LAB QUIZ - 2

Question 1

Pre-Focusing Knob

Answer 1

Controls the mechanism for preventing collision between the specimen and objective.

Question 2

Coarse Adjustment Knob

Answer 2

Used to adjust the height of the stage so that the specimen can be brought into focus.

Question 3

Fine Adjustment Knob

Answer 3

Used to finely adjust the height of the stage so that the specimen can be brought into focus. The increments are lesser than that of the Coarse Adjustment Knob.

Question 4

Stage Controls [x-axis]

Answer 4

Controls the stage for the x-axis [back and forth].

Question 5

Stage Controls [y-axis]

Answer 5

Controls the stage for the y-axis [left and right].

Question 6

Light Switch

Answer 6

Used to turn on and off the light of the microscope.

Question 7

Brightness Adjustment

Answer 7

Used to regulate the intensity of the light.

Question 8

Illuminator [light source]

Answer 8

Used to produce light to enlighten the specimen. Light source of the microscope.

Question 9

Iris Diaphragm

Answer 9

Used to control the amount of light that is admitted into the condenser.

Question 10

Condenser Lens

Answer 10

Concentrates the light on a specimen and increases the resolution

Question 11

Condenser Adjustment Knob

Answer 11

Used to reduce to reduce the amount of light and increase the contrast of the image by moving the condenser lens up and down.

Question 12

Objective Lenses

Answer 12

Used to magnify specimen. It is the second point of magnification after the Ocular lenses.

Question 13

Nose piece [Revolving Turret]

Answer 13

Holds the objective lenses and revolves to give access to the other lenses.

Question 14

Diopter Adjustments

Answer 14

Used to change the focus on one eyepiece to compensate for difference between your own two eyes.

Question 15

Ocular lenses

Answer 15

Used to look through the microscope and is the first point of magnification which usually has a strength of 10X.

Question 16

Stage clip

Answer 16

Used to hold the specimens and the plates for viewing

Question 17

Equation Field of View?

Answer 17

[Total magnification scanning lens]/[total magnification of Lens M] *[Diameter of field of view in scanning lens] = Diameter of the field of view when it on lens M

Question 18

Parcentric

Answer 18

when you change objectives the centred specimen should remain somewhat centred

Question 19

Parfocal

Answer 19

the specimen remains in rough focus when the objective is changed.

Question 20

Relationship between the Total magnification and the field of view?

Answer 20

As the magnification increases, one sees less of the specimen. In other word, the field of view decreases. However, one gains the ability to see in greater detail the specimen. Namely, one gets see a smaller portion of the specimen, but in return get to see in greater detail a given part of the specimen.

the field of view and total magnification are inversely proportional.

Question 21

what happens when objective is increased to the highest power?

Answer 21

As the total magnification increases, the field of view decreases and so does the diameter of area observe. This indicates that as the magnification increases, one can see less of the specimen. Nonetheless, one gains the ability to see the specimen in greater details.

similarly, the relative are also decrease when the magnification is increase. In other words, the magnification and the relative area are inversely proportional.

Question 22

equation for total magnification

Answer 22

Ocular X objective = total magnification

Example: 4.5X x 10X = 45X

Question 23

ocular micrometer

Answer 23

this is a scale, fitted into a ocular lens, whose image appears imposed onto your specimen. Unit are Ocular units [o.u]

need a constant to transfer them into µm.

Question 24

Graphical interpretation

Answer 24

Smallest to biggest

bacteria < Animal cell < plant cell ~ euglena < paramecia < Amoeba

Question 25

Elodea

Answer 25

Anacharis canadensis / Eukarya / Plantae

o Cell size: (110 x 20) µm
o Autotroph by photosynthesis (photoautotroph)
o Visible organelles: cell wall; cytoplasm; chloroplast.
o Organelles not visible but present: plasma membrane; nucleus; central vacuole.
o Particular motility: cytoplasmic streaming

Question 26

Paramecium

Answer 26

Paramecium caudatum / Eukarya / Protista

o (200 x 80) µm
o Holozoic Heterotrophic
o Visible organelles: Contractile vacuole, cilia, macronucleus, plasma membrane, oral groove, cytoplasm, food vacuoles
o Organelles not visible but present: cytopharynx, buccal cavity, vestibule, micronucleus
o Particular motility: whiplash movements of the cilia

