N4 BiologyUnit 3 Life on EarthKA 3.1 Biomes and ecosystems

World Biomes

Learning Intention: Identify and describe how ecosystems are different across the world.

Success Criteria: •Define the term biome.•Describe the global distribution of world biomes.•Describe how temperature and rainfall affect the distribution of world biomes.•Present detailed information about one world biome.

What is a biome?• Biomes are large areas of the Earth which are

dominated by specific types of vegetation and are home to certain types of ecosystem.

• This is caused by differences in the climate in different parts of the world.

• Major biomes on Earth include tropical rainforests, savannah, coral reef, desert, tundra and temperate forests.

World Biomes

Tropical Rainforest

Arctic

Desert

Temperate forest

Coral reef

Biome project

• Choose a biome

• Make a word document or powerpoint about it.

Temperate forest

Desert

Coral reef

Arctic/Tundra

Tropical rainforest

Starter Activity:

How many different plant species are in this field?

Which is the most common species?

What animals live in or visit this field?

How would you find this out?

Sampling Techniques

Learning Intention:• Using practical techniques to sample plants

and animals.

Success Criteria:• Describe ways to measure abundance of

plants in an ecosystem.• Describe ways to sample animals in an area.

Appropriate Clip art to topic

Studying ecosystems

• Ecosystems are smaller areas within the biomes.

• Examples could be a woodland, a pond or a river.

• Studying an ecosystem involves:– Finding out what plants and animals live

there.– Finding out how many of them live there.– Finding out why they live there.

Abundance

• Abundance is the measure of how frequently a species of plant or animal appears in particular area.

• Abundance can be measured using sampling techniques.

Counting plants

• It would be very difficult to count every single plant in a field. How could you resolve this problem?

• We can sample using a quadrat.

• Sampling using a quadrat:– A quadrat is a square frame with a known area

such as 1m2

– It is used to estimate numbers of plants (or slow moving animals like slugs or snails).

1m

1m

How to sample using a quadrat

Estimating the number of thistles in a field:

• Quadrat placed at random and number of thistles in quadrat counted.

• Repeated several times.• Average number per square metre is calculated. • Area of whole field measured• Estimate of total number of thistles in field

calculated

Calculate the number of flowers in a field with a total area of 150m2

_______flowers in 1m2.

_______ x ________= ____ flowers

in a field of 150m2.

Example

12

12 1800150

1m

1m

To make the results of abundance more reliable, many samples would be taken using quadrats and the results then averaged before calculating the abundance of the entire area.

Quadrat Number of flowers

1 12

2 10

3 8

4 14

Average 11

So for the 150m2 area, Abundance = 11 x 150 = 1650 flowers

Quadrat practical• Area 1

Quadrat 1

Quadrat 2

Quadrat 3

Average

Moisture

pH

Light intensity

Number of species

Area 2 Quadrat 1

Quadrat 2

Quadrat 3

Average

Moisture

pH

Light intensity

Number of species

– Animals are difficult to count because they move around, and they tend to hide from humans.

– Some are well camouflaged as well.– The best way to estimate their numbers is

by live traps.

Sampling Animals

– A container is placed in a hole in ground to trap animals that are active at the soil surface.

– The trap is left overnight and checked next day.– Several traps should be set up to increase

reliability of the results.

Sampling Animals Using a Pitfall Trap

Pitfall Trap• Traps can be placed to compare

different areas and see what animals are more common in each.

• Tullgren funnel• Tree beating• Sweep netting• Pond netting

Other Methods of Sampling

Using a Tullgren funnel

WaterMost animals will float on surface

Starter Activity

How would you explain to a small child how to identify the following farm

animals?

Classification Keys

Learning Intention:• Branching keys.

Success Criteria:• I can use a branching key to identify

organisms• I can construct a branching key

Appropriate Clip art to topic

Classification Keys

• When using sampling methods, it is important that you are able to identify the plants or animals you have found.

• One method of identification is to use a key.

Keys

• Used to identify organisms while sampling.

• There are two types

–Branching keys–Paired Statement keys

Branching keys

• A key is a series of questions. Each question leads to another until eventually the name of the organism is found.

Branching keysA leech has noshell, no legs, nofins and asegmented body.

1. Name theanimal with no

shell and eight legs which is really small.

2. Describe a) a freshwater

shrimpb) A bullhead fish

Branching keysDescribe thefollowinganimals usinginformation inthe key.

1. Woodlouse2. Centipede3. Harvestman

Branching keysPut theseanimals into

the correct

positionin the key:

SnailWoodlouseSpiderButterflyWormMoth

Paired Statement Key

• In this type of key, instead of asking questions at branching points on a diagram, you are asked to choose between two statements.

• Each pair of statements is numbered and the instructions send you to the next relevant pair of statements.

1. Has green coloured body ......go to 2Has purple coloured body ..... go to 4

2. Has 4 legs .....go to 3Has 8 legs .....................................

3. Has a tail ............................ Does not have a tail ....................................

4. Has a pointy hump ...................................... Does not have a pointy hump.....go to 5

5. Has ears ............ Does not have ears ......

Paired Statement Key

Click on a leaf number 1 to start, then complete leaves 2-6 in that

order

1.

2.

3.

4.5.

6.

Invertebrate

Number of legs

Wings

Body Stripe

Spider 8 No No

Wasp 6 Yes Yes

Fly 6 Yes No

Springtail 6 No No

Construct a branching key for the information below:

Example 1

Plant Does it have chlorophyll?

Does it have

cones?

Does it have

flowers?

Does it live in water?

Grass Yes No Yes No

Spruce Yes Yes No No

Yeast No No No No

Moss Yes No No No

Seaweed

Yes No No Yes

Construct a branching key for the information below:

Example 2

Bird Type of feet Crest on head

Beak shape

Head colour

Swan Webbed Absent Straight White

Curlew Not Webbed Absent Curved Brown

Rook Not Webbed Absent Straight Black

Puffin Webbed Absent Straight Black

Skylark Not Webbed Present Straight Brown

Avocet Not Webbed Absent Curved Black

Construct a branching key for the information below:

Example 3

What is biodiversity?

Biodiversity is the variety of different species in an area, or on the planet as a whole.It is important to maintain biodiversity to ensure that important species do not become extinct.

What can affect biodiversity?

The following factors can affect levels of biodiversity:

•Abiotic factors- these are non-living factors like light, temperature, water, pH etc.

•Biotic factors- these are factors to do with other living things, like predators, food, competition and disease.

Watch the following Glow video clips Abiotic Factors Biotic Factors

Changes in Ecosystems

Imagine a disease wiped out the mosquito larvae. Which ecosystem would be most affected?Why?What might happen to the number of tadpoles in the loch if mosquito larvae disappeared? Why?

Here are two similar ecosystems.

Changes in Ecosystems

The prawns in this ecosystem are killed by pollution. What would happen to the numbers ofa)troutb)carpc)slugs