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Thames & Kosmos 635213, Experiment Manual

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Detectives on the Trail

25

       DID YOU KNO

W?

There are research

ers who claim  

that the number o

f microorganisms 

living on and insid

e our body is 

greater than the n

umber of all our 

body’s cells. But d

on’t worry! Most o

f 

these living things a

re not harmful to 

us, and in any case o

ur body possesses 

a lot of defense m

echanisms against 

any microorganism

s that might cause 

diseases. 

EXPLANATION

The number of legs that a dust mite has 

— you can see eight of them under the 

microscope — is an indication of the 

close relationship between mites and 

spiders. Along with scorpions, spiders, 

and ticks, mites belong to a family 

known as arachnids. True insects, by 

contrast, have just six legs.

Summary of Contents for 635213

Page 1: ...anual carefully Not to be used by children except under adult supervision Franckh Kosmos Verlags GmbH Co KG Pfizerstr 5 7 70184 Stuttgart Germany 49 0 711 2191 0 www kosmos de Thames Kosmos 301 Friendship St Providence RI 02903 USA 1 800 587 2872 www thamesandkosmos com Thames Kosmos UK Ltd Goudhurst Kent TN17 2QZ United Kingdom 01580 212000 www thamesandkosmos co uk ...

Page 2: ...he supply terminals are not to be short circuited A short circuit can cause the wires to overheat and the battery to explode The battery is to be inserted with the correct polarity Press it gently into the battery compartment Follow the instructions on the inside back cover Always close the battery compartment with the lid after installing the battery Non rechargeable batteries are not to be recha...

Page 3: ... 2 slides pipette 1 glass of tap water 1 newspaper HERE S HOW 1 Use the pipette to place a drop of water on the slide see illustration and carefully set the slide on the newspaper Now look through the drop at the newspaper page 2 Next place another drop of water on the second slide and hold this second slide above the first one in such a way that you can look through both water drops to the newspa...

Page 4: ...towels white paper letter size newspaper razor blade fabric tape permanent marker cotton swabs polystyrene foam pieces string small plastic bags pocket knife plastic bag with gravel or sand wine cork desk lamp Also for viewing under the microscope Onion elodea waterweed pine needle raw meat hair and fabric samples dust sample honey more precise descriptions accompany each experiment TIP You can us...

Page 5: ...edles in the slicing tool and as specimens under the microscope Animal Cells and Guinea Pigs 18 A size comparison between two really different animal muscle cells types Detectives on the Trail 22 Fibers and hair samples reveal the perpetrator Uncover the house dust mite in the vacuum cleaner bag Gateway to the Microcosm 26 Build your own algae collecting device and examine flower pollen in honey P...

Page 6: ...lenses wipe it off carefully with a soft dry cloth Your Microscope s Lenses CAUTION Never touch the lenses with your fingers and be careful not to let the lens in the eyepiece or nosepiece bump against other objects Dirtied or scratched lenses will not produce a sharp image Eyepiece lens Eye Light source Actual intermediate image plane Intermediate lens Objective lens Slide Stage Diaphragm Apparen...

Page 7: ... will be getting to know the microscope and all of its accessories The most important parts of the microscope will be explained and the experiments will help you learn practical tips for using the microscope and exploring the world of cells ...

Page 8: ...t through depending on its size Always start by selecting the largest diaphragm setting 3 Take the prepared slide and clamp it under the clips on the stage The specimen should be positioned as precisely as possible over the center of the stage opening so it is well illuminated by the bulb TIP Before turning the microscope upside down in order to remove the lighting unit for battery replacement or ...

Page 9: ...urry image it is because the two lenses in the eyepiece and the nosepiece are not yet at the optimum distance from each other To get a clear enlarged image the distance between the lenses just as with the two drop microscope in the first experiment will have to be adjusted To do this slowly turn the fine adjustment knob while looking through the eyepiece and you will get a clear image If you don t...

Page 10: ...pe When you do this you will cover the specimen with a cover slip in order to get the best image and protect the specimens from getting dirty Use the sharp dissecting needle be careful when you want to place or move a specimen on the slide The tweezers and sample container will come in handy when you re searching for new specimens The objects that you view under the microscope will have to be very...

Page 11: ...y have thick edges cell walls The wool sheep s hair is thick and round hollow and with scaly cell walls Silk by contrast is a lot thinner with no hollow interior with a smooth and even surface that makes it look similar to an artificial fiber such as polyester or nylon TIP You can use the mirror for illumination instead of the light bulb With the proper adjustment you can use it to guide the light...

