Sampling Techniques

Sampling techniques are used to estimate population numbers when total counts cannot be made.

Capture Mark Recapture:
Is one of the several ways biologists estimate population size. It is a method which involves catching a certain number of individuals of a particular species, marking or tagging them in a way that does not affect their life expectancy then releasing them into the wild and after catching another group and counting the number of tagged amongst the recaptured. A formula can then be used to estimate the total size of the population. This method is suited for mobile populations where it is impossible to count all individuals at one time i.e: birds, fish, butterflies.
Quadrant:
A quadrant is a defined area which measures the distribution or number in a population. The size of the quadrant is usually determined by the size of the organism being counted.
The quadrants can be placed randomly in the area and numbers of organisms in each quadrant is recorded.
Random quadrants are useful to estimate population size of stationary organisms, or organisms that do not rapidly move to other areas over long distances.
The more quadrants and the more you sample the more accurate the abundance. A tally of the numbers in each quadrant can be used to estimate the total number in one area, or the average number per quadrants. It can be used for the density.
A transect is a line, strip or profile for counting and mapping the number of individuals at different distances along the line. Quadrants are often placed specified distances along the transect and individuals counted in these quadrants. Transects are often used to show how the diversity of species changes across an area. Transects often include scale to show only the height of the plants but any change in topography such as valleys or mountains.
Percentage cover is a sampling technique which uses a 100 percent point guide to estimate abundance. It is used when it is extremely hard to count each individual or it is not clear how many individuals are present. The estimate is given as a percentage.

MEASURING ABIOTIC FACTORS
A data logger is a useful instrument that you can take on a field study. It will gather data that can be taken back to a computer and analysed.
Sampling techniques measuring abiotic factors:
Sampling is carried out when it is not possible to count every individual in a population. A small is area is counted in detail and then multiplied to get a estimate for the whole area.
Measuring Distribution: Transect Lines
A transect is a straight line usually a string is laid across and area and the organism along the line are recorded a transect is used to sample plant populations. Can be used for animals especially if they attached to one sport, for example larnicle on a rock platform.
The organism that lie on the transect line or string are recorded.
Continuous sampling along a transect records every organisms that touches the string. The transect can be designated width either side (for example, a 1 meter string of the line transect). Transects are particularly for studying the changing distribution as the abiotic factors change so does the vegetation. A transect is a good way of monitoring the change.
Measuring Abundance:
Plants:
The quadrant method is used for population that does not move.
It can be made using 4 wooden stakes and string.
Quadrant (squares of a fixed area) are replaced randomly in an area.
The abundance of the organism in that area is counted.
This is then repeated several times and an average is taken
Then the size of the whole area is measured and multiplied by the average from the quadrant results. The quadrants are placed at random.
You can count the actual numbers of each plant or work out a percentage cover for each species. It is necessary to take enough samples to have a reasonable estimate of the population.
Sample size:
When studying an area you have to make a decision on the size of your quadrant.
The number of quadrants that you taken
Count the organisms that are completely within the quadrant
Count an organism if any part of it lies within the quadrant.

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ESTIMATING USING THE RANDOM QUADRANT METHOD
you will need a four meter length of string and four wooden pegs or a quadrant.
if you have a garden avaliable, use the lawn for the following practical.
1. select a random spot in lawn. you can do this by throwing a stick over your shoulder and starting one of your corners of the quadrant where the stick lands.
2. select a plant that you can recognise, such as dandelion, bindi eye, clover it does not matter if you don't know the name just as long as you can recognise it.
3. make your quadrant using the four pegs + the string. a good size is a meter X a meter but a smaller quadrant is acceptable. whatever size you use, make sure you can work out the size of your quadrant.
4. count the number of your chosen plants in the square.
5. repeat so that you have 10 measurements.
6. work out the average number of your plant in your samples.
you can now work out the total number of plants in the lawn by multiplying the density by the total area. measure or estimate the size of you are (multiply by the length of the breadth).
length of area:
width of area:
area in square meters:
multiply the area by the average number of plants in a quadrant.
this will give you an estimate of your chosen plant.
chosen plant per square meter.
Percentage cover:
in some cases when you are investigating an ecosystem it is more useful to record the percentage cover value than the actual number or organisms. a very small but dense plant is very difficult to count.
again you can use a quadrant to estimate the abundance of this type of plant of animal. this time the quadrant is divided into a grid using string.
to work out the percentage cover you have to count the number of squares that are covered by the plant. if the plants dosen't cover an entire square, you have to estimate the percentage of squares covered.
work out the percentage cover of the small plant from the following plan diagram.
rough estimate:
total number of squares: 10 X 10 = 100
number of squares covered: 3 + 2+ 2.4 + 4 11.5
percentage cover: number of squares covered / total number of squares x 100
11/5 /100 X 100 = 11.5%

