Ecology and the Environment

Section 4: Ecology and the environment a) The organism in the environment Students will be assessed on their ability to: 4.1 understand the terms population, community, habitat and ecosystem 4.2 recall the use of quadrats to estimate the population size of an organism in two different areas 4.3 describe the use of quadrats as a technique for sampling the distribution of organisms in their habitats. b) Feeding relationships Students will be assessed on their ability to: 4.4 recall the names given to different trophic levels to include producers, primary, secondary and tertiary consumers and decomposers 4.5 understand the concepts of food chains, food webs, pyramids of number, pyramids of biomass and pyramids of energy transfer 4.6 understand the transfer of substances and of energy along a food chain 4.7 explain why about only 10% of energy is transferred from one trophic level to the next. Key wordsProducer Consumer PrimarySecondary Tertiary PyramidsNumbers Biomass Energy

February 10, 2015

How can we use this quadrat to learn about the type of plants and the distribution?

animation

Food chains

• http://www.youtube.com/watch?v=TE6wqG4nb3M

Consumers can be grouped into different types:

CarnivoresThese consumers eat other consumers. They eat animals.

Herbivores These consumers eat producers. This means plants and possibly bacteria.

OmnivoresThese consumers eat other consumers and producers. They eat animals and plants. Most humans are omnivores.

Feeding types

What is the food chain in this habitat?

Copy the food chain and add the following labels.Producer Primary consumer Tertiary consumer Herbivore Secondary consumer Sun Carnivore

Copy the food chains and then label the rank of the consumers

blue tit

chiffchaff

aphid

moth larva

vole

stoat

owl

spider

ladybird

plants

Questions

1. Explain what the arrows in the food chain represent?

2. Not all energy is passed from one level to the next. Explain how it can be lost along the way.

Thinking time

• How many zebra do you think a lion eats in a month?

• How many grass plants do you think a zebra eats in a month?

Pyramid of numbers

• The arrows in a food chain show the flow of energy

• In a day, one crab would eat more than one mussel, and each mussel would eat more than one seaweed plant

Seaweed Mussels Crab• If you count the number of crabs, mussels and seaweed

plants you can draw a scale diagram. You can represent the size of a population by a bar

SEAWEEDSEAWEED

MUSSELSMUSSELS

CRABSCRABS

Draw pyramids of numbers using a scale for the following food chains

Tertiary 1 cat 100 fleasConsumer

Secondary 5 thrushes 5 robinsconsumer

Primary 20 slugs 100 caterpillarsconsumer

Producer 5 cabbages 1 oak tree

QuestionsQuestions

Draw the following pyramids of numbers to scale on graph paper.15 nettle plants 12 caterpillars 1 robin5 rose bushes 100 greenfly 25 ladybirds50 lettuce 20 slugs 1 thrush

Pyramid of numbers

• The size of each block represents the number of organisms

• Each level in the pyramid represents a trophic level

• Has its shape because there is less energy available as you go up the trophic levels therefore there are fewer organisms at each level

InterdependenceMake 5 correct sentences by choosing a word or Make 5 correct sentences by choosing a word or

phrase from each columnphrase from each column

A food chainA food webA pyramid of numbers

shows how food chainsenergy flowsmany

organisms

depend on each other for energylink to each otherfrom one organism to anotherorganisms there are at each stage in the food chain

You have 30 seconds to talk through this diagram

• Plants utilise only about 1 percent of the energy the earth receives from the sun.

• Where does the other energy go? , make a list where you think it goes.

Starter

Efficiency

Energy Transfers

• Energy comes into an ecosystem from sunlight and is fixed by plants by photosynthesis.

• There is another process called chemosynthesis (involves bacteria).

• The energy stored in the plants can be passed onto other organisms along food chains.

• Each link in a food chain is called a trophic level.

• During this process a lot of energy is lost – dissipation.

Key Points

• Plants are not very efficient at capturing energy from the sun.

• The products of photosynthesis can be used to increase the biomass of plants.

• This biomass can be eaten by herbivores

• Most of the biomass eaten by the primary consumer is used in respiration to– Move– Maintain body temperature

Key points

• Some biomass will be undigested and pass through the animal without being used.