Question 27

Amoeba

Answer 27

Amoeba proteus / Eukarya / Protista

o Cell size: (212.5 X 250) µm
o Heterotrophs by phagocytosis
o Visible organelles: cell membrane; nucleus; pseudopodium; food vacuoles
o Particular motility: Amoeboid motion led by their pseudopodia

Question 28

Euglena

Answer 28

Euglena gracilis / Eukarya / Protista

o Cell size: 11 X 114 µm
o Photoautotrophs
o Visible organelles: paramylon body, body wall (pellicle), locomotor flagellum, vacuole, nucleus, endosome, chromatophores, cytoplasm
o Organelles not visible but present: stigma, paraflagellar body (photo receptor), reservoir, contractile vacuoles, pyrenoid, stria
o Particular motility: locomotor flagellum

Question 29

Common bacteria

Answer 29

cocci / Bacteria
(spherical) / Bacteria
(spherical)

Cell size: 1 X 1 µm
Mode of nutrition:  can be autotrophic and heterotrophic
Visible organelles: Cell Wall and round shape
Particular motility: flagella

Question 30

Human/animal cell

Answer 30

Homo sapiens / Eukarya / Animalia

Cell size 12 X 20 µm
Mode of nutrition: heterotrophic
Visible organelles: nucleus, nucleolus, cytoplasm, cell membrane
Organelles not visible but present: Mitochondrion, ribosome, lysosome, golgi, vacuole, Endoplasmic reticulum (smooth and rough), chloroplast
Particular motility: flagellar motility

Question 31

link with cell theory [bacteria missing

Answer 31

Eukaryotic organisms are bigger and more complex than other domains which can be visualized with section 3. They are compartmentalised since they have membrane bound organelles, which have specific specialized functions. For instance, organelles were observed namely, a double membraned nucleus in certain organisms. These cells can be found in the following kingdoms: Animalia, Plantae, Fungi, and protist. Moving on, the procured data can be used to support the cell theory. It is evidently suggested from the diagram images in section 4 that all organisms are composed of one or more cell which is mostly observed from the cells of kingdom animalia and plantae, since they form structures of with similar cells. To add on, the data supports the cell theory proclaiming that cells are the smallest living things, since we have observed a living unicellular organism such as an amoeba. With a conversion in units, it was possible to obtain its cell size in micrometers using a compound microscope and an ocular micrometer. This points out the fact that cells are so small in sized and invisible to the naked eye to the point that the use of several materials is needed to be able to perceive it. However, the data does not confirm the last part of the cell theory which states that: “cells can only arise by the division a pre-existing cell” because such event was not observed.

Question 32

Cell theory

Answer 32

1 -all living organisms are composed of one or more cells.

2- The cell is the basic unit of structure and organization in organisms.

3- Cells arise from pre-existing cells.

Question 33

Permanent Mount

Answer 33

specimens have been treated and preserved for long term use.

Question 34

Wet-Mount

Answer 34

temporary mount of living specimen

Question 35

Elodea - Aquatic plante [teacher’s description]

Answer 35

Young leaves at the growing tip of Anacharis canadensis are commonly examined for cell structure
because the leaves are only a few cells thick. However there are still too many layers to easily view a single cell, so try to rip the leaf to create a thin section. Focus on the ripped side with your microscope. Look very carefully at the architecture of cells before you decide what a single cell actually looks like. Notice that by focusing up and down with the fine focus many layers of cells become visible. Also notice that the cell wall appears to be a double lined structure. The cell wall is actually only one line. The second line comes from the surrounding cells. Since you are drawing only ONE cell, be sure to only have one line indicating the cell wall.

If the plant cell is left on the stage long enough you may be able to observe cytoplasmic streaming. The chloroplasts inside one cell mysteriously begin to circulate around the invisible, ventral vacuole.
Be able to locate, label and identify: cell wall (note that a plasma membrane exists as well, but is not visible due to the presence of a cell wall), cytoplasm, chloroplast (draw only a few but be true to size and shape), the nucleus often is not be visible unless stained, and if cytoplasmic streaming occurs you may use the motion of the chloroplasts to outline the central vacuole using dashed lines as the chloroplasts circulate around it.