Transects--plan sketches and profile sketches:
Rope or measure tape marks the line that is drawn to scale.
The area is selected at random across the ecosystem.
Species are plotted along the line, in surface view for a plan sketch or in side on view for a profile sketch.
Advantages: proves a quick, easy and inexpensive method for measuring species occurance.
Minimal disturbance to the environment.
Disadvantages: only suitable for plants or slow-moving animals. species occuring in low numbers may be missed.
Quadrant sampling:
Measuring tape, metre rulers or quadrants are used to randomly place the 1m X 1 m square areas.
The occurance of organisms in the quadrant is recorded and repeated a number of times.
Individual species can be counted if in small numbers or percentage cover can be calculated for larger numbers by estimating the percentage cover fro each quadrant and then finding an average of the of the quadrants taken.
Advantages: quadrants can also be used for determining the distribution of species along a transect. easy and inexpensive method for measuring abundance in large populations. minimal disturbance to the environment.
Disadvantages: only suited for plants and slow moving animals.
Mark-Release-Recapture:
Animals are captured, tagged or marked and then released.
After a suitable time to mix with others, a sample is recaptured.
The number of tagged or marked animals recaptured is counted.
Numbers are then entered into the formula.
Abundance = number captured x number recaptured / number marked in recapture
Advantages: a simple method that provides an estimate of abundance for animals in large populations that are difficult to count.
Disadvantages: only suitable for mobile animals.
Can be time consuming depending on the type of species captured, method of tagging, and time Suitable for waiting while tagged group mix with others.
Can be disturbing to the environment.

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AND LASTLY, THE WORKS GIVEN FROM MY SCIENCE TEACHER. 

Energy: Respiration & Photosynthesis

All living things need energy to remain alive.

Photosynthesis is the chemical process used by chlorophyll containing cells to convert inorganic raw materials into organic compounds, using light energy. All plants have chloroplasts which contain chlorophyll and carry out photosynthesis. Cyanobacteria also carries out photosynthesis.

Lighter energy from the sun is used to drive the photosynthesis reaction. The light energy is converted into chemical energy which is stored in complex organic molecules such as carbohydrates. When an animal eats a plant it obtains this chemical energy. Thus energy is passed along the food chain.

Photosynthesis has a dual role in ecosystems; it begins food chains by capturing light energy and converting it into chemical energy and it also releases oxygen as a by product. The oxygen can then be used by all organisms in respiration. 

All living organisms depend upon photosynthesis or organisms that photosynthesise for survival.

THE PHRASES (there are two stages for photosynthesis):

Light reaction: 

Light energy is trapped by chlorophyll and is used to split up water molecules into hydrogen and oxygen.

Dark reaction: 

Carbon dioxide form the air combines with the hydrogen to form carbohydrates.

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RESPIRATION:

There are two types of respiration

Aerobic: requires oxygen and forms carbon dioxide, water and energy.

Anaerobic: occurs without oxygen and its product depends on the situation.

Respiration is the breakdown of glucose with oxygen to release energy. The energy is held in the glucose bonds, when they are broken down energy is released.

Respiration is a series of chemical reactions which releases energy from complex carbohydrates. All living things respire. Aerobic respiration is the complete breakdown of molecules such as sugars, using oxygen to form carbon dioxide and water. Anaerobic respiration occurs when there is no oxygen avaliable, or the cell has insufficient oxygen. The products of anaerobic respiration depend upon the situation. 

