Use of Biological Resources

Question 1

how can we use microorganisms

Answer 1

Microorganisms can be used by humans to produce foods and other useful substances

Question 2

why do we need flour in bread

Answer 2

contains starch which the yeast can break down into glucose for respiration

Question 3

why do we need water in bread

Answer 3

to bind the ingredients

to active the dry yeast

Question 4

why do we need yeast in bread

Answer 4

respires the glucose which creates air pockets in the bread making it rise

Question 5

why do we knead bread

Answer 5

to mix all the ingredients together and to increase the SA

Question 6

why do we prove the bread

Answer 6

prove at 35-40c which is optimum temperature for yeast which allows them to respire quickly

allows the yeast to respire and rise and create the air bubbles (CO2) in the bread

Question 7

why do we bake the bread

Answer 7

the high temperature denatures the enzymes in the bread stopping them from respiring further

high temperature also evaporates the ethanol produced from anaerobic respiration

Question 8

5.6 practical - investigate the role of anaerobic respiration by yeast in different conditions

Answer 8

1. Dissolve sugar in previously boiled water.
2. Add yeast and mix to form a suspension, and pour into a boiling tube.
3. Add a layer of vegetable oil. (prevents any oxygen getting to the yeast making the yeast respire anaerobically)
4. Connect a delivery tube to a second boiling tube, this time containing limewater

to investigate temperature place the boiling tube with the yeast into a warm water bath (not too hot other the enzymes would denature)

to investigate sugar concentration change the amount of sugar added to the yeast

the limewater will turn cloudy as the yeast respires as it will produce CO2

Question 9

anaerobic respiration formula in bacteria and fungi

Answer 9

glucose –> ethanol + carbon dioxide

Question 10

what is the type of bacteria used to create yogurt

Answer 10

lactobacillus bulgaricus

Question 11

how does lactobacillus produce yogurt

Answer 11

Lactobacillus respires anaerobically producing lactic acid. This lowers the pH, acting as a preservative. The acid also coagulates the milk protein, as the acidic conditions change the shape of the proteins, giving yoghurt its texture and flavour

Question 12

how is milk converted to yogurt

Answer 12

treated at 90c to remove oxygen, kill any harmful bacteria present, change proteins

cooled to 46c which is the optimum temperature for the bacteria

bacteria then respires and creates lactic acid which creates the acidic taste in yogurt

Question 13

how can glasshouses and polythene tunnels be used to increase the yield of certain crops

Answer 13

growing plants outside does not allow the farmer to control any factors affecting photosynthesis
by growing plants in an enclosed environment the farmer can control these factors better

Question 14

how do glasshouses and polythene tunnels increase crop yield

Answer 14

several conditions can be manipulated and controlled

artificial heating - enzymes controlling photosynthesis can work faster due to more kinetic energy
artificial lighting - plants can photosynthesis for longer
increasing cardon dioxide content - plants can photosynthesis quicker
regular watering - plants can photosynthesis quicker
high moisture content - lots of water water vapour reduces water loss via transpiration allowing the plants to keep stomata open

burning fossil fuels or wood raises the temperature and also produces CO2 and water vapour

they also protect crops from effects of the weather:
- excessive wind
- excessive rain
- extreme temperatures

Question 15

what effect does increased CO2 levels have on crop yield

Answer 15

plants can photosynthesis quicker and so grow quicker

the more CO2 present the more photosynthesis however at some point other factors will become limiting

Question 16

what effect does increased temperature have on crop yield

Answer 16

enzymes controlling photosynthesis can work faster due to more kinetic energy so more photosynthesis and growth

if temperature increases too much then the enzymes will denature

Question 17

how can fertiliser increase crop yield

Answer 17

fertilisers increase the amounts of key nutrients in the soil for crop plants meaning the plants can grow larger and quicker and are more healthy which increase yields

Question 18

what mineral ions does fertiliser provide

Answer 18

Nitrogen:
Absorbed in the form of nitrates
Needed to make amino acids which are the building blocks of proteins
Lack of nitrogen causes weak growth and yellowing of the leaves of plants

Phosphorous:
Absorbed in the form of phosphates
Needed to make DNA and cell membranes
Lack of phosphorus can cause poor root growth and discoloured leaves

