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• Featured , Workshop

University of Newcastle | ExperimentFest

• Tuesday 13 June 2023, 12:00 am
• to Friday 23 June 2023, 12:00 am
• Central Coast NSW , Hunter , Newcastle

For the more than 20 years, the University of Newcastle has been working with local high schools to provide authentic, engaging, and hands-on experiences for HSC students.

For those studying Stage 6 Science/Food Tech Subjects, Experiment Fest is the chance to improve laboratory skills and use specialised equipment that isn’t readily available in regular classrooms, while conducting experiments that directly relate to the HSC syllabus in the areas of;

• Earth and Environmental Science
• Food Science and Human Nutrition

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Tomaree High School

Respect • Responsibility • Success

T: Telephone 02 4981 1444

E: Email [email protected]

ExperimentFest University of Newcastle

For the more than 20 years, the University of Newcastle has been working with local high schools to provide authentic, engaging, and hands-on experiences for HSC students.

For students studying Stage 6 Science/Food Tech Subjects, Experiment Fest is the chance to improve laboratory skills and use specialised equipment that isn't readily available in regular classrooms, while conducting experiments that directly relate to the HSC syllabus in the areas of;

• Earth and Environmental Science
• Food Science and Human Nutrition

General enquiries

address 169 Salamander Way Salamander Bay NSW, 2317

telephone 02 4981 1444

email [email protected]

Get directions

We would like to pay our respects and acknowledge the traditional custodians of the land and also pay respect to Elders both past and present.

Copyright for this website is owned by the State of New South Wales through the Department of Education. For more information go to http://www.dec.nsw.gov.au/footer/copyright.

• Health Science

Bio experiments: Kidney dissection

www.newcastle.edu.au

Introduction

Studying biology.

Kidney Function

Measuring oxygen saturation in the blood

Notes: using microscopes.

Experiment Fest 2011

INTRODUCTION

ExperimentFest is an experiment program designed to provide enriching educational experiences for senior high school students who are studying

Physics, Chemistry and Biology. ExperimentFest is supported by the

University of Newcastle’s Faculty of Science and Information Technology and takes place at both the Callaghan and Ourimbah (Central Coast) campuses of the University of Newcastle. It is run at the Callaghan Campus from 20-

23 June 2011 for Physics and Chemistry; and 17-24 June 2011 for Biology; and at the Ourimbah Campus from 27 June– 30 June 2011. Students may attend either morning sessions (9am-12pm) or afternoon sessions (12:45pm-

3:45pm). Physics Experimentfest is also running at Tuncurry (June 25 2011).

The activities allow students to engage in a range of hands-on experiments that are difficult to organise within a school setting, all under the supervision of University Staff and Postgraduate students. Each experiment is chosen to complement the NSW HSC syllabus for Biology, cementing classroom theory and providing a good basis for examination preparation.

Experiments include:

Measuring oxygen satration in the blood

All experiments are complemented by notes, follow-up discussions and questions to enhance your learning experience.

For booking information contact:

Larry Milton on 49 469 159 or 0404 460 470; or

David Rushton on 4333 6965 or 0414 238 464

Welcome to the Faculty of Science and Information Technology at the University of Newcastle. ExperimentFest is a wonderful chance to give you practical experience which complements your classroom learning while giving you a first hand look at University life and facilities. Science is an exciting field of study, allowing you to move with the times and contribute actively and responsibly to society. There are many education opportunities in science after high school. Here in the Faculty we provide study and research programs in fastmoving modern fields that make our world work.

The Faculty staff and students who will be taking you through the experiments today are involved in contemporary science research. Please ask questions and utilise your time with them.

Take this day to enjoy being out of the class room, exploring science with fellow students and participating in valuable experiments and discussions which will help you in your HSC and beyond.

I wish you well in your studies. I hope you apply yourselves to the learning process with enthusiasm and you enjoy your time at the University. We hope to see you studying with us in the future!

