Mineral & Soil Resources — Drills · Grade 12 Science

Chapter: Energy, Water & Material Resources

What these drills covers

By the end of Mineral & Soil Resources you should be able to:

6 questions, multiple choice, numeric and written answer, each with a worked explanation.

Vocabulary used: ore, soil horizon, soil degradation, reclamation.

Problem 1

An ore is a rock or deposit that...
  1. is always made of fertile soil
  2. is a renewable energy source
  3. contains no useful materials at all
  4. holds enough of a valuable mineral to be worth mining
Answer and explanation

holds enough of a valuable mineral to be worth mining

An ore contains a high enough concentration of a valuable metal or mineral that mining it is worthwhile.

Problem 2

Which soil layer is the fertile topsoil?
  1. The A horizon
  2. The deepest solid-rock layer
  3. The bedrock
  4. The C horizon (parent rock)
Answer and explanation

The A horizon

The A horizon is the dark, fertile topsoil where most plant roots grow.

Problem 3

New soil forms at about 1 inch every 400 years, but a bare, poorly managed field can lose 1 inch of topsoil in just 25 years. How many times faster is soil being lost than formed?
Answer and explanation

16 times

Divide the formation time by the loss time: 400 / 25 = 16 times faster.

Problem 4

Which practice conserves soil by keeping roots in the ground and the surface covered all year?
  1. Mountaintop-removal mining
  2. Planting cover crops
  3. Deep plowing every season
  4. Removing all plant residue after harvest
Answer and explanation

Planting cover crops

Cover crops keep living roots and ground cover in place between main crops, holding the soil against erosion.

Problem 5

Recycling metals like aluminum helps conserve mineral resources mainly because it...
  1. is impossible to actually do
  2. uses more energy than mining fresh ore
  3. uses far less energy and ore than making new metal
  4. creates much more mining waste
Answer and explanation

uses far less energy and ore than making new metal

Recycling aluminum uses only about 5% of the energy of making it from ore, and it avoids mining new ore altogether.

Problem 6

The 1930 s Dust Bowl destroyed millions of acres of farmland. Explain what caused it and name one practice that could have helped prevent it.
Answer and explanation

Farmers plowed up the deep-rooted native prairie grasses to plant crops, leaving loose, bare topsoil. When a severe drought struck, there were no roots to hold the soil, and strong winds blew it away in enormous dust storms. Practices such as planting windbreaks, keeping ground cover with cover crops, using contour plowing, or leaving some native grass in place could have anchored the soil and reduced the erosion.

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