Stages of respiration (aerobic respiration):

The general equation for aerobic respiration shows the reactants and the final products however, the process does not occur in one step. It occurs in a series of controlled chemical reactions with about 50 different stages, each catalysed by a different enzyme. An enzyme is a chemical made by living things and its function is to control the rate of a specific chemical reaction that occurs in the body.

GENERAL EQUATION FOR AEROBIC RESPIRATION:

glucose + oxygen -> carbon dioxide + water

Respiration can be divided into two main stages:

The first stage breaks down glucose, a 6 carbon sugar, into two 3-carbon molecules called pyruvate. A small amount of energy is released at this stage. 

The second stage is the breakdown of this 3 carbon molecule, pyruvate, into a 1 carbon molecule instead, carbon dioxide. This stage uses oxygen and releases a much larger amount of energy.

There are two stages in respiration (in which this information relates to the above stages):

GLYCOLYSIS

—occurs in the cytoplasm

—2 ATP molecules are gained

—splits the 6 carbon glucose into two 3 carbon molecules (pyruvate).

—does not require oxygen.

KREBS CYCLE

-- occurs in the mitochondria

-- pyruvate is broken down into water and CO2 (one carbon) 

-- 36 ATP molecules are gained

-- oxygen is required

TERMS:

ATP -- adenosine triphosphate (one adenosine attached to three phosphate groups). This is the energy carrier of all cells.

For every glucose molecule 38 ATP molecules are produced.

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ENERGY

According to the first law of thermodynamics, energy can neither be destroyed nor created; rather, it is converted from one from into another.

Energy can take many forms:
--kinetic
--energy
--potential energy
--light
--electricity
--mechanical
--chemical
In cells the energy released in respiration comes from the carbon bonds in food molecules. If a cell is not given sufficient external food it will use any organic compound as the fuel source for respiration i.e: any carbohydrate, fat, protein etc.
The energy released by respiration can be used by the organism in several different ways. Some of the energy is released as heat and this is used to maintain body temperature. This is important for endotherms (warm-blooded animals). If a human gets cold, muscles will start to shiver, this is their way of increasing activity, respiring at a higher rate and releasing heat for the body. Heat is needed by the body for reactions as the enzymes in the body require an optimum temperature for maximum efficiency. At low temperatures the random movement of molecules decreases, reducing their chance of bumping into each other and hence having a reaction.

Use of energy by organisms:
--maintaining body temperature
--growth
--active transport
--cell maintenance
--repair
--synthesis of fats.


The released energy can also be used to cause other chemical reactions in cells to occur and for repair of damaged or old cells, or for active transport of materials across cell membranes.

DISCLAIMER: I DO NOT OWN THESE NOTES ALL RIGHTS BELONG TO THEIR OWNER: THE AUTHOR OF MY WORKSHEETS, THE AUTHOR OF MY BROUGHT, GIVEN OR BORROWED TEXTBOOKS.

AND LASTLY, THE WORKS GIVEN FROM MY SCIENCE TEACHER. 

Ecology: Distribution and Abundance

The factors that determine distribution and abundance can be divided into physical factors, chemical factors, biotic factors and dynamic factors.

Distribution refers to the region where an organism is found. Abundance is the number of individuals in the area. Both distribution and abundance can change seasonally or yearly. Abundance is usually described as density - the number on individuals in a certain area - as this gives an idea of crowding. 

The factors that determine distribution and abundance can be divided into physical factors, chemical factors, biotic factors and dynamic factors.

Physical factors:

Include temperature, soil composition, rainfall patterns, altitude, pressure, soil composition, light penetration etc. 

Most organisms prefer to live in environments with temperatures between 0 degrees to 45 degrees. Some animals can live in certain temperatures others cannot, this is what it means by temperature as a physical factor affecting abundance and distribution. 

Rainfall patterns include not only the amount of rain, but how it is spread over the year. 