Best wishes,

Prof. Bill Hogarth

Pro Vice-Chancellor – Faculty of Science and Information Technology

University of Newcastle

STUDYING BIOLOGY

Why study biological sciences.

Biological Sciences is the science of life. Biologists study the world of living organisms; taking life and putting it into perspective, from microbes to human beings. Biology is a research-intensive science that can lead to a wide range of areas in which to study from environmental work to microbiology to agriculture.

The discipline of Biological Sciences provides you with a great deal of hands-on learning and engaging research, moving you beyond text books and lectures. Course work provides you with the fundamental framework of knowledge, while labs provide you with practical hands-on experience.

Opportunities for further studies in Biological Sciences:

The Bachelor of Science degree program at the University of Newcastle provides a foundation of knowledge, skills and attributes that allows graduates to be employable not just today but into the future and to contribute actively and responsibly to society. Majoring in Biology, you have the opportunity to sample and/ or specialise in any one of the following:

Animal Biology

Animal Research Science

Biochemistry

Biophysics (double major)

Biostatistics (double major)

Biotechnology

Cell and Molecular Biology

Environmental Biology

Environmental Plant Biology

Molecular Microbiology

Park and Wildlife Biology

Plant Bioinformatics

Plant Biology

Plant Ecology

Reproductive Biology

Research in Biological Sciences at the University of Newcastle:

We conduct research on a wide range of contemporary biological problems. Staff are grouped in four major research themes but there are extensive collaborative links between these themes. By this approach we can develop areas of expertise and also generate multi-disciplinary and innovative research connections. The major research groupings are:

• Drug Design and Discovery

Environmental Biology and Biotechnology

Plant Science Group

Reproductive Science Group

The discipline hosts two Australian Research Council Centres of Excellence, one University Priority Research Centre and one Research Centre:

ARC Centre of Excellence in Biotechnology and Development

ARC Centre of Excellence in Integrative Legume Research

University PRC in Reproductive Sciences (joint with medicine)

Centre for Sustainable Ecosystem Restoration (CSER)

Careers in Biological Sciences:

The Faculty of Science and IT care about our students and are interested in giving as much direction as possible to those making career choices and beyond. The possible career paths listed below include a range of opportunities for graduates at degree, honours, and post graduate study levels.

Animal Biologist

Animal Research Scientist

Biotechnologist

Botanist / Plant Scientist

Bushland Assessment Officer

Clinical Research Coordinator

Conservationist / Ecologist

Environmental/Ecological Biologist

Field Assistant

Food Technologist

Forensic Biologist

Graduate Trainee (Graduate Program)

Laboratory/Research Assistant

Marine Biologist

Medical Scientist

Microbiologist

Molecular Biologist

National Parks Ranger / Field Officer

Pathology Assistant

Pharmaceutical Sales

Physiologist

Reproductive Medicine / IVF Chemist

Research Scientist

Science Information/Education Officer

Science/Biology Teacher

Sciences Technician

For more information on these career paths, please visit the University’s careers website: http://www.newcastle.edu.au/ students/degrees-to-careers/

For more information on the Faculty of Science and IT check out our website: http://www.newcastle.edu.au/faculty/science-it/

ENZYMES IN ACTION

HSC Biology Syllabus 9.2 Maintaining a Balance

• Identify data sources, plan, choose equipment or resources and perform a first-hand

investigation to test the effect of:

- increased temperature

- change in pH

- change in substrate concentrations on the activity of a named enzyme

Enzymes are proteins that catalyse (speed up) biochemical reactions. There are thousands of known enzymes and each cell contains hundreds of different ones.

In an enzyme-catalysed reaction the reactant is called the substrate. When enzymes and substrates combine they bind together at an area of the enzyme called the active site.

Each enzyme is highly specific to the reaction that it catalyses. One enzyme will catalyse only one particular substrate because of the exact match required between the shape of the substrate and the shape of the active site of the enzyme. The lock and key model is used to explain this specificity of enzyme action.

