Essay Questions

Question 1

Crop Protection - chemical and biological control of weeds and other pests (4)

Answer 1

Chemical Control

• Herbicides, selective, greater effect on certain plant species (broad leaved weeds)
• Herbicides, systematic, spread through the vascular system of plants and prevents regrowth
• Pesticides, systematic and spread through the vascular system of the plant and kill pests feeding on the plant
• fungicides prevent fungal diseases and are more effective when applied based on the disease forecast then treating diseased crops

Biological Control

• control agent is a natural predator, parasite or pathogen of the pest
• Integrated past management, combination of chemical, biological and cultural control
• The control organism may become an invasive species, or a parasitise, predator or pathogen of other species.

Question 2

Animal Welfare (4)

Answer 2

Intensive Farming

• less ethical
• poorer animal welfare
• more cost effective, higher profit
• low cost
• less land
• less labour intensive

Free range

• requires more land
• more labour intensive
• sold at a higher price and
• animals have a better quality of life.
• ethical

Indicators of poor welfare

• stereotypy - repetitive movement
• misdirected behaviour- normal behaviour done to extremes
• failure in sexual or parental behaviour
• altered levels of activity - very low (apathy)
  - very high (hysteria)

Question 3

Metabolic Pathways - features, types and proteins (8)

Answer 3

Features

• Irreversible
• reversible
• enzyme controlled
• can follow alternative routes
• anabolic reactions require energy and build up large molecules from smaller molecules
• catabolic reactions release energy and break down larger molecules into smaller molecules

Proteins embedded in the cell membrane

• enzymes-speed up chemical reactions
• pumps-active transport
• pores-allow osmosis and diffusion which are passive transport

Question 4

Regulators and Thermoregulation (8)

Answer 4

Regulators

• maintain their internal environment regardless of external environment
• they use metabolism to control internal environment
• can have a wide range of ecological niches
• high metabolic cost

Thermoregulation

• controlled by negative feedback
• hypothalamus is the temperature monitoring centre

Corrective responses to a decrease in body temperature

• shivering-muscle contraction generates heat
• hair erector muscles-traps layer of insulating air
• increased metabolic rate-more heat produced
• vasoconstriction-decreases blood flow to skin-less heat loss

Corrective responses to an increase in body
Sweating-body heat used to evaporate water in the sweat, cooling the skin.
Vasodilation-increased blood flow to the skin increases heat loss.
Decreased metabolic rate-less heat produced.