biological molecules

what elements r found in lipids (fats)?

carbon, hydrogen, oxygen

what is the structure of a lipid?

3 fatty acids + 1 glycerol molecule

what are oils?

plant lipids , liquid at room temp

what is the test for lipids?

add ethanol add water and shake positive result: milky white emulsion forms

what elements are found in proteins?

carbon, hydrogen, oxygen, nitrogen, sometimes sulfur

what are proteins made up of? (structure)

long chains of amino acids there are 20 different amino acids

give some examples of proteins found in the human body

collagen and keratin found in skin and nails all enzymes haemoglobin

what is the test for protein?

add Biuret reagent positive result = purple

what elements are found in carbohydrates?

carbon, hydrogen and oxygen

what is the test for glucose?

heat with water and Benedict's solution positive result: brick red

what are starch and glycogen made up of?

simple sugars (e.g. glucose) joined together

what is the test for starch?

add iodine positive result : turns blue/black

what is a monosaccharide?

a simple sugar, such as glucose or fructose

what is the general molecular formula for a monosaccharide?

C6H12O6

what is a disaccharide?

formed when two monosaccharides join together

what is maltose?

formed by two glucose molecules

what is sucrose?

formed from one glucose and one fructose molecule

what is a polysaccharide?

formed when lots of monosaccharides join together

provide some examples of polysaccharides

starch, glycogen and cellulose- formed when lots of glucose molecules join together

how do amino acid sequences change the function of the protein?

different proteins have different amino acid sequences different sequences = polypeptide chains fold in different ways every protein has a unique 3D shape that enables it to carry out its functiion

define enzyme

biological catalyst speeds up reaction without being used up

what is metabolism?

the rate at which chemical reactions take place in the body

what is a substrate?

a molecule an enzyme acts upon

what is the active site?

an area on an enzyme at which enzyme activity is fastest

what is the definition of 'optimum'

the temperature or pH at which enzyme activity rate is fastest

what does it mean for an enzyme to denature?

when an enzyme changes shape so substrate no longer fits active site

how does the lock and key mechanism work?

enzymes + substrates randomly move about in solution when an enzyme and its complimentary substrate collide, with the substrate fitting into the active site of the enzyme- an enzyme-substrate complez forms, and the reaction occurs a product/s forms from the substrate/s which are then released from the active site. the enzyme is unchanged and will go on to catalyse further reactions

describe and explain the effect of too high temp on enzyme activity

dec activity enzyme denatures and substrate can no longer fit the active site

why does dec the temp below the optimum dec enzyme activity?

lower kinetic energy fewer collisions between enzymes + substrates

why is it imp that we control our internal temp?

too high = enzymes denature too low = enzymes work too slowly (little kinetic energy) and cant catalyse chemical reactions fast enough

describe and explain the effect of too high or too low pH on enzyme activity

decreases activity enzyme denatures and substrate can no longer fit the active site

why is a balanced diet important?

helps maintain good health

give the consequences of having a diet that contains too much fat

obesity blockage of arteries high blood pressure / heart disease diabetes

outline the components of protein

role = growth/repair of muscles food rich in nutrient = meat, fish, eggs, cheese deficiency disease = kwashiokor

outline the components of carbohydrates

role = energy store food rich in nutrient = glucose - fruits and vegetables lactose - milk sucrose - table sugar starch - rice, potato, wheat

outline the components of lipids

role = insulation and long-term energy store food rich in nutrient = butter, cheese

outline the components of water

supports chemical reactions inside cells

outline the components of fibre

prevents constipation helps move food through gut food rich in nutrient = fruit and vegetables

outline the components of calcium

role = strong teeth and bones found in= milk and cheese

outline the components of iron

used to make haemoglobin food rich in = red meat deficiency disease = anaemia

outline the components of vitamin c

role = sticks together cells lining the mouth present in = citrus eg lemons + oranges lack of = scurvy (bleeding gums)

outline the components of vitamin a

role = good vision present in = fish liver oils, butter, carrots lack of = night blindness

outline the components of vitamin d

role = strong bones present in= fish liver oils, made by skin in sunlight lack of = rickets

how do energy requirements vary with activity levels?