Figure 1.0 The lock and key model for enzyme action

Factors Affecting Enzyme Activity

The activity and efficiency of an enzyme can be significantly affected by temperature, pH and substrate concentration.

Enzyme activity is measured by the rate of the enzyme-catalysed reaction.

Temperature

Enzymes have an optimum temperature at which they are most active. At low temperatures the molecules of the enzyme and substrate have low energy and the activity of the enzyme is low. As temperature increases the activation energy is reached by more molecules and the rate of reaction increases.

The pH is a measure of the acidity of a solution and ranges from 1 to 14 on the pH scale. The presence of hydrogen ions (H+) in solution causes acidity and the higher the hydrogen ion concentration, the lower the pH. An acidic solution has a pH below 7. An alkaline or basic solution has few hydrogen ions and a pH above 7. A neutral solution has a pH of 7.

Different enzymes have different optimum pH values depending on their environments. Amylase is found in the mouth and has a pH range of 5 to 9 with an optimum pH of 7. Pepsin is found in the stomach and has a pH range of 1 to 4 with an optimum pH of 2.

Enzymes are most active at the optimum pH. They lose activity if the pH varies too much from the optimum pH as this changes the shape of the enzyme molecules.

At high temperatures and extremes of pH enzymes become denatured. This is when the protein molecules of enzymes are unravelled and the active site is destroyed.

Substrate Concentration

In most enzyme-catalysed reactions of biological systems the enzyme concentration is much lower than the substrate concentration. An increase in the enzyme concentration results in a linear increase in the rate of reaction (Figure 2.0).

Figure 2. 0 Incr easing enz yme con centr ation

Figur e 3.0 Inc reasing sub strate con centr ation

When the substrate concentration is increased, and the enzyme concentration remains the same, the rate of reaction eventually reaches a constant rate even with further increases in substrate concentration. This point is called the maximum velocity

(Vmax) and is reached when all the active sites of the enzyme are occupied (or saturated) with substrate and the reaction proceeds at its maximum rate (see Figure 3.0).

The Experiment

In this experiment you will investigate the effect of change in temperature, pH, and substrate concentration on the activity of the catalase enzyme.

Hydrogen peroxide (H2O2) is a toxic by-product of metabolism that can damage and destroy cells if not quickly removed or decomposed. Catalase is an enzyme that rapidly catalyses the decomposition of hydrogen peroxide into less reactive gaseous oxygen and water molecules.

Hydrogen peroxide Water Oxygen

Catalase is one of the most efficient enzymes known. It is present in peroxisomes of nearly all aerobic cells. Peroxi somes are specialised microstructures in the cell which contain oxidation reactions that produce toxic peroxide byproducts. All animals use catalase in every organ, with the liver containing particularly large concentrations.

Equipment Setup

Each bench will have:

Prepared fresh cow liver pieces in graduated 10ml centrifuge tubes stored on ice

3% hydrogen peroxide with detergent added (this causes the bubbles of oxygen from the reaction to produce foam)

Range of different concentrations of Hydrogen peroxide (0.75%, 3%, 6%)

Range of different pH solutions of hydrogen peroxide (pH 2, 5, 7, 11)

Centrifuge tube containing hydrogen peroxide and liver

Equip ment Setup

Calculating enzyme activity as the Rate of Reaction

The amount of foam produced from a reaction, in a given period of time, is used as a measure of how active the catalase enzyme is under various conditions. The graduated markings on the centrifuge tubes will show the volume (mL) of foam produced over this time.

Use these results to calculate the rate of reaction in ml/sec:

Rate of Reaction (ml/sec) = volume of foam (ml)

Reaction time (sec)

Procedure A: Testing the effect of different temperatures on enzyme activity

• Remove five of the liver containing centrifuge tubes from the esky and label as 4oC, 25oC, 37oC, 60oC and 90oC.

