1Which type of tissue is observed in a human cheek cell preparation?
Observation of human cheek epithelial cells
Easy
A.Nervous tissue
B.Epithelial tissue
C.Connective tissue
D.Muscle tissue
Correct Answer: Epithelial tissue
Explanation:
The inner lining of the cheek is made of epithelial tissue.
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2Which instrument is commonly used to collect cells from the inside of the cheek?
Observation of human cheek epithelial cells
Easy
A.Sterile cotton swab
B.Plastic forceps
C.Glass stirring rod
D.Metal ruler
Correct Answer: Sterile cotton swab
Explanation:
A sterile cotton swab can gently collect cells from the cheek lining.
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3Where are cheek epithelial cells collected from?
Observation of human cheek epithelial cells
Easy
A.Back of the hand
B.Inside the cheek
C.Surface of the tongue
D.Tip of the nose
Correct Answer: Inside the cheek
Explanation:
Cheek epithelial cells are collected from the inner surface of the cheek.
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4Why is a stain used when observing cheek cells?
Observation of human cheek epithelial cells
Easy
A.To make cells move faster
B.To make cell structures clearer
C.To increase cell size
D.To prevent light from passing
Correct Answer: To make cell structures clearer
Explanation:
A stain increases contrast, making structures such as the nucleus easier to see.
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5Which stain is commonly used to observe the nucleus in cheek cells?
Observation of human cheek epithelial cells
Easy
A.Iodine vapor
B.Safranin powder
C.Methylene blue
D.Sudan III
Correct Answer: Methylene blue
Explanation:
Methylene blue commonly stains the nucleus of cheek epithelial cells.
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6Which structure usually appears darker after staining cheek cells?
Observation of human cheek epithelial cells
Easy
A.Chloroplast
B.Vacuole
C.Nucleus
D.Cell wall
Correct Answer: Nucleus
Explanation:
The nucleus takes up the stain and usually appears darker than the surrounding cytoplasm.
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7Which microscope part is used to support the glass slide?
Observation of human cheek epithelial cells
Easy
A.Fine adjustment knob
B.Eyepiece
C.Diaphragm
D.Stage
Correct Answer: Stage
Explanation:
The stage is the flat platform that supports the slide.
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8What is placed over the cheek-cell sample before viewing?
Observation of human cheek epithelial cells
Easy
A.Rubber stopper
B.Filter paper
C.Cover slip
D.Test-tube cap
Correct Answer: Cover slip
Explanation:
A cover slip spreads over and protects the sample for microscope observation.
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9What is the main purpose of a cover slip?
Observation of human cheek epithelial cells
Easy
A.To stain the sample blue
B.To remove the cell membrane
C.To increase the sample temperature
D.To flatten and protect the sample
Correct Answer: To flatten and protect the sample
Explanation:
A cover slip helps keep the sample thin, flat, and protected.
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10Which structure controls many activities of a cheek cell?
Observation of human cheek epithelial cells
Easy
A.Nucleus
B.Cell membrane
C.Cytoplasm
D.Ribosome
Correct Answer: Nucleus
Explanation:
The nucleus contains genetic material and controls many cell activities.
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11Which structure surrounds the cytoplasm of a cheek cell?
Observation of human cheek epithelial cells
Easy
A.Chloroplast
B.Cell membrane
C.Capsule
D.Cell wall
Correct Answer: Cell membrane
Explanation:
The cell membrane forms the outer boundary of an animal cell.
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12Which structure fills much of the inside of a cheek cell around the nucleus?
Observation of human cheek epithelial cells
Easy
A.Chlorophyll
B.Starch grain
C.Cell wall
D.Cytoplasm
Correct Answer: Cytoplasm
Explanation:
Cytoplasm is the material inside the cell membrane that surrounds the nucleus.
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13Human cheek epithelial cells are classified as which kind of cells?
Observation of human cheek epithelial cells
Easy
A.Bacterial cells
B.Animal cells
C.Fungal cells
D.Plant cells
Correct Answer: Animal cells
Explanation:
Cheek cells come from the human body, so they are animal cells.
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14Which structure is absent from normal human cheek cells?
Observation of human cheek epithelial cells
Easy
A.Cell membrane
B.Nucleus
C.Cell wall
D.Cytoplasm
Correct Answer: Cell wall
Explanation:
Human cheek cells have a cell membrane but do not have a cell wall.
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15Which objective should usually be used first when focusing a cheek-cell slide?
Observation of human cheek epithelial cells
Easy
A.Oil-immersion objective
B.Special dark-field objective
C.Lowest-power objective
D.Highest-power objective
Correct Answer: Lowest-power objective
Explanation:
Starting with the lowest power makes it easier to locate and focus the specimen.