Soil composition depends on the rock type, rainfall, temperature, and length of formation of the soil -- many plant species prefer specific soil types i.e: desert plants which are prone to lesser rainfall conditions and higher temperatures (desert plants cannot live in winter conditions).

Light penetration influences distribution and abundance as plants require light for photosynthesis. 

Biotic factors:

Include food source, predators, competitors, parasites, disease-causing pathogens, members of the same species and the impact of human activities.

If an organism is a consumer, it depends on other species as a food source, thus many organisms are only found where their food source is found.

The number of individuals of the same species can also affect survival rates i.e: when overcrowding occurs, fewer offspring are usually born and rabbits will drive out some of the rabbits when the warren reaches a certain size etc.

Underpopulation:

Can also be a problem as some species need a certain population size to function properly. For example, a wolf pack or hyena pack needs to be a certain size to make a kill. Competitors refer to other species that compete for the same resource, whether it is growing space for a plant, a nesting site, nesting materials or food source.

Chemical factors:

Include the pH of the soil/water and salinity levels. Most species have a specific tolerance for chemical factors i.e some plants prefer acidic soil while some prefer more alkaline ones--some are also more salt tolerant (this relating to salinity levels).

Dynamic factors: 

Include wind speed and patterns, and wave action. Only a few species are able to withstand harsh sea winds and salty spray, an example of one that can is the she-oak. 

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MEASURING THE DISTRIBUTION OF A SPECIES IN AN ECOSYSTEM:

Types of distribution:

Where an organism can be found is the distribution of that organism. Distribution may differ from species to species. Some may randomly distribute themselves around an ecosystem or they may be found distributed in patterns, determined by the resources around them. Some organisms can be found in clumped patters, others in uniform patterns.

Type of distribution:

Regular distribution (very rare in nature):

-------

-------

-------

Possible explanation for this type of distribution is: territorial species.

Random distribution:

-     -

-    - -  -    - -

- -      -

-  ---          - --- -

Possible explanation for this type of distribution is: random distribution of resources (food to eat etc).

Clumped distribution: (possibly the most common pattern reflecting the fact that species need resources that are not distributed uniformly). 

0 0     0

0   0

            0

Possible explanation for this type of distribution: patch distribution of resources. 

Transects:

There are different techniques that may be used to measure the distribution of a species in an ecosystem. In large areas transects are commonly used to give an idea of the variation that may occur. A transect is a narrow strip that crosses the entire area being studied, from one side to the other. Transects provide an accurate and easy method of representing an area simply.

Two examples of transects are a plan sketch and a profile sketch.

A plan sketch is an aerial or surface view of a representative area within an ecosystem. It shows to scale the distribution of organisms in a measured and plotted view. 

A profile sketch is a side in view of an area showing to scale the distribution of organisms along a line.

DISCLAIMER: I DO NOT OWN THESE NOTES ALL RIGHTS BELONG TO THEIR OWNER: THE AUTHOR OF MY WORKSHEETS, THE AUTHOR OF MY BROUGHT, GIVEN OR BORROWED TEXTBOOKS.

AND LASTLY, THE WORKS GIVEN FROM MY SCIENCE TEACHER. 

Ecology

The distribution, diversity and number of plants and animals found in ecosystems are determined by biotic and abiotic factors. 


Ecology is the study of the distribution and abundance of living organisms and how these properties are affected by interactions between the organisms and their environment.
These are a few important forms that need to be defined prior to understanding the study of ecology.
biotic: living things
abiotic: non living features--chemical and physical factors e.g: temperature, rainfall, salinity etc.
These chemical factors are (for abiotic):
-- rainfall
-- salinity
-- soil type
-- water
-- air composition
-- PH
These physical factors are (for abiotic):
-- temperature
-- pressure
-- sunlight
-- light and heat intensity


AGAIN (for better understanding): 
Here is a list of some abiotic and biotic factors of ecosystems:
Chemical factors-- water, oxygen, nitrogen, carbon dioxide, pH, salinity.
Physical factors-- light, temperature, humidity, tide, wind.
Plants-- grasses, algae, shrubs, trees.
Animals-- micro-organisms, fish, birds, reptiles, mammals.
Fungus-- yeast, mushrooms, toadstools.
Bacteria-- Rhizobium sp, Escherichia coli.


