National 5 Unit 3.1 and 3.4 Ecosystems and Energy in Ecosystems Pupil Course Notes

Life on EarthSub-Topics: 3.1 and 3.4 Ecosystems

and Energy in EcosystemsOn completion of this sub-topic I will be able to state that An ecosystem is the community of organisms living in a habitat and

their interactions with the non-living components of the system.

A habitat is the place where an organism lives.

A community is all the living organisms in an ecosystem.

A population is all the living things of one type of species.

Biodiversity is the existence of a wide variety of plant and animal species living in their natural environment.

A species is a group of organisms capable of breeding to produce fertile young.

A population is all the organisms of one species found in a particular area.

A producer is a green plant which makes its own food by photosynthesis.

A consumer is an organism which eats other organisms to gain energy, a primary consumer is a herbivore (an animal which eats plants), a secondary consumer is a carnivore (an animal which eats other animals), an omnivore is an organism which eats both animals and plants.

A predator is an animal that kills or eats another animal.

Prey are the animals that get eaten.

A food chain is a diagram that shows feeding relationships between different living things in a particular environment.

The arrows in a food chain or web represent the direction of energy flow.

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National 5 Unit 3.1 and 3.4 Ecosystems and Energy in Ecosystems Pupil Course Notes

90% of the energy is lost from a food chain or food web at each stage and only 10% is used for growth.

The majority of the energy lost is lost as heat (maintenance of body temperature) and movement.

A food web is a number of food chains joined together.

Food chains can be represented as pyramids.

A pyramid of numbers is diagram which shows the relative total number of organisms present at each stage in the food chain.

A pyramid of energy is a diagram which shows the total energy of organisms present at each stage in the food chain.

A niche is the role that an organism plays within the community.

A niche relates to the resources in its ecosystem such as light and nutrient availability and its interactions with other organisms in the community. It involves competition, and predation and the conditions it can tolerate such as temperature.

Competition in ecosystems can occur when resources are in short supply.

Interspecific competition occurs when organisms of different species compete for one or a few of the resources they require.

Intraspecific competition occurs between organisms of the same species and is for all the resources they require.

Intraspecific competition is more intense than interspecific competition.

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National 5 Unit 3.1 and 3.4 Ecosystems and Energy in Ecosystems Pupil Course Notes

Ecosystems

Ecology is the scientific study of relationships in the natural world. It includes relationships between organisms and their physical environment, between organisms of the same species and between organisms of different species.

An ecosystem consists of all the organisms (the community) living in a particular habitat and the non-living components with which the organisms interact.

habitat - the place where an organism lives community - all the living organisms that live within a habitat

Ecosystem = Habitat + Community

Ecologists study these interactions in order to understand the biodiversity and distribution of life within Earth's ecosystems.

Biodiversity is the existence of a wide variety of plant and animal species living in their natural environment.

Interdependence of Organisms

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A species is a group of organisms which can interbreed to produce fertile offspring.

Donkey X Donkey

Donkey - it is fertile

Donkey X Donkey Donkey X Donkey Donkey X Donkey Donkey X Donkey Donkey X Donkey Donkey X Donkey Donkey X Donkey Donkey X Donkey Donkey X Donkey Donkey X Donkey Donkey X Donkey Donkey X Donkey Donkey X Donkey Donkey X Donkey Donkey X Donkey Donkey X Donkey Donkey X Donkey Donkey X Donkey Donkey X Donkey Donkey X Donkey

National 5 Unit 3.1 and 3.4 Ecosystems and Energy in Ecosystems Pupil Course NotesSometimes two different species can interbreed, but the offspring they produce are infertile. An example is shown below.

A mule is the offspring of a horse and a donkey.

x

The resulting mule is infertile

Horses and donkeys are different species.

Complete the table below

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A population is a group of living organisms of the one species e.g. the population of rabbits or the population of dandelions found in a particular area.

All the populations that live within a habitat make up the community.

Name DefinitionHabitat

CommunityPopulation

National 5 Unit 3.1 and 3.4 Ecosystems and Energy in Ecosystems Pupil Course Notes

Producers and consumers

Organisms can be divided into two groups:

Producers Consumers

An animal which kills or eats another animal is called a predator. The animal that gets eaten is called prey.

Food chains

One of the best ways to show feeding relationships is in a food chain.