age - older people need less food than young people as activity levels are lower pregnant women need more food, iron and calcium to support growing baby

why is food needed?

for growth and repair of tissues fight disease supply fuel needed to release energy

what is digestion?

the break down of large, insoluble molecules into small, soluble ones for absorption through the wall of the small intestine

what is mechanical digestion?

the physical breakdown of food eg. teeth chew food, muscles in stomach churn food

what is chemical digestion?

enzymes act as biological catalysts break down large, insoluble molecules into small, soluble ones

how does digestion start in the mouth?

mechanical breakdown of food by teeth amylase released - digests starch into maltose

what is peristalsis?

contraction and relaxation of circular and longitudinal muscles which push food along the gut

what is the role of the stomach?

secretes hydrochloric acid to kill pathogens muscular walls churn food (mechanical digestion)

what is the role of hydrochloric acid?

kill pathogens

what is the role of bile?

emulsifies - breaks down large lipid droplets into small ones to inc the surface area neutralises hydrochloric acid

where is bile made, stored and released into?

made - liver stored - gallbladder released into - small intestine

what is the effect of bile on lipids?

what is the role of maltase?

to digest maltose into glucose

what is the role of amylase?

to digest starch into maltose

where is amylase made?

salivary glands, pancreas

where does amylase act?

mouth, small intestine

what is the role of lipase?

to digest lipids into fatty acids and glycerol

where is lipase made?

pancreas

where does lipase act?

small intestine

what is the role of protease?

to digest proteins into amino acids

where is protease made?

stomach, pancreas

where does protease act?

stomach, small intestine

how is the small intestine adapted for its function?

large surface area provided by villi and microvilli

lots of capillaries

thin wall - short diffusion distance

lacteals -absorption of fats

what is the role of the rectum?

stores faeces

what is ingestion?

when food enters the mouth

what is absorption?

the movement of soluble food through the wall of the small intestine into the blood stream

what is assimilation?

when small food molecules are used to build large ones

what is excretion?

the removal of waste products of metabolism

what is egestion?

the removal of faeces from the anus

what is the word equation for photosynthesis?

carbon dioxide + water (+light energy0 —> oxygen and glucose

what is the balanced symbol equation for photosynthesis?

6CO2+6H20 —> 6O2 + C6H12O6

what is a limiting factor?

factor in a reaction which is in shortest supply

lack of this factor is the reason why the rate of reaction no longer increases

what are the limiting factors of photosynthesis?

carbon dioxide

light intensity

temperature

increasing any of the above will increase the rate of photosynthesis until another factor becomes limiting

why is the rate of photosynthesis low in the morning?

temperature is the limiting factor

low temperatures inhibit enzyme activitty

carbon dioxide levels are high

why is the rate of photosynthesis high at midday?

high temp maximises enzyme activity

co2 is the limiting factor as its in the shortest supply

how is the leaf adapted to their role?

thin and broad (large surface area)

why do chloroplasts appear green?

chlorophyll absorbs red/blue light

reflects green light

why do different coloured lights affect the rate of photosynthesis?

green is reflected (not absorbed) = low rate of photosynthesis

blue and red is absorbed - results in faster rate of photosynthesis

what does the plant use glucose for?

making cellulose cell walls

making proteins and DNA

making starch for storage

making sucrose for transport

what is the role of nitrate in plants?

making amino acids and proteins

making DNA

growth

deficiency symptom = stunted growth

what is the role of magnesium ions in plants?

making chlorophyll

deficiency symptom = yellow leaves

how is the waxy cuticle adapted for its role?

prevents evaporation of water and stops pathogen entry

how is th3 upper epidermis adapted for its role?

transparent to allow light to enter the leaf

how is the palisade mesophyll adapted for its role?

contains lots of chloroplasts for photosynthesis

how are the air spaces in spongy mesophyll adapted for their role?

allow gases to diffuse

how is the xylem adapted for its role?

allows entry of water and mineral ions by transpiration stream

how are the guard cells adapted for its role?

control opening and closure of stomata

how is the stomata adapted for its role?

allow co2 t0 enter, o and h20 to leave