Biology Energy In Ecosystems 1 Roles of Organisms

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 Rooted underwater photosynthesis 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

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

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 CONSUMER Water flea ORGANISM/S EATEN Algae Caddis fly larvae Pondweed / Algae Snail Pondweed / Algae Stickleback Water beetle Tadpole Perch Pike Water flea / Caddis fly larvae / tadpole Pondweed Tadpole / Water beetle Perch / Water Beetle / Stickle back / Tadpole

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

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

4. Pyramids • 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

Pyramid of numbers - problems 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 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) • No Protein = No Growth (All hormones, enzymes, antibodies & cell membranes are made from proteins) • Limited Supply In Nature = Recycling • The only form in which plants utilise nitrogen is nitrates

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

Word Definition Decomposers Nitrifying Bacteria microorganisms in the soil responsible for breaking down wastes & returning nutrients to the soil 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

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

• 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