Page 12: ...the they feed themselves they grow they reproduce and they consist of tiny building blocks called cells Most plant or animal cells are incredibly small To study them you need a microscope That s the only way that you can see and study all their tiny structures 10 ...

Page 13: ...towel 2 3 EXPLANATION You will see the elongated onion skin cells each one with a round cell nucleus In red onions the walls and contents of the cell are colored reddish purple by a natural pigment With white or yellow onions the translucent cell walls and contents appear colorless to slightly yellow under the microscope EXPERIMENT 3 CAUTION Razor blades are very sharp so the first thing you have ...

Page 14: ...owever CHECK IT OUT An onion is composed of many layers with each individual layer covered by a very thin skin This skin has a silvery sheen and consists of just a single layer of cells You can easily view this prototypical plant cell under the microscope a typical cell with a large round cell nucleus The living portion of the elongated cells is surrounded by a protective cell wall The cytoplasm t...

Page 15: ...r Repeat if necessary Plant Cells Waterweed cells Draparnaldia algae The green color of plant cells comes from tiny leaf green structures that biologists call chloroplasts You can very easily study the way these green granules look and move in the elodea waterweed a common aquarium plant Its leaves consist of just two layers of cells so they can be viewed directly under the microscope without any ...

Page 16: ...e lamp The green chlorophyll plant pigment is important for manufacturing sugar and starch which it does with the help of sunlight TIP Most leaves consist of several layers of cells That is why you first have to cut these specimens in order to get layer thin enough for the light of the microscope to penetrate Before practicing your cutting technique in the next chapter try finding other types of p...

Page 17: ...ody and the brain controls it all With plants by contrast you will find many different structures depending on where the plant grows The corresponding tasks in plant bodies are handled by specialized cell tissues In leaves stalks and roots you will discover a lively division of labor It is especially easy to see the various cell tissue types in a cross section of a pine needle or other conifer nee...

Page 18: ...ou will have to stay sharp too The dissecting needle is also sharp Be careful using both tools TIP You will always need a sharp razor blade to cut your specimens The blade that comes with the kit will become dull over time Be absolutely sure to have an adult help you change the blade Making thin slices is an art unto itself and it requires time and practice It s always best to prepare several slic...

Page 19: ...edge you can easily see the outer cuticle covering composed of lots of small cells 2 Set the slicing tool on its base and turn the handle until you can no longer see the silver blade through the oblong openings Insert the pine needle through one of the slicing tool openings 3 Now slowly turn the handle until the pine needle has been completely cut through 4 Turn the blade back again and make anoth...

Page 20: ... little ones Or is it just that their bodies are composed of more cells If you can find an adult willing to serve as a guinea pig you will be able to answer these questions easily enough Let s assume you are about 4 feet 1 3 meters tall and your adult guinea pig is 6 feet 1 8 meters tall In that case the guinea pig s cells would have to be at least about one and a half times the size of yours assu...

Page 21: ... Prepare a second slide and ask your guinea pig to provide a tissue sample using the second cotton swab 5 Cover both samples with cover slips and compare the cell sizes of the two specimens under the microscope EXPLANATION When you rub the inside of your cheek with the cotton swab it releases cells from the mucous membrane These cells are then transferred to the slide where you can observe them un...

Page 22: ...e center of each one with the pipette 2 Have an adult help you cut off a lentil sized piece of meat and an equal sized piece of fat 3 Carefully maneuver these two samples into the water droplets on the slides with the help of the dissecting needle and the tweezers Remove any thick non transparent pieces from the slide 4 Cover both specimens with a cover slip and observe them in turn under the micr...

Page 23: ... in the droplets of oil inside the fat cells There are dozens of different types of cell in our bodies such as skin bone blood and nerve cells Each one of these cell types has its own special work to do and each looks different from the others Fat cells in the skin DNA sample DID YOU KNOW All plant and animal cells have a cell nucleus that contains the genetic information DNA Unlike animal cells h...

Page 24: ...chen last night Who was the hungry culprit The first thing to do is to collect any possible pieces of evidence such as hair or clothing fibers from around the scene of the crime and save them in a special sample container Then you will need samples from all the suspects for comparison Collect a hair or a thread from the pajamas of each of the suspected perpetrators and pack each one into a separat...

