5.1-5.8 food production from crop plants, microorganism

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

• enclosed environment protects crops from harsh weather

• Carbon dioxide levels are maintained in glasshouses to optimise the rate of photosynthesis

• Heat is trapped from the sun so optimum temp of enzymes can be reached

• Plants are protected from pests that can damage plants or carry diseases

How does an increase of carbon dioxide affect crop yield? And methods?

• enhanced photosynthesis, increased yield, prevents CO2 from being the limiting factor

• Methods: burning natural gas or paraffin lamps, releasing from tanks

How does an increase in temperature effect crop yield and methods?

• Allows enzymes in photosynthesis to work at optimum temp, increase photosynthesis and increased yield

• Heat is trapped by the sun in glasshouse which raises the temp

How does fertiliser increase crop yield?

• contains nutrients that allow plants to grow faster

• Water soluble minerals can be absorbed into the plants roots by active transport

Examples of minerals in fertiliser that increase yield

• nitrates - required to make amino acids for proteins to allow plant to grow

• Phosphates are required for respiration and root growth

• Potassium is n ended for growth of flowers and fruit, allows enzyme reactions to take place

What is pest control

Using pesticides (including fungicides, herbicides, insecticides) or biology control to prevent insects from eating the plants.

Advantages of pest control

• quick and efficient

• Can kill pest populations

Disadvantages of pest control

• organisms can develop resistance

• Non specific so it can kill other organisms

• Bioaccumulation (buildup) can make it toxic to others in the food chain

• Have to continuously apply

Role of yeast in the production of bread

Uses anaerobic respiration in order to make bread rise: glucose → ethanol + carbon dioxide

The carbon dioxide bubbles cause the bread to rise

Practical to investigate the role of anaerobic respiration by yeast in different conditions

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 to prevent oxygen from entering (only anaerobic respiration)

4. Connect the boiling tube to a test tube of lime water

5. Count number of bubbles over time

6. Repeat with changes of different conditions (temp, sugar concentration)

What bacteria is used to make yoghurt?

Lactobacillus

Describe the process of production of yoghurt using lactobacillus

• All equipment is sterilised to kill unwanted microorganisms

• Milk is heated to 72°C for 15sec to kill microorganisms in the milk (pasteurisation)

• Milk is cooled and lactobacillus is added

• Mixture is incubated (kept warm) at around 40°C in fermenter - lactobacillus breaks down lactose in milk to lactic acid

• This acid lowers the pH of the milk, denaturing proteins to give yoghurt texture and flavouring, colorants, fruit are added

What does an industrial fermenter do?

It is a container that grows bacteria and fungi in large amounts

What conditions are required in an industrial fermenter?

• aseptic conditions to ensure no other microorganism grows and contaminates

• Nutrients for organism to use in respiration

• Optimum temp and pH for enzymes

• Agitation by stirring paddles is required to ensure nutrients, oxygen, temp, pH and microorganisms are distributed evenly