Biology

5. Use of Biological Resources
5.1 Food Production>5.2 Selective Breeding>5.3 Genetic Modification (Genetic Engineering)>5.4 Cloning>

1. The Nature & Variety of Living Organisms

1.1 Characteristics of Living Organisms >

2. Structure & Function in Living Organisms

2.1 Level of Organization >2.2 Cell Structure >2.3 Biological Molecules >2.4 Movement of Substances Into and Out of Cells >2.5 Nutrition (in Plants) >2.6 Nutrition (in Human) >2.7 Respiration >2.8 Gas Exchange (in Plants) >2.9 Gas Exchange (in Human) >2.10 Transport (in Plants) >2.11 Transport (in Human) >2.12 Excretion (in Plants) >2.13 Excretion (in Human) >2.14 Coordination and Response (in Plants) >2.15 Coordination and Response (in Human) >

3. Reproduction & Inheritance

3.1 Reproduction (in Plants) >3.2 Reproduction (in Human) >3.3 Inheritance >

4. Ecology & The Environment

4.1 The Organism in the Environment >4.2 Feeding Relationships >4.3 Cycles within Ecosystems >4.4 Human Influences on the Environment >

5.1 Food Production

5.1.1 Describe how glasshouses and polythene tunnels can be used to increase the yield of certain crops

Crops:

The environment of crops grown outside cannot be controlled
Environment inside glasshouses and polythene tunnels can be controlled to increase crop yield

Glasshouse:

Temperature is controlled:
- Enzymes controlling photosynthesis are in their optimum range
Light supply is controlled:
- Provide plants with constant supply of light for photosynthesis
CO2 levels is controlled:
- Increases the rate of photosynthesis
Plants watered at regular intervals
- Increases rate of photosynthesis
Increased rate of photosynthesis leads to:
- Increased growth
- Higher crop yield

Polythene tunnel:

Protects crops from environmental conditions such as:
- Wind
- Rain
- Snow
Increases the temperature inside the tunnel
- Can increase or decrease rate of photosynthesis depending on the climate

Prevent pests from entering and damaging the crops

5.1.2 Understand the effects on crop yield of increased carbon dioxide and increased temperature in glasshouses

Factors affecting crop yield:

Plants require the following for photosynthesis:
- CO₂
- H₂O
- Light
- Suitable temperature
The supply of these factors limit the rate of photosynthesis
Increasing the limiting factors increases plant growth rate
Increased plant growth rate increases yield

Effect of CO₂

on yield:

Increased carbon dioxide concentration eliminates it from being the limiting factor
Provides an unlimited supply of CO₂
for plants to absorb
CO₂ can be absorbed more readily and at a faster rate
Rate of photosynthesis increases

Effect of temperature on yield:

The kinetic energy of enzymes involved in photosynthesis increases with temperature
Increased rate of reaction as enzymes and substrates are more likely to collide
Enzymes can work at their optimum temperature to increase rate of photosynthesis

5.1.3 Understand how the use of fertiliser can increase crop yield

Effect of fertilisers on crop yield:

Minerals absorbed from the soil need to be replaced for monoculture crop growth
Fertiliser contain key nutrients for plant growth:
- Nitrogen
- Phosphorus
- Potassium
Nitrogen:
- Absorbed in the form of nitrates
- Required for amino acid production
- Lack of nitrogen reduces growth
Phosphorus:
- Absorbed as phosphates
- Required for the production of DNA and cell membranes
- Lack of phosphorus leads to poor root formation
Potassium:
- Absorbed as many different compounds
- Assists in ATP production
- Required for enzymes used in photosynthesis
- Lack of potassium leads to reduced growth of flower and fruits

5.1.4 Understand the reasons for pest control and the advantages and disadvantages of using pesticides and biological control with crop plants

Pest control:

Pests are organisms that:
- Damage crops (insects)
- Compete with them (weeds)
- Infect crops with diseases (fungi)
Controlled by:
- Chemical control such as pesticides
- Biological control such as introduction of a new species

(Micro-organisms) 5.1.5 Understand the role of yeast in the production of food including bread

Yeast in bread:

Yeast produce ethanol and CO₂ during anaerobic respiration
In an abundance of sugar, yeast respires anaerobically
- Regardless of presence of oxygen
For the production of bread:
- Enzymes from the yeast break down starch in the flour
- Sugar released is used for anaerobic respiration
- CO₂ is produced and trapped in air pockets within the dough
- Dough rises
- Yeast is killed during the baking process

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

Mix 1 teaspoon of sugar with 1 teaspoon of yeast and 4cm³ of water to a test tube
Add a layer of oil on top of the solution to cut off oxygen supply
Using a capillary tube, connect the test tube to another tube containing limewater
At room temperature, count the number of bubbles produced in the lime water in a minute
Rate of CO2 production can be used as a measure of rate of anaerobic respiration
Repeat this experiment at 15ºC, 20ºC , 35ºC and 40ºC

Results:

Compare the rate of anaerobic respiration at different temperatures
Deduce the optimum temperature for anaerobic respiration in yeast
At 35ºC, the most bubbles would be seen as the enzymes
- Yeast would be closer to their optimum temperature
As the enzymes get closer to their optimum temperature, their activity increases
- Respiration would take place at a faster rate
At 40ºC, temperature is beyond optimum
- The rate of anaerobic respiration will decrease
- Enzymes involved would start to denature

5.1.7 Understand the role of bacteria (Lactobacillus) in the production of yoghurt

Bacteria in yoghurt:

Yoghurt production relies on a specific bacteria: Lactobacillus
Lactobacillus breaks down lactose present in milk into lactic acid
Lactic acid decreases the pH of the milk
- Proteins in the milk denatures
- Milk curdles
- Forms yoghurt

Method:

All equipment is sterilised to kill any bacteria
Milk is then pasteurised at 80ºC to kill of any bacteria in it
Milk is then cooled down to 37ºC so that lactobacillus can be added
The milk – bacteria mixture is incubated for 12 hours to allow lactobacillus to digest the milk proteins and ferment the lactose in the milk
Lactobacillus converts the lactose into lactic acid
1. Makes the milk acidic and thickens it to form yoghurt
2. Lower pH also prevents growth of other harmful bacteria
Yoghurt is then cooled to 4ºC to stop the reaction

5.1.8 Understand the use of an industrial fermenter and explain the need to provide suitable conditions in the fermenter, including aseptic precautions, nutrients, optimum temperature and pH, oxygenation and agitation, for the growth of micro- organisms

5.1.9B Understand the methods used to farm large numbers of fish to provide a source of protein, including maintaining water quality, controlling intraspecific and interspecific predation, controlling disease, removing waste products, controlling the quality and frequency of feeding, and selective breeding

Large populations of fish are kept in fresh or seawater enclosures to control their environments for high yield