Question 36

Protista [teacher’s description]

Answer 36

Of the four eukaryotic kingdoms, the oldest and most diverse is the Protists. The Protista taxon is generated by organisms that do not fit readily into the other Kingdoms as they lack the distinguishing features of animals, plants or fungi, so are labelled as are Protists. Thus single celled forms such as amoeba and euglena are lumped, somewhat uneasily, with slime molds and huge multicellular algae such as kelp.
Protists perform all manner of ecological roles. Some are pathogens, causing plant and animal diseases such as malaria and sleeping sickness. Others aid bacteria and fungi as decomposers, breaking down and recycling the waste products of life. Some Protists live symbiotically in or on other life forms, which may include living in or on other Protists.
Protists vary nutritionally. Some are heterotrophs (consumers) that engulf their food, others absorb organic molecules through their surface. The heterotrophic Protists are the so-called protozoa. Most protozoa are motile, moving about using cilia, flagella or pseudopods. Protists may generally be distinguished by their modes of locomotion or peculiarities of their life cycles. They live in aquatic environments. Others are autotrophic having photosynthetic. Some oddities like the Euglenoids have the ability to be both autotrophic and heterotrophic.

Question 37

Euglena (plant-like protist) [teacher’s description]

Answer 37

As Euglena actively swim throughout their culture vessel, any drop of green culture fluid should show them in enormous numbers. Prepare a wet mount and look for tiny dust sized particles under the scanning lens. Gradually increase magnification to the high-dry lens for most of your observations, as these cells are quite small.
Euglena are small tear-drop shaped, unicellular, usually photosynthetic protists with a single, whip like flagellum that may be visible at 400X . It projects from the end nearest the eyespot (a red pigmented structure). If you adjust the lighting quite critically by closing down the diaphragm to reduce glare you should be able to see not only the flagellum at the pointed end of the cell but also chloroplasts in the cytoplasm and perhaps the clear region of the nucleus.
Cells with free flagella may show either of two different methods of locomotion. Whiplash flagella push the cells, as is the case of human sperm cells; while tinsel flagella pull them. Which type is seen in Euglena?

Question 38

Paramecium [teacher’s description]

Answer 38

Paramecium is a typical free-living ciliate (possess cilia) which is cigar shaped. These complex heterotrophic protozoans cruise smoothly through the water propelled by thousands of rippling cilia covering most of their surface. They feed by sweeping bacteria into a slit on their “side” (the oral groove or gullet) where they are collected in food vacuoles. These food vacuoles follow a looping path around the cell, ending at the anal pore, where waste is discharged. Two contractile vacuoles pump osmotically accumulated water out of the cell at regular intervals. A video-clip of Paramecium feeding and the activity of the contractile vacuoles is available.
Don’t let the paramecia get away without observing them closely! Slow them down by adding a small drop of methylcellulose (ProtosloTM) to your wet mount before adding the organism. This compound is highly viscose (thick as molasses) thus hindering the movement of organisms

Question 39

what is “drop of methylcellulose (ProtosloTM)”

Answer 39

This compound is highly viscose (thick as molasses) thus hindering the movement of organisms

Question 40

Amoeba [Teacher’s description]

Answer 40

Amoeba cells change shape from moment to moment. They literally flow across surfaces from place to place using amoeboid motion, led by their pseudopodia (pl.) or “false feet” produced by flowing cytoplasm. They engulf their food and take it inside by phagocytosis. This involves encircling the food with their body, forming a food vacuole. It maintains homeostasis between the internal and external watery environment by expelling internal buildup of water through the contractile vacuoles.
Locate the amoeba on the bottom of the culture vessel using a stereo microscope. They look like miniature dust-bunnies and usually float near or adhere to the bottom of the vessel. Carefully suck one or two into the tip of a Pasteur pipette and immediately transfer the drop to a slide. Place the slide under the stereo microscope to verify if you captured the organism. Let the slide rest to give the organism time to settle on the bottom.

Question 41

common Bacteria. [Teacher’s description]

Answer 41

Prokaryotic cells are non-eukaryotic cells that constitute, by far the majority of cells on earth; their small size makes detailed examination by light microscopy next to impossible. Observe a sampling of prokaryotes set up as a demonstration in the lab. The organisms you will see represent the different shapes bacterial cells possess. Cocci are spherical, bacilli are rod shaped and spirochetes are spiral. All are covered by a durable cell wall composed of peptidoglycan. The cell wall is the only visible structure for these tiny cells.

Question 42

4x

Answer 42

Scanning lens

Question 43

10X

Answer 43

Mid range lens

Question 44

40x

Answer 44

High and dry lens

Question 45

Heterophic protist

Answer 45

Protozoa