Edaphic Factors Affecting Organisms

Question 1

What are edaphic factors?

Answer 1

Edaphic factors relate to soil

Question 2

Give some examples of edaphic factors that affect organisms.
(6)

Answer 2

Soil pH

Soil type

Organic matter (humus) in the soil

Water content of the soil

Air content of the soil

Mineral content of the soil

Question 3

What are the two main edaphic factors affecting organisms?

Answer 3

Specific pH values of the soil

Soil type

Question 4

What are the different pH values a soil can have?

3

Answer 4

Acid soils - pH less than 7

Neutral soils - pH close to 7

Alkaline soils - pH higher than 7

Question 5

Write a note on how the specific pH value of a soil affects organisms
(4)

Answer 5

Plants and animals are adapted to specific pH values

Acid soils (e.g. bogs) have a pH less than 7 and support bog moss and heather

Neutral soils have pH values close to 7 and are preferred by most plants

Alkaline soils have pH values greater than 7 and are preferred by lime-loving plants, e.g. birdsfoort trefoil and bee orchid

Question 6

What pH do acid soils have?

Answer 6

A pH less than seven

Question 7

Give an example of an acidic soil.

Answer 7

Bogs

Question 8

What plants are supported by acidic environments?

2

Answer 8

Bog moss

Heather

Question 9

What pH do neutral soils have?

Answer 9

pH less close to seven

Question 10

What plants are supported by neutral environments?

Answer 10

Neutral soils is preferred by most plants

Question 11

What pH do alkaline soils have?

Answer 11

Greater than 7

Question 12

What type of plants prefer alkaline soils?

Answer 12

Lime-loving plants

Question 13

Give two examples of lime-loving plants that are supported by alkaline soils.

Answer 13

Birdsfoot trefoil

Bee orchid

Question 14

Write a note on how the type of soil affects organisms

6

Answer 14

Soil type is determines by the size of soil particles

Sandy soils have large soil particles which gives the soil good drainage and air content but sandy soils ma have low mineral and water content

Sandy soils have few earthworms due to the lack of humus

Plants growing in sandy soil such as Marram grass have to have long, deep roots to absorb moisture deep down in the soil

Clay soils have small particles which makes them impermeable to water and air and causes clay soils to be waterlogged easily

Plants do not grow well in clay soils, as the soil is too wet and difficult to penetrate

Question 15

What are the two main types of soils?

Answer 15

Sandy soil

Clay soil

Question 16

What determines soil type?

Answer 16

The size of soil particles

Question 17

Describe the soil particles in sandy soil.

Answer 17

Sandy soils have large soil particles

Question 18

What is the benefit of sandy soils?

Answer 18

Their large soil particles give sandy soils good drainage and air content

Question 19

What is the disadvantage of sandy soils?

Answer 19

Sandy soils may have low mineral and water content

Question 20

What do sandy soils lack?

Answer 20

Humus or dead organic matter

Question 21

Due to the lack of humus, what is there few of in sandy soils?

Answer 21

There are few earthworms

Question 22

Why are there few earthworms in sandy soil?

Answer 22

Because there is a lack of humus or dead organic matter

Question 23

What type of plant grows well in sandy soils?

Answer 23

Marram grass

Question 24

How has Marram grass adapted to grow in sandy soils?

Answer 24

they have long, deep roots to absorb moisture deep down in the soil

Question 25

Describe the soil particles in clay soils.

Answer 25

Clay soils have small particles

Question 26

What is the benefit of small particles in clay soils?

Answer 26

They are impermeable to water and air

Question 27

What is the disadvantage of small particles in clay soils?

Answer 27

Clay soils become waterlogged easily

Question 28

What plants grow well in clay soil?

Answer 28

No plant grows well in clay soil

Question 29

Why do plants not grow well in clay soil?

Answer 29

As the soil is too wet and difficult to penetrate