1. Producer & Consumers
All organisms in our world are connected to each other & termed
Producers
Consumers

2. Producers
Producers make their food by a process called photosynthesis.

3. Food Chain
The way in which organisms interact can be shown by a food chain.

4. Food Chains
The arrows show the direction of energy flow.

5. (secondary consumer)
(primary consumer)
The 1st consumer is called the primary consumer The 2nd consumer is called the secondary consumer

6. Energy loss in Food chains
Only 10% of energy is passed on to next level in a food chain.

7. Energy loss in Food chains
Most of the energy is lost as: A) Heat B) Movement C) Undigested material

8. Calculation
1000 units of energy in grass – how much energy does the owl receive?

9. Calculation
1000 units of energy in grass – how much energy does the owl receive?

10. Key word Definition Consumer Omnivore Carnivore Herbivore Prey
Eats another organism
Omnivore
Eats animals and plants
Carnivore
Only eats other animals
Herbivore
Only eats plants
Prey
Gets eaten by the predator
Predator
Feeds on the prey
Producer
Makes its own food by photosynthesis

11. Food webs
Animals usually eat many different things and are involved in lots of different food chains. These more complicated feeding relationships can be shown in a food web.

12. Analysing food webs
What would happen to the _________ if the ________ died out? Increase or decrease – why?

13. Fiercer Interspecific vs. Intraspecific
There is a lot of competition for resources among organisms in a food web.
Fiercer
Interspecific
vs.
Intraspecific
Between organisms of different species for similar resources.
Between organisms of the same species for the same resources.

14. There is a lot of competition for resources among organisms in a food web.
Animals compete for...
Food
Mates
Habitats
Plants compete for...
Nutrients
Water
Space

15. 1. Pyramid of Energy
BLACKBIRD
LADYBIRD
GREEN FLY
ROSE BUSH
Shows the total energy received by organisms at each stage of a food chain

16. 2. Pyramid of Numbers
Show the total number of organisms at each stage of a food chain.
Small numbers of large organisms
1 fox
30 Rabbits
100,000 blades of grass
Large numbers of small organisms

17. Problems with Pyramids of Numbers
What if tree is the producer?
Oak tree greenfly wasp blue tit
What if insects are the top consumer?
Grass zebra lion flea

18. Pyramid of numbers = not always a pyramid!
Oak tree Greenfly Finch
Pyramid of numbers = not always a pyramid!

19. Biodiversity Variety and abundance of all living organisms.
Importance of biodiversity;
Variety of organisms is important so that they can adapt to changing environment conditions.

20. Habitat Community Where the animals/plants live.
All the organisms living together.

21. An area made up of living & non living parts.
Population
The number of ONE species living in an area.
Ecosystem
An area made up of living & non living parts.

22. Factors affecting biodiversity
1. Biotic
2. Abiotic
(living)
(non-living)

23. Biotic factors Living factors affecting biodiversity; Predation
Grazing
Disease
Competition
Food availability

24. Predator/Prey Graphs

25. Abiotic factors Non-living factors affecting biodiversity; Temperature
Light intensity pH
Moisture

26. Sampling Techniques
Techniques used to measure various biotic and abiotic factors in the environment.
Animals
Pitfall traps
Tree beating
Plants
Quadrats

27. Quadrats Thrown at random (not placed down).
Don’t count number of flowers, count number of squares the flower is in.
Repeat for increased reliability.

28. Errors with quadrats Not thrown randomly (throw randomly)
Organisms wrongly identified
(use key)

29. Pitfall Trap (e.g. woodlouse) Hole dug level with ground.
Covered with stones, leaves.
Checked regularly.

30. Errors with pitfall traps
Hole not level with ground – insects won’t fall in.
Trap not hidden – insects will avoid the trap.
Not checked regularly – insects could eat each other.

31. Abiotic sampling techniques
Light intensity
Moisture pH
Temperature

32. Light intensity Measured with a light meter.
Hold the light meter arms distance away so that you don’t cast a shadow over it.
Point at maximum light.

33. Errors with light intensity
Accidentally shading the light meter.

34. Moisture or pH Measured with a moisture meter/pH meter.
Push the probe into the soil and read the meter.

35. Errors with moisture or pH
Not wiping pH meter/moisture meter probes between readings.

36. General rule;
Results are made more reliable by taking many samples (REPEATING experiment).

37. Identifying Organisms
It’s all very well counting/collecting organisms, but not all of them will be familiar to us.
To identify unfamiliar organisms, we would use a key.
There are different kinds of key.

38. Branching Key Animals Legs No legs 8 legs More than 8 legs Shell
No shell
Snail
Earthworm
Spider
Centipede

39. Paired Statement Keys
Paired statement keys work in the same way as branching keys.
At each stage you are given a choice.
Make the appropriate choice and go to where you are asked to go.
Again, if the organism is present, you should end up with a name for it.

40. Mutation Random Change to DNA bases. Mutations are: Randomly Occurring
Low frequency (ROLF)

41. Mutation Types 1. Disadvantage (genetic disease)
2. Advantage (new variety of species)
3. Neutral

42. 3 copies of chromosome 21 (instead of just 2).
Genetic Disease: Down Syndrome
3 copies of chromosome 21 (instead of just 2).
Occurs in 1 in every 1,000 children born each year.

43. Advantageous Mutations
Mutations create variety (new alleles).
Variation helps animals or plants cope with environmental change.

