ENERGY AND NUTRIENT TRANSFER

Why are organisms dependent on each other?Where does energy come from and where does it go?What happens to waste materials?Is decay a waste of resources?

Energy Flowo The sun is the principle source of

energy input of biological systemso Two main types of energy

• Light energy (solar)• Heat energy

o Photosynthetic plants and some bacteria trap light energy and convert it into chemical energy.

o This chemical energy is then available to other organisms.

Energy Flow through an ecosystem

o Energy is transferred from one organism to another.

o This is shown in food chains and food webs

o Energy given out by organisms is lost to the environment.

Light energy available to the planto 100% solar energy reaching the

Eartho Some solar energy

• Reflected by clouds or dust in the air

• Reflected by plants• Does not fall on leaves• Wrong wavelength for

chlorophyll to trap• Pass through leaves

Definitionso Herbivore:

• An animal that eats grass and other green plants in a food chain;

o Carnivore: • A flesh-eating animal.

o Prey: • An animal hunted or caught for food

o Predator: • An organism that lives by preying

on other organisms.

Definitionso Primary consumer:

• An animal that eats grass and other green plants in a food chain; an herbivore.

o Secondary consumer: • An animal that feeds on smaller

plant-eating animals in a food chain. o tertiary consumer:

• An animal that feeds on secondary consumers in a food chain.

definition

o Population: • All the organisms of the same

species living in the same place at the same time.

Learning Outcomeso use data to construct and interpret pyramids

of numbers and biomass and understand that food chains and food webs show the transfer of energy between organisms.

o know that radiation from the Sun is the source of energy for all ecosystems/communities of living organisms and that green plants capture a small percentage of the solar energy which reaches them.

o understand that at each stage in the food chain energy is lost in waste materials, in repair and maintenance of cells and as heat during respiration.

Energy Flow – Progress question

o What is the source of energy for ecosystems?

o How does energy from that source become available to a predator like a tiger?

Food Chains

o Colour in the food chain on the worksheet• Complete questions 1,2,3,7,9

• Finish off questions for prep.

Food Chains

o Food chains are one way of showing how organisms interact.

o For example:

Grass Rabbit Fox

o The arrows represent the transfer of energy between organisms.

Food Chainso All food chains start with plants, they

use sunlight during photosynthesis to build up food (energy) stores, these are then passed on to animals.

o Important terms:• Plants are producers because

they make their own food• Animals are consumers because

they eat food to obtain energy.

Consumers and Decomposerso There are 3 types of consumer

• Herbivores eat plants• Carnivores eat other animals• Omnivores eat plants and

animals

o Organisms that breakdown dead plants and animals are called decomposers• e.g. fungi, bacteria and worms

Producer primary secondary tertiary consumer consumer

consumer

o Each feeding level is known as a trophic level

Energy Loss in a food chain

o Energy is lost at each level in the food chain • Respiration (lost as heat)• Used up in movement• Maintaining constant body

temperature• Faeces and urine (lost as heat)• Some material not being eaten

by the consumer

Plants are at the start of every food chain

Food chains show the flow of energy through an ecosystem

Energy loss in a food chaino 90% of energy is lost at each

level in a food chain

Tree aphid ladybird little bird big bird100 10 1 0.1 0.01Energy units

o In long food chains, very little energy is left for the top carnivore

o In short food chain, less energy is lost.

Shortening the food chain

o The fewer the trophic levels, the less food energy is lost so the more food is available to consumers.

Shortening the food chaino Energy transfer between producers

and consumers is inefficient because:• Some plant material is not digested

and passes out of the herbivore body as faeces

• The herbivore uses energy to stay alive

• When the herbivore dies, its body represents “locked up” energy, which transfers to decomposers

Eating meat is therefore wasteful in terms of food energy.

Pupil Activity

o Practice question on food chains and energy flow.

Food Webs

o If food chains in a habitat are linked, they form a FOOD WEB.

Food web for a single tree

Which are the primary and secondary consumers in this photograph?

Changing Food Webs

o Look at the two examples of ecosystems given.

o For each question give a suggestion of what might happen to the populations of organisms and explain why you think this.

Food Webs

o Food webs are easily unbalanced if one population of organisms in the web disappears due to:• Over-predation or hunting• Disease• Pollution• Use of pesticides• Lack of food• emigration

Learning Outcome

o describe and interpret pyramids of biomass, numbers and energy

Food Pyramidso Each trophic level is represented

by a horizontal baro The width of the bar represents

• The number of organisms• The amount of biomass• The amount of energy

o The base of the pyramid represents the producer

o The second level is the primary consumer, etc

Pyramids of numbero This represents the relative number

of each type of organism at each trophic level.

o Draw a pyramid of number for each of the three food chains below:

Grass antelope lion

Oak tree caterpillar blue tits owl fleas

Rose bush aphid ladybird blackbird

Pyramids of Biomasso This represents the amount of living

material (biomass) at each level.o Draw a pyramid of biomass for each of

the three food chains below:

Grass antelope lion

Oak tree caterpillar blue tits owl fleas

Rose bush aphid ladybird blackbird

Pyramid of Energyo Represents the amount of energy

available at each level in the food chain.

o Energy is measured over a period of time.

o Draw a pyramid of energy for each of the three food chains below:

Grass antelope lion

Oak tree caterpillar blue tits owl fleas

Rose bush aphid ladybird blackbird

Practice Questions on Pyramids

o Collect • a question sheet• A sheet of A4 paper• Graph paper

Food Chains and energyo Short food chains are more efficient

than long food chains at supplying energy to the top consumer.

