Biology Energy In Ecosystems

1. Roles of Organisms in Food Chains/Webs A food chain is a relationship where one organism feeds on the previous one in the series and in turn provides food for the next one The niche of a species is the role it plays in an ecosystem Every food chain/web will begin with a producer- a green plant able to produce its own food by photosynthesis Rooted underwater producer Simple food chain example:

A primary consumer will eat the plant, energy is transferred from the plant to the animal A secondary consumer will eat the animal, energy is transferred from the first animal to the second animal A herbivore is an animal that only eats plants (producers) A carnivore will eat only other animals An omnivore will eat both plants and animals Small swimming herbivore (primary consumer) Carnivorous bird of prey Omnivore

Producer Primary consumer Secondary consumer 3. The arrows in a food chain show the direction of energy flow from one organism to another 2. Food Chains and Webs 2. Using the cards, come up with 4 different food chains.

2. Food Chains and Webs In ecosystems, many food chains interconnect to form a food web This is an example of a food web with over 20 food chains! Your teacher may now ask you to complete a food webs task

In your groups complete the food webs task using the table below & materials provided by your teacher CONSUMERORGANISM/S EATEN Water fleaAlgae Caddis fly larvaePondweed / Algae SnailPondweed / Algae SticklebackWater flea Water beetleWater flea / Caddis fly larvae / tadpole TadpolePondweed PerchTadpole / Water beetle PikePerch / Water Beetle / Stickle back / Tadpole

Lettuce Sparrowhawk Thrush Slug Rabbit Grass Fox Chaffinch Grain Dormouse Owl THINK!- What would happen to the number of sparrowhawks? 2. Food Chains and Webs

As energy flows from one trophic level to another in a food chain, energy is lost This energy is lost as: – Undigested waste – Movement90% of energy is lost – Heat only 10% of energy is passed on to the next level 3. Loss of energy from an Ecosystem 90% of energy lost

A pyramid of numbers shows the number of each organism at each stage in the food chain As you go up a pyramid of numbers, the size of the organisms increases & number of organisms decreases 4. Pyramids

This pyramid of numbers looks strange. This is because the producer is a large tree. Producers such as shrubs and bushes would have the same effect. Pyramid of numbers - problems

Pyramid of biomass Biomass is a measurement of the mass of all the living material present at each level in a food chain These pyramids may be irregular if the producer is consumed quickly by the primary consumer

Pyramid of Energy Pyramids of energy show the energy present at each level at a particular time and will always be higher at the bottom than the top

Pyramid of Energy Pyramids of energy always take a regular shape & are therefore the most accurate representation of what is happening in a food chain Energy is lost at each stage of a food chain, so decomposers fit into each level

5. The Nitrogen Cycle Essential Elements In Proteins (C, H, O and N) Essential Elements In Proteins (C, H, O and N) No Protein = No Growth (All hormones, enzymes, antibodies & cell membranes are made from proteins) No Protein = No Growth (All hormones, enzymes, antibodies & cell membranes are made from proteins) Limited Supply In Nature = Recycling Limited Supply In Nature = Recycling The only form in which plants utilise nitrogen is nitrates The only form in which plants utilise nitrogen is nitrates

Atmosphere (containing Nitrogen gas) = contains nitrogen in the form of protein ammonia nitrites nitrates Nitrifying bacteria Denitrifying bacteria Nitrogen- fixing bacteria in roots of legumes Decomposers

WordDefinition Decomposers microorganisms in the soil responsible for breaking down wastes & returning nutrients to the soil Nitrifying Bacteria convert ammonia into nitrite and then into nitrates Leguminous Plant a plant with root nodules packed full of nitrogen-fixing bacteria Nitrogen fixing bacteria converts nitrogen gas from the air into nitrates directly Denitrifying bacteria convert nitrates in the soil back into nitrogen gas

Leguminous plants

Plants that are not leguminous such as cereals cannot grow in nitrogen poor soils so nitrates will need to be added as a source of nitrogen Farmers do this by adding fertilisers This can help increase their yield (therefore make more money) Natural fertiliser is manure/slurry

Competition occurs when organisms require the same resources e.g. food, space, mates Plants compete for: light, water, space and soil nutrients Animals: compete for food, water, space and mates Sunflowers competing for:- Light, Water, Root Space, Soil Nutrients Rabbits competing for:- Food, Mates, Space 6. Competition

Competition for resources between the same species is called Intra-specific Competition Competition for resources between two different species is called Inter-specific Competition Intra-specific Competition is more intense than Inter-specific Competition because the organisms require EXACTLY the same resources Intense competition can result in organisms being forced to leave the ecosystem, or can lead to the death of the organisms Intraspecific Competition Interspecific Competition