biology digestion, enzymes and ecology

mouth

food is chewed and mixed with saliva containing amylase

oesophagus

the tube that takes food to the stomach

liver

stores bile which emulsifies fats and neutralises stomach acid

pancreas

makes all three enzymes

stomach

food is mixed with hcl acid, which kills pathogens, and also 3 enzymes

large intestine

water is absorbed here

small intestine

enzymes break down the food. small soluble molecules can be absorbed into bloodstream

rectum

waste is stored here

anus

muscle that opens and closes to let faeces out

enzymes

enzymes are biological catalysts which speed up the rate of a reaction without being used up or changed in the process

what are enzymes made up of

large proteins molecules made up of chains of amino acids

how do the chains of amino acids make the enzyme up

chains of amino acids fold and form a specific 3d shape with region called the active site

factors that affect enzyme action

temperature, pH,

how does temperature affect enzyme action (2 bullet points)

• temp increase= more kinetic energy so more likely to collide,

• more kinetic energy = particles more likely to collide successfully so faster rate of reaction

how does pH affect enzyme action (4 bullet points)

• different enzymes have different optimum - pH,

• chemical bonds + forces hold active site together in specific shape

• pH change weakens forces, changing the shape of the active site

• enzyme becomes denatured

where is amylase made and used?

• made: pancreas, salivary gland

• used: small intestine, mouth

what does amylase break down?

breaks the chemical bonds between the glucose molecules in each carbohydrate chain

where is protease made and used?

• made: stomach, pancreas, small intestine

• used: stomach, small intestine

what does protease break down?

the chemical bonds between chains of amino acids

where is lipase made and used?

• made: pancreas, small intestine

• used: stomach, small intestine

what does lipase break down

lipase breaks down lipids (fats) to glycerol and fatty acids

what are the products of digestion used for?

to make new carbohydrates, lipids and proteins. some glucose is used in respiration

carbohydrates

• provide us with fuel

• made of carbon, hydrogen, and oxygen

simple carbohydrates ( 2 bullet points)

• made of one or two sugar molecules

• monosaccharides+ disaccharides

monosaccharides

glucose fructose and galactose

disaccharides

maltose, lactose and sucrose

complex carbohydrates (2 bullet points)

• larger molecules, many glucose molecules joined together

• starch, glycogen and cellulose

starch

straight chain of glucose

cellulose

many crosslinks to make it strong

glycogen

branched chains of glucose

uses of carbohydrate ( 3 bullet points)

• respiration- to release energy

• energy storage (starch in plants, glycose in humans)

• structural (cellulose for plant cell walls

test for glucose ( 3 bullet points)

benedicts reagent

• add 2ml of solution to test tube and 1ml of benedict reagent

• place in water bath of temp >80oC

• if glucose present will go blue→ brick red

test for starch (3 bullet points)

iodine solution

• add 2 drops of solution to 2 dimples in tile

• add drop of solution

• if starch is present it will go yellow orange→ blue black

required practical 5 ( effect of pH on amylase enzyme) (5 bullet points)

• 1 drop iodine solution in all of 2 dimple tiles

• 3cm³ starch, 2cm³ pH

• add 1cm³ amylase and start stop clock

• every 10s use stirring rod to transfer solution to a dimple

• do until iodine solution stops turning blue-black and stays yellow

emulsion test for lipids (4 bullet points)

• put food solution in test tube+ label

• put in ethanol

• put in a bung + shake vigorously

• cloudy liquid- fat present

biuret test for proteins (3 bullet points)

• food solution in test tube + label

• add biuret solution + shake gently

• blue→ purple=positive test

abiotic factors

non-living parts of the environment that influence the number and distribution of organisms in a community

biotic factors

living organisms that influence the number and distribution of organisms in a community

habitat

where an organism lives

individual

a living thing, carries out MRS GREN. single member of species

population

a group of organisms of the same species interacting with each other in the same place at the same time

community

a group of interdependent populations of different species living and interacting in the same area

ecosystem

a community of living organisms interacting with the non-living parts of their environment

biotic factors (5 bullet points)

• availability of food,

• numbers of predator population,

• new predators,

• new competitor species,

• new disease organism,

abiotic factors ( 8 bullet points)

• availability of water

• availability of carbon dioxide

• availability of oxygen in water,

• temperature,

• soil mineral content + soil pH,

• light intensity,

• wind intensity + direction,

• natural disaster

interdependance

the network of relationships in between different organisms in a community for example each species depends on other species for food, shelter, pollination, seed dispersal etc

stable community

all the species and environmental factors are in balance so population sizes remain relatively constant e.g. coral reef, tropical rainforest

animals compete for

food, territory, mates

why do animals compete for food ( 3 bullet points)

• herbivores feed on some kind of plant

• carnivores compete for prey

• prey animals compete to not get caught

how/why do animals compete for territory (4 bullet points)

• place to build nest,

• find food

• , reproduce

• compete for best spaces

how/why do animals compete for mates (2 bullet points)

• compete by fighting

• adaptations to stand out e.g bright feathers

what do plants compete for (4 bullet points)

• light,

• water,

• nutrients,

• space

why do plants compete for light + water

for photosynthesis to make food

food chain + food webs

show feeding relationships in an ecosystem.

trophic level

a stage of a food chain, a feeding level

producer (4 bullet points)

• level 1 ,

• makes glucose by photosynthesis,

• plant or algae,

• producers of all biomass on earth

primary consumer

level 2, herbivore

secondary consumer

level 3, carnivore that eats herbivore

tertiary consumer

level 4 carnivore

apex predator

carnivores with no predators, at the top of the food chain

biomass

the dry mass of an organism; the mass of an organism after all water is removed

predator- prey cycle. ( 5 bullet points)

• plenty of food = prey numbers increase

• prey numbers increase = predator numbers increase

• predator numbers increase= prey numbers fall

• prey numbers fall= predator numbers fall

• repeat

light intensity matters bc…

plants need light

temperature matter bc..

limiting factor in photosynthesis

moisture levels matter bc….

plants + animals need water

soil pH + mineral content matter bc….

affects what can grow + rate of decay

wind intensity + direction matter bc

plants will need to transpire fast + shape of trees + landscape

oxygen availability matters bc….

in water for fish

CO2 availability matters bc….

plants need for photosynthesis

food availability matters bc….

organisms breed w/ more food

new pathogens matter bc…..

• organisms have no resistance eg leaf miner in horse chestnut trees

• get wiped out

new predators matter bc…

• organism have no defences so get wiped out

• eg dodo bird with introduction of pigs + monkeys

new competitor species matter bc…

• species cant compete for food so numbers get too low for breeding

• eg grey squirrels an red squirrels

extremophiles (4 bullet points)

• live in difficult conditions (high/low pH/temp

• lots are microorganisms like bacteria living in deep sea vents

• enzymes have extreme optimum pH/temp

• useful for scientists

how to draw pyramid of biomass (5 bullet points)

• wedding cake shape

• bars same height

• labelled axis

• 1% of light on earth is used

• 10% of biomass is transferred between levels