B6.2 Feeding the Human Race 1

Question 1

What is food security?

Answer 1

The ability of the human population to access affordable food of sufficient quality and quantity

Question 2

Some factors that threaten food security

Answer 2

• increasing human population
• changing diets
• climate change
• new pests and pathogens may evolve
• increasing agricultural costs=higher prices

Question 3

How does changing diets affect food security?

Answer 3

People become more wealthy and tend to eat a more varied diet

Often = more meat = more energy intensive to produce

Question 4

How does climate change affect food security?

Answer 4

Scientists predict that global warming will result in more droughts, expansion of deserts = harder to farm

HOWEVER increase in levels of CO2 in atmosphere may = increasing yield of some crops?

Question 5

Ways to increase food production

Answer 5

• maximising photosynthesis
• fertilisers
• removing competition + pests (eg. Herbicides to kill weeds, insecticides to remove insects, fungicides to destroy disease-causing fungi)
• planting varieties of pest resistant crops or that produce a higher yield

Question 6

How to maximise photosynthesis

Answer 6

Control light levels, temperature, water supply in industrial glasshouses

Question 7

What does using fertilisers do?

Answer 7

As a plant grows it removes minerals from the soil, fertilisers help land remain fertile

Question 8

Aim of intensive farming

Answer 8

To produce maximum food product yield from minimum area of land

Question 9

What techniques is intensive farming achieved through?

Answer 9

• using fertilisers and pesticides to aid plant growth
• maximising animal growth rates
• minimising labour inputs through machinery use

Question 10

What is organic farming?

Answer 10

Farming through use of more natural methods of producing crops and rearing animals, avoiding use of artificial chemicals.
Yields generally smaller = products more expensive

Question 11

Sustainable food production

Answer 11

Producing food in ways that can be continued indefinitely

Eg. fish farming

Question 12

Results of overfishing

Answer 12

Reductions in populations of some fish species so that they cannot regenerate

Question 13

What have international organisations done to combat fish farming?

Answer 13

Introduce fishing quotas so that enough fish can survive an reproduce to maintain their population

• limits of numbers + types of fish caught in area
• limit mesh size of nets (bigger holes = young, smaller fish can escape)

Question 14

What is fish farming?

Answer 14

When fish are bred and reared in large cages in the sea or rivers

Question 15

Advantages of fish farming

Answer 15

• Protection from predators
• easier to catch fish
• allows wild populations to recover

Question 16

Disadvantages of fish farming

Answer 16

• fish kept close together = disease can spread quickly

- risk of disease spreading to wild populations

Question 17

What do farmers use instead of artificial fertilisers?

Answer 17

Replace soil nutrients by spreading manure

Question 18

What does crop rotation do?

Answer 18

Different crops take different nutrients from the soil, by planting different crops in the same soil each year =

• soil recovers
• maximises plant growth
• prevents build up population of particular crop pest

Question 19

What is biological control?

Answer 19

Using the natural predators of crop pests to kill the pests
Predators (usually other insects) are bred in large numbers and are released onto crops where they eat the pests
(Instead of spraying pesticides which may damage other organisms like in intensive farming)

Question 20

How are scientists developing crop varieties?

Answer 20

Through gene technology

Creating crop varieties more resistant to pests and disease

Question 21

What is a hydroponic system?

Answer 21

Growing a plant in water containing dissolved minerals to ensure that it is receiving necessary minerals

Question 22

Advantages of hydroponic systems

Answer 22

• Enables plants to grow quickly
• Glasshouse may contain several rows of hydroponic plants stacked above each other = many plants grown in same space
• mineral solution not absorbed is collected and recycled

Question 23

What is selective breeding?

Answer 23

When, in order to produce the highest yields, farmers breed their best plants/animals in order to produce desired characteristic in offspring

Question 24

5 steps to selective breeding

Answer 24

1. Decide on desired characteristic
2. Select parents with high levels of this characteristic
3. Breed from these individuals
4. Select best offspring and breed again
5. Repeat for many generations

Question 25

How has selective breeding changed the characteristics of wheat?

Answer 25

Small ears + few seeds —> large ears + many seeds
Brittle stalks + ears fall often —> stronger stalks + ears stay on
Ears ripen at different times —> ears ripen at same time
Stalks grow to different height —> stalks grow to same height

Question 26

Disadvantages of selective breeding?

Answer 26

• reduced gene pool / number of alleles of a species = less variation (disease, more likely to become extinct)
• increased chances of inheriting genetic disease (eg. pugs + short stubby noses = breathing problems)