactions?

Answer 30

Anabolic reactions use energy to convert smaller molecules into larger ones. Protein synthesis is an anabolic reaction.

Question 31

What are catabolic reactions?

Answer 31

Catabolic reactions release energy when a complex molecule is broken down to a simpler form. Respiration, digestion and decay are catabolic reactions.

Question 32

Draw a diagram of the structures of monosaccharides, disaccharides and polysaccharides.

Answer 32

Question 33

Draw a diagram of a triglyceride and a phospholipid.

Answer 33

Question 34

What are reducing sugars?

Answer 34

Reducing sugars are those that act as reducing agents. All monosaccharides and some disaccharides(maltose) are reducing sugars.

Question 35

Why are minerals needed in plants and animals?

Answer 35

Minerals are needed to form rigid body structures(calcium). They are needed to make soft body parts such as muscle(nitrogen and sulfur). They form salts in tears, saliva and liquid blood(sodium) and to form biomolecules such as haemoglobin(iron) and chlorophyll(magnesium).

Question 36

What minerals do plants need? Name source and use.

Answer 36

Plants need magnesium from salts in soil to help form chlorophyll. Plants also need calcium from salts in the soil to help cell walls attach to each other.

Question 37

What minerals do animals need? Name sources and uses.

Answer 37

Animals need iron, found in liver, meat and green vegetables, used to form haemoglobin. Animals also need calcium, found in dairy products, used to form bones and teeth.

Question 38

Why is water essential to life?

Answer 38

Water is the liquid in which all metabolic reactions take place. It provides the basis for transport systems in organisms and it is the environment in which many organisms live.

Question 39

What is the importance of water to organisms?

Answer 39

Water is a component of cytoplasm and tissue fluid. Water is a good solvent, so chemical reactions can take place in cell organelles and molecules can be dissolved in water for transport. Water participates in some biochemical reactions. In photosynthesis, water supplies hydrogen ions and electrons. In respiration water is formed as an end product and in digestion water is needed to break down food. Water is needed for osmosis in the body. Water is a good absorber of heat which helps keep body temperature stable.

Question 40

How many common amino acids are found in proteins

Answer 40

20