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Understanding Our Understanding Our EnvironmentEnvironment

W Richards

The Weald School

(OCR)

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Taking Population SamplesTaking Population SamplesUsing different “sampling techniques” we can measure

the population in a given area, for example:

Using traps Taking animal samples

Help!

Taking samples using

quadrats

Help!

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EcosystemsEcosystemsAn “Ecosystem” is a physical environment with a particular set of organisms living in it. They can be natural, e.g. a woodland, or artificial, e.g. a greenhouse.

A natural ecosystem with high “biodiversity”

An artifical ecosystem – biodiversity will be controlled and low

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ClassificationClassificationThe world is populated by millions of different species of animals and plants…

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Classifying organismsClassifying organismsAll organisms are classified into groups. For example:

Organism

Plants Animals

Vertebrates Invertebrates

Reptiles FishBirds Mammals

Amphibians

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Classification DifficultiesClassification DifficultiesSome organisms do not fit into an obvious category. For example...

MushroomsArchaeopteryx

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VariationVariation“Species” means “a group of similar organisms”, e.g. dogs:

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Reproduction between speciesReproduction between species

Liger

GeepZebroid

Mule

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Similar SpeciesSimilar Species

What is a common ancestor?

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PhotosynthesisPhotosynthesis

PHOTOSYNTHESIS is when a plant makes its own food.

Photosynthesis USES:

Carbon dioxide

Water

Energy (from the sun)

Photosynthesis PRODUCES:

Oxygen

Glucose

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PhotosynthesisPhotosynthesis

Travels up from the roots

WATER

CARBON DIOXIDEEnters the leaf through small holes on the underneath

SUNLIGHTGives the plant energy CHLOROPHY

LL The green stuff where the chemical reactions happen

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Photosynthesis EquationsPhotosynthesis Equations

Carbon dioxide + _____ glucose + _____

6CO2 + 6H20 C6H12O6 + 6O2

Sunlight

Chlorophyll

Sunlight

Chlorophyll

The GLUCOSE produced by photosynthesis is used by the plant for _______ (through ____________). It is stored in the plant as ___________.

Words – respiration, starch, water, oxygen, energy

20/04/23Factors Affecting Factors Affecting PhotosynthesisPhotosynthesis

1. Temperature – the best temperature is about 300C – anything above 400C will slow photosynthesis right down

2. CO2 – if there is more carbon dioxide photosynthesis will happen quicker

3. Light – if there is more light photosynthesis happens faster

20/04/23Drawing graphs of these Drawing graphs of these factorsfactors

1. Temperature

Photosynthesis is controlled by enzymes – these are destroyed at temperatures above 450C

2. Carbon dioxide

3. Light

Photosynthesis increases at first but is then limited by a lack of increase in temp or CO2

Photosynthesis increases at first but is then limited by a lack of increase in temp or light

20/04/23What is the glucose used What is the glucose used for?for?

1) Glucose (sugar) can be used to make long chains of insoluble starch…

Glucose molecules

Starch molecule

2) Glucose can be used to make cellulose for cell walls…

3) Glucose can be combined with nitrates to make proteins (for growth)…

4) Glucose can be converted into lipids (fats or oils) to store in seeds…

Glucose molecules

Glucose molecules

Glucose molecules

Cellulose

Proteins

Lipid structure

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RespirationRespiration

As well as photosynthesis, plants also undergo respiration:

The plant uses this energy to work, grow and reproduce.

Glucose + oxygen water + carbon dioxide + ENERGY

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CompetitionCompetitionAny living species competes with each other. They may compete for:

- Living space

- Food

- WaterIn addition to this competition, the population of a species can be affected by predators, disease, migration etc

Get off my land

Yum!

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Food chainsFood chainsA food chain shows where the energy goes in a food chain (in other words, “what gets eaten by what”):

Cabbage

Rabbit Stoat Fox

The arrows indicate where the energy is going

Plants convert the sun’s energy into

food

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Predators and PreyPredators and PreyA PREDATOR is an animal that hunts and eats another animal

The PREY is the animal it eats, for example…

Consider the populations of these two animals over time:

Hey! I ordered a

steak

Population of animal

Time

Rabbit

Fox

Prey Predator

20/04/23Interdependent Interdependent RelationshipsRelationships

1) Parasitic relationships

2) Mutualistic Relationships

Parasites take food from another living host _______. For example, if a human eats pork infected with bladderworm the worms attach themselves to the ___ wall and a young tapeworm grows, which _______ food from the gut.

Mutualistic relationships are when two organisms benefit from each other. For example, pea plants have nitrogen-fixing ______ which convert nitrogen into nitrates for plant _____. The bacteria benefit by taking sugars from the plant for ___________.

