Topic 4 - Ecology
4.1 Communities and Ecosystems
4.1.1
Define: (1)
Ecology—the study of relationships between living organisms and
between organisms and their environment.
Ecosystem—a community and its abiotic environment.
Population—a group of organisms of the same species who live in the
same area at the same time.
Community—a group of populations living and interacting with each
other in an area.
Species—a group of organisms which can interbreed and produce
fertile offspring.
Habitat—the environment in which a species normally lives or the
location of a living organism.
4.1 Communities and Ecosystems
4.1.2
Explain how the biosphere consists of
interdependent and interrelated
ecosystems. (3)
Biosphere – the thin layer of ecosystems
that cover the earth (all of them!)
4.1 Communities and Ecosystems
Interdependence Example:
Many ecosystems depend on oxygen from
the rain forests, or from algae in the ocean
Interrelationship Example:
Rising temperatures in the poles resulting in
melting of the ice would have great effects
on coastal ecosystems all over the world
4.1 Communities and Ecosystems
4.1.3
Define: (1)
autotroph (producer) – organisms that use
an external energy source to produce
organic matter from inorganic raw
materials
Examples: trees, plants, algae, blue-green
bacteria
4.1 Communities and Ecosystems
heterotroph (consumer) – organisms that
use the energy in organic matter,
obtained from other organisms
Three Types:
1. consumers
2. detritivore
3. saprotroph
4.1 Communities and Ecosystems
1. consumers – feed on other living things
2. detritivore – feed on dead organic matter
by ingesting it
3. saprotroph (decomposer) – feed on dead
organic material by secreting digestive
enzymes into it and absorbing the
products
4.1 Communities and Ecosystems
4.1.4
Describe what is meant by a food chain
giving three examples, each with at least
three linkages (four organisms). (2)
A food chain is a sequence of relationships
between trophic levels where each
member feeds on the previous one.
4.1 Communities and Ecosystems
4.1.5
Describe what is meant by a food web. (2)
A food web is a a diagram that shows the
feeding relationships in a community. The
arrows indicate the direction of energy
flow.
4.1 Communities and Ecosystems
4.1.6
Define trophic level. (1)
A trophic level is where an organism is
positioned on a food web.
Producer
Primary consumer
Secondary consumer
Tertiary consumer
4.1 Communities and Ecosystems
4.1.7
Deduce the trophic level of organisms in a
food chain and a food web. (3)
• The student should be able to place an
organism at the level of producer, primary
consumer, secondary consumer etc, as
the terms herbivore and carnivore are not
always applicable.
4.1 Communities and Ecosystems
4.1.8
Construct a food web containing up to 10
organisms, given appropriate information.
(3)
4.1 Communities and Ecosystems
4.1.9
State that light is the initial energy source for
almost all communities. (1)
• xref- 2.8.2- Photosynthesis
• Reference to communities that start with
chemical energy is not required. Such as
deep sea ocean vents.
4.1 Communities and Ecosystems
4.1.10
Explain the energy flow in a food chain. (3)
• Energy losses between trophic levels
include material not consumed or material
not assimilated, and heat loss through cell
respiration.
4.1 Communities and Ecosystems
4.1.11
State that when energy transformations take
place, including those in living organisms,
the process is never 100% efficient,
commonly being 10–20%. (1)
4.1 Communities and Ecosystems
4.1.12
Explain what is meant by a pyramid of
energy and the reasons for its shape. (3)
• A pyramid of energy shows the flow of
energy from one trophic level to the next in
a community. The units of pyramids of
energy are therefore energy per unit area
per unit time, eg J/m2/yr.
4.1 Communities and Ecosystems
4.1 Communities and Ecosystems
4.1 Communities and Ecosystems
4.1.13
Explain that energy can enter and leave an
ecosystem, but that nutrients must be recycled.
(3)
Energy enters as light and usually leaves as heat.
