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AQA Biology Unit 1
This PowerPoint supports sections B1.4, B1.5, B1.6, B1.7 and B1.8 of the 2011 AQA Biology Unit 1 module
W Richards

2. Adaptation
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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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7. Deep sea volcanic vents
Extreme environments
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Mountains
Deep sea volcanic vents
The Arctic

8. Competition
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Any living species competes with each other. They may compete for:
Get off my land
- Living space
- Food
- Water
In addition to this competition, the population of a species can be affected by predators, disease, migration etc
Yum!

9. Sabre-toothed tigers and mammoths
Extinct Species
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Sabre-toothed tigers and mammoths
What factors have caused these species to become extinct?
Dodo

10. Endangered Species
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What factors have caused these species to become endangered?

11. Pollution Indicators Lichens can be used as air pollution indicators:
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Lichens in very clean air
Lichens can be used as air pollution indicators:
Lichens in clean air
Lichens in slightly dirty air

12. Pollution Indicators
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In dirty water leeches and midges will survive
The quality of water can be monitored by looking at the species of insect in the water:
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

13. Measuring Environmental Changes
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Recording temperature changes
Recording oxygen levels
Measuring rainfall

14. Biomass
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Plants use glucose from photosynthesis to produce starch and cellulose. This plant material is called “biomass”:

15. Food chains
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A food chain shows where the biomass or energy goes in a food chain (in other words, “what gets eaten by what”):
Rabbit
Cabbage
Fox
Stoat
The arrows indicate where the energy is going
Plants convert the sun’s energy into food through photosynthesis

16. Pyramids of biomass
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In 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 foxes
Mass of stoats
Mass of rabbits
Mass of cabbages

17. Energy flow in a food chain
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Consider the energy flow in this food chain:
100%
10% 1%
0.1%
Cabbage
Rabbit
Stoat
Fox
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:
Each organism has to ____, keep warm etc
Energy is lost through faeces (______)
Words – 10%, move, sun, waste, cabbage

18. Recycling ourselves Eating Waste Death Absorption Broken down
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Eating
Waste
Death
Absorption
Broken down
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.

19. The Carbon Cycle CO2 in air
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2. Plants and algae release CO2 through respiration
Burning fossil fuels also releases CO2
CO2 in air
1. CO2 is taken in by plants and algae for photosynthesis and turned into carbohydrates, fats and proteins
6. These microbes also release CO2 through respiration
4. Animals release CO2 through respiration
5. Animals (and plants) die and their remains are fed on by microbes and detritus feeders
3. The carbon taken in by plants is then eaten by animals and the animals that eat them

20. Variation
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“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:
Ways in which they are the same:
Ways in which they are different:

21. Sexual Reproduction
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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.

22. Genes, Chromosomes and DNA
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23. An example - Boy or Girl?
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Girl
Boy

24. Boy or Girl?
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Mother
Son
Daughter
Father

25. Sexual vs. Asexual reproduction
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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)

26. Words – clones, damp, independent, roots, identical
Cloning Plants
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Plants 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

27. Cloning Plants by tissue culture
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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

28. Cloning Animals Method 1 – “Embryo transplants”
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Method 1 – “Embryo transplants”
A developing embryo is “split” before the cells specialise and the identical embryos are implanted into host mothers.

29. Cloning Animals
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Method 2 - Fusion
Host mother
Clone

30. Uses of Genetic Engineering
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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.

31. Genetic engineering - Insulin
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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.

32. Should genetic engineering
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Yes No
Should genetic engineering
be allowed?

33. Evolution
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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.
Charles Darwin ( )

34. The “Evolution Tree” Family Hylobatidae (Lesser Apes)
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Family Hylobatidae (Lesser Apes)
Family Hominidae (Great Apes)
Subfamily Ponginae
Subfamily Hominidae
Tribe Panini
Tribe Homini
Tribe Gorillini
Gibbons
Orangutans
Chimpanzees
Gorillas
Humans

35. Evidence for Evolution
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The Grand Canyon
Fossil records
Humans with tails
“Missing links”

36. Evolution
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The 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:

37. Natural Selection 1) Each species shows variation:
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1) Each species shows variation:
There is competition within each species for food, living space, water, mates etc
Get off my land
The “better adapted” members of these species are more likely to survive – “Survival of the Fittest”
Gutted!
Yum
These survivors will pass on their better genes to their offspring who will also show this beneficial variation.

38. An example – the peppered moth
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An example – the peppered moth

39. Jean Baptiste Lamarck (1744 - 1829
Darwin vs Lamarck
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Darwin 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 (
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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