• The only biomass available to consumers at the next level is that that is used for growth.

• This process happens at each trophic level in the pyramids of biomass– There is less and less biomass available at each

subsequent level.

• The energy in all ecosystems originally come from the sun.

• Most of the sunlight that falls on leaves is not absorbed and used.

• Some is reflected by the leafs surface.• Some passes through the leaf.• Only part of the light is useful and can be

absorbed by the chlorophyll.

You have 30 seconds to talk through this diagram

• Transfer of food energy from producers to primary consumers also involves wastage.

• For every 100g of plant material available only about 10g ends up as part of the herbivores body.

• Reasons for 90% energy wastage:• Some food may not be eaten.• Some food passes through the body of the

herbivore without being digested.

Energy flow through consumers

• A lot of food is used in respiration.

• Similar losses in food energy occur between other trophic levels.

• Some carnivores are able to achieve a 20% conversion effeincey. So for every 100g of herbivore that they eat 20g ends up as part of their body.

Pyramids of biomass

• The mass of living things at each stage in the food chain

• Measured in dry mass• The size of each box

represents the mass of each kind of organism

• Always makes a pyramid shape (a pyramid of numbers can be upside down)

Difficulties with food pyramids

• Many organisms eat lots of things• Could be at different levels

• Calculating dry mass involves killing and drying organisms

Numbers or Biomass?Numbers or Biomass?

PlenaryPlenary

• Pyramids of numbers tell us the number of predators-prey at each feeding level, however, they do not give a very good indication of the energy transferred.

• Can you think of a better way of measuring how much energy is transferred between stages in the food chains? What other quantity could we use in a pyramid instead of number of animals/plants?

Food chains

• http://www.youtube.com/watch?v=TE6wqG4nb3M

1. Give three ways in which fish are adapted to live underwater.

2. Explain how a polar bear is adapted to its environment.

3. Explain how a camel is adapted to its environment.

Extension: How is a tree adapted to its environment?

Life on land - Mammals

What features does a mammal have?

Warm bloodFur

LungsGives birth to live young

Produces milk

What adaptations do you think mammals have to be able to

survive in:1. Desert conditions2. Arctic conditions

Life in water - Fish

How is a fish adapted to live in

water?

• Think about its shape, how it moves through the water.

• How does it get oxygen?

• What protects it from skin infections?

Adaptation and competition

• Animals, plants and other organisms are adapted to their environment.

• Where there are limited resources, individuals must compete for resources.

• Individuals that are unable to compete will die out and not pass their genes onto the next generation.

Exponential growth

• When resources are unlimited, the population will grow

The population will double in every period of time

Time

Num

ber

of in

divi

dual

s

T1 T2 T3 T4

10

100

1000

1 ???

Limited resources

Competition between individuals

R.I.P

• The population is limited by the amount of resources

• Strongest individuals survive to the next generation

Competing for resources

List the resources that each of the following compete

for:

• Animals

• Plants

When limits are reachedN

umbe

r of

indi

vidu

als

T1 T2 T3 T410

1001000

1 ???

Num

ber

of in

divi

dual

sT1 T2 T3 T4

10100

1000

1 ???

Population CrashPopulation growth limited

Lynx and Snowshoe Hare Pop. Data (n x 1000)

Year Lynx Hare1845 30 201850 10 801855 35 821860 10 151865 75 1301870 55 1001875 20 151880 84 1351885 20 401890 58 821895 63 651900 5 401905 52 101910 12 851915 62 5

Plot a graph of year against population. Plot lynx in one colour and hare in another.

1. What is the relationship between number of lynx and number of hare?

2. Explain why this happens.3. Extension: Which is the predator?

How can you tell from the graph?

Lynx and Snowshoe Hare Pop. Data (n x 1000)

Year Lynx Hare1845 30 201850 10 801855 35 821860 10 151865 75 1301870 55 1001875 20 151880 84 1351885 20 401890 58 821895 63 651900 5 401905 52 101910 12 851915 62 5

Plot a graph of year against population. Plot lynx in one colour and hare in another.

1. What is the relationship between number of lynx and number of hare?

2. Explain why this happens.3. Extension: Which is the predator?

How can you tell from the graph?