• Place each of these tubes in the corresponding water baths and leave for a few minutes to allow the liver to reach the required temperature.

• Label five of the small empty culture tubes with 4 o C, 25 o C, 37 o C, 60 o C and 90 o C.

• Using a Finnpipette set at 1000 (= 1mL) add 2ml of 3% hydrogen peroxide to each of these tubes, replace the lid, then place them next to the labelled centrifuge tubes in the water baths, leave for a few minutes to reach the required temperature.

• Add the 2mL of 3% hydrogen peroxide from the small culture tube into the corresponding centrifuge tube containing liver and simultaneously start the stopwatch (keep the centrifuge tube in the water bath during the reaction).

• After 30 seconds (reaction time) record the volume of foam (height of the bubbles in tube) in mL.

• Repeat for the other tubes in the other water baths.

• EXCEPTION – remove the tubes from the 90oC water bath and place in a test tube rack on the bench before starting the reaction.

• Record your results (and other groups) in the table.

• Graph your results to show the effect of temperature on enzyme activity (rate of reaction).

Volume of foam produced in reaction time (mL)

Rate of Reaction

Volume/reaction time

(mL/second)

Graph your results

Explain the shape of your graph considering what happens to the enzyme activity at low and high temperatures, and identify the optimum temperature for catalase.

……………………………………………………………………………………………………………………………………

……….....…………………………………………………...................................................................................................

NOTE: Variables are quantities that change during an experiment, either deliberately by the experimenter or due to external influences. The independent variable is the quantity that is deliberately changed by the experimenter. The dependent variable is the quantity that responds to the change made to the independent variable.

Identify the independent variable and dependent variable for this experiment.

…………………………….................................................................................................................................................

• Remove four of the liver containing centrifuge tubes from the esky and label as pH 2, pH 5, pH 7, pH

• Place them in a test tube rack on the bench and leave for a few minutes to allow the liver to reach room temperature.

• Label four of the small empty culture tubes with pH 2, pH 5, pH 7 and pH 11. Using a Finnpipette set at 1000 (= 1mL) add 2ml of each of the pH hydrogen peroxide solutions into the corresponding culture tubes, replace the lid, then place them next to the matching centrifuge tubes in the test tube rack.

• NOTE - use a new pipette tip for each pH solution.

• Add the 2mL of a pH hydrogen peroxide solution from the small culture tube into the corresponding centrifuge tube containing liver and simultaneously start the stopwatch.

• After 30 seconds (reaction time) record the volume of foam in mL (height of the bubbles in tube).

• Repeat for the other tubes in the test tube rack.

• Graph your results to show the effect of pH on enzyme activity (rate of reaction).

Rate of reaction

Explain the shape of your graph considering what happens to the enzyme activity in conditions of low pH and high pH. Identify the optimum pH for catalase.

…………………………………………………………..........................................................................................................

List the variables from this experiment that were kept constant.

……………………………………………………………………………………………………………………………….........

What is pH?

……………………………...................................................................................................................................................

• Remove five of the liver containing centrifuge tubes from the esky and label as 0%, 0.75%, 3%, 6% and 12%.

• Label five of the small empty culture tubes with 0%, 0.75%, 3% and 6%. Using a Finnpipette set at

1000 (= 1mL) add 2ml of each of the different concentrations of hydrogen peroxide solution into the corresponding culture tubes, replace the lid, then place them next to the matching centrifuge tubes in the test tube rack.

• NOTE - use a new pipette tip for each concentration of hydrogen peroxide.

• For the 0% tube just add 2mL of distilled water.

• Add the 2mL of hydrogen peroxide solution from the small culture tube into the corresponding centrifuge tube containing liver and simultaneously start the stopwatch.

• Record your results (and other groups) in the table .

• Graph your results to show the effect of substrate concentration on enzyme activity (rate of reaction).

