Unit 3 Key Area 3

Question 1

Why do weeds, pests, and diseases all have a negative impact on food production?

Answer 1

• Weeds compete with crop plants for natural resources
• pests and diseases cause damage to crop plants
  Both of these reduce the productivity of the crop plants.

Question 2

What are the different types of weeds?

Answer 2

• Annual weeds
• perennial weeds

Question 3

What are some of the key properties of annual weeds?

Answer 3

• Rapid growth
• Short life cycle
• High seed output
• Long term seed viability (the seeds are able to stay alive for long periods of time)

Question 4

What are some of the properties of perennial weeds?

Answer 4

• Storage organs
• vegetative reproduction

Question 5

What are the different ways of controlling weeds, pests and diseases by cultural methods?

Answer 5

• Ploughing
• weeding
• Crop rotation (changing the times of year at which you grow certain crops)

Question 6

What are the different types of pesticides/herbicides?

Answer 6

• Selective pesticides
• Systemic pesticides
  (when we say pesticides in this context this also includes herbicides)

Question 7

In what situation might we use selective herbicides?

Answer 7

Selective herbicides have a greater effect on certain kinds of plants such as in killing broad leaved weeds

Question 8

What does a systemic herbicide do?

Answer 8

A systemic herbicide will spread through the vascular system of the weed and prevent regrowth

Question 9

What do systemic pesticides do?

Answer 9

Systemic pesticides spread through the vascular system of the plant killing any pests that feed on the plant

Question 10

What are some of the problems with using pesticides?

Answer 10

• pesticides have toxicity to non-target species
• pesticides bioaccumulate and biomagnify in food chains this causes damage to the ecosystem
• excessive use of pesticides can cause a population of pesticide resistant pests to develop

Question 11

What is bioaccumulation?

Answer 11

Bioaccumulation is the build up of a chemical in an organism

Question 12

What is biomagnification?

Answer 12

The increase in the concentration of a chemical between trophic levels of a food chain

Question 13

Describe the process of biological control?

Answer 13

In biological control the control agent is a natural predator, pathogen, or parasite to the pest species.

Question 14

What is meant by integrated pest management?

Answer 14

Integrated pest management is a combination of chemical, biological, and cultural control. (a balance of all three methods of reducing pests)