W2 5(a) Food production

Explain the use of fertilisers in increasing crop yield. (5)

• M1: (increase) growth / yield of plants / crops;

• M2: fertiliser contains ammonium / nitrates; (Ignore nitrogen)

• M3: amino acids / protein / DNA;

• M4: magnesium for chlorophyll / chloroplasts; (Allow other named mineral and function e.g., phosphates for ATP / DNA / calcium for cell walls / sulphates for protein / eq)

• M5: crops deplete soil minerals / ions / salts / soil lacks minerals / ions / salts / named mineral / minerals need to be replaced / eq;

• M6: organic fertiliser / manure retains water;

Define the term pesticide. (1)

M1: chemical / solution / eq that kills / destroys / eq pests / animals / plants / insects / eq;

Give two alternatives to the use of chemical pesticides. (2)

• M1: use biological control;

• M2: use nets / exclude insects from plants; (Allow: introduce consumer of insect / ladybird for aphids)

Explain why using a biological control could be better than using a chemical control. (3)

• M1: BC (biological control) numbers decline slower / CC (chemical control) numbers lower at start / eq;

• M2: BC stays low / less variable / CC go up and down / eq;

• M3: BC no need to reapply / insects reproduce / eq;

• M4: BC less risk of pollution / eq;

• M5: BC less risk of resistance / eq;

• M6: BC is specific / not affect (other) food chains / eq;

• M7: BC no bioaccumulation / eq; (Allow biomagnification)

State the word equation for anaerobic respiration in yeast. (1)

M1: glucose »»»»» ethanol + carbon dioxide;

Explain why bread dough rises when yeast is added. (3)

• M1: (yeast) respires / fermentation / respiration;

• M2: producing carbon dioxide; (Reject: oxygen produced)

• M3: (carbon dioxide) bubbles become trapped / stuck / inflate in dough;

Describe and explain the effect of increasing temperature from 25°C to 35°C on the rate of yeast respiration. (6)

At 25°C

• M1: (kinetic) energy lower / molecules move slower / eq;

• M2: fewer collisions / fewer enzyme substrate complexes / further away from enzyme optimum / eq;

• M3: less carbon dioxide / gas released / eq;

At 35°C

• M4: enzymes not denatured;

• M5: substrate fits into active site / active site shape not changed / eq;

• M6: so respiration continues / more carbon dioxide produced / yeast cells are alive / eq;

yeast denatures at around 49°C+

Describe an investigation to determine which type of yeast is best for producing low alcoholic beer. (6)

• C: use yeast A and yeast B / use (both) varieties of yeast;

• O: same concentration of yeast / same number of yeast (cells) / same mass of yeast / same volume of yeast / eq; (Ignore: amount)

• R: repeat (for each species);

• M1: measure / determine / test concentration / percentage / content (of alcohol in beer);

• M2: stated time;

• S1: add same mass / volume / concentration of starch / grains / barley / sugar / carbohydrate / glucose / maltose / malt / wort / substrate; (Ignore: amount / water)

• S2: control temperature / pH / oxygen / allow not far to diffuse ref to anaerobic respiration;

Explain why air is bubbled into the fermenter during the production of mycoprotein. (2)

• M1: oxygen is required;

• M2: for respiration;

Explain why the fermenter is cleaned using steam before the fungus and nutrients are added. (3)

• M1: to kill pathogens / other microorganisms / sterilises the fermenter / eq; (Accept: remove bacteria)

• M2: to prevent contamination (of the product) / competition;

• M3: steam condenses to water so does not affect product / taste / flavour / eq;

Explain how fish farmers can increase the yield of fish on a fish farm. (6)

• M1 (Method): keep adults from young / keep sizes apart / eq;

• E1 (Explanation): control intraspecific competition / large fish eat small fish / prevent young being eaten / eq;

• M2 (Method): keep different species apart / use nets / use cages / eq;

• E2 (Explanation): prevent fish being eaten / control predation / control interspecific competition / eq;

• M3 (Method): antibiotics / vaccination / prevent overcrowding;

• E3 (Explanation): control disease / infection; (Ignore: prevent disease if linked to feeding/water quality)

• M4 (Method): selective breeding / use growth hormones / use GM fish;

• E4 (Explanation): for named desired quality such as mass / yield;

• M5 (Method): use wrasse / insecticide / pesticide / biological control / eq;

• E5 (Explanation): to prevent / remove / kill parasites;

Note: For a 6-mark "Explain" question, you usually need a mix of Methods (M) and Explanations (E).

