What are the answers to questions 6a, 6b, 6c, and 6d regarding mosquito control, environmental impact of gold extraction, cover cropping, and uses of metals/non-metals?

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6.

• a) State four (4) ways of controlling mosquitoes in the community.

  • Eliminate stagnant water bodies (breeding sites).
  • Use insecticide sprays or larvicides.
  • Encourage the use of mosquito nets.
  • Promote proper waste management.

• b) Give four (4) measures that can be taken to minimize the negative impact of gold extraction on the Ghanaian environment.

  • Implement and enforce strict environmental regulations.
  • Reclaim and reforest mined-out areas.
  • Treat wastewater from mining operations before discharge.
  • Promote environmentally friendly mining technologies (e.g., reducing mercury use).

• c) State four (4) importance of cover cropping in crop production.

  • Soil erosion control: Protects soil from wind and water.
  • Weed suppression: Outcompetes weeds.
  • Soil fertility improvement: Adds organic matter and fixes nitrogen.
  • Moisture retention: Reduces evaporation.

• d) State two (2) uses of each of the following

  • i) Metals
    • Used in construction (e.g., steel for buildings).
    • Used for electrical wiring (e.g., copper).
  • ii) Non-metals
    • Oxygen is essential for respiration.
    • Carbon (as coal) is used as a fuel source.

7.

• a) i) Define light energy. Light energy is a form of electromagnetic radiation that is visible to the human eye and travels in waves.

• a) ii) Explain two (2) ways in which light energy is useful to living organisms.

  • Photosynthesis: Plants use light energy to convert carbon dioxide and water into glucose and oxygen.
  • Vision: Animals use light energy to perceive their surroundings, aiding navigation and food finding.

• b) i) Define an atom. An atom is the smallest unit of an element that retains the chemical identity of that element, consisting of a nucleus surrounded by electrons.

• b) ii) An atom has 11 electrons.

  • a) Draw the electronic configuration of the atom. The electronic configuration is $\boxed{\text{2, 8, 1}}$.
  • b) Type of bond the element will form with chlorine. The element will form an ionic bond with chlorine.
  • c) Give two (2) reasons for the type of chemical bond stated in (β) above.
    • There is a large difference in electronegativity between the metal (sodium) and the non-metal (chlorine).
    • Sodium transfers its valence electron to chlorine, forming stable ions (Na$^+$ and Cl$^-$).

• c) i) Define food poisoning. Food poisoning is an illness caused by consuming food contaminated with harmful microorganisms or their toxins.

• c) ii) Explain two causes of food poisoning.

  • Improper cooking: Food not cooked to the correct temperature may not kill harmful pathogens.
  • Cross-contamination: Transfer of pathogens from raw foods to ready-to-eat foods.

• d) State two (2) methods of soil conservation.

  • Contour plowing: Plowing across slopes to reduce runoff.
  • Crop rotation: Alternating crops to maintain soil fertility and structure.

8.

• a) i) State the law of floatation. The law of floatation states that a floating object displaces a weight of fluid equal to its own weight.

• a) ii) Explain how a submarine operates. A submarine operates by changing its buoyancy. It fills ballast tanks with water to increase density and dive, and expels water with compressed air to decrease density and surface.

• b) i) State three (3) ways of preventing dental decay.

  • Brush teeth regularly with fluoride toothpaste.
  • Limit sugary foods and drinks.
  • Floss daily.

• b) ii) State one (1) cause each of:

  • a) Constipation: One cause is insufficient fiber in the diet.
  • b) Indigestion: One cause is eating too quickly or consuming fatty/spicy foods.

• c) i) What is an alloy? An alloy is a mixture of two or more elements, at least one of which is a metal, combined to create a new material with enhanced properties.

• c) ii) Name the main elements present in each of the following:

  • a) Bronze: $\boxed{\text{Copper and Tin}}$
  • b) Nichrome: $\boxed{\text{Nickel and Chromium}}$
  • c) Duralumin: $\boxed{\text{Aluminium, Copper, Magnesium, and Manganese}}$

• d) i) List two (2) types of animal parasites.

  • Endoparasites (e.g., tapeworms)
  • Ectoparasites (e.g., ticks)

• d) ii) State three (3) economic importance of the grasshopper.

  • Crop damage: They are agricultural pests that destroy crops, causing economic losses.
  • Food source: They serve as a food source for various animals in the ecosystem.
  • Bait: They can be used as bait for fishing.