B7 Abiotic and Biotic Factors (page 84)

Question 1

What is Abiotic and Biotic mean?

Answer 1

The environment in which organisms live changes all the time.

Things that change are either

Abiotic - They are Non-living
or
Biotic - Living factors

(they can have a big affect on the community).

Question 2

Abiotic Factors are living or non-living?

Answer 2

Non-living factors.

Question 3

Give examples of Abiotic factors?

Answer 3

1) Moisture level
2) Light intensity
3) Temperature
4) Carbon dioxide level (for plants)
5) Wind intensity and direction
6) Oxygen level (for aquatic animals)
7) Soil pH and mineral content.

Question 4

A change in temperature environment could be an increase or decrease in an abiotic factor, give an example?

Answer 4

e.g. an increase in temperature. These changes can affect the size of the populations in a community. This means they can also affect the population sizes of other organisms that depend on them (see page 83)

Question 5

A change in the light intensity, temperature or level of carbon dioxide in the environment could be an increase or decrease in an abiotic factor, give an example?

Answer 5

e.g. a decrease in light intensity, temperature or level of carbon dioxide could decrease the rate of photosynthesis in a plant species (see page 50). This could effect plant growth and cause a decrease in the population size.

(also Animals depend on plants for food, so a decrease in a plant population could affect the animal species in a community)

Question 6

A decrease in the mineral content of the soil (e.g. a lack of nitrates) could cause nutrient deficiencies, explain why?

Answer 6

This could affect plant growth and cause a decrease in the population size.

Question 7

Is Biotic factors living or non-living factors?

Answer 7

they are living factors.

Question 8

Give some examples of Biotic factors?

Answer 8

1) New predators
2) Competition (one species may outcompete another so that numbers are too low to breed.
3) New pathogens
4) Availability of food

Question 9

Why would a change in the environment be the introduction of a new biotic factor with a new predator or pathogen?

Answer 9

These changes can affect the size of populations in a community, which can have knock-on effects because of interdependence (see page 83).

(e.g. A new predator could cause a decrease in the prey population. There’s more about predator-prey populations on pg. 86)

Question 10

Why could a change in the environment be the decreasing of red squirrels, where grey squirrels out compete the red squirrels, who live in the same habitat and eat the same food?

Answer 10

Grey squirrels outcompete the red squirrels - so the population of red squirrels is decreasing.

Question 11

Look at the graph on page 84, it shows the effect of a new pathogen on species A. Explain what the graph is showing?

Answer 11

The population size of species A was increasing up until 1985, when it decreased rapidly until 1990. - this suggests that 1985 was the year that the new pathogen arrived. The population started to rise again after 1990.

Question 12

Give four examples of abiotic factors that could affect a plant species? (4 marks)

Answer 12

Any four from:

moisture level
light intensity
temperature
carbon dioxide level
wind intensity
wind direction
soil pH
mineral content of soil (1 mark for each correct answer, up to 4 marks)

Question 13

Cutthroat trout are present in lakes in Yellowstone National Park. In the last few decades, lake trout have been introduced to the lakes. However, lake trout have emerged as predators of the cutthroat trout. Give two other biotic factors that could affect the size of the cutthroat trout population (2 marks)

Answer 13

Any two from:

availability of food
competition for resources
new pathogens (1 mark for each correct answer, up to 2 marks)