B6 - Life in soil

Question 1

What does soil contain?

Answer 1

• different sized particles
• living plants and animals
• decayed remains of dead plants and animals
• air
• water containing dissolved minerals

Question 2

Why can plants grow in soil on Earth?

Answer 2

Because it provides:

• minerals needed for growth
• water to stay alive
• anchorage for roots

Question 3

What are the three states of soil?

Answer 3

• acidic
• alkaline
• neutral

Question 4

Why do sandy soils drain well?

Answer 4

Sandy soils drain well because they have large mineral particles with big air spaces.

Question 5

Why do clay soils become waterlogged easily?

Answer 5

Clay soils become waterlogged easily because they have small particles that are close together.

Question 6

Why is loam a good soil?

Answer 6

Loam is a good soil because it contains clay and sand and has large mounts of humus.

Question 7

What is humus?

Answer 7

Humus is decomposed material.

Question 8

Why do plants find it difficult to live in dry soils?

Answer 8

They need water for photosynthesis.

Question 9

Why do plants find it difficult to live in waterlogged soils?

Answer 9

This is because they need oxygen for respiration.

Question 10

What would be the pH of a neutral soil?

Answer 10

The pH would be 7.0

Question 11

Describe the test for air.

Answer 11

Using a tin to collect a soil sample, find the mass of the soil and the tin and then fill it with water until the tin is completely full. Then find the mass of all three and find the difference in masses.

Question 12

Describe the test for water content.

Answer 12

Weigh a sample of the soil and then slowly dry the soil in an oven. Then weigh the soil again. The loss in the mass is the mass of water in the soil.

Question 13

Describe the test for humus.

Answer 13

Take a sample of dry soil, burn it with a bunsen burner and then weight it again. The loss in mass will be equivalent to the humus content.

Question 14

What is aerating the soil?

Answer 14

Aerating is increasing the amount of air in soil.

Question 15

What does a food web show?

Answer 15

A food web shows the feeding relationships of some animals and their predators.

Question 16

What are decomposers?

Answer 16

Decomposers are organisms that break down dead plants and animals, releasing elements into the soil.

Question 17

Name five things that live in the soil.

Answer 17

Herbivores, detritivores, carnivores, bacteria and fungi.

Question 18

What are detritivores?

Answer 18

Detritivores feed on dead organic matter.

Question 19

How do earthworms improve the structure of soil?

Answer 19

• burrowing, which aerates the soil and improves drainage
• eating and burrowing through the soil which mixes the layers in the soil
• adding chalk as it eats the soil, neutralizing acid soils

Question 20

Explain the importance of earthworms to agriculture.

Answer 20

Earthworms naturally improve the structure and fertility of the soil, and without them the layers of soil would be thin and few plants would grow.