biological molecules !

Question 1

water functions (humans) !

Answer 1

solvent for chemical reactions
essential component of cells, tissue fluids, digestive juices and blood
helps control body temperature : sweat -> removes latent heat
transport of dissolved substances (glucose, amino acids, carbon dioxide)

Question 2

water functions (plants) !

Answer 2

keeps plant cell turgid & plant upright
transport mineral salts up the plant through the xylem
needed to transport glucose from leaves to all parts of the plant by the phloem

Question 3

amt of water needed !

Answer 3

how active a person is : plays sports / carry out physical labour -> need more water
how healthy a person is : diabetes causes sufferers to pass more urine -> need more water than healthy ppl

environmental conditions :

• living in hot & dry climates need more water than those icing in temperate climates
• those who have lived in hot conditions for a long time become adapted & require less water than those who have not adapted

Question 4

water loss !

Answer 4

exhaled hair
urine
faeces
sweating

Question 5

carbohydrates !

Answer 5

made up of elements : carbon, hydrogen, oxygen

types :

• sugars (monosaccharides, disaccharides)
• polysaccharides (starch, glycogen, cellulose)

Question 6

simple sugars - monosaccharides

Answer 6

small molecules -> cannot be further digested

- can pass through cell membranes & be absorbed into the cells

Question 7

monosaccharides formula !

Answer 7

C6 H12 O6

- arranged differently within the molecules-> give the sugars different chemical & biological properties

Question 8

monosaccharides examples !

Answer 8

glucose
fructose
galactose

Question 9

double sugars - disaccharides !

Answer 9

made up of 2 molecules of monosaccharides condensed together

Question 10

disaccharides formula !

Answer 10

C16 H12 O11

Question 11

disaccharides examples !

Answer 11

sucrose

lactose

maltose

Question 12

disaccharides - condensation !

Answer 12

condensation reaction : chemical reaction in which 2 simple molecules are joined together to form a larger molecule with the removal of 1 molecule of water

• glucose + fructose -> sucrose + water
• glucose + galactose -> lactose + water
• glucose + glucose -> maltose + water

Question 13

disaccharides - hydrolysis !

Answer 13

hydrolysis reaction : reaction in which a water molecule is needed to break up a complex molecule into smaller molecules

• sucrose + water -> glucose + fructose
• lactose + water -> glucose + galactose
• maltose + water -> glucose + glucose

Question 14

complex carbohydrates - polysaccharides !

Answer 14

made up of many monosaccharides chemically bonded together by polymerization

Question 15

polysaccharides examples !

Answer 15

starch
glycogen
cellulose

Question 16

cellulose - polysaccharides !

Answer 16

made up of many glucose molecules chemically bonded together

Question 17

cellulose functions !

Answer 17

protect plant cells from mechanical damage & bursting

cannot be digested by humans -> serves as dietary fibre
- prevent constipation in humans

Question 18

starch - polysaccharides !

Answer 18

made up of many glucose molecules condensed together

Question 19

starch functions !

Answer 19

storage form of carbohydrates in plants

- when needed : digested to glucose-> provide energy for cell activities

Question 20

starch structure !

Answer 20

mixture of branched & straight chains

Question 21

starch hydrolysis !

Answer 21

starch -> maltose : by amylase
maltose -> glucose : by maltase

when starch is hydrolysed : bonds within the polysaccharide -> broken
- glucose molecules : released

Question 22

glycogen - polysaccharide !

Answer 22

made up of many glucose molecules condensed together

Question 23

glycogen functions !

Answer 23

storage form of carbohydrates in mammals & fungi

- when needed : digested to glucose -> provide energy for cell activities

Question 24

glycogen structure !

Answer 24

highly branched chains of glucose units

Question 25

storage molecules !

Answer 25

- starch & glycogen insoluble in water large molecules : osmotic pressure / water pressure -> not affected in cells easily hydrolysed to glucose when needed have complex shapes : occupy less space than all the individual glucose molecules than what makes up a glycogen / starch molecule

Question 26

storage molecules - similarities !

Answer 26

made up of glucose units storage forms of glucose units storage of energy

Question 27

storage molecules - differences !

Answer 27

starch : found in plants, straight and branched | glycogen : found in animals & fungi, highly branched

Question 28

carbohydrates - functions !

Answer 28

substrate for respiration : provide energy for cellular activities form supporting structures (cell walls) form other organic compounds (amino acids, fats) synthesise lubricants (mucus) synthesise nectar in some flowers

Question 29

fats !

Answer 29

organic molecules made up of carbon, hydrogen & oxygen - proportions of elements : not fixed -> no formula hydrolysis : fats -> fatty acids + glycerol

Question 30

fats - functions !

Answer 30

source & storage of energy acts as an insulating material : prevents excessive heat loss solvent for fat-soluble vitamins & other vital substances (insulin) essential part of protoplasm (cell membrane) reduces water loss from skin surface : glands in skin secrete oily substance - forms a thin layer over skin surface : reduces rate of evaporation of water & heat loss from skin

Question 31

proteins !

Answer 31

organic molecules made up of carbon, hydrogen, oxygen & nitrogen

Question 32

protein - functions !

Answer 32

synthesis of new protoplasm : growth & repair of worn-out cells synthesis of enzymes & some hormones formation of antibodies : combat diseases