5. use of biological resources

Question 1

5.1 describe how glasshouses can be used to increase the yield of certain crops

Answer 1

in glasshouse, several conditions can be manipulated to inc rate of photosynthesis, incl:
- artificial heating (enzymes controlling photosynthesis can work faster at slightly higher temps - only used in temperate countries e.g. UK)
- artificial lighting (plants can photosynthesise for longer)
- inc CO2 content of air inside (plants can photosynthesise quicker)
- regular watering

Question 2

5.1 what do farmers need to consider when using glasshouses?

Answer 2

need to balance extra cost of providing heating, lighting & CO2 against the inc income

Question 3

5.1 how can glasshouses be changed for tropical countries?

Answer 3

may still be used to control other conditions however may need to be ventilated to release hot air & avoid temps rising too high, which could cause denaturation of enzymes controlling photosynthesis reaction

Question 4

5.1 describe how polythene tunnels can be used to increase the yield of certain crops

Answer 4

• poly(thene) tunnels: large plastic tunnels that cover crops
• can protect crops grown outside from the effects of the weather, incl excessive wind, rain & extreme temps
• also inc temp slightly inside tunnel
• can prevent entry of pests that can damage plants or diseases that can kill plants

Question 5

5.2 what are the effects on crop yield of increased carbon dioxide in glasshouses?

Answer 5

• as glasshouses are enclosed, CO2 conc can be controlled
• farmers can burn paraffin lamps to inc CO2 levels in glasshouses
• as conc of CO2 inc, rate of photosynthesis will inc
• as CO2 is a reactant in photosynthesis, the inc in CO2 conc will allow more photosynthesis to occur, hence inc rate of photosynthesis to inc crop yield
• however, as conc of CO2 inc beyond a certain point, rate of photosynthesis will plateau as another factor will be limiting factor - crop yield will halt

Question 6

5.2 what are the effects on crop yield of increased temperature in glasshouses?

Answer 6

• as glasshouses are enclosed, heat from sun can be trapped to create warm climate
• as temp inc towards optimum, rate of photosynthesis will inc to inc crop yield
• this bc the inc in temp towards optimum allows optimum enzyme activity for photosynthesis, hence inc rate of it
• but as temp inc above optimum, enzymes involved in photosynthesis will denature, so cause rate of photosynthesis to decrease - crop yield will decrease

Question 7

5.3 understand how the use of fertiliser can increase crop yield

Answer 7

• plants require range of mineral ions in order to grow well
• as crop plants take up these mineral ions from soil, mineral ions need to be replaced if crops are grown repeatedly in same field (i.e. yr after yr)
• fertilisers are used to replace these mineral ions
• they can make crops grow faster & bigger so that yields inc
• fertilisers can be in form of organic fertiliser or chemical fertiliser
• they mainly provide crop plant w N, Phosphorus, and K

Question 8

5.3 what are examples of organic fertilisers?

Answer 8

farmyard manure and compost

Question 9

5.3 what are examples of chemical fertilisers?

Answer 9

often applied to the soil as dry granules or can be sprayed on in liquid form

Question 10

5.3 why is nitrogen in fertilisers, and what form is it absorbed in?

Answer 10

• absorbed in form of nitrates
• needed to make amino acids (building blocks of proteins)
• lack of N causes weak growth & yellowing of leaves of plants

Question 11

5.3 why is phosphorus in fertilisers, and what form is it absorbed in?

Answer 11

• absorbed in form of phosphates
• needed to make DNA and cell membranes
• lack of phosphorus can cause poor root growth and discoloured leaves

Question 12

5.3 why is potassium in fertilisers, and what form is it absorbed in?

Answer 12

• absorbed in form of various compounds of potassium
• allows enzyme reactions to take place to produce ATP in respiration, as well as being needed for the enzymes involved in photosynthesis
• lack of potassium can cause poor growth of flowers & fruits, as well as brown spots on leaves

Question 13

5.3 fertilisers increase the… meaning that they can grow… which increases…

Answer 13

fertilisers increase the amount of key nutrients in the soul for crop plants, meaning that they can grow larger and are more healthy, which increases yields

Question 14

5.4 what is the definition of pest control?

