Explain the causes of mortality in day-old chicks, identify decomposers in a forest ecosystem, describe the function of parts of the mammalian ear, and list ways to demagnetize a magnet.

b) Five causes of mortality during brooding of day-old chicks are:

• Starvation or dehydration due to inability to find food or water.
• Temperature stress (chilling or overheating) due to improper brooder temperature.
• Diseases such as Coccidiosis or Salmonella.
• Poor ventilation leading to ammonia buildup.
• Predation by other animals or cannibalism among chicks.

c)

i) Decomposers are organisms that break down dead organic matter, returning nutrients to the ecosystem.

ii) Four examples of decomposers in a forest ecosystem are:

• Fungi (e.g., mushrooms, molds)
• Bacteria
• Earthworms
• Insects (e.g., millipedes, certain beetles)

d) The function of each part of the mammalian ear:

i) Pinna: Collects sound waves and directs them into the ear canal.

ii) Cochlea: Converts sound vibrations into nerve impulses that are sent to the brain.

iii) Eustachian tube: Equalizes air pressure between the middle ear and the outside atmosphere.

iv) Semi-circular canal: Detects rotational movements of the head and helps maintain balance.

e)

i) Demagnetization of a magnet is the process of reducing or completely removing its magnetic properties.

ii) Three ways a magnet could be demagnetized are:

• Heating it above its Curie temperature.
• Hammering or dropping it repeatedly.
• Placing it in an alternating magnetic field and slowly withdrawing it.

f)

i) A hazardous substance is any substance that can cause harm to human health or the environment due to its chemical or physical properties.

ii) One example for each: * ($\alpha$) Corrosive household substance: Bleach * ($\beta$) Inflammable laboratory substance: Ethanol * ($\gamma$) Toxic laboratory substance: Mercury

g)

i) Explanation of breeding systems: * ($\alpha$) Hand mating: This is a controlled breeding system where the male and female animals are intentionally brought together by a handler for mating. It allows for precise record-keeping and selection of breeding pairs. * ($\beta$) Pasture mating: This is an uncontrolled breeding system where male and female animals are allowed to roam freely together in a pasture, and mating occurs naturally without direct human intervention.