Words – growth, respiration, organism, gut, bacteria, absorbs

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AdaptationAdaptation

Organisms are ADAPTED to the habitat they live in. In other words, they have special features that help them to survive. Some examples:

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EvolutionEvolution

Charles Darwin (1809-1882)

Evolution is the slow, continual change of organisms over a

very long time. All living things on the Earth have developed

from the first simple life forms that arrived 3,000,000,000

years ago.

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EvolutionEvolutionMy key observations:1) All living things produce more

offspring than survive to adulthood

2) In spite of this, population sizes remain roughly constant

3) Variation exists among species4) Characteristics can be passed on

from one generation to the next.

These observations led me to the conclusion that species evolve over a along period of time by a mechanism called “Natural Selection”. The main evidence for this is from fossil records.

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Natural SelectionNatural Selection1) Each species shows variation:

2) There is competition within each species for food, living space, water, mates etc

4) These survivors will pass on their better genes to their offspring who will also show this beneficial variation.

Get off my land

Gutted!

Yum

3) The “better adapted” members of these species are more likely to survive – “Survival of the Fittest”

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Darwin vs LamarckDarwin vs LamarckDarwin wasn’t the first to come up with evolution – he was simply the one credited with explaining how it worked (i.e. Natural Selection). An earlier scientist called Lamarck explained evolution by different means:

Jean Baptiste Lamarck

(1744 - 1829

The giraffe has a long neck because it “stretches” its neck to reach the food, and these long necks are passed on to

their offspring. Organs which aren’t used will eventually

disappear.

20/04/23An example – the peppered An example – the peppered mothmoth

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A smaller example…A smaller example…Consider the four steps of natural selection in the example of some bacteria that has become resistant to penicillin:

1) Variation – some strains of bacteria are resistant and some aren’t.

2) Competition – The non-resistant bacteria are killed by the penicillin.

3) Survival of the fittest – the resistant bacteria survive.

4) Passing on of genes – the resistant bacteria reproduce and pass on their adaptations to their offspring.

Bacteria

Penicillin

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The “Evolution Tree”The “Evolution Tree”

Family Hominidae

(Great Apes)

Family Hylobatidae (Lesser Apes)

Subfamily Hominidae

Subfamily Ponginae

Tribe HominiTribe Panini

Tribe Gorillini

HumansChimpanzees

GorillasOrangutans

Gibbons

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Evidence for EvolutionEvidence for Evolution

The Grand Canyon

Fossil records

“Missing links”

Humans with tails

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Population and PollutionPopulation and Pollution

The human population is growing exponentially:

Population

Time

This has a number of effects on the environment:

Bigger population means…

Building – more

buildings needed

Land –less land and

water available

Waste –more waste needs to be disposed of

with more pollution

Quarrying and mining –

raw materials and sources of energy are

being used up

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OzoneOzone

Diagram showing the quantity of ozone in different parts of the southern hemisphere

Global production of CFCs over the last 60 years

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PollutionPollutionHumans pollute the Earth in a number of ways:

Water – with sewage, fertiliser or toxic chemicals

Air – with smoke or gases such as sulphur dioxide

Land – with toxic chemicals, pesticides and waste

NO, NO2

and CO

Acid rain

Power stations produce CO2, SO2 and NO2

Cars produce NO, NO2 and CO

These gases produce acid rain (which affects tress and buildings) and worsens the greenhouse effect

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The Greenhouse EffectThe Greenhouse EffectWe get heat from the sun:

A lot of this heat is _______ back into space.

However, most of it is kept inside the Earth by a layer of gases that prevent the heat escaping by _______ and then re-radiating it back again.This is called the _________ Effect. It has always been around, but is

currently being made worse due to:

1) Burning (releasing CO2)

2) __________ (removing trees that remove CO2)

3) Increased micro organism activity (from rotting ______)

4) Cattle and rice fields (they both produce _______)

These changes will cause GLOBAL WARMING and RISING SEA LEVELSWords – methane, radiated, absorbing, deforestation, waste, greenhouse

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Pollution IndicatorsPollution Indicators

Lichens in very clean air

Lichens in clean air

Lichens in slightly dirty air

Lichens can be used as air pollution indicators:

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Pollution IndicatorsPollution Indicators

In dirty water leeches and midges will survive

In average water more species (like the dragonfly and cranefly) will survive

In clean water a lot more species (like the mayfly and caddisfly) will survive

The quality of water can be monitored by looking at the species of insect in the water:

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Sustainable DevelopmentSustainable DevelopmentSustainable development is all about preserving the world

for tomorrow. There are three main strands:

1) Economic development

2) Social development

3) Environmental protection

Examples of sustainable development include:

1) Replanting trees after chopping them down

2) Limiting the number of fish allowed in a catch

3) Protecting endangered species

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Extinct SpeciesExtinct Species

Dodo

Sabre-toothed tigers and mammoths

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Endangered SpeciesEndangered Species

20/04/23Protecting Endangered Protecting Endangered SpeciesSpecies

Ways of protecting endangered species