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20/04/23
Understanding Our Understanding Our EnvironmentEnvironment
W Richards
The Weald School
(OCR)
20/04/23
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!
20/04/23
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
20/04/23
ClassificationClassificationThe world is populated by millions of different species of animals and plants…
20/04/23
Classifying organismsClassifying organismsAll organisms are classified into groups. For example:
Organism
Plants Animals
Vertebrates Invertebrates
Reptiles FishBirds Mammals
Amphibians
20/04/23
Classification DifficultiesClassification DifficultiesSome organisms do not fit into an obvious category. For example...
MushroomsArchaeopteryx
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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
20/04/23
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
20/04/23
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
20/04/23
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
20/04/23
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!
20/04/23
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
20/04/23
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
20/04/23
AdaptationAdaptation
Organisms are ADAPTED to the habitat they live in. In other words, they have special features that help them to survive. Some examples:
20/04/23
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.
20/04/23
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.
20/04/23
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”
20/04/23
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.
20/04/23
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
20/04/23
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
20/04/23
Evidence for EvolutionEvidence for Evolution
The Grand Canyon
Fossil records
“Missing links”
Humans with tails
20/04/23
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
20/04/23
OzoneOzone
Diagram showing the quantity of ozone in different parts of the southern hemisphere
Global production of CFCs over the last 60 years
20/04/23
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
20/04/23
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
20/04/23
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:
20/04/23
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:
20/04/23
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