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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

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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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Extreme environmentsExtreme environments

Deep sea volcanic

vents

Mountains

The Arctic

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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.

18/04/23Genes, Chromosomes and Genes, Chromosomes and DNADNA

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An example - Boy or Girl?An example - Boy or Girl?

X Y X

XX XYGirl Boy

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Father

Mother

Son

Daughter

Boy or Girl?Boy or Girl?

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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Cloning AnimalsCloning AnimalsMethod 2 - Fusion

Host mother

Clone

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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.

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Genetic EngineeringGenetic EngineeringYes No

Should genetic engineering

be allowed?

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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”

18/04/23An example – the peppered An example – the peppered mothmoth

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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.

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