Distribution Of Organisms

Question 1

Give 5 examples of abiotic factors

Answer 1

• light intensity
• soil moisture
• humidity
• temperature
• soil pH

Question 2

Give 5 examples of biotic factors

Answer 2

• competition
• disease
• food availability
• grazing
• predation

Question 3

Why does low levels of grazing lead to low biodiversity?

Answer 3

Slower growing plants are outcompetes by taller, fast growing plants which are not eaten by herbivores

Question 4

Why does high levels of grazing lead to high biodiversity?

Answer 4

Dominant plants are eaten by herbivores, giving smaller less dominant plants the change to grow

Question 5

Why does moderate levels of grazing lead to biodiversity?

Answer 5

All plants are eaten by herbivores

Question 6

When measuring abiotic factors, name a possible source of error and how to minimise it when using a thermometer to measure temperature

Answer 6

Source of error - touching thermometer bulb

How to minimise - don’t touch bulb and take several reading

Question 7

When measuring abiotic factors, name a possible source of error and how to minimise it when using a light intensity metre to measure light intensity

Answer 7

Source of error - shading the light sensitive panel

How to minimise - ensure light sensitive panel isn’t shaded, take several reading and calculate an average

Question 8

When measuring abiotic factors, name a possible source of error and how to minimise it when upswing a moisture metre to measure soil moisture

Answer 8

Source of error - having left over soil from previous readings on the probe

How to minimise - wipe probe clean between reading, take several reading and calculate an average

Question 9

When using a pitfall trap name 4 sources of error and how to minimise

Answer 9

1. Some animals trap and eat others - check traps regularly
2. Birds may eat small animals - always have a cover
3. Rain causes pitfall traps to overflow - place a hole in bottom of cup for drainage
4. Animals do not fall into trap as rim of cup is avoided soil level - ensure rim of cup is level with soil

Question 10

What is a transect?

Answer 10

A transects is a line across a habitat or part of a habitat. It can be a string or a rope placed in a line on the ground.

Question 11

What is an indicator species?

Answer 11

Their presence or absence will indicate environmental quality/levels of pollution in an area