Biological Molecules

Question 1

what are three types of chemical found in living things?

Answer 1

• carbohydrates
• proteins
• lipids
• nucleic acids

Question 2

what is the biological name for “single-sugars” and what are 2 features and 2 examples of this

Answer 2

monosaccharides

features:

• sweet taste
• soluble in water

examples:

• glucose
• fructose

Question 3

what is the biological name for “double-sugars” and what are 2 features and 2 examples of this

Answer 3

disaccharides

features:

• sweet taste
• soluble in water

examples:

• sucrose
• lactose

Question 4

what is the biological name for “complex-sugars” and what are 2 features and 3 examples of this

Answer 4

polysaccharides

features:

• not sweet tasting
• insoluble in water

examples:

• glycogen
• cellulose
• starch

Question 5

what is the test for starch?

Answer 5

• add iodine
• if it remains orange there is no starch present
• it it turns blue-black there is starch present

Question 6

what is the test for glucose?

Answer 6

• add benedict’s reagent and heat
• it it remains blue there is no glucose present
• if it turns yellow/orange there is glucose present 3

Question 7

describe lipids (fats and oils)

Answer 7

lipids are chemicals found in living things
insoluble in water
soluble in benzene and petrol

Question 8

list four functions of lipids

Answer 8

• source of energy in food
• store of energy in animals
• insulation in nervous system
• thermal insulation against heat loss

Question 9

which atomic elements make up lipids?

Answer 9

• hydrogen
• oxygen
• carbon

Question 10

describe a lipid molecule

Answer 10

one part glycerol

three parts fatty acids

Question 11

describe a test for lipids

Answer 11

• dissolve sample in ethanol
• decant clear layer
• add water and shake
• lipid present if mixture becomes cloudy

Question 12

what are the elements contained in protein?

Answer 12

• carbon
• hydrogen
• oxygen
• nitrogen

Question 13

list foods that contain lots of protein

Answer 13

• meat
• fish
• egg white
• nuts

Question 14

describe a protein molecule

Answer 14

a chain of dissimilar components twisted and folded into a 3-D shape

Question 15

what determines a proteins function?

Answer 15

its shape

Question 16

list and explain five functions of proteins

Answer 16

• strcutural eg. muscles and tendons
• hormones eg. insulin
• antibodies - destroy pathogens
• enzymes - speed up chemical reactions
• transport - haemoglobin carries O2 in blood

Question 17

what is an enzyme?

Answer 17

a large molecule made from protein

Question 18

what do enzymes do?

Answer 18

speed up/control chemical reactions
often called “biological catalysts”

we couldn’t live without enzymes

Question 19

what factors effect how an enzyme works?

Answer 19

temperature and pH

Question 20

what temperatures do enzymes work best at and what happens if they are exposed to temperatures outside these conditions

Answer 20

35-40 degrees C

below this particles slow down so don’t collide as much
above this enzymes become denatures

Question 21

how do enzymes work?

Answer 21

• lower activation energy of a reaction

- use special structures

Question 22

list four uses of enzymes

Answer 22

• in baby foods
• in making glucose syrup
• in diet foods
• in washing powder

Question 23

what are the 6 components of a balanced diet?

Answer 23

1) carbohydrates
2) lipids
3) proteins
4) minerals
5) vitamins
6) water and fibre

Question 24

what can getting too few minerals result in?

Answer 24

mineral deficiency disease

eg. not enough calcium can lead to rickets
not enough iron can lead to anaemia