Tube Substrate

Explain the shape of your graph considering what happens to the enzyme activity as substrate concentration increases. What is the maximum rate?

……………………………………………………………………………………………..........................................................

Use your graph to predict what would happen to the enzyme activity with a substrate concentration of 30% hydrogen peroxide.

KIDNEY DISSECTION

• Perform a first-hand investigation of the structure of a mammalian kidney by dissection, use a model or visual resource and identify the regions involved in the excretion of waste products.

Background Information

The human urinary system is made up of a pair of kidneys, a pair of ureters, one bladder and one urethra. The main function of the urinary system is to remove nitrogenous wastes such as urea, from the body.

Homeostasis is the maintenance of a relatively stable, internal, physical and chemical environment of an organism. The kidney is the most important homeostatic organ in the body and has six main roles.

1. Ion balance . E.g. Sodium [Na

Potassium [K +

] concentrations in the blood and also the control of the loss of micronutrients such as iron, calcium and trace metals.

2. Osmotic balance . By controlling the volume of urine produced, the kidneys control water balance.

3. Blood pressure . By controlling the volume of blood, the kidneys regulate blood pressure over the long term.

4. pH balance . E.g. controls the retention and excretion of H + and HCO

thereby regulating the pH of extracellular fluid.

5. Excretion . Important role in the excretion of nitrogenous wastes and other water-soluble toxins.

6. Hormone production . Produces and releases hormones such as renin, that regulates blood pressure.

Figure 1. 0 The Urinary Sy stem

URINARY SYSTEM

The kidneys are continually filtering blood plasma; retaining and transferring required nutrients back into the blood, while simultaneously removing excess water, ions and urea, forming urine.

Kidney Structure

The kidney is composed of two layers, the outer cortex and inner medulla. Blood passing through the kidney is under very high pressure. As it enters the kidney from the renal artery it is forced through millions of functioning units, called nephrons (located in the cortex), for filtering.

Once urine is formed it collects in the major calyx and is then released into the ureter that leads to the bladder for storage. A sphincter muscle periodically releases urine from the bladder into the urethra from where it leaves the body.

Major c alyx

In this experiment you will investigate the structure of a mammalian kidney by dissecting a sheep’s kidney, and identify regions involved in the excretion of waste products with the aid of microscopes, models, posters and slides.

Figure 2. 0: Dissected mammalian (sh eep) kidney

• Examine the kidney (wear gloves for this); take note of the shape, size, weight and feel.

Observe the presence (or not) of the adrenal gland, adipose tissue (storage tissue containing fat cells) and renal capsule.

• Notice the pinched in area of the kidney where the renal blood vessels and ureter are attached to the kidney.

• Use the dissecting microscope to help identify and compare the wall thicknesses, of the ureter, renal artery and renal vein. Generally the tube with the most adipose around it is the ureter.

• Place the kidney back on the dissecting tray so a demonstrator can slice the kidney in half lengthwise.

• Use the dissecting microscope to examine the internal structures of the kidney.

• Identify the following structures:

Renal columns

Ureter (if present)

Record your observations (describe what you see).

………………………………………………………………………………………………………………………………

……………………………………………………...................................................................................................

.........................................................................................................................................................................

.....................................................................………………………………………………………………................

Draw and label a diagram of a dissected sheep’s kidney.

• Obtain a slide of the longitudinal section of a mouse kidney.

• Refer to your notes on setting up a compound microscope and observe the slide under low and high power.

• Identify the kidney structures listed above.

• Dispose of the kidney waste in the appropriate biological waste bin.

Identify the structures in the kidney that collect urine and transport it to the bladder.

…………………………………………………………………………………………………………………………

…………………………………...............................................................................................................................

Describe the main functions of the kidney.

…………………………………………………………………….............................................................................

Name the location, and structure, in the kidney responsible for filtration from the capillaries into the nephron (may need to refer to biology text and review the structure and function of a nephron).