Potassium:
Absorbed in the form of various compounds of potassium
needed in vital processes such as photosynthesis and water + nutrient transport
Lack of potassium can cause poor growth of flowers and fruits, as well as brown spots on leaves

Question 19

advantages of organic fertilisers

Answer 19

improves soil structure
greater range of minerals
releases minerals over a longer time period
less cost

Question 20

disadvantages of organic fertilisers

Answer 20

slow acting
may contain pests
harder to apply then inorganic ones

Question 21

advantages of inorganic fertilisers

Answer 21

releases minerals quickly
contents known
easy to apply

Question 22

disadvantages of inorganic fertilisers

Answer 22

can lead to eutrophication
requires regular reapplication

Question 23

why do we need pest control

Answer 23

Pests such as insects and other animals can damage crops by eating them
Weeds can outcompete crop plants for space, water and soil nutrients
Fungi can infect crop plants and spread disease which can affect growth and yield

Question 24

advantages of pesticides

Answer 24

easily accessible and relatively cheap
immediate effect
kill entire population of pests

Question 25

disadvantages of pesticides

Answer 25

the organisms can develope a resistance to the pesticide
non-specific chemicals which kill other organisms
the chemicals don’t break down so can lead to bioaccumulation
need to be repeatedly applied

Question 26

advantages of biological control

Answer 26

natural method so no pollution
no resistance can be built up
can target specific species
long lasting
does not need to be repeatedly applied

Question 27

disadvantages of biological control

Answer 27

may eat other organisms instead of the pest
takes a longer time to be effective
cannot kill entire population so some pests will always be present
may not adapt to the new enviroment or may move out of the area
may become a pest itself

Question 28

how can selective breeding develop plants with desired characteristics

Answer 28

pick 2 best plants with desired characteristics and breed them
pick 2 best offspring and breed again

this reduces the gene pool and increases the chances of getting desired genes

Question 29

how can selective breeding develop animals with desired characteristics

Answer 29

pick 2 best animals with desired characteristics and breed them
pick 2 best offspring and breed again

this reduces the gene pool and increases the chances of getting desired genes

Question 30

what are some examples of desired characteristics animals are bred for

Answer 30

disease resistance
quicker growing
quicker reproduction
fur coat colour

Question 31

advantages of fish farming

Answer 31

raises a lare number of fish in a small area
allows for selective breeding
protection against predators
can control water quality
control feeding

Question 32

fish farming water quality method

Answer 32

water is filtered to remove waste and harmful bacteria which prevents diseases

water is also cleaned to maintain high levels of O2 for aerobic respiration

Question 33

fish farming control of intraspecific predation method

Answer 33

fish are seperated based on size and age so to minimize the chance of them eating each other

Question 34

fish farming control of interspecific predation method

Answer 34

different species are seperated by nets and tanks to prevent fighting

Question 35

fish farming control of disease method

Answer 35

antibiotics are given to fish as well as fish being kept in small numbers to stop disease spread

Question 36

fish farming removal of waste products method

Answer 36

water is filtered to remove faeces and sewage and the tanks are cleaned

Question 37

fish farming feeding method

Answer 37

fish are fed food that is high in nutrients to ensure fast growth
fed little and often to not waste food and prevent them over eating or eating each other

Question 38

fish farming use of selective breeding method

Answer 38

fish are seperated by gender so that farmers can selectively breed

Question 39

suitable conditions needed in an industrial fermenter

Answer 39

aseptic precuations - must clean fermenter with steam to kill other microorganisms and prevent chemical contamination to ensure only desired organisms grow

nutrients - nutrients are needed in respiration to ensure the bacteria can reproduce

optimum temp + pH - must be kept at optimum temp + pH for the enzymes of the desired microorganisms to allow them to reproduce as quick as possible

oxygenation - oxygen is needed for aerobic respiration

agitation - stirring paddles ensures that microorganisms, nutrients, oxygen, temperature and pH are evenly distributed

Question 40

what is the use of an industrial fermenter

Answer 40

Fermenters are containers used to grow (‘culture’) microorganisms like bacteria and fungi in large amounts
These can then be used for brewing beer, making yoghurt and mycoprotein and other processes not involving food, like producing genetically modified bacteria and moulds that produce antibiotics (e.g. penicillin)
The advantage of using a fermenter is that conditions can be carefully controlled to produce large quantities of exactly the right type of microorganism