Unit 3 key area 3

Question 1

State two examples of things that reduce plant productivity?

Answer 1

• Pests and diseases kill crop plants reducing plant productivity
• weeds compete with crops for nutrients reducing the plant productivity

Question 2

State the two types of weeds?

Answer 2

• Perennial weeds
• annual weeds

Question 3

Describe the properties of annual weeds?

Answer 3

• Short life cycle
• High seed output
• fast growth
• long-term seed viability

Question 4

Describe the competitive adaptations of perennial weeds?

Answer 4

• Perennial weeds have storage organs
• Perennial weeds are capable of vegetative reproduction

Question 5

State two examples of pest species for crops?

Answer 5

Most pest species for crops are invertebrates such as
- nematode worms
- insects
- molluscs

Question 6

State three cultural means that we can use to prevent weed growth?

Answer 6

• Ploughing
• Weeding
• Crop rotation

Question 7

State the two types of herbicides?

Answer 7

• Selective herbicides
• Systemic herbicides

Question 8

Describe where a selective pesticide would be used?

Answer 8

Selective pesticides have a greater effect on certain plant species they work the best on broad leafed plants

Question 9

Describe how systemic herbicides work?

Answer 9

Systemic herbicides spread through the vascular system of the weed and prevent regrowth

Question 10

Describe how systemic pesticides work?

Answer 10

systemic pesticides spread through the vascular system of the crop and kill any pest that feeds on it

Question 11

Explain the disadvantages of using pesticides?

Answer 11

• Pesticides can be environmentally damaging
• Pesticides can cause bioaccumulation and biomagnification in food chains
• Pesticides can be toxic to non-target species
• Overuse of pesticides can produce resistant populations of pests

Question 12

define bioacumulation?

Answer 12

Bioaccumulation is the buildup of chemicals in an organism

Question 13

define biomagnification?

Answer 13

Biomagnification is the increase in the concentration of a chemical between trophic levels.

Question 14

Describe the process of biological control?

Answer 14

In biological control a control agent is introduced into the ecosystem that is a predator of the pest species. The control agent reduces the population of the pest species.

Question 15

Define the term integrated pest management?

Answer 15

Integrated pest management is the use of cultural, chemical, and biological control to reduce pest populations

Question 16

Explain the risks of using biological control?

Answer 16

Using biological control can result in the control agent becoming an invasive species either being a parasite to, or preying on other species.