The document provides information on the key concepts of ecology. It discusses ecology as the study of organisms in relation to their environment, including their relationships with each other and non-living components. Some key abiotic and biotic factors that influence organisms are described. The document also outlines different types of ecosystems and communities, and explains concepts such as niche, population, food webs, trophic levels, and energy flow through ecosystems.

1. ECOLOGY

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

3.  Polar
 Temperate
 Tropic
Temperate
Polar
Tropic

4.  control each other’s
population size

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

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

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

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 nonliving 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

13. same species

14. different species
Camels, goats and
sheep compete for
food.

15. a) Distinguish between intraspecific and
interspecific competition. (2)
b) Explain why intraspecific competition is
likely to be more intense than interspecific
competition. (1)
Members of a species use the same resources
but different species use different resources.

16. c. i) List TWO resources that animals compete for.
(2)
space,
food,
water,
mate

17. ii) List TWO resources that plants compete for.
(2)
Space, light, water, ions in soil, carbon dioxide

18. d) What is the effect of competition on the
growth of a population? (1)
Reduces the growth rate of a population.

19. Before 1859 there were no
wild rabbits in Australia but
in 1859 some domestic
rabbits escaped from their
pen, when it was swept
away by a flood. These
rabbits ran wild and bred at
such a rate that parts of
Australia soon became
overrun with them. The
following graph shows how
the population of rabbits
increased with time.

20. a. Describe and explain the growth of the
rabbit population at stages 1, 2 and 3. (12)
STAGE 1:
Slow increase in population.
Few individuals able to
reproduce.
Rabbits need to acclimatise.
STAGE 2:
Rapid increase in population.
Many individuals able to
reproduce.
Resources are abundant.

21. a. Describe and explain the growth of the
rabbit population at stages 1, 2 and 3. (12)
STAGE 3:
Population stable.
Resources become limited
and can support a certain
number of individuals.

22. b. Discuss the effect of the observed growth rate
of rabbits on agricultural activity in Australia. (2)
Rabbits fed upon crops and caused damage to
agriculture.
c. Suggest how the observed growth rate of
rabbits affected the natural ecosystem in
Australia. (2)
Many wild plants were eaten leading to loss of
plant species, more soil erosion as soil was no
longer covered by vegetation.

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

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

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

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

28.  Ecosystem: Field
grass
aphid
leaves
ladybird
caterpillar
sparrow
 Ecosystem: Oak tree
oak tree
insect larvae
thrush
 Ecosystem: Freshwater pool
algae
tadpole
waterbeet
le
hawk

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

30. 5
1. There are …… primary consumers.
2. The top carnivore
owl
is the ……… .

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

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

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

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

35. 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
secondary
tertiary
a ………………. or a ……………….. consumer.

36. 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.

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

39. a) Pyramid of Numbers
b) Pyramid of Biomass
c) Pyramid of Energy

40.  shows the total number of individuals at each
trophic level

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

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

43. From the food
web write a food
chain including
four trophic
levels. (2)
[Any food chain as
long as 4 trophic
levels are present]

44. b) In the space below draw a pyramid of
numbers for the food chain you answered in
‘a’. (In your diagram label each trophic level).
(3)

45.  shows the transfer of energy from one
trophic level to the next

46. Pyramid
of Energy

47. 1. excretion
2. moving about
3. keeping the
body warm
4. egestion
5. respiration

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

49. 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.

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

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

52.  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

53. Green light is reflected by the leaf.

54. 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]

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

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

58. Excretion
and death
Nutrients
in living
organisms
Absorption
by living
things
Nutrients in
dead bodies
and waste
Decomposition
by bacteria
and fungi
Nutrients in
environment
available for
use

59.  all living things need carbon to make:
 carbohydrates
 fats
 proteins

60. CO2 in
air
0.03%
1. Respiration
2. Decomposition
3. Combustion
1. Photosynthesis

61. carbon dioxide
gas
photosynthesis
plant
respiration
animal
respiration
combustion
decay
carbon compounds
in animals
animal
nutrition
carbohydrates in
green plants
death
death
fossilisation
carbon compounds
in dead organic matter
(humus)
coal

62. 1) More fossil fuels
are being burnt
than in the past.
2) Large areas of
forest are being
removed and so
less CO2 is
removed from the
air.

