Key Area 3.3

Question 1

What is an advantage of a natural ecosystem

Answer 1

Genetic variety amongst species make them MORE RESILIENT to weeds, pests and diseases.

Question 2

What is a monoculture

Answer 2

one species

genetically identical

very susceptible to weeds pests and diseases

Question 3

What is the problems with monocultures?

Answer 3

ideal growing conditions for:

• weeds
• pests-
• disease causing micro-organisms

so control methods needed

Question 4

Economical impacts of weeds?

Answer 4

• reduction in crop productivity (due to competition)
• reduction in crop growth (due to chemical inhibitors)
• cause disease (as they act as hosts for pests)

Question 5

Name the types of weeds

Answer 5

Annual and Perennial

Question 6

Give a definition and adaptations of annual weeds

Answer 6

Definition:
one year life cycle

Adaptions:
•rapid growth
•short life cycle
•high seed output
•long period of seed viability (seeds stay dormant until conditions are right)

Question 7

Definition and adaptations of perennial weeds?

Answer 7

Definition:
Weeds all year round

Adaptations:
•storage organs for food in adverse conditions
•vegetative reproduction (runners and bulbs)
•competitive advantage because they are established before crops

Question 8

Name and describe the types of pests

Answer 8

Nematodes -parasites in plant roots
e.g eel worms

Molluscs - eat leaves using rasping mouth parts which are ideal for touch plant materials
E.g snails/slugs

Insects - feed on plants using piercing or biting
E.g caterpillars

Question 9

What kinds of microorganism causes diseases

Answer 9

Bacteria
Fungi
Viruses

Question 10

Name the 3 types of controls for pests weeds and diseases

Answer 10

Cultural control
Chemical control
Biological control

Question 11

What is the main purpose of cultural control

and

give examples of cultural control

Answer 11

Purpose?
To prevent

Examples:
Ploughing - first layer of soil flipped and weeds buried and die

Crop rotation: dissimilar plants planted in a cycle

Question 12

Types of chemical controls

Answer 12

Herbicides
Pesticides
Fungicides

Question 13

Types of herbicides

Answer 13

Selective
Systemic
Contact

Question 14

How do selective herbicides work

Answer 14

Mimic growth hormones

Causes the broad leaf plant (weeds) metabolism to speed up until they exhaust their food resource and die

Narrow leaf plants (crops) absorb little of the herbicide and are not affected

Question 15

What is an advantage and disadvantage of selective herbicides

Answer 15

Advantage: Biodegradable so do not chase harm to soil communities

Disadvantage: residue that may enter food chains

Question 16

How do contact herbicides work

Answer 16

Kill green plant tissue they come into contact with

Question 17

Advantage and disadvantage of contact herbicides

Answer 17

Advantage: biodegrade and short lived

Disadvantage: roots survive so weed can regrow

Question 18

How do systemic herbicides work

Answer 18

Absorbed by the plant and transported to all areas of the plant

Question 19

Advantage and disadvantage of systemic herbicides

Answer 19

Advantage:
attacks vascular system of the weed and totally destroy a it, stopping it from growing back

Disadvantage:
Slower acting

Question 20

Name the types of pesticides

Answer 20

Contact

Systemic

Question 21

Describe contact pesticides

Answer 21

Kills the pest when it comes into contact with it either through:

• spray
• layer of posing us residue (on crop)

Question 22

Describe systemic pesticides

Answer 22

Absorbed by the plant and transported to all parts of the plant

When a pest eats the plant it intakes position as well as sap and dies

Question 23

Name the types of fungicides

Answer 23

Contact

Systemic

Question 24

Describe contact fungicides

Answer 24

Sprayed into crops

When fungal spores land and begin to grow they absorb poison and die

Question 25

Disadvantage of contact fungicides

Answer 25

New leaves are unprotected and rain can wash off fungicides

SO repeated applications = money

Question 26

Describe systemic fungicides

Answer 26

Absorbed by the crop plant and transported to all parts of the plant

Question 27

Advantage of systemic fungicides

Answer 27

Provides better protection than contact fungicides

Question 28

Name and describe the problems associated with chemicals

Answer 28

•toxicity to animals:
If chemicals is not specific to weed pest or disease it can be toxic to humans and other animals

•persistence in environment:
If chemical persists (doesn’t break down) it can lead to the accumulation in food chains

•accumulation in food chains:
Concentration of chemicals increases as it moves throughout tropic levels until the top where it is toxic to the tertiary consumer

•creating resistant populations:

• Few pests may be resistant because of MUTATIONS THAT CONFER AN ADV
• Natural selection occurs and resistant population survive to pass their pesticide resistance to next generation
• Eventually whole population is resistant

Question 29

What is biological control?

Answer 29

The reduction of a pest pest population by the deliberate introduction of one of its natural enemies

E.g. Predator, parasite, disease

Question 30

Advantage and disadvantage of biological control?

Answer 30

Advantage:
Does not use chemicals which persists in the environment

Disadvantage:
Control can become invasive species and a threat to indigenous species of it escapes

Question 31

What is the best way to use biological control and why?

Answer 31

Best used in enclosed environments

Why?
Predator cannot escape

Environment conditions can be controlled to favour control

Question 32

What is IPM and what does it stand for

Answer 32

Combination of cultural,chemical and biological control to improve yield

INTEGRATED PEST MANAGEMENT

Question 33

What are IPM aims?

Answer 33

Reduce pests numbers

Reduce chemical use