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Biomes: are made up of habitats.

Community: made up of a variety of organisms. 

Habitats: containing a community.

Populations: made up of one type of organism.

Biosphere -> ecosystems -> communities -> populations -> individuals.


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COMPONENTS OF ECOSYSTEMS:
An ecosystem is the combination of all organisms (biotic factors) living in a community and all the non-living features (abiotic factors) with which they interact. There is a fine balance between the biotic and abiotic factors in ecosystems. The distribution of the different Australian ecosystems is due to the variation in biotic and abiotic factors found within each particular area.

Terrestrial and aquatic ecosystems:

Terrestrial environments are those found on land, for example desert or rainforest ecosystems. 

There are two main types of aquatic (water) environments:

Saltwater or marine environments (e.g coral reefs) and freshwater environments (e.g lakes).

However some aquatic environments are exposed to freshwater and saltwater, such as an estuarine environment affected by tidal changes. The major types of organisms found in aquatic environments are influenced by the level of water salinity.

Abiotic factors in aquatic and terrestrial environments:
Biotic and abiotic factors differ greatly between aquatic and terrestrial environments. biotic factors create various conditions which suit different types of organisms and hence affect biotic factors (abiotic factors affect biotic factors).
Abiotic factors of water environments differ depending on whether the water is saltwater or freshwater.


Examples of aquatic ecosystems include: wetlands and mangrove swamps, rock platforms--bare rock and littoral zones; estuaries, rivers and lakes; oceans and coral reefs. 
Examples of common terrestrial ecosystems found in australia include: desert, grassland, shrub land, woodland, temperate forest, rainforest. 


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POPULATION:


A population is a group of similar organisms living in a given area at a given time.
Populations can never be 100 percent accurately counted this is because of the difficulty of describing in detail large areas also it would be too time consuming and damaging to the environment.
Populations are estimated using sampling techniques. These make an estimate, which is roughly accurate of the population.


LIMITING FACTORS CONTROLLING POPULATION:


Populations will increase in number until they are confronted by a limiting factor. limiting factors include:
--lack of space
--predators
--disease
--competition for food between members of the same species
--competition from members of other species
--physical factors (weather conditions)


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GLOSSARY (USEFUL TERMS):
Abiotic: non-living features--physical and chemical factors (e.g temperature, rainfall, and salinity).
Aquatic environment: an environment existing mainly in water either freshwater, saltwater or both.
Biome: large regional system characterised by major vegetation type (e.g. desert); region of earth with similar ecosystems grouped together.
Biosphere: the part of the earth and atmosphere in which living organisms are found.
Biotic: living features--all living things (e.g. numbers, distribution, interactions).
Community: groups of different populations in an area or habitat. 
Ecology: study of the relationships living organisms have with each other and their environment.
Ecosystems: a community together with its environment: any environment containing organisms interacting with each other and the non-living parts of the environment (e.g. rainforest, freshwater pond).
Environment: both living (biotic) and non-living (abiotic) surroundings of an organism. 
Habitat: place where an organism lives.
Niche: place of a species within a community involving relationship wit other species. 
Organism: living thing (e.g: plant, animal).
Population: group of organisms of the same species living in the same area at a particular time.
Species: groups of similar individuals that can reproduce fertile offspring (e.g. kookaburra, snow gum)
Terrestrial environment: an environment existing mainly on land. 


Notes:
Compare requires a discussion of both the similarities and differences in abiotic characteristics of the two environments.

DISCLAIMER: I DO NOT OWN THESE NOTES ALL RIGHTS BELONG TO THEIR OWNER: THE AUTHOR OF MY WORKSHEETS, THE AUTHOR OF MY BROUGHT, GIVEN OR BORROWED TEXTBOOKS.

AND LASTLY, THE WORKS GIVEN FROM MY SCIENCE TEACHER.