Nutrients do not usually enter an ecosystem and
must be used again and again. Nutrients such
as Carbon dioxide, Nitrogen, and Phosphorus
4.1 Communities and Ecosystems
4.1.14
Draw the carbon cycle to show the
processes involved.
(1)
• The details of the carbon cycle should
include the interaction of living organisms
and the biosphere through the processes
of photosynthesis, respiration, fossilization
and combustion. Recall of specific
quantitative data is not required.
4.1 Communities and Ecosystems
4.1.15
Explain the role of saprotrophic bacteria and
fungi (decomposers) in recycling nutrients.
(3)
The digestive enzymes secreted by
saprophytes breaks down the organic
molecules in dead material releasing the
nutrients that were ‘locked up’
4.2 Populations
4.2.1
Outline how population size can be affected
by natality, immigration, mortality and
emigration. (2)
4.2 Populations
• Natality – offspring are produced and
added to the population
• Mortality – individuals die and are lost from
the population
• Immigration – individuals move into the
area from somewhere else and add to the
population
• Emigration – indivuals move out of the
area and are lost from the population
4.2 Populations
4.2.2
Draw a graph showing
the sigmoid (Sshaped) population
growth curve. (1)
4.2 Populations
4.2.3
Explain reasons for the exponential growth
phase, the plateau phase and the
transitional phase between these two
phases. (3)
4.2 Populations
Exponential Phase
Population increases exponentially because
the natality rate is higher than the mortality
rate. This is because there is an
abundance of food, and disease and
predators are rare.
4.2 Populations
Transitional Phase
Difference between natality and mortality
rates are not as great, but natality is still
higher so population continues to grow,
but at a slower rate.
Food is no longer as abundant due to the
increase in the population size. May also
be increase predation and disease.
4.2 Populations
Plateau Phase
Natality and mortality are equal so the population
size stays constant.
Limiting Factors:
shortage of food or other resources
increase in predators
more diseases or parasites
If a population is limited, then it has reached its
carrying capacity
4.2 Populations
4.2.4
Define carrying capacity. (1)
The maximum population size that can be
supported by the environment
4.2 Populations
4.2.5
List three factors which set limits to
population increase. (1)
Limiting Factors:
shortage of food or other resources
increase in predators
more diseases or parasites
4.2 Populations
4.2.6
Define random sample. (1)
In a random sample, every individual in a
population has an equal chance of being
selected.
4.2 Populations
4.2.7
Describe one technique used to estimate the
population size of an animal species based on a
capture-mark-release-recapture method.
(2)
• Various mark and recapture methods exist.
• Knowledge of the Lincoln index (which involves
one mark, release and recapture cycle) is
required.
4.2 Populations
population size =
n1xn2
n3
where . . .
• n1= number of individuals initially caught, marked and released
• n2 = total number of individuals caught in the second sample
• n3 = number of marked individuals in the second sample
4.2 Populations
4.2.8
Describe one method of random sampling
used to compare the population numbers
of two plant species, based on quadrant
methods.
(2)
4.2 Populations
Random sampling of plant species usually
involves counting numbers in small,
randomly located, squares within the
total area.
These squares are usually marked with
frames called quadrats.
4.2 Populations
1. mark out gridlines along two edges of the
area
4.2 Populations
1. mark out gridlines along two edges of the
area
2. use a calculator or tables to generate two
random numbers to be used as coordinates. Place a quadrat at the coordinates
such as 14, 31
4.2 Populations
2. use a calculator or tables to generate two
random numbers to be used as coordinates. Place a quadrat at the coordinates
3. count how many individuals are inside the
quadrat. Repeat 2 and 3 as many times
as possible
4.2 Populations
3. count how many individuals are inside the
quadrat. Repeat 2 and 3 as many times
as possible
4. Measure the total size of the area
occupied by the population, in square
meters
4.2 Populations
4. Measure the total size of the area
occupied by the population, in square
meters
5. calculate the mean number of plants per
quadrat. Then calculate the population
size using the following equation:
4.2 Populations
mean number per quadrat  total area
population size 
area of each quadrat
4.2 Populations
4.2.9Calculate the mean of a set of values.