44. Example: Peppered moth

45. E.g. different coloured eyes
Neutral Mutations
Changes in DNA bases that are neither beneficial nor detrimental to the ability of an organism to survive and reproduce.
E.g. different coloured eyes

46. Mutagenic Agents Increase the frequency of a mutation occurring.
Examples include;
X-rays
UV radiation
Mustard gas
High temperatures

47. 1. X-rays

48. 2. UV radiation

49. 3. Mustard gas

50. Adaptations
Mutations (increased variety) allows organisms to adapt to be better suited to their environment/cope with environmental change.

51. Adaptations of the desert rat
Burrowing into sand when temperature is too high.
Large back feet help them to jump away from predators.
Behavioural
Structural

52. Adaptations of the cactus
The leaves are reduced to spines in order to decrease the surface area for water loss.
Vast root system to maximise water uptake.
Structural

53. Adaptations of the camel
Rest during the day when the temperatures in the desert are very high.
Humps store fat which produces water when metabolised.
Behavioural
Structural

54. The theory of evolution states that evolution happens by natural selection.
Key points:
Individuals in a species show a wide range of variation.
Individuals with characteristics most suited to the environment are more likely to survive and reproduce.
The genes that allowed the individuals to be successful are passed to the offspring in the next generation.

55. “Survival of the fittest”
Darwin’s Theory of Evolution
“Survival of the fittest”

56. The organism best suited to the environment survive.
Natural Selection
The organism best suited to the environment survive.

57. Natural Selection
There is natural variation in the population.

58. Natural Selection
Those with the selective advantage for survival increase in population.

59. Natural Selection
These organisms are able to breed and pass on their desirable genes.

60. Natural Selection
Organisms without the selective advantage die out.

61. Likely exam question!
Q. Explain the concept of “survival of the fittest”. (2)
Natural Selection chooses organisms that have a SELECTIVE ADVANTAGE for survival who then reproduce & pass on successful alleles.

62. What is a species?
A group of related organisms that interbreed & produce fertile offspring.

63. Horses and donkeys are closely related, and look very similar, but they are members of different species.
Horses mate with each other to produce young horses, which themselves will be able to mate (fertile).

64. Donkeys can mate with each other to produce young donkeys, which themselves will be able to mate (fertile).

65. If a donkey mates with a horse, they produce a mule, which is infertile and cannot mate to produce offspring.
Fertile
Fertile
Infertile

66. Speciation
Creating a new species.

67. Speciation – 3 stages 1. Isolating Mechanism 2. Mutations
3. Natural Selection
New species formed!

69. One species of organism.

70. The species is split into 2 sub-populations, separated by an isolating mechanism.
The isolating mechanism prevents gene flow across sub-populations.

71. Mutations (low frequency) occur on either side of the barrier.

72. Natural Selection chooses organisms that have a selective advantage for survival, who then reproduce & pass on successful alleles.

73. A new species is formed. This new species cannot interbreed with the original species to produce fertile offspring (even if the barrier is removed).

74. Types of Isolating Mechanisms
Geographical
Ecological
Reproductive

75. Importance of isolating mechanisms
Prevents gene flow (exchange of genes) between sub-populations. 2 3 4
Free flow of genes between all population
Population 3 becomes extinct
Population 4 becomes isolated 1
Flow of genes only 1 to 2

76. How many species?

77. How many species?
Isolating mechanism

78. Common error in ‘isolating mechanism’ answer
“the barrier separates different species”.
Barriers separate groups of the same species, which then undergo mutation and natural selection until they become separate species.

79. I’m a new species. Speciation! Quick recap… Just remember……
1. Isolation
2. Mutation
3. Natural selection
Speciation!

80. Food Science Challenge
What’s the problem?
Not enough food to feed everyone.
Food Science Challenge
Need to increase yield of crops grown.

81. Solution? Intensive Farming 2. Biological Control
3. Genetically Modified (GM) Crops

82. Advantages of Intensive Farming
Increased yield making food more affordable/available.

83. Features of Intensive Farming
Fertilisers
Nutrients to help crops grow (nitrates).
Pesticides
To kill pests that eat crops.

84. Problems with pesticides
Pesticides aren’t broken down, so they build up at each stage of the food chain.
This can be toxic for the predators at the top of the food chain.

85. Problems with fertilisers
Creates algae bloom in water.

86. Disadvantage of fertilisers
1. Fertiliser washes into rivers from fields.
2. Increased algae bloom.
3. Increased bacteria as they feed on algae.
4. Decreased oxygen levels (all the bacteria use the oxygen for respiration).
5. Decreased biodiversity.

87. Intensive Farming Summary
1. Algae bloom
Deoxygenates water as bacteria that feed on algae use up oxygen and reduce biodiversity.
2. Pesticide build up (DDT)
DDT builds up to toxic levels in food chains.
Pesticide resistance.

88. Indicator Species
A species whose presence/absence indicates level of pollution in environment.
Lichen only grows where there is little air pollution (little SO2).

89. Indicator Species Example
Stone fly nymph
Only present in high oxygen levels in water (no algae bloom).

90. Biological Control Natural method of control (no chemicals).
a) Using predator
b) Deliberately introducing a disease

91. Advantages 1. No chemicals so no algae bloom/pesticides building up.
2. Cheap after initial set up costs.

92. Disadvantages 1. Can’t guarantee that all pests will be killed.
2. Predator or disease could become the problem in place of the pest.

93. Genetic Engineering (Cell Biology unit)
A useful gene from another species is inserted into the plant to produce a GM crop.

94. Examples of GM crops
Golden Rice with added nutrients.
Tomatoes with a longer shelf life.
Disease resistant potatoes.