A food chain is a diagram that shows the feeding relationships between different living things in a particular environment.

It shows the flow of energy between organisms.

Energy is used for

movement, chemical reactions maintenance of body temperature growth and repair of tissue

When an animal eats a plant, energy is transferred from the plant to the animal (the primary consumer).

When the primary consumer is eaten by a second animal (the secondary consumer) energy is again transferred and so on.

Grass rabbit fox

The arrows indicate the direction of energy flow.

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Make their own food (e.g. a green plant) by carrying out photosynthesis.

Feed on other organisms, they can be:

Herbivores -plant eatersCarnivores -meat eatersOmnivores -eat plants and animals

National 5 Unit 3.1 and 3.4 Ecosystems and Energy in Ecosystems Pupil Course NotesA food chain does not give you the complete information on the feeding relationships of an organism as producers generally are eaten by more than one consumer, which in turn is preyed on by several different predators.

An ecosystem really contains many interconnecting food chains. These can be shown in a food web.

Using the food web above complete the following table.

Producers Primary consumers Secondary consumers

All food webs are delicately balanced.

A change in the number of one type of organism can have an effect on the number of every other plant or animal in the food web.

Using the information in the food web above answer the following questions.

1. What would happen to the number of caterpillars if all the rabbits died? Explain why?________________________________________________________________

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National 5 Unit 3.1 and 3.4 Ecosystems and Energy in Ecosystems Pupil Course Notes2. What would happen to the number of rabbits if the weasels died? Explain

why?

________________________________________________________________

Energy Loss

Energy is lost at each link in the food chain.

-some energy is converted to heat-some energy is used for movement-some energy remains in undigested material e.g.

bones

1000kJ 100kJ 10kJ 1kJplant plankton animal plankton mackerel human

Only 10% of the energy is passed on at each transfer. 90% is lost.

The longer the food chain the more energy is lost.

Ecosystem research taskChoose one ecosystems to research.Describe the habitat present and give examples of the populations that could be found living there.

Ecosystem name -

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10% 10% 10%

90%%

90%90%

National 5 Unit 3.1 and 3.4 Ecosystems and Energy in Ecosystems Pupil Course Notes

Pyramid of Numbers

In general, the producers are found to be the most numerous, followed by the primary consumer and so on along the chain.

This relationship takes the form of a pyramid because the energy loss at each link in the food chain limits the quantity of living matter that can be supported at the next level; also the final consumer tends to be larger in body size than the one below it and so on. The size of the area of the pyramid represents the number of organisms (bigger area, more organisms).

for example: a sparrow hawk will eat 2 thrushes in a day to survive.a thrush will eat 20 snails a day.snails feed on large quantities of green plants.

Therefore, to support just ONE Sparrow Hawk for one week you need:

In some food chains, the producer is a single large plant and the pyramid takes a different form. This is caused by one, large producer such as a tree feeding many primary consumers.

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This is a diagram used to represent the total number of organisms at each stage in the food chain.

Organism Number Requiredsparrow

hawk 1

thrush1 (sparrow hawk) x 2 (number of thrush eaten by each sparrow hawk) x 7 (number of days) = ...

…...

snails….. (thrush) x ….. (number of snails eaten by

each thrush) x 7 = ……...

National 5 Unit 3.1 and 3.4 Ecosystems and Energy in Ecosystems Pupil Course Notes

Pyramid of Energy

NUTRIENT CYCLES

Nutrients are chemical substances needed by living things to stay alive and grow.

When an organism dies, the chemicals present in its dead body (and in wastes produced during its lifetime) are released back into the ecosystem by the action of decomposers (bacteria and fungi).

They can then be used by other organisms in the ecosystem i.e. recycled.

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producer(such as tree)

10 Kcal/m2/year

100 Kcal/m2/year

1000 Kcal/m2/year

10000 Kcal/m2/year

This is used to represent the total energy at each stage in the food chain.

National 5 Unit 3.1 and 3.4 Ecosystems and Energy in Ecosystems Pupil Course Notes

Niche

A niche is the role occupied by an organism within a community.

It relates to the resources in its ecosystem such as light and nutrient availability and its interactions with other organisms in the community. It involves competition, and predation and the conditions it can tolerate such as temperature.