(2)
mean = sum of values / number of values
5 3 6 7 2 4 6 8 9 10 7 14 18 6 3
5+3+6+7+2+4+6+8+9+10+7+14+18+6+3= 108
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15
108 / 15 = 7.2
4.2 Populations
4.2.10
State that the term standard deviation is
used to summarize the spread of values
around the mean and that 68% of the
values fall within ±1 standard deviation of
the mean. (1)
4.2 Populations
4.2.11
Explain how the standard deviation is useful for
comparing the means and the spread of
ecological data between two or more
populations. (3)
A small standard deviation indicates that the data
is clustered closely around the mean value.
Conversely a large standard deviation indicates a
wider spread around the mean.
4.5 Human Impact
4.5.1
Outline two local or global examples of
human impact causing damage to an
ecosystem or the biosphere. One example
must be the increased greenhouse effect.
(2)
4.5 Human Impact
• In studying the greenhouse effect students
should be made aware that it is a natural
phenomenon and that without it organisms
may have evolved differently. The problem
lies in its enhancement by certain human
activities. Knowledge that gases other
than carbon dioxide exert a greenhouse
effect is required (eg methane and CFCs).
4.5 Human Impact
4.5.2
Explain the causes and effects of the two
examples in 4.5.1, supported by data. (3)
4.5.3
Discuss measures which could be taken to
contain or reduce the impact of the two
examples, with reference to the
functioning of the ecosystem. (3)
Greenhouse Effect
Phenomenon
The mean global temperature has
risen about 1 degree Celsius since
1856. We saw an increase
between 1910 and 1940, and from
1970 onwards.
Greenhouse Effect
Human Activities
Increased burning of fossil fuels releasing
Greenhouse gases
Deforestation – less trees to convert CO2
back to O2
Other industrial activities that release other
Greenhouse gases
Greenhouse Effect
Causes
Light from the sun has short wavelengths
and can pass through most of the
atmosphere.
This sunlight warms the earth which in turn
emits long wave radiation.
This long wave radiation is bounced back by
the greenhouse gases, such as carbon
dioxide, methane, water vapour, and
sulphur dioxide
Greenhouse Effect
Effects
Global warming by up to 3 degrees
Celsius over the next 50 years
Rising sea levels due to thermal
expansion of water
Greenhouse Effect
Flooding of low –lying land
Melting of glaciers and polar ice
More frequent storms and
hurricanes
Changes in weather patterns
Greenhouse Effect
Measures
Increase photosynthesis and reduce
emissions by:
restoring ecosystems where there has
been deforestation or desertification
spreading nutrients such as iron in
nutrient-deficient oceans to
encourage algal growth
Greenhouse Effect
reducing energy consumption;
insulation, smaller vehicles, local
grown food instead of transported
changing from fossil fuels to solar,
wind, or nuclear
4.5 Human Impact
Your turn now!
Research Your own example of human
impact damaging the environment.
You will work in groups of 2 to create a
Power Point Presentation that you will
present in class.
4.5 Human Impact
Requirements:
Your Power Point should contain 5 sections
(phenomenon, human activity, causes,
effects, measures) and a title slide.
Each member will need to present
approximately half of the information.
You must provide me with your presentation
BEFORE the day you present!
Which means on or before . . .
4.5 Human Impact
Also, absolutely NO:
SOUNDSCOLOR COMBINATIONS
WEIRD
SENTENCES
OUT ONE
THAT
MAKE COMING
IT IMPOSIBLE
TOWORD
READ
AT A TIME SO THAT IT TAKES
FOREVER.
SEE HOW STUPID I LOOK WAITING?
OTHER CRAZY ANIMATIONS THAT
MAKE US WAIT FOR INFORMATION
4.3 Evolution
4.3.1
Define Evolution—the process of cumulative
change in the heritable characteristics of a
population.
