Biology Form 4 Chapter 8 :Dynamic Ecosystem Part 1

1. DYNAMIC ECOSYSTEM PART 1

2.  organisms in relation to their environment
 this includes the relationship of organisms
with:
organisms
 each other
 non-living
components of
their environment

4.  is the particular locality in an environment
in which an organism lives
FOOD
SPACE
WATER

5. rock pools
(limpets, barnacles, top shells)
soil burrows
(earthworms)

6.  is the role or job of an organism within the
community

7. Biosphere
Ecosystems
Communities
Populations
Organisms

8.  is the group of
individuals of the
same species living in
a particular area at
the same time

9.  includes all the
populations of all the
species within an
ecosystem

10.  is a natural unit composed of living and non-living
components whose interactions result
in a stable self-perpetuating system

11.  is a community of
organisms in
conjunction with
the nonliving
components of
their environment
(things like air,
water and mineral
soil), interacting
as a system

12. ponds
an oak tree
a field
a rockpool
the sea

14. Levels of
Ecological
Investigation

15. Recap : Ecological Levels
Same species,
living in same
area
All various populations
interacting in one location
Community of
populations, plus the
abiotic factors in the
environment.
Community of
populations, plus the
abiotic factors in the
environment.

16. Biotic factor
living organisms
e.g. predators,
competitors,
parasites
Abiotic factor
non-living factors which
influence organisms
e.g. light, temperature,
soil, rainfall

17.  Nonliving factors in an environment
 Examples:
– pH level- most prefer neutral conditions
– Temperature –poikilothermic, homoiothermic
– Humidity
– Light intensity- photosynthesis, animal behavior
– Topography-altitude, slope, aspect
– Microclimate- small habitat climate

18.  Polar
 Temperate
 Tropic
Polar
Tropic
Temperate

19.  Mountains have a significant effect on
– The amount of sunlight reaching an area
– Local temperature
– Rainfall
Farther inland, precipitation
increases again as the air
moves up and over higher
mountains. Some of the world’s
deepest snow packs occur here.
On the eastern side of the
3
Sierra Nevada, there is little
precipitation. As a result of
this rain shadow, much of
central Nevada is desert.
As moist air moves in
off the Pacific Ocean and
encounters 1
the
westernmost
mountains, it flows upward,
cools at higher altitudes,
and drops a large amount
of water. The world’s tallest
trees, the coastal
redwoods,
thrive here.
2
East
Pacific
Ocean
Wind
direction
Coast
Range
Sierra
Nevada

20. Topography also affects climate.

21.  Climate has a great impact on the
distribution of organisms,
Figure 50.18
Desert Temperate grassland Tropical forest
Temperate
broadleaf
forest
Coniferous
forest
Arctic and
alpine
tundra
Annual mean precipitation (cm)
Annual mean temperature (ºC)
100 200 300 400
30
15
0
15

22.  Sunlight intensity
– Plays a major part in determining the
Earth’s climate patterns
Figure 50.10
Low angle of incoming sunlight
Sunlight directly overhead
Low angle of incoming sunlight
North Pole
60N
30N
Tropic of
Cancer
0 (equator)
30S
60S
Atmosphere
LALITUDINAL VARIATION IN SUNLIGHT INTENSITY
Tropic of
Capricorn
South pole

24. a) PRODUCERS
b) CONSUMERS
– autotrophic plants
– heterotrophic organisms,
mainly animals
c) DECOMPOSERS
– saprophytic bacteria & fungi
– break down dead matter to
return nutrients to the soil

26.  Producers: harness energy from the sun
– e.g. plants, algae

27.  Consumers: organisms that eat something else
– e.g. animals

28. Consumers
 Four types
 Herbivore: eats only plants
 E.g. Cows, horses
 Carnivore: eats only meat
 E.g. Polar bear
 Omnivore: eats plants and animals
 E.g. Humans, bears
 Scavenger: carnivore that feeds on bodies of
dead organisms
 e.g. Vultures
Vultures

29.  Organisms that feed on the producers.
 Ex: Herbivores

30.  Organisms that feed on the Primary
Consumers.
 Ex: Carnivores

31.  Decomposers: return energy to the environment
– e.g. fungus, bacteria

32. Decomposers:
1. secrete enzymes to
digest organic matter
2. then absorb the
ensuing molecules
 The decomposers
 break the
organic
compounds
in inorganic
form and
then
 absorb
whatever
they need for
nutrition

33. CONSUMERS
PRIMARY
PRODUCERS
DECOMPOSERS
NUTRIENTS
CO2
Death
C6H12O6

34. Distinguish between a community of plants and
a population of plants. (2)
Distinguish between producers and consumers.
(4)

35. Food Chains &
Food Webs

36. A Food Chain is the:
energy flow from one trophic level to the other
One organism at each trophic level.

37. What does an arrow show?
The direction of the energy transfer, NOT
“what ate what”
Rose Aphid Ladybird

38.  the movement of food energy from one
organism to the next
PRODUCER
PRIMARY
CONSUMER
SECONDARY
CONSUMER
TERTIARY
CONSUMER
1st Trophic
level
2nd Trophic
level
3rd Trophic
level
4th Trophic
level
Trophic level = feeding level
Top carnivore

39. Trophic Levels [Feeding Levels]
heterotrophs
autotrophs

40. Organisms in one trophic level feed in the same way
4th Trophic Level
3rd Trophic Level
2nd Trophic Level
1st Trophic Level
Terrestrial food chain Aquatic food chain

41.  Ecosystem: Field
grass aphid ladybird
leaves caterpillar sparrow hawk
 Ecosystem: Oak tree
oak tree insect larvae thrush
 Ecosystem: Freshwater pool
algae tadpole waterbeetle

42.  are made up of many food
chains linked together
 give a more complex
picture of how animals
feed
 are more stable than food
chains

43. 5
1. There are …… primary consumers.
2. The top carnivore
is the ……… owl
.

