Recycling of materials

Question 1

The cycling of water- The cycling of water is essential to ensure that:

Answer 1

1. Plants have a continuous supply of water to manufacture organic food byphotosynthesis.’
2. All living organisms have a continuous supply of water to keep their cells hydrated and toact as asolvent (see page 54).
3. Aquatic organisms have a constant environment in which to live

Question 2

The cycling of carbon

The cycling of carbon is essential to ensure that:

Answer 2

Carbon atoms are cycled by being convertedinto different compounds containing carbon, e.g.carbon dioxide and all organic compounds.
1. Plants have a continuous supply of carbon dioxide to manufacture organic food by photosynthesis.
2. Animals and decomposers have a continuous supply of organic food.

Question 3

The cycling of nitrogen

The cycling of nitrogen is essential to ensure that:

Answer 3

Nitrogen atoms are cycled by being convertedinto different compounds containing nitrogen,e.g. nitrates and proteins.
1. Plants have a continuous supply of nitrates to manufacture proteins.
2. Animals and decomposers have a continuous supply of proteins

Question 4

Recycling of manufactured and other waste materials

Recycling and Recycable materials can be divided into two categories:

Answer 4

Recycling changes waste materials into new products.
* Biodegradeble materials
* Non-biodegradeable

Question 5

Biodegradable materials:

Answer 5

these can be decomposed by the action of living organisms, mainly bacteria and fungi. They include waste from the food industry, farmyardand garden waste, mostpaper and bagasse from the sugar industry.

Question 6

Non-biodegradable Materials

Answer 6

these cannot be decomposed by living organisms. They include glass, plastics, rubber, construction waste, synthetic fabrics such as nylon, and metals such as iron, steel, aluminium, copper and lead.

Question 7

why it is important to recycle

Answer 7

• Prevents wastage of potentially useful materials.
• Conserves natural resources by reducing the quantity of fresh raw materials used in manufacturing.
• Reduces energy usage.
• Reduces the quantity of waste requiring disposal.
• Reduces pollution of air, land and water.

Question 8

Difficulties encountered in recycling manufactured materials:

Answer 8

• It can be difficult to persuade households and industries toseparate their waste into different types.
• It is more difficult to collect, transport andstore waste items when separated into different types.
• It can be time consuming because items have to be cleaned before they are recycled. Also, different manufactured materials can have very different properties and they have to be sortedinto theirdifferent types before recycling, e.g. there are many different types of plastics.
• It can be uneconomical in small countries such as the Caribbean islands because it is labourand energy intensive, and the quantity of recyclable materials generated by these countries isinsufficient to maintain the full-time operation of recycling plants.