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18/04/23
AQA Biology Unit 1AQA Biology Unit 1
W Richards
This PowerPoint supports sections B1.4, B1.5, B1.6, B1.7 and B1.8 of the 2011 AQA Biology
Unit 1 module
18/04/23
AdaptationAdaptation
Organisms are ADAPTED to the habitat they live in. In other words, they have special features that help them to survive. Some examples:
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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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Extinct SpeciesExtinct Species
Dodo
Sabre-toothed tigers and mammoths
What factors have caused these species to become extinct?
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Endangered SpeciesEndangered Species
What factors have caused these species to become endangered?
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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:
18/04/23Measuring Environmental Measuring Environmental ChangesChanges
Recording temperature
changes
Measuring rainfall Recording oxygen levels
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BiomassBiomassPlants use glucose from photosynthesis to produce starch and cellulose. This plant material is called “biomass”:
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Food chainsFood chainsA food chain shows where the biomass or 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
through photosynthesis
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Pyramids of biomassPyramids of biomassIn this food chain we can see that the mass of organisms in each stage is less than in the previous stage:
Cabbage
Rabbit Stoat Fox
We can draw a “Pyramid of Biomass” to show this pattern:
Mass of cabbages
Mass of rabbits
Mass of stoats
Mass of foxes
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Energy flow in a food chainEnergy flow in a food chainConsider the energy flow in this food chain:
Cabbage
Rabbit Stoat Fox
100% 10% 1% 0.1%
Clearly, not all of the ___’s energy that becomes stored in the _______ will end up in the fox. Only around ______ is passed on to the next stage in each food chain.
Energy is lost to the surroundings at each stage because of a number of reasons:
1) Each organism has to ____, keep warm etc
2) Energy is lost through faeces (______)
Words – 10%, move, sun, waste, cabbage
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Recycling ourselvesRecycling ourselves
Microbes are the key to this – they break down waste and dead bodies so that the products can be used by plants for growth. Microbes work best in warm, moist conditions where there is plenty of oxygen.
Eating
Waste
Death
Broken
down
Absorption
18/04/23The Carbon The Carbon CycleCycle
CO2 in air 1. CO2 is taken
in by plants and algae for photosynthesis and turned into carbohydrates, fats and proteins
2. Plants and algae release CO2 through respiration
3. The carbon taken in by plants is then eaten by animals and the animals that eat them
5. Animals (and plants) die and their remains are fed on by microbes and detritus feeders
6. These microbes also release CO2 through respiration 4. Animals
release CO2 through respiration
Burning fossil fuels also releases CO2
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VariationVariation“Variation” is the name given to differences between individuals of the SAME species.
Variation is due to GENETIC or ENVIRONMENTAL causes. For example, consider dogs:
1) Ways in which they are the same:
2) Ways in which they are different:
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Sexual ReproductionSexual Reproduction
The human egg and sperm cell contain 23 chromosomes each.
When fertilisation happens the egg and sperm fuse together to make a single cell. This cell has 46 chromosomes (23 pairs) and continues to grow.
18/04/23Sexual vs. Asexual Sexual vs. Asexual reproductionreproduction
Sexual reproduction:•2 parents are needed
•Offspring will have “pairs” of chromosomes
•This will cause genetic variation
Asexual reproduction:•Only 1 parent needed
•Offspring are GENETICALLY IDENTICAL to parent (“clones”)
“Snuppy” – the first cloned
dog (Aug 05)
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Cloning PlantsCloning PlantsPlants can reproduce ASEXUALLY. The offspring are genetically ________ to the parent plant and are called _________. Two examples:
1) This spider plant has grown a rooting side branch (“stolon”) which will eventually become __________.
2) A gardener has taken cuttings of this plant (which probably has good characteristics) and is growing them in a ____ atmosphere until the ____ develop.
Words – clones, damp, independent, roots, identical
18/04/23Cloning Plants by tissue Cloning Plants by tissue cultureculture
1) Scrape off a few cells from the desired plant
2) Place the scrapings in hormones and nutrients
3) 2 weeks later you should have lots of genetically identical plants
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Cloning AnimalsCloning AnimalsMethod 1 – “Embryo transplants”
A developing embryo is “split” before the cells specialise and the identical embryos are implanted into host
mothers.
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Uses of Genetic EngineeringUses of Genetic Engineering
With genetic engineering I can produce milk that contains:• Extra protein• Lower levels of cholesterol• Human antibodies
Genetic engineering can also be used to grow bigger crop yields and to develop plants that are resistant to pesticides and herbicides.
18/04/23Genetic engineering - Genetic engineering - InsulinInsulin
Step 1: Using enzymes “cut out” the part of the human chromosome that is responsible for producing insulin.
Step 2: Using another enzyme cut open a ring of bacterial DNA. Other enzymes are then used to insert the piece of human DNA into it.
Step 3: Place it into a bacterium which will start to divide rapidly. As it divides it will replicate and make millions of them, each with the instruction to produce insulin. Commercial quantities of insulin can then be produced.
18/04/23
EvolutionEvolution
Charles Darwin (1809-1882)
Evolution is the theory of slow, continual change of organisms over a very long time. All living
things on the Earth have supposedly developed from the
first simple life forms that arrived 3,000,000,000 years
ago.
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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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EvolutionEvolutionThe main evidence for my theory
came from fossil records. However, these records didn’t exist when I came up with my theory. Also, there was little evidence about how species evolved so few people believed my ideas.
These days scientists understand that the process that causes evolution is called “Natural selection” and it works like this:
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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”
18/04/23
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.
This slideshow has been made freely available on the TES Resources website.
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