Topic 4 - Ecology

4.1 Communities and Ecosystems

4.1.1Define: (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

4.1.3Define: (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

4.1.6Define trophic level. (1) A trophic level is where an organism is

positioned on a food web.ProducerPrimary consumerSecondary consumerTertiary 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

4.1.14Draw 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

4.1.15Explain 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 (S-shaped) 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 PopulationsPlateau PhaseNatality and mortality are equal so the population

size stays constant.

Limiting Factors:shortage of food or other resourcesincrease in predatorsmore 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

4.2.5List three factors which set limits to

population increase.(1)

Limiting Factors:shortage of food or other resourcesincrease in predatorsmore 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 =

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

3

21

n

xnn

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 co-ordinates. Place a quadrat at the co-ordinates

such as 14, 31

4.2 Populations

2. use a calculator or tables to generate two random numbers to be used as co-ordinates. Place a quadrat at the co-ordinates

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

quadrateach of area

area totalquadrat per number mean size population

4.2 Populations

4.2.9 Calculate 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=

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15

108 / 15 =

108

7.2

sum of values number of values

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

CausesLight 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:

SOUNDS

SENTENCES COMING OUT ONE WORD AT A TIME SO THAT IT TAKES FOREVER. SEE HOW STUPID I LOOK WAITING?

OTHER CRAZY ANIMATIONS THAT MAKE US WAIT FOR INFORMATION

WEIRD COLOR COMBINATIONS THAT MAKE IT IMPOSIBLE TO READ

4.3 Evolution

4.3.1Define 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

4.3.3Explain 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

4.3.7Discuss 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 name2. the genus name is capitalized3. the second name is the species name4. the species name is not capitalized5. italics are used if the name is printed6. 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)

Kingdom

Phylum

Class

Order

Family

Genus

Species

Animalia

Chordata

Mammalia

Cetacea

Balaenopteridae

Balaenoptera

musculus

Plantae

Coniferophyta

Pinopsida

Pinales

Taxodiaceae

Sequoia

sempervirens

King Phillip Came Over For Good Supper

Blue Whale Coast Redwood

King Phillip Came Over For Good Soup Kissing P

retty Cute O

tter Feels

Gross S

ometim

es

or make your o

wn!

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