USE OF A PULSE OXIMETER

• Identify current technologies that allow measurement of oxygen saturation and carbon dioxide concentrations and explain the conditions under which these technologies are used

Haemoglobin is a protein found in red blood cells and is responsible for carrying most of the oxygen in the blood. It can bind with oxygen and/ or carbon dioxide. Oxygen saturation is the amount of oxygenated haemoglobin in the blood. Haemoglobin with oxygen attached to it is called

Oxyhaemoglobin. The amount of oxygen bound to haemoglobin is determined by the oxygen concentration, carbon dioxide concentration and pH.

How haemoglobin works…

1. Blood entering the lungs has haemoglobin bound with carbon dioxide in it.

2. Through breathing, the lungs contain high concentrations of oxygen and low concentrations of carbon dioxide.

3. In the lungs, haemoglobin releases carbon dioxide and binds oxygen.

4. Haemoglobin gets transported through the heart and blood vessels to the muscle.

5. In muscle, the carbon dioxide concentration is high and the oxygen concentration is low due to metabolism.

6. Haemoglobin releases oxygen and binds carbon dioxide.

7. Haemoglobin gets transported back to the lungs to repeat the cycle.

The pulse oximeter is a non-invasive device that measures the amount of oxygen in blood (oxygen saturation SpO

), and the pulse (heart) rate. It is used on adults and children in hospitals, medical clinics, and at home. It is a simple, quick, and effective instrument that consists of a probe attached to a person’s finger (some can attach to toes, nose or ear lobes), and a digital display showing both the percentage of haemoglobin saturated with oxygen and the pulse rate.

Pulse oximeters use two low powered LEDs of different wavelengths of light (red 660nm and infra-red 910nm), and a photodetector to record the amount of light absorbed as it passes through the finger. A processor in the device uses this information to calculate oxygen saturation (%SpO

(BPM – Beats Per Minute).

) and pulse

Factors affecting pulse oximeter results:

• Poor circulation in the fingers, toes, or earlobe.

Severe hypotension.

Cardiac failure.

Cold temperature.

Bright external light.

• Smoking can affect blood oxygenation.

Typical ‘normal’ readings from a resting adult are 95 – 100

% oxygen saturation and 50 – 90 BPM pulse rate. It is considered abnormal if oxygen saturation declines by more than 5% during exercise or sleep.

Figure 1.0 Pulse Oximeter in use

In this experiment you will use a pulse oximeter to investigate the changes in blood oxygen saturation during aerobic exercise.

During exercise your blood vessels dilate to increase the flow of oxygen-rich blood to your muscles.

The metabolic activity is high, and the pH is lower than normal as more hydrogen ions and lactic acid are produced. The low pH weakens the attachment between oxygen and haemoglobin causing the haemoglobin to release more oxygen than usual. This increases the oxygen delivered to the muscle.

• Obtain a pulse oximeter and stop watch from a demonstrator.

• Choose someone in your group to be the ‘rider’ of an exercise bike!

• Turn the pulse oximeter on by pushing the button on the front, and attach it to the ‘rider’s’ index finger, allow 8 seconds before recording the ‘at rest’ readings of oxygen saturation and pulse rate.

• Start the stopwatch as the rider starts pedalling (at a moderate to fast rate).

• After 2 minutes record the oxygen saturation and pulse rate readings.

• Continue recording the oxygen saturation and pulse rate at 2 minute intervals.

• Stop riding the bike after 10 minutes then walk slowly around the room to cool down and catch your breath, continue recording the oxygen saturation and pulse rate at 2 minute intervals for another 3 readings.

0 2 4 6 8 10 12 14 16

Graph your results showing two curves, one for % oxygen saturation

Oxygen Saturation

Pulse Rate (BPM)

Time (minutes)

Explain the shape of these curves considering what happens to blood oxygen saturation and pulse rate before, during, and after aerobic activity.