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16What should be done before placing a cheek-cell slide on the microscope stage?
Observation of human cheek epithelial cells
Easy
A.Prepare and cover the sample
B.Remove the eyepiece
C.Heat the microscope
D.Paint the slide surface
Correct Answer: Prepare and cover the sample
Explanation:
The sample should be prepared on a slide and covered before microscopic observation.
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17What is the usual shape of a cheek epithelial cell when viewed under a microscope?
Observation of human cheek epithelial cells
Easy
A.Flat and irregular
B.Rectangular and green
C.Long and branched
D.Round and thick-walled
Correct Answer: Flat and irregular
Explanation:
Cheek epithelial cells are generally flat with irregular or roughly polygonal outlines.
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18Which feature distinguishes cheek cells from typical plant cells?
Observation of human cheek epithelial cells
Easy
A.They lack chloroplasts
B.They have a rigid cell wall
C.They contain chloroplasts
D.They have a large central vacuole
Correct Answer: They lack chloroplasts
Explanation:
Cheek cells are animal cells and do not contain chloroplasts.
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19Why should a cheek-cell sample be handled with a clean tool?
Observation of human cheek epithelial cells
Easy
A.To increase cell division
B.To reduce contamination
C.To change the cell shape
D.To produce more nuclei
Correct Answer: To reduce contamination
Explanation:
Using a clean tool helps prevent unwanted microorganisms or materials from entering the sample.
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20Which microscope control is used to make small focusing adjustments?
Observation of human cheek epithelial cells
Easy
A.Stage clip
B.Revolving nosepiece
C.Light switch
D.Fine adjustment knob
Correct Answer: Fine adjustment knob
Explanation:
The fine adjustment knob makes small changes to sharpen the image.
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21Why is a clean toothpick or sterile swab used to collect cheek cells?
Observation of human cheek epithelial cells
Medium
A.To make the nucleus disappear
B.To dissolve the cell membrane
C.To reduce contamination of the sample
D.To increase the cell size
Correct Answer: To reduce contamination of the sample
Explanation:
Using a clean collection tool helps prevent bacteria, food particles, and other materials from being mistaken for cheek-cell structures.
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22What is the main purpose of placing a drop of methylene blue on a cheek-cell preparation?
Observation of human cheek epithelial cells
Medium
A.To remove excess cytoplasm from the cells
B.To stain the nucleus for easier observation
C.To increase the magnification of the microscope
D.To make the slide permanently sterile
Correct Answer: To stain the nucleus for easier observation
Explanation:
Methylene blue binds to cellular components, especially the nucleus, increasing contrast between the cell and the background.
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23A student sees many irregular, flat, transparent structures after preparing a cheek-cell slide. Which observation best supports that these are cheek epithelial cells?
Observation of human cheek epithelial cells
Medium
A.They have visible nuclei after staining
B.They form organized vascular bundles
C.They have rigid cell walls
D.They contain many chloroplasts
Correct Answer: They have visible nuclei after staining
Explanation:
Human cheek epithelial cells are animal cells without cell walls or chloroplasts, and their stained nuclei are commonly visible.
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24Why should a coverslip be lowered at an angle onto the cheek-cell sample?
Observation of human cheek epithelial cells
Medium
A.To change the cells into a cuboidal shape
B.To increase the cell division rate
C.To prevent or reduce trapped air bubbles
D.To make the nucleus chemically larger
Correct Answer: To prevent or reduce trapped air bubbles
Explanation:
Lowering the coverslip gradually from one side allows air to escape and produces a clearer field of view.
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25A student begins viewing a cheek-cell slide with the objective. What is the most appropriate correction?
Observation of human cheek epithelial cells
Medium
A.Remove the coverslip before focusing
B.Begin with the lowest-power objective
C.Use only the fine-adjustment knob immediately
D.Add stain while the objective touches the slide
Correct Answer: Begin with the lowest-power objective
Explanation:
Starting with low power makes it easier to locate the specimen and focus safely before increasing magnification.
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26If the eyepiece is and the objective is , what is the total magnification?
Observation of human cheek epithelial cells
Medium
A.
B.
C.
D.
Correct Answer:
Explanation:
Total magnification is calculated by multiplying eyepiece magnification by objective magnification: .
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27A cheek cell appears larger when the objective is changed from to . What happens to the field of view?
Observation of human cheek epithelial cells
Medium
A.It becomes narrower
B.It becomes wider
C.It becomes completely colorless
D.It remains exactly the same
Correct Answer: It becomes narrower
Explanation:
Increasing magnification enlarges the image but reduces the area visible through the microscope.
Incorrect! Try again.
28Which structure forms the flexible outer boundary of a human cheek epithelial cell?
Observation of human cheek epithelial cells
Medium
A.Large central vacuole
B.Cell membrane
C.Cell wall
D.Chloroplast
Correct Answer: Cell membrane
Explanation:
Animal cells, including cheek cells, are surrounded by a selectively permeable cell membrane rather than a rigid cell wall.
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29Why are cheek epithelial cells suitable for a basic microscope investigation?
Observation of human cheek epithelial cells
Medium
A.They have unusually thick cell walls
B.They contain visible chloroplasts
C.They are easily collected from the mouth
D.They are naturally arranged in leaf tissue
Correct Answer: They are easily collected from the mouth
Explanation:
Cheek cells can be collected without invasive procedures and are thin enough to observe after staining.
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30A student observes dark blue spots inside several cheek cells. These spots most likely represent the:
Observation of human cheek epithelial cells
Medium
A.Nuclei
B.Extracellular mucus layer
C.Mitochondrial membranes
D.Cell walls
Correct Answer: Nuclei
Explanation:
Methylene blue commonly produces a dark stain in the nucleus, making it easier to identify within the cell.
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31What is the most likely result if a cheek-cell smear is too thick?
Observation of human cheek epithelial cells
Medium
A.The cells develop rigid walls during observation
B.The microscope automatically increases contrast
C.Every nucleus becomes perfectly transparent
D.Individual cell boundaries become difficult to distinguish
Correct Answer: Individual cell boundaries become difficult to distinguish
Explanation:
A thick smear causes cells to overlap, making it harder to identify their boundaries and internal structures.
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32Which technique would most likely produce a clearer cheek-cell image?
Observation of human cheek epithelial cells
Medium
A.Use a thin smear and adequate stain
B.Use several coverslips at once
C.Leave the slide completely unstained
D.Scrape the cheek repeatedly until tissue clumps
Correct Answer: Use a thin smear and adequate stain
Explanation:
A thin, evenly stained preparation reduces overlap and improves contrast, allowing cell structures to be seen more clearly.
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33Why should a student avoid pressing hard while scraping the inside of the cheek?
Observation of human cheek epithelial cells
Medium
A.It causes the microscope lens to lose magnification
B.It prevents methylene blue from staining nuclei
C.It converts epithelial cells into plant cells
D.It may injure the tissue and cause bleeding
Correct Answer: It may injure the tissue and cause bleeding
Explanation:
Gentle scraping is sufficient to collect epithelial cells while reducing discomfort and the risk of damaging the cheek.
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34A student cannot find the cheek cells after switching to high power. What should the student do first?
Observation of human cheek epithelial cells
Medium
A.Move the slide rapidly in all directions
B.Remove the objective and clean the specimen
C.Increase the amount of immersion oil
D.Return to low power and relocate the specimen
Correct Answer: Return to low power and relocate the specimen
Explanation:
The specimen is easier to locate at low power, after which it can be centered and viewed at higher magnification.
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35Which feature would distinguish a cheek epithelial cell from a typical onion epidermal cell?
Observation of human cheek epithelial cells
Medium
A.The cheek cell is surrounded by cellulose
B.The cheek cell lacks a rigid cell wall
C.The cheek cell has a large central vacuole
D.The cheek cell contains chloroplasts
Correct Answer: The cheek cell lacks a rigid cell wall
Explanation:
Cheek cells are animal cells, so they have a cell membrane but not the cellulose cell wall found in onion epidermal cells.
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36Why might unstained cheek cells be difficult to observe with a light microscope?
Observation of human cheek epithelial cells
Medium
A.They have little natural contrast against the background
B.They are too large to fit under a coverslip
C.They reflect all light as a metallic surface
D.They contain no cytoplasm at all
Correct Answer: They have little natural contrast against the background
Explanation:
Cheek cells are nearly transparent, so staining increases contrast and makes the nucleus and cell outline easier to identify.
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37A student records that the cheek cells are thin and irregularly shaped. What conclusion is most appropriate?
Observation of human cheek epithelial cells
Medium
A.The cells are likely bacterial colonies
B.The cells are consistent with squamous epithelial tissue
C.The cells are specialized for photosynthesis
D.The cells must be conducting nerve impulses
Correct Answer: The cells are consistent with squamous epithelial tissue
Explanation:
Cheek lining cells are squamous epithelial cells, which are generally flat and irregular in outline.
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38If the microscope image moves left when the slide is moved right, what does this demonstrate?
Observation of human cheek epithelial cells
Medium
A.The stain has damaged the nucleus
B.The microscope reverses image movement
C.The cells are actively migrating
D.The objective is producing chlorophyll
Correct Answer: The microscope reverses image movement
Explanation:
A compound light microscope