63. How can the greenhouse effect be:
1) an advantage to plants?
Plants grow more as photosynthesis increases
due to a higher temperature.
2) a disadvantage to plants?
More chances to wilt as more
water is lost by evaporation.

64.  plants & animals need nitrogen to make:
proteins
 plants cannot use
atmospheric nitrogen
From where do plants
get the nitrogen they
need?
Nitrogen
78%
Gases in air.

65. Mention THREE ways by
which these ions can end up
in the soil.
1. Erosion
2. Burning fossil
fuels (generates
nitric oxide)
3.

66. Nitrates
in soil
1. Lightning
2. Nitrogen-fixing
bacteria
3. Nitrifying
bacteria
1. Absorption by plants
2. Leaching
3. Denitrifying bacteria

67. NITROGEN
(in the air)
Denitrifying
bacteria
lightning
Nitrogen-fixing
bacteria
SOIL
NITRATES
taken up
by plants
Nitrifying
bacteria
Plant protein
Dead organisms
and faeces
NITRITES
Animal protein
Nitrifying
bacteria
excretion
decomposition
AMMONIA

68. LIGHTNING
 causes N2 & O2 to combine at high
temperatures and nitrogen oxides
form
 these oxides are washed into the soil
by rain where they form nitrates
O2 & N2: most
abundant gases in air.

69. NITROGEN-FIXING BACTERIA
 absorb nitrogen gas from the air and ‘fix’ it into
a form which the plant can use to build protein
 change nitrogen gas into ammonium
compounds
Root nodule
full of bacteria.

70. NITROGEN-FIXING BACTERIA live:
1) freely in the soil e.g. Clostridium
2) in the root nodules of leguminous plants
(e.g. peas, beans, clover) e.g. Rhizobium
Root nodules

71. Mutualism:
 is the relationship between nitrogen fixing
bacteria and leguminous plants
Bacteria gain:
1. Food
2. Shelter
Plant gains:
Ammonium
compounds

72. SYMBIOSIS:
 is a relationship between two organisms
MUTUALISM:
 is a type of symbiosis
 is a close relationship between two different
organisms where both benefit from each other

73. When leguminous plants decay:
 the nitrogen which the bacteria have fixed
goes into the soil where it can be used by
plants
Nitrogen-fixing bacteria are very useful
because they increase the amount of useful
nitrogen compounds in the soil.

74. Clover
Beans
Peas
1.can live in soils poor in
nitrates
2.are used in crop
rotation to increase
nitrates in soil

75. NITRIFYING BACTERIA
 change ammonia into nitrites and then into
nitrates
 this is called nitrification
 ammonia is present in:
 dead remains
 animal waste

76. Organic nitrogen
in dead bodies or
animal waste
Bacillus
Decay
ammonia
Nitrification
Nitrosomonas
nitrite
Nitrification
Nitrobacter
nitrate

77. 1) Absorption by plants
root hairs provide a large
surface area for absorption
salts are absorbed by:
 diffusion
 active transport

78. 2) Leaching
is when salts are lost
from the soil and reach
the groundwater
Nitrates

79. 3) Denitrifying bacteria
live in water-logged soil
carry out denitrification by changing
nitrates into nitrogen gas
e.g. Pseudomonas
Why do farmers dig up the land?
To improve drainage and
aeration thus denitrification does
not occur.

80. Distinguish between nitrification and
denitrification. (5)
Nitrification is carried out under aerobic
conditions but denitrification under anaerobic
conditions.
In the process of nitrification, ammonia is
converted into nitrites and then into nitrates.
In denitrification, nitrates are converted into
nitrogen gas.

82. During a fieldwork
activity a biology student
used a pitfall trap for
sampling animals.
The diagram above shows the pitfall trap.
a) List ONE advantage and ONE disadvantage of this
method.
Advantage: cheap; easy to set up; no maintenance
needed; animals remain alive (1)
Disadvantage: animals eat each other; flooding of pitfall
trap if it rains (1)

83. The photo below shows
a student using another
sampling technique.
The photo below shows a student using
another sampling technique.
a) Name the piece of apparatus being used to
sample plant density and diversity in the
field. (1)
Quadrat

84. The following photo shows three biology
students during fieldwork in a woodland area.
Explain why the
sampling equipment
shown in the diagram
cannot be used for
animals. (1)
Animals move out of the quadrat and so cannot
be counted.