Similar species will occupy similar niches. For example, red squirrels and grey squirrels are two different species. They occupy similar but slightly different niches.

Describe the niche of the fox in this food web; account for every arrow connected with the fox and add any additional information you may know.

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The arrows in a food chain or food web indicate the direction of energy flow

In this food web, the niche of the frog is that of a consumer of crickets and the prey of snakes and owls.

In addition frogs live in or near water.

The eggs (frog spawn) laid by the frogs can provide an additional food source in this food web.

National 5 Unit 3.1 and 3.4 Ecosystems and Energy in Ecosystems Pupil Course Notes

Research task

Investigate the niche of one of the following organisms;

Scottish wild catRed deerScottish crossbillBadgerPtarmiganSea eagle Capercaillie

Organism 1 name –

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National 5 Unit 3.1 and 3.4 Ecosystems and Energy in Ecosystems Pupil Course Notes

Competition

Competition occurs naturally between living organisms which co-exist in the same environment. For example, animals compete over water supplies, food, mates, and other biological resources.

Competition in ecosystems can occur when resources are in short supply.

There are two types of competition Interspecific and intraspecific competition. These are the driving forces of adaptation, and ultimately of evolution. Competition serves as a mechanism for determining the best-suited group.

Interspecific competition occurs when organisms of different species compete for one or a few of the resources they require

Intraspecific competition occurs between organisms of the same species and is for all the resources they require. Therefore, intraspecific competition is more intense than interspecific competition.

Examples

Interspecific competition

Red and grey squirrel

Although two types of squirrel species can be seen in Scotland today, this wasn't always the case. The red squirrel is classed as a native species to the UK.  Red squirrels were once the only squirrel species in Britain and were widely distributed.    

The grey squirrel is classed as an invasive non-native species in the UK.  Grey squirrels have been introduced to the UK at various locations since the 19th Century. 

The spread of grey squirrels is the main threat to red squirrel survival and the main reason for their catastrophic decline in Britain.  Grey squirrels compete more successfully than red squirrels for food and habitat, they are larger and more robust, and can digest seeds with high tannin content, such as acorns, more efficiently.  This means grey squirrels can access a more abundant food supply than red squirrels.  Duncanrig Secondary 2017 Page 12 of 14

National 5 Unit 3.1 and 3.4 Ecosystems and Energy in Ecosystems Pupil Course NotesGrey squirrels can also carry squirrel pox virus (SQPV), which causes disease and death in red squirrels without causing any symptoms in the grey carriers.

As a result, the arrival of grey squirrels in an area occupied by red squirrels tends to cause reduced red squirrel breeding and survival rates, leading to a gradual decline in their numbers.  

Rainbow and brown trout

Rainbow trout were successfully introduced here from western North America in 1885. They were released into rivers to provide fish for sport and also sent to breed on fish farms.

The rainbow trout are more aggressive than the native brown trout and have a more voracious appetite. As a result, they grow faster than the native brown and can out compete it for both food and habitat.

Example

Intraspecific competition

Plants

Plants growing in the same habitat compete with one another for factors such as light, water and soil nutrients if any one of these is in short supply.Plants of the same species have exactly the same growth requirements. When grown together, they will be in direct competition with one another if any resource is limiting and this competition will be intense.

The experiment shown was set up to investigate the effect of density on germinating cress seeds.

Container A with only 100 seeds represents low density of planting; container B with 500 seeds represents high density.

After 5 days, almost all the seeds in A are found to have successfully germinated and grown into healthy seedlings.

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National 5 Unit 3.1 and 3.4 Ecosystems and Energy in Ecosystems Pupil Course Notes Although most of the seeds in B also germinate, many fail to grow into healthy plants and are yellow and sickly. Of the seedlings that do germinate successfully, most are found to be smaller than those grown in A.

In the space below explain the results of this experiment.

______________________________________________________________

Animals

Individuals may compete over mates, water, territory or food energy sources. Intraspecific competition is an important factor limiting the population size of many species.

If members of the same species are competing for limited resources, then each individual would receive fewer resources when the population size of intraspecific competitors increases. Fewer resources per individual will

decrease the growth rates of individuals, increase the chance that individuals die of starvation, decrease the number of offspring that a female can produce.

Thus, as population density increases, there will be a resultant decrease in population growth rate.

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