Topic 5: Use Of Biological Resources

Question 1

Glasshouses and polyethene tunnels

Answer 1

· The enclosed environment protects the crops from harsh weather conditions
· Carbon dioxide levels, and so therefore rate of photosynthesis
· Heat is trapped from the Sun, so the optimum temperature of enzymes can be reached
· The plants are protected from pests that can damage plants or carry diseases

Question 2

Factors affecting crop yield

Answer 2

Carbon dioxide
· Paraffin lamps can be burned to increase carbon dioxide levels
· This ensures that carbon dioxide is not the limiting factor in the rate of photosynthesis
Temperature
· The heat trapped by the Sun in the glasshouse raises the temperature
· This allows the enzymes in photosynthesis to work at the optimum temperature and so the rate of photosynthesis increases

Question 3

Fertiliser

Answer 3

· Fertilisers contain nutrients that allow plants to grow faster
· These water-soluble minerals can be absored into the plant roots by actve transport
· Nitrates are required to make amino acids for proteins, to allow the plants to grow
· Phosphates are required for respiration and root growth
· Potassium is needed for growth of flowers and fruit, as it allows enzyme reactions to take place

Question 4

Pest Control

Answer 4

Using pesticides or biology control to prevent insects eating the plants. Pesticides include fungicides, herbicides and insecticides

Question 5

Advantages of Pest control

Answer 5

· Quick and efficient
· Can kill entire populations

Question 6

Disadvantages of pest control

Answer 6

· Organisms can develop resistance
· Non-specific so kills other organisms
· Bioaccumulation can make it toxic to others in the food chain
· Have to continuously apply

Question 7

Yeast

Answer 7

Yeast uses anaerobic respiration in order to make bread rise.
The carbon dioxide bubbles are what causes the bread to rise

Question 8

Yeast equation

Answer 8

Glucose (C6H12O6) –> Ethanol + Carbon dioxide (CO2)

Question 9

Practical: Investigate the role of anaerobic respiration by yeast in different conditions

Answer 9

1) Dissolve sugar in boiled water
2) Mix yeast with the sugar solution in a boiling tube
3) Add a layer of oil on top in order to prevent oxygen from entering (ensuring that it is only anaerobic respiration taking place)
4) Connect the boiling tube to a test tube of lime water
5) Count the number of bubbles see over a set time
Different conditions can be investigated, such as temperature (by using a water bath) or concentration of sugar

Question 10

Production of yoghurt

Answer 10

· Lactobacillus is a useful bacterias in making yoghurt
· Milk contains a sugar called lactose, which lactobacillus can break down to form lactic acid
· This acid lowers the pH of the milk, which denatures proteins to give the yoghurt texture

Question 11

The process of yoghurt

Answer 11

1) All equipment is sterilised to kill unwanted microorganisms
2) Milk is heated to 72°C for 15 seconds to kill any microorganisms in the mlk - this is called pasteurisation
3) The milk is cooled and lactobacillus is added
4) The mixture is incubated at around 40°C in a fermenter - here the bacteria breaks down lactose to lactic acid
5) The thickened yoghurt is produced and any flavouring, colorants or fruits are added before packaging

Question 12

Industrial fermenter

Answer 12

Fermenters are containers that grow bacteria and fungi in large amounts. This can be useful when producing transgenic bacteria for example:
· Aseptic conditions are required to ensure that no ther microorganism grows and contamnates te containers
· Nutrients are needed for the microorganism to use is respiration
· Optimum temperature and pH are needed in order for enzymes to work at the high rate but are not denatured
· Agitation by stirring paddles is required to ensure that the nutrients, oxygen, temperature, pH and microorganisms are distributed evenly

Question 13

Fish farming Method: Maintaining water quality

Answer 13

Filter water to remove waste an harmful bateria to prevent disease

Question 14

Fish farming Method: Controlling intraspecific predation

Answer 14

This isto stop compatition within the same species. Fishes are separated by size and age to prevent competition

Question 15

Fish farming Method: Controlling interspecific prediction

Answer 15

This is to stop competition between species. Different species are separated by nets or tanks

Question 16

Fish farming Method: Controlling disease

Answer 16

Antibiotics are given to increase chances of survival

Question 17

Fish farming Method: Removing of waste products

Answer 17

Water is filtered to remove waste faeces

Question 18

Fish farming Method: Controlling quality and frequency of feeding

Answer 18

Fish are fed frequently but in small amounts so they do not overhear and to avoid food wastage

Question 19

Fish farming Method: Selective breeding

Answer 19

Selective breeding to reproduce fish with desired characteristics

Question 20

Selective breeding

Answer 20

Selective breeding is when humans choose which organisms to breed in order to produce offspring with a certan desirable characteristic (e.g. animals with more meat, plants ith disease resistance or big flowers)

Question 21

How does selective breeding work?

