Food Production

Question 1

Describe how glasshouses can increase crop yield?

Answer 1

Easy to keep free form pests & disease.
Helps control water.
Often artificial light - plants have more time to photosynthesise.
Trap sun’s heat to keep plants warm - optimum temp - photosynthesis (enzymes).
CO2 - Paraffin heater - as it burns - CO2 released as by-product - higher rate of photosynthesis.
Higher photosynthesis rate means crops grow more - greater crop yield.

Question 2

How does increased temperature lead to greater crop yield?

Answer 2

Higher temperature - enzymes in crops closer to their optimum temperature.
As molecules gain KE & so greatest rate of successful collisions & E-S complexes formed per unit time.
Therefore greatest rate of production of glucose - plants grow biggest - so greater yield.

Question 3

How does increased CO2 lead to greater crop yield?

Answer 3

Co2 needed for photosynthesis.
More co2 means more co2 will be absorbed by chloroplasts.
Leads to greater rate of photosynthesis - more glucose made - plants grow more.

Question 4

How does fertiliser lead to greater crop yield?

Answer 4

Minerals could be missing due to previous crops using them up:
Fertilisers are a source of mineral ions needed for growth.
E.g. Nitrogen & Magnesium.
Mg - makes chlorophyll - more chlorophyll = more photosynthesis…
Nitrogen - makes amino acids - makes proteins …. = greater crop yield

Question 5

What are reasons for pest control?

Answer 5

Fewer pests feed on crops & destroy them - increases crop yield as more of them can grow.

Question 6

Describe on example of the use of biological control?

Answer 6

Using predators like ladybirds to eat aphids who feed on leaves - the ladybirds don’t destroy the leaves - increases crop yield.

Question 7

3 advantages of using biological control over pesticide?

Answer 7

BC - lasts longer than pesticide.
BC - doesn’t need to be reapplied.
BC - avoids bioaccumulation unlike pesticides.
BC - no development of resistance.

Question 8

Problems of biological control?

Answer 8

Could become pests themselves.

Question 9

What is herbicide?

Answer 9

To kill weeds.

Question 10

How do animal faeces increase crop yield?

Answer 10

Contain mineral ions/nutrients like magnesium/nitrogen needed for growth.
Faeces contain microorganisms that decompose it - broken down to help with absorption.

Question 11

How does increased oxygen in soil help plants grow?

Answer 11

More O2 - more aerobic respiration - provides more energy for active transport of mineral ions across root hair cells into the plant.

Question 12

How do animals eating weeds help plants grow?

Answer 12

Weeds eaten - reduced competition for mineral ions e.g. Nitrates - greater availability of these nutrients means plants can use more of these to grow more.

Question 13

What is fermentation?

Answer 13

When microorganisms breakdown sugars to release energy - usually by anaerobic respiration.

Question 14

Describe the production of yogurt?

Answer 14

Equipment sterilised to kill unwanted microorganisms.
Milk pasteurised (heated 72degrees for 15secs) - to kill unwanted microorganisms & then cooled.
Lactobacillus added & mixture incubated (40c) in a fermenter.
Lactobacillus bacteria ferment lactose sugar in milk to lactic acid.
Lactic acid causes milk clotting - solidifies into yogurt.

Question 15

What happens in a fermenter?

Answer 15

Microorganisms grown.
Fermenter is full of a liquid ‘culture medium’ – in which microorganisms can grow and reproduce.

Question 16

Why are conditions inside fermentation vessels kept at the optimum levels for growth?

Answer 16

So the yield of products from microorganisms can be as big as possible.

Question 17

Describe the role of nutrients?

Answer 17

Nutrients needed by microorganisms for growth are provided in the culture medium.

Question 18

Describe the role of pH?

Answer 18

PH is monitored – kept at optimum pH – for microorganisms enzymes to work efficiently.
Keeps rate of reaction and product yield as high as possible.

Question 19

Describes the role of temperature?

Answer 19

Temperature kept at optimum.
Water cooled-jacket – fermentation vessel doesn’t get so hot that enzymes denature.

Question 20

Describe the role of the rotating paddles?

Answer 20

Microorganisms kept in contact with fresh medium by paddles.
Paddles circulate medium around the vessel.
Higher product yield – microorganisms can always access nutrients needed for growth.

Question 21

Describe the role of the oxygen?

Answer 21

If microorganisms need oxygen for respiration – added by pumping in sterile air.
Higher product – microorganisms can always respire – to provide energy for growth.

Question 22

Describes the aseptic conditions?

Answer 22

Vessels sterilised between uses – with superheated steam – kills unwanted microbes.
Aseptic conditions – microorganisms don’t compete with unwanted organisms – increases product yield.
Also means product isn’t contaminated.

Question 23

Describe how yeast is used to make bread?

Answer 23

Yeast mixed with flour, water, sugar.
Dough left in warm place to rise.
Enzymes breakdown carbs in the flour into sugars.
Yeast then uses these sugars for aerobic respiration - producing CO2.
When oxygen runs out - yeast switches to anaerobic respiration.
(Fermentation) - produces CO2 & Ethanol.

Question 24

What happens when oxygen runs out?

Answer 24

Fermentation - anaerobic respiration - CO2/Ethanol produced.
CO2 trapped in dough bubbles - gas expands - dough rises.
Then dough baked in oven - yeast continues to ferment.

Question 25

Explain why bread stops rising when baked in the oven?

Answer 25

Yeast continues to ferment until temperature so high that its enzymes denature & the yeast is killed.
Alcohol produced during anaerobic respiration is boiled away.
As yeast dies - bread stops rising - pockets left in bread where CO2 trapped.

Question 26

Describe experiment of changing temperature on yeast production?

Answer 26

Mix sugar/yeast/distilled water & place in TT.
Attach bung with tube leading to 2nd TT.
Place in water bath at set temperature.
Count how many bubbles in 2nd TT over set time (1min).
Rate of co2 = number of bubbles / time ~ rate of respiration.
Repeat with water bath at different temperatures.

Question 27

Why are the two TT’s sealed with bungs?

Answer 27

Prevents more Oxygen from entering - causes yeast anaerobic respiration.

Question 28

How can we repeat this for concentration?

Answer 28

Vary sugar concentration each time.

Question 29

How can we make results more accurate?

Answer 29

Replace 2nd TT with gas syringe - measures volume of gas instead.

Question 30

How can selective breeding develop plants/animals with desired characteristics?

Answer 30

Select organisms with the desired characteristics.
Breed them together.
Select best offspring & breed them together.
Repeat this over many generations - stronger & stronger desirable traits.

Question 31

What features are organisms cross-bred for?

Answer 31

Maximum yield of milk/grain/meat.
Good health / disease resistance.

Animals - speed / fertility.
Plants - scent / taste.

Question 32

How does selective breeding develop cows? (Example)

Answer 32

E.g. - high meat yield.
Select two largest cows & bulls.
Breed them together.
Select strongest offspring with most meat & size - breed them together.
Repeat over many generations.

Question 33

Describe artificial insemination?

Answer 33

Natural mating can be difficult:
Safer for cow & cheaper to transport semen than bulls.
Semen can also impregnate multiple cows.

Question 34

How can selective breeding increase crop yield?

Answer 34

Tall wheat plants - good yield but damaged by wind/rain.
Dwarf wheat plants - lower yield but resist wind/rain.
CROSS-BRED both together - best resulting plants CROSS-BRED again & repeat over many generations.
New variety of plant - dwarf plants resistant to wind but greater yield.