…….....................................................................................................................................................................................

Describe some benefits and limitations of pulse oximetry.

.……………………………………………………………………………………………………………………………………

……....................................................................................................................................................................................

USING MICROSCOPES

The microscope is a major tool of biologists. Through the use of the compound light microscope, knowledge of cell structure was gained and one of the fundamental theories of biology, the Cell Theory, was developed. Without the microscope, we would have very little knowledge of living things too small to be seen by the unaided human eye (e.g. cells and their contents).

During the kidney dissection experiment you will be using these two microscopes:

Figure 1. 0: Dissecting microsco pe Figure 2. 0: Compou nd micro scope

The dissecting microscope is used for the three-dimensional examination of whole organisms, parts of organisms and detailed dissection of organisms. It has two light sources, transmitted and incident illumination. The transmitted light source enables you to illuminate the specimen from below, and the incident light source enables you to illuminate the specimen from above.

Dissecting microscopes are also called ‘stereo’ microscopes as most of them have a double objective sys tem that uses two eyepieces and two objective lenses to give a stereoscopic (3-dimensional image).

The binocular compound microscope is used for detailed examination of thin sections of plant and animal tissues. It has a magnification range of 32X to 1000X . Magnification is calculated as the power of the eye piece times the power of the objective lens e.g. eye piece 10X, objective lens 40X, magnification = 10 x 40

Precautions for Microscope Use

• Microscopes are expensive and delicate instruments – please be gentle.

• If you need to move the microscope, always carry it in an upright position with one hand holding the arm of the microscope and the other supporting the base.

• Never place the microscope close to the edge of the lab bench.

• Never touch the lens of the microscope with your hands; only special lens paper should be used to clean the lenses in the eyepiece and objectives.

• Always turn on the microscope light first, before you look down the eyepiece.

• When you have finished using the microscope, turn off the light and rotate the low-power (short est) objective into viewing position. Never leave the high-power objective in the viewing position.

• Always use the low-power objective to locate the specimen to be studied and bring it into focus using the large focus knob, then turn to the high-power objective for more detail.

• Use the fine focus knob when the high-power objective is in the viewing position.

• When changing to a higher objective lens always watch it from the side (not through the eye piece) to pre vent damaging the objective lens by hitting the stage or slide.

• Ask a Demonstrator for help if you’re having difficulty using the microscope or your microscope is faulty

– do not attempt to make any repairs yourself.

Using the Compound Microscope

Refer to figure 3.0 below to help you identify parts of a compound microscope.

Coar se Focus Knob

Fine Focus Knob

Figure 3.0: Parts of a compound microscope

Rotating No se Piece

Ligh t Source

Setting up the compound microscope to view a slide

1. Ensure the microscope is securely on the bench and everything is in working order.

2. Rotate the nose piece so that the lowest power objective is in position.

3. Obtain a slide (hold it by its edges to avoid fingerprints) and, making sure it is the correct way up with the cover slip on top, put it on the stage and hold it in place with the stage clips.

4. Switch on the microscope light and adjust the light intensity.

5. Using the coarse focus knob and watching from the side of the microscope, wind the stage up until the tip of the low power objective lens is 5mm from the slide.

6. Look through the eyepiece and use the coarse focus knob to slowly move the stage downwards to bring the specimen into focus.

7. Use the fine focus knob to bring the specimen into sharp focus. If necessary move the slide around so that it is in the centre of the field.

8. Adjust the diaphragm until it just fits your field of view.

Using high power

1. First set up for low power examination as detailed above.

2. Find the part of the slide to be examined under low power first, centre it in the field of view, then carefully rotate the nose piece until the next highest power objective is in position.

3. Use the fine focus knob to bring the specimen into sharp focus and re-centre it in the field of view.

4. Rotate the highest objective lens into position and refocus and re-centre the slide.

5. If necessary adjust the diaphragm and condenser to give the sharpest and brightest image possible .

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