State two ways to reduce intraspecific predation on a fish farm. (2)

• M1: keep sizes / ages / sexes apart; (Ignore: species / separate by nets alone)

• M2: provide sufficient food;

Intraspecific competition Competition between members of the same species.

Intraspecific and Interspecific DIFFERENCE

• Intraspecific competition Competition between members of the same species.

• Interspecific competition Competition between members of different species.

Discuss the advantages and disadvantages of using antibiotics on fish farms. (4)

• A1: prevent disease / infection; (Ignore: kill bacteria / pathogens)

• A2: increase fish growth / yield;

• D1: (antibiotic) resistance (in bacteria);

• D2: antibiotic / resistant bacteria into humans;

Note: A is advantage and D is disadvantage

Describe the methods used by fish farmers to increase the yield of fish. (6)

• M1: separate different species to prevent predation / use nets to prevent predation / eq;

• M2: separate different sizes / ages to prevent predation / eq;

• M3: feed protein rich food / feed (frequently) in small quantities (to prevent accumulation of waste) / eq; (Note: not just "control diet" unqualified)

• M4: use antibiotics / fungicides to reduce disease / eq;

• M5: (filter water to) remove faeces / waste / algae / remove dead fish / eq;

• M6: aerate water / use pumps to maintain oxygen levels / eq; (Note: not just "clean the water" unqualified)

• M7: use selective breeding / GM (to maximise yield) / eq;

Describe an experiment to investigate the effect of the build-up of faeces on fish growth. (6)

• C: plus and minus faeces / range of faeces;

• O: same species of fish / same age / same mass / same size / same sex;

• R: repeat investigation / use more than one tank / use more than one fish (per tank) / same number of fish (per tank);

• M1: measure mass / weight / length; (Ignore: number that survive / size / growth)

• M2: same stated time period greater than one day;

• S1: same type of food / same frequency / same mass of food / same diet / same protein / same number of pellets / eq; (Allow: amount)

• S2: same oxygen / same temperature / same light / same volume of water/tank / same size of tank / eq; (Ignore: same quality of water / pH / type of faeces)

Explain how fish farms can reduce environmental pollution within their farming method and increase profits. (5)

• M1: waste food / faeces eaten / removed (by lobsters and crabs) / eq; (Accept: can sell crabs / lobsters / seaweed)

• M2: less decomposition / fewer decomposers / fewer bacteria;

• M3: less disease / infection (due to fewer bacteria);

• M4: less (bacterial/decomposers) respiration; (Accept: more fish/animal respiration)

• M5: more oxygen in the water / less removal of oxygen / seaweed releases oxygen;

• M6: nitrate / minerals / nutrients / carbon dioxide removed by seaweed; (Accept: fish provide CO₂ for seaweed)

• M7: less algae growth / algal bloom / eutrophication / eq;

• M8: more products to sell;

• M9: no need to buy food for lobsters / crabs / no need to buy minerals for seaweed;

answer the whole q

Compare the data for fish caught by traditional fishing and fish produced by fish farming between 1960 and 2016. (5)

Fish Caught / Traditional Fishing (Graph 1)

• M1: increased (in all countries);

• M2: increased by almost same proportion in each country;

Fish Farming (Graph 2)

• M3: increase in farming (in all countries);

• M4: increased most in A;

• M5: higher growth in C than B;

Comparison

• M6: more tonnes from farming (Graph 2) than catching in A / more tonnes from farming than catching in C / less in B;

• M7: A has the highest for both (caught and farmed) / eq;

Other / Limitations

• M8: no information on fish species / type of fish;

• M9: no information on sustainability / fish supply / eq;

• M10: data not expressed as per capita / eq;

Evaluate the use of keeping farmed animals (such as livestock or fish) indoors rather than outdoors. (5)

• M1: less heat loss if indoors / eq;

• M2: depends upon outside temperature / different in hot country;

• M3: but only small / 5% difference / eq;

• M4: animals move around less;

• M5: more energy for growth / making meat / eggs / milk / less energy used to keep warm / eq;

• M6: diseases easier to spread;

• M7: protected from predators;

• M8: ethical objection / cruel / quality of life idea / eq; (Ignore: natural)

• M9: eat variety of food outdoors / taste / eq;