(1)
Macroevolution – the change from one species to
another. i.e. – reptiles to birds
Microevolution – the change from one variation
within a species to another. i.e. – a Chihuahua
and a Great Dane
4.3 Evolution
4.3.2
State that populations tend to produce more
offspring than the environment can
support. (1)
4.3 Evolution
4.3.3
Explain that the consequence of the
potential overproduction of offspring is a
struggle for survival. (3)
Populations tend to grow exponentially, but
population sizes tend to remain constant.
More offspring are produced than can be
supported, therefore there is a struggle to
survive, where some live and some die.
4.3 Evolution
4.3.4
State that the members of a species show
variation. (1)
4.3 Evolution
4.3.5
Explain how sexual reproduction promotes
variation in a species. (3)
See notes on meiosis (3.2)
And make reference to fertilization (5.2)
4.3 Evolution
4.3.6
Explain how natural selection leads to the
increased reproduction of individuals with
favourable heritable variations. (3)
• The Darwin–Wallace theory is accepted by
most as the origin of ideas about evolution
by means of natural selection
Since organism’s traits vary, some
organisms are more adapted to survival
than others. When there is a struggle to
survive those with favorable traits tend to
survive long enough to pass them on.
Those that have less favorable traits die
before being able to pass the traits on.
4.3 Evolution
4.3.7
Discuss the theory that species evolve by natural
selection.
(3)
There is evidence that the traits of populations
change over time in relation to changes in their
environment. However, these recently observed
changes are relatively small. These
observations do not prove that the different
species evolved from other species. Evolution is
simply a theory. There are other theories as
well.
4.3 Evolution
Two useful terms for discussion:
Micro-Evolution – changes within a species
due to natural selection in response to
environmental changes. Observed.
Scientific fact.
Macro-Evolution – change from one species
to another species through natural
selection. Has not been observed. Still
remains a theory.
4.3 Evolution
4.3.8
Explain two examples of evolution in
response to environmental change; one
must be multiple antibiotic resistance in
bacteria. (3)
See handout . . .
4.4 Classification
4.4.1
Define (1)
Species—a group of organisms which can
interbreed and produce fertile offspring.
4.4 Classification
4.4.2
Describe the value of classifying organisms.
(2)
Species identification
Predictive value
Evolutionary links
4.4 Classification
4.4.3
Outline the binomial system of
nomenclature.
(2)
Also referred to a Scientific Name
Internationally recognized name for each
species
4.4 Classification
Rules for binomial nomenclature:
1. the first name is the genus name
2. the genus name is capitalized
3. the second name is the species name
4. the species name is not capitalized
5. italics are used if the name is printed
6. the name is underlined if handwritten
Homo sapiens, Panthera leo, etc.
4.4 Classification
4.4.4
State that organisms are classified into the
kingdoms Prokaryotae, Protoctista, Fungi,
Plantae and Animalia. (1)
• This system uses the five kingdom
classification system of Margulis and
Schwartz (based on Whittaker), which is
found in most textbooks.
4.4 Classification
4.4.5
List the seven levels in the hierarchy of taxa
- using an example from two different
kingdoms for each level. (1)
Blue Whale
Animalia
Chordata
Mammalia
Cetacea
Balaenopteridae
Balaenoptera
musculus
Plantae
Coniferophyta
Pinopsida
Pinales
Taxodiaceae
Sequoia
sempervirens
King Phillip Came Over For Good Supper
Gross Sometimes
Kingdom
Phylum
Class
Order
Family
Genus
Species
Coast Redwood
Kissing Pretty Cute Otter Feels
King Phillip Came Over For Good Soup
4.4 Classification
4.4.6
Apply and/or design a key for a group of up
to eight organisms. (2, 3)
4.5 Human Impact
Insert Student Research Projects Here
Other Example
Phenomenon
Other Example
Human Activities
Other Example
Causes
Other Example
Effects
Other Example
Measures