Answer 14

the use of pesticides (chemicals such as fungicides, herbicides and insecticides) to control pests from consuming or damaging plants

Question 15

5.4 what do fungicides, herbicides and insecticides do?

Answer 15

fungicides: kills fungi
herbicides: kills herbs
insecticides: kills insects

Question 16

5.4 what are the advantages and disadvantages to pest control?

Answer 16

advantages:
- efficient as it’s a quick method
- immediate effect
- targets & kills entire pop.

disadvantages:
- pests can develop resistance
- may kill other organisms - non-specific chemicals
- toxic to food chain - bioaccumulation
- need for continuous application

Question 17

5.4 what are the advantages and disadvantages of biological control?

Answer 17

advantages:
- natural method
- no resistance
- ability to target specific species
- long-lasting
- efficient as minimal effort required

disadvantages:
- may kill other organisms - non-specific
- time lag in effect
- cannot kill entire pop.
- organism may be unadaptable to new environment & die

Question 18

5.4 what’s the definition for biological control?

Answer 18

a natural method to control pests using organisms that feed on pests

Question 19

5.5 what is the role of yeast in the production of food (including bread)?

Answer 19

yeast uses anaerobic respiration in order to make bread rise:
glucose –> ethanol + carbon dioxide
the CO2 bubbles are what causes the bread to rise

Question 20

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

Answer 20

1. dissolve sugar in boiled water
2. mix yeast w the sugar solution in a boiling tube
3. add layer of oil on top in order to prevent oxygen from entering (ensuring it’s only anaerobic respiration taking place)
4. connect boiling tube to test tube of lime water
5. count no. of bubbles seen over a set time
   - different conditions can be investigated, e.g. temp (by using water bath) or conc. of sugar

Question 21

5.7 what is the role of the bacteria lactobacillus in the production of yoghurt?

Answer 21

• first equipment sterilised & milk pasteurised (heated to 72°C for 15 secs)
• milk cooled to 40-45°C & lactobacillus added
• mixture incubated at this temp. for several hours, while lactobacillus digests milk proteins & ferments the sugar (the lactose) in the milk
• lactobacillus anaerobically respires and converts lactose into lactic acid and this increased acidity sours & thickens the milk to form yoghurt
• the thickened yoghurt is produced & any flavouring, colorants or fruit are added before the packaging

Question 22

5.8 what are fermenters?

Answer 22

containers that grow bacteria & fungi in large amounts

Question 23

5.8 what conditions are needed for the growth of micro-organisms in industrial fermenters?

Answer 23

• aseptic conditions required to ensure no other microorganism grows & contaminates containers
• nutrients needed for microorganism to use in respiration
• optimum temps & pH needed in order for enzymes to work at high rate but not denatured
• agitation by stirring paddles required to ensure that the nutrients, oxygen, temp, pH & microorganisms distributed evenly

Question 24

5.9B understand the methods used to farm large numbers of fish to provide a source of protein

Answer 24

• maintaining water quality: filter water to remove waste & harmful bacteria to prevent disease
• controlling intraspecific predation: stops competition within same species; fishes separated by size & age to prevent this
• controlling interspecific predation: stops competition between species; different species separated by nets/tanks
• controlling disease: antibiotics given to inc chances of survival
• removal of waste products: water filtered to remove waste faeces
• controlling quality & freq of feeding: fish fed freq but in small amounts so they don’t overeat & to avoid food wastage
• selective breeding: reproduces fish w desired characteristics

Question 25

what is the definition of selective breeding?

Answer 25

selecting individuals with desirable characteristics and breeding them together, and repeating this for many successive generations

Question 26

5.10 & 5.11 how does selective breeding develop plants/animals with desired characteristics?

Answer 26

- select individuals with desirable characteristics & breed them together - breed offspring that show the desired characteristics together - process repeated for many successive generations so that they will reliably show those selected characteristics in all offspring

Question 27

5.10 & 5.11 how can selective breeding lead to inbreeding?