Answer 21

1) Parents with desired characteristics are chosen
2) They are bred together
3) From the offspring those with desred characteristics are bred together
4) The process is repeated many times until all the offspring have the desired characteristic

Question 22

The problem with selective breeding is that it can lead to inbreeding

Answer 22

· Breeding those with similar desirable characteristics means it is likely you are breeding closely related individuals
· This results in the reduction of the gene pool, as the number of different alleles reduce (as they mostly have the same alleles)
· This means if the environment changes or there is a new disease, the species could become extinct as they all have the same genetic make-up (so the chance of a few organisms having survival advantage and not dying is reduced)
· Another problem is that the small gene pool leads to a greater chance of genetic defects being present in offspring, as recessive characteristics are more likely to present

Question 23

Genetic enginnering

Answer 23

Modifying the genome of an organism by intoducing a gene from another organism to give a desired characteristics

Question 24

Genetic modification

Answer 24

· Plant cells have been engineere for disease resistance ot to have larger fruits
· Bacterial cells have been engineered to produce substances useful to humans, such as human insulin to treat diabetes

Question 25

Restriction enzymes

Answer 25

enzymes which are able to cut DNA at specific sites, leaving ‘sticky ends’ (short sections of exposed, unpaired bases)

Question 26

Ligase enzymes

Answer 26

Enzymes that are used to join pieces of DNA together
The virus or plasmid DNA is then cut using the same restriction enzyme and the desired gene is placed inside and then joined by ligase enzymes

Question 27

The process of human insulin production

Answer 27

1. The insulin gene for a healthy individual is ‘cut out’ using restriction enzymes leaving ‘sticky ends’
2. A virus or bacterial plasmid is cut using the same restriction enzyme to also create sticky ends
3. The sticky ends from the virus or plasmid and the sticky ends from the genes are then joined together by ligase enzymes
4. The combined loop is placed in a vector, such as a bacterial cell, and then allowed to multiply as it will now contain the modified gene

Question 28

Genetically modified crops

Answer 28

· They are engineered to be resistant to insects and herbicides
· This will result in increased yields as less crops will die

Question 29

Transgenic

Answer 29

Transfer of genetic material from one species to a different species

Question 30

Micropropagation (tissue culture)

Answer 30

· Plant cells taken and placed in growth medium with nutrients and hormones to stimulate growth
· These plants grown are genetically identical clones of the parent as the only cells used were from the one parent plant
· This process is very important to preserve rare plant species or to make commercial quantities of genetically identical plants with desirable characteristics
· An older method to produce clones was cutting, where a section of the stem is cut and planted to form clones

Question 31

Cloning in animals

Answer 31

The first succesful experiment cloning animal cells resulted in Dolly the Sheep:
1) The nucleus is removed from an unfertilised egg cell
2) The nucleus is removed from an adult body cell and placed in the enucleated egg cell
3) Through the stimulation of an electric shock, the egg cell begins to divide to form an embryo
4) The embryo is implanted into the womb of a female
5) The offspring born is a clone of the adult body cell

Question 32

Transgenic animals

Answer 32

An animal containing genes from a different species
they can be used to produce human proteins, such as antibiotics

Question 33

Advantages of Cloning

Answer 33

· Clones produce identical offspring
· Large number of clones can be produced
· Can produce organs can be used as organ transplants that will not be rejected by the immune system

Question 34

Disadvantages of Cloning

Answer 34

· Decrease variation in population
· More susceptible to disease as no variation

Question 35

Biological control of pests

Answer 35

The use of other species to kill pests e.g. ladybirds eating aphids

Question 36

Lactobacillus

Answer 36

A bacterial species used to make yoghurt

Question 37

Pesticides

Answer 37

Chemicals used to kill pests, such as weed (herbicides) and insects (inseticides)

Question 38

Insulin

Answer 38

A hormone involved in the control of blood glucose concentration. Genetically modified bacteria grown in a fermenter can produce large amounts of insulin

Question 39

Plasmids

Answer 39

Loops of DNA found in the cytoplasm of prokaryotic cells. They can be used as vectors to transfer recombinant DNA into host cells

Question 40

Recombinant DNA

Answer 40

DNA created from joining the genetic material of two or more different organisms

Question 41

Vector

Answer 41

A structure responsible for transferring DNA into a cell. Commonly used vectors include plasmids and viruses

Question 42

Cloning

Answer 42

The production of an organism genetically identical to another one e.g. Dolly the sheep

Question 43

Diploid nucleus

Answer 43

A nucleus that contains two sets of chromosomes. It is inserted into an enucleated egg cell during cloning

Question 44

Explants

Answer 44

Small samples from a parent plant that are used for micropropagation

Question 45

Micropropagation

Answer 45

The multiplication of plants using tissue culture methods. It can be used to produce large numbers of plants, all genetically identical, with desirable characteristics originating from the parent plant

Question 46

Tissue Culture

Answer 46

A method of growing living tissue or cells in a suitable medium to produce clone plants