Page 25: ...tor detectives Who was the perpetrator YOU WILL NEED Slides cover slips pipette sample container tweezers natural fibers prepared slide Water various hair and fiber samples from around the house small plastic bags reseal able 1 permanent marker for identifying the bags and slides HERE S HOW 1 Prepare several slides by placing a drop of water onto the center of each one with the pipette 2 Set the h...

Page 26: ...WILL NEED 1 Slide 1 cover slip pipette tweezers Water 1 sheet of white letter size paper sample from the vacuum cleaner bag desk lamp kitchen sieve HERE S HOW 1 Place a dust sample in a fine meshed kitchen sieve and shake the sieve gently over the sheet of paper Little dust particles and a few mites will fall onto the sheet when you do that 2 House mites don t like air that is too warm or dry As s...

Page 27: ...are not harmful to us and in any case our body possesses a lot of defense mechanisms against any microorganisms that might cause diseases EXPLANATION The number of legs that a dust mite has you can see eight of them under the microscope is an indication of the close relationship between mites and spiders Along with scorpions spiders and ticks mites belong to a family known as arachnids True insect...

Page 28: ...e just the thing to carry them The preferred hunting grounds for microorganisms are algae filled pools the edges of ponds rain barrels puddles and plant pot saucers It s also worth using the dissecting needle to scrape off some rocks that have been lying around in water for a while and collect the scrapings with a little water in the sample container Water flea Daphnia ...

Page 29: ...e top end of the string to serve as a float and tie the sand filled bag to the bottom end to serve as an anchor or sinker 4 Mark the slides with a symbol or H1 H2 horizontal and V1 V2 vertical and take the collecting station to a pond 5 After about a week or two bring your pond specimen collection station home in a bucket of pond water Before you look at your prey under the microscope wipe one sid...

Page 30: ... on a fixed surface Every animal or plant species has its own preferences in this regard Some look for sunny horizontal spots while others prefer to settle on vertical surfaces On the surface of the water you will often find flower pollen such as pine pollen which is spread by the wind In the water itself there are all sorts of algae single celled organisms and a lot of other aquatic organisms tha...

Page 31: ...pped harpoons with which it shoots its prey upon contact wounding or killing it While some polyps are visible with the naked eye some are up to 2 5 cm long their prey can only be seen under the microscope The World of Microbes in Our Water Systems Gateway to the Microcosm TIP First study the water samples with your naked eye A lot of specimens such as water fleas and some diatoms can easily be see...

Page 32: ...ater glass Then set the spoon on the saucer 3 Now use the pipette to suction up a little of the solution one sample from the bottom of the glass and one from higher up and drip the two samples onto the two slides 4 Place a cover slip on each slide carefully blot up any extra liquid and study the samples under different levels of magnification using the microscope s different color filters 5 After ...

Page 33: ...honey is often mixed together with other types resulting in a mixture of different kinds of pollen from the various field forest and meadow plants that the bees feed on Pure types of honey are more expensive to produce and therefore cost more In your honey sample you will see various pollen shapes and structures and you might even be able to check whether the honey really does come from the source...

Page 34: ...om head to foot You shouldn t be surprised then if a few of those pollen grains end up in the honey Pollen grains are interesting objects to study under a microscope You will be able to discover lots of different shapes and surface structures among them The round prickly pollen of a sunflower for example looks completely different from the air bladder equipped pollen grains of a pine tree or spruc...

Page 35: ...uld assist with installation or replacement of the battery 1 Remove the lighting unit from the microscope Gently pull the lighting unit holder arms 1 apart so that the retaining pins 2 can be pushed out of the retaining holes 3 2 Open the lighting unit by removing the screw 4 with a small Phillips head screwdriver Remove the top half from the bottom half 3 To install a fresh battery you need to fi...

Page 36: ...Nehring p 30 m p 31 mr bl Pagade sign p 25 tr PeJo29 p 19 tr twobluedogs p 4 br Zmeel Photography p 21 bl all previous istockphoto de M Ba chofer Stuttgart p 1 m p 9 tl mb bl p 12 r p 13 tl p 15 p 16 br p 17 m bl p 19 m p 20 m p 24 b p 29 bl Dr Gerd Betz Aichwald p 3 br p 23 br p 26 p 28 tl bl p 29 tr p 31 ml Stephen Durr London p 3 mt p 10 b p 28 m C Rayhle Bietigheim p 2 F Werth Horb p 6 p 7 all...

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