Answer 27

- breeding those w similar desirable characteristics means it's likely you're breeding closely related individuals - this results in reduction of **gene pool**, as no. of diff alleles reduce (as they mostly have same alleles) - this means if environment changes or there's new disease, species could become **extinct** as all have **same genetic make-up** (so chance of a few organisms having a survival advantage & not dying reduced) - another problem is that small gene pool leads to **greater chance of genetic defects** being present in offspring, as recessive characteristics more likely to be present

Question 28

5.12 what are restriction enzymes & ligase enzymes used for/what are they?

Answer 28

restriction enzymes: enzymes which are able to **cut DNA** at specific sites, leaving **'sticky ends'** (short sections of exposed, unpaired bases) ligase enzymes: enzymes that are used to **join pieces of DNA** together

Question 29

5.13 what can plasmids and viruses act as

Answer 29

vectors: - the virus/plasmid DNA then cut using same restriction enzyme; the desired gene is placed inside & then joined by ligase enzymes - they can then insert this recombinant DNA into other cells

Question 30

what is the definition for genetic engineering?

Answer 30

modifying the genome of an organism by introducing a gene from another organism to give a desired characteristic

Question 31

5.14 how are large amounts of human insulin manufactured from genetically modified bacteria grown in a fermenter?

Answer 31

1. human insulin gene located on the chromosome 2. insulin gene is 'cut out' from rest of chromosome using **DNA restriction enzymes** leaving 'sticky ends' 3. a **virus** or **bacterial plasmid** is cut using **same** restriction enzyme to also create **sticky ends** 4. the human insulin gene & plasmid join together due to complementary base pairing at the sticky ends. a **DNA ligase enzyme** forms bonds between the nucleotides to make this a single piece of DNA - we say the plasmid is now **recombinant DNA** - it's a combination from 2 diff sources 5. the combined loop is placed in a vector, e.g. a bacterial cell, & then allowed to multiply as it will now contain the modified gene - the plasmid carrying the human DNA is referred to as a **vector** 6. transgenic bacteria then placed in a **fermenter** to inc in no.

Question 32

5.14 what conditions do the bacteria in the fermenter need to produce human insulin?

Answer 32

if they have enough nutrients & are kept at their optimum conditions, e.g. - oxygen provided via the air line - stirring the mixture to prevent clumping & a shortage of nutrients - monitoring temp & cooling fermenter if needed - adding more nutrient medium

Question 33

5.15 understand how genetically modified plants can be used to improve food production

Answer 33

- they're engineered to be resistant to insects & herbicides - this results in inc yields as less crops will die

Question 34

5.15 what are the advantages & disadvantages of genetically modified plants?

Answer 34

advantages: - more precise method than selective breeding - higher crop yield/better food quality - less pesticide/herbicide used so less pollution - disease/pest/herbicide resistant disadvantages: - not accepted by public - long term affects unknown - may affect food chains or environment - reduces variation

Question 35

5.16 what does the term transgenic mean?

Answer 35

the transfer of genetic material from one species to a different species

Question 36

5.17B describe the process of micropropagation (tissue culture) in which explants are grown in vitro

Answer 36

- plant cells are taken and placed in the growth medium w nutrients & hormones to stimulate growth - these plants are genetically identical clones of the parent as the only cells used were from the one parent plant

Question 37

5.18B why is micropropagation important?

Answer 37

- v important to preserve rare plant species - or to make commercial quantities of genetically identical plants w desirable characteristics

Question 38

5.18B what was an older method to produce plant clones?

Answer 38

cuttings, where a section of the stem is cut & planted to form clones

Question 39

5.19B describe the stages in the production of cloned mammals

Answer 39

1. nucleus removed from an **unfertilised egg** cell 2. nucleus removed from an adult body cell & placed in the **eunucleated 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 40

5.20B what could cloned transgenic animals be used to produce?

Answer 40

human proteins, e.g. antibodies, in their milk - proteins could be collected from milk & used to treat patients w weak immune systems, like cancer or HIV patients