(Units of energy)

Maize cow human 100 10 1

Maize human100 10

Food Chains and energy

o Ten times more energy is available to humans in the second food chain.

o Farmers try to maximise meat production by• Restricting animal movement• Keeping animals warm

o This means less energy is wasted by the animals.

Nutrient Cycling

Learning outcomeso know that materials decay because

they are broken down by bacteria and fungi which use these digested materials for growth and other life processes so continually recycling materials. In a stable community, the processes which remove materials are balanced by processes which return materials.

o know that when plants and animals die, microbes feed on their bodies bringing about decay. These microbes respire and release carbon dioxide into the atmosphere.

Nutrient Cyclingo Living things remove materials from

the environment for growth and other processes.

o These materials are returned to the environment in waste materials or when living things die and decay.

o We say that they are recycled.o This decay is caused by organisms:

• Detritivores e.g. worms• Decomposers e.g. bacteria and

fungi

o Bacteria and fungi release enzymes which are adapted to breakdown organic material; therefore they have no effect on man-made household waste.

o Humans use micro-organisms:• At sewage works to break down

waste from humans• In compost heaps to break down

waste plant materials.

o For decay to be successful the following conditions are required.• Oxygen – for respiration• Warmth – bacteria will reproduce

more quickly, increasing the number of decomposers.

• Water For normal life processes To secrete solutions of digestive

enzymes To absorb the products of

digestion

o Matter is recycled not destroyed between living and non-living parts of the environment.

o Most living matter is made up of just 6 elements; carbon, hydrogen, oxygen, nitrogen, phosphorous and sulphur.

o Living things need these elements to make proteins, carbohydrates and fats.

Learning Outcomes

o know that carbon is constantly recycled in nature by the carbon cycle via photosynthesis, food chains and respiration.

o understand what happens when decay is prevented. Burning fossil fuels releases carbon dioxide and substances which contribute towards acid rain.

Fossil fuels

Coal, oil, gas, peat

Combustion (burning)

Carbon dioxideIn the air (CO2)

photosynthesis

respiration

Carbon compounds in plants

Carbon compunds in animals

decay

feeding

The carbon cycle

Fossil Fuels

• The combustion of fossil fuels releases gases into the atmosphere.

• These include– Carbon dioxide (CO2)

• This is the main greenhouse gas

– Sulphur dioxide (SO2)– Nitrous oxides (NOx)

• SO2 and NOx dissolve in rain water to form nitric acid and sulphuric acid to form acid rain

Acid Rain• Acid rain has severe effects on the

environment and individual ecosystems within it.

• The acid rain will kill trees and damage buildings made from limestone.

• The water will also make lakes and rivers more acidic. This will kill fish and other aquatic life.

• The increased acidity of the water also allows aluminium salts to dissolve more easily. The aluminium ions are very poisonous to fish and birds.

Nitrogen Cycle

Learning Outcomes

• know that nitrogen is also recycled through the activity of soil bacteria and fungi acting as decomposers, converting proteins and urea into ammonia. This is converted to nitrates which are taken up by plant roots and used to make new protein.

• investigate the action of urease on urea.

• Plants and animals need nitrogen to make proteins, but they cannot get nitrogen directly from the air because, as a gas, nitrogen is fairly unreactive.

• Plants are able to take up nitrogen compounds such as nitrates and ammonium salts from the soil.

Nitrogen fixation

• Making nitrogen compounds from nitrogen in the air is called nitrogen fixation.

Nitrogen fixation happens in three ways:

• The energy in lightning splits nitrogen molecules into individual nitrogen atoms. These react with oxygen to form nitrogen oxides. Nitrogen oxides are washed to the ground by rain, where they form nitrates in the soil.

Nitrogen fixation happens in three ways:

• Nitrogen-fixing bacteria found in the soil and in the root nodules of leguminous plants, such as peas, beans and clover, fix nitrogen gas into nitrogen compounds. – .

Nitrogen fixation happens in three ways:

• The Haber process is used by industry to produce ammonia from nitrogen and hydrogen. Ammonia is used to make nitrogen compounds that are used as fertiliser by farmers

• Nitrogen compounds in living things are returned to the soil through: – excretion and egestion by animals – the decay of dead plants and

animals by putrefying bacteria and fungi

• Denitrifying bacteria present in soil break down nitrogen compounds and release nitrogen gas into the air.

Nitrogen Fixation

Feeding

Putrefaction and decay (nitrification)

Putrefaction and decay(nitrification)

denitrification

The bacteria

• The nitrogen cycle involves four different types of bacteria– Putrefying – Nitrifying– Denitrifying– Nitrogen-fixing

• In an exam, you will need to be able to describe the roles of these bacteria

Urease and decay

• The enzyme urease can cause decay by breaking down urea to form ammonia and carbon dioxide

• As ammonia is alkaline it can be detected using universal indicator paper

• In an experiment the action of urease can be investigated using universal indicator paper