nutrients

Question 1

importance of nutrients

Answer 1

• provide energy for vital activities of the body
• synthesise new protoplasm for growth and replacing of worn-out parts of the body
• to stay healthy

Question 2

organic nutrients

Answer 2

carbohydrates
proteins
fats

Question 3

inorganic nutrients

Answer 3

water

mineral salts

Question 4

function of water in animals

Answer 4

main component of protoplasm and body fluids

• lubricants
• digestive juices
• blood (blood plasma)
• tissue fluid

used in hydrolysis of carbohydrates, fats and proteins during digestion

helps to transport dissolved substances within the body

• digested products (from small intestine to other parts of the body)
• excretory waste products (from tissue cells to excretory organs for removal from the body)
• hormones (from endocrine glands to target organs)

helps to reduce body temperature through sweating

acts as a solvent or medium for metabolic and chemical processes in the body.

Question 5

function of water in plants

Answer 5

raw material for photosynthesis

needed to transport mineral salts up the xylem from the roots to the leaves

keeps the plant cells turgid and firm, keeps plant upright

needed to transport sucrose from the leaves to the other parts of the plants (transport in sucrose, store as starch)

Question 6

carbohydrates

Answer 6

(carbon, hydrogen, oxygen) - C6:H12:O6

• substrate for respiration, which provides energy for cellular activities
• key component of supporting structure (cell wall) in plants
• needed for synthesis of :
• > other organic compounds ( amino acids, fats)
• > lubricants (e.g. mucus)
• > nucleic acid (DNA)
• > nectar in flowers

Question 7

proteins

Answer 7

(carbon, hydrogen, oxygen, nitrogen, sulfur)

• needed for synthesis of:
• > antibodies to combat diseases
• > protoplasm for growth and repair of worn out cells
• > enzymes
• > hormones

Question 8

fats

Answer 8

(carbon, hydrogen, oxygen) - not in fixed proportion

• a source and store of energy
• act as an insulating material that prevents excessive heat loss (e.g. blubber in whales)
• essential component of cell membrane (lipid bilayer)
• solvent for fat soluble vitamins and some hormones
• helps to reduce water loss from skin surface by forming a hydrochloric layer that prevents the evaporation of water

Question 9

amount of water needed

Answer 9

• environmental conditions
• state of health
• activity level

Question 10

monosaccharides

Answer 10

glucose
fructose
galactose

Question 11

disaccharides

Answer 11

maltose
sucrose
lactose

Question 12

polysaccharides

Answer 12

starch
glycogen
cellulose

Question 13

condensation

Answer 13

a chemical reaction in which 2 simple molecules are joined together to form a larger molecule with the removal of one molecule of water

Question 14

hydrolysis

Answer 14

a reaction in which a water molecule is needed to break up a complex molecule into simple molecules
A double sugar can be split up into 2 single sugar molecules by hydrolysis in the presence of an enzyme/without enzyme

Question 15

basic units

Answer 15

carbohydrates
polysaccharide - disaccharide - monosaccharide (glucose)

protein
protein - polypeptide - amino acids

fats
fats - fatty acid + glycerol

Question 16

iodine test

Answer 16

test for: starch

✔ turn from brown to blue-black
✘ remains brown

Question 17

benedict’s test

Answer 17

test for: reducing sugar (monosaccharide and disaccharide except sucrose)

✔ turns from blue to green precipitate - trace amount
✔ turns from blue to yellow/orange precipitate - moderate amount
✔ turns from blue to brick-red precipitate - large amount
✘ remains blue

Question 18

biuret test

Answer 18

test for: peptide bonds
✔ turns from blue to purple/violet solution
✘ remains blue

Question 19

ethanol emulsion test

Answer 19

test for: fats

✔ turns from colourless to cloudy-white emulsion
✘ remains colourless/clear