44. 3. Suppose all the woodmice died from a
poison,
i) the acorn would
(increase / decrease).

45. 3. Suppose all the woodmice died from a
poison,
i) the acorn would
(increase / decrease).

46. 3. Suppose all the woodmice died from a
poison,
i) the acorn would
(increase / decrease).
ii) the weasel would
(increase / decrease).

47. 3. Suppose all the woodmice died from a
poison,
i) the acorn would
(increase / decrease).
ii) the weasel would
(increase / decrease).

48. 4. Draw a food chain with 5 links from this food
web.
oak leaf greenfly ladybird shrew owl
5. In this food web, the shrew can be either
a ………………. secondary or a ……………….. tertiary
consumer.

49. The following organisms can be found in
the same habitat:
weasel, rabbit, greenfly, green plant,
caterpillar, small bird and ladybird.
Construct a food web to include all the
organisms found in the list above.

50. weasel, rabbit, greenfly, green plant,
caterpillar, small bird and ladybird
weasel
ladybird
small bird
rabbit greenfly caterpillar
green plant
Weasel eats
small mammals
& birds.

52.  diagramatic representations of feeding
relationships and energy transfer through the
biotic component of ecosystems

53. a) Pyramid of Numbers
b) Pyramid of Biomass
c) Pyramid of Energy
Secondary
consumers
Primary
consumers
Producers

54. 4th Trophic Level
3rd Trophic Level
2nd Trophic Level
1st Trophic Level
Tertiary Consumer
1 eagle
Secondary Consumer
8 frogs
Primary Consumer
29 grasshoppers
Producers
1500 blades
of grass

55. 4th Trophic
Level
3rd Trophic
Level
2nd Trophic
Level
1st Trophic
Level
Tertiary Consumer
1 eagle
Secondary Consumer
8 frogs
Primary Consumer
29 grasshoppers
Producers
1500 blades
of grass
Decreases

56.  indicates the weight of all individuals at each
trophic level
 biomass is the weight of living material

57. c) Pyramid of Energy
 This loss of energy with each transfer in a food chain
 Can be represented by a pyramid of net production
Tertiary
consumers
Secondary
consumers
Primary
consumers
Primary
producers
10 J
100 J
1,000 J
10,000 J
1,000,000 J of sunlight

58. Pyramid of Numbers
Pyramid of Biomass
Ladybird
Aphid
Rosebush
Rosebush Aphid Ladybird

59. Energy Losses in
Ecosystem

60. Why does a food chain rarely have more
than 5 trophic levels?
Substantial losses in
energy at every trophic
level

61. Energy Losses in Ecosystem
 Only about 10% of energy passes through
each step of a food chain
 90% of energy is lost at each step

62. If the pea plant contains 100 units of energy,
how much energy would be present in the
hawk?
100 10 1 0.1 0.01

63. Energy is lost at each trophic level.
What could cause the energy to be lost?
 Heat
 Movement
 Waste e.g. faeces, urine
 Respiration
 Uneaten parts
e.g. bones, fur,
shells, wood

64. Why are energy losses greater in homeotherms
(birds & mammals) than in poikilotherms (fish,
reptiles)?
Homeotherms use a great proportion of food eaten
to keep a constantly warm body temperature.
Heat
Heat

65. Pyramid
of Energy

66. Give a reason why the
number of trophic
levels seldom exceeds
5. (1)
Great (90%) losses in
energy at every
trophic level.

67. Approximately what percentage of all the
energy present at one trophic level is
transferred to the next higher trophic
level? (1)
Only 10% of the energy is transferred to
the next trophic level.

68. Why is energy not recycled in ecosystems?
(1)
Lost as heat to the surrounding
environment.

69. ENERGY FLOW
nutrients
Flow of ENERGY is LINEAR but
flow of NUTRIENTS is CYCLIC.
SUN
Light
energy
Biotic
component
Heat
energy
Abiotic
component

70.  the shorter the food chain, the more people
can be fed REASON: the 90% ‘wastage’ of
energy that occurs between each
trophic level is cut down

71. Green light is reflected by the leaf.

72. Only 1% of the light falling on a leaf is used in
photosynthesis. What happens to the rest?
30% evaporates water from plant
20% is reflected
from plant
40% warms up soil, air and
vegetation [transmitted]

74.  respiration :
is not available for the next trophic
level
 growth:
is passed on the next
trophic level

75.  over half of the energy in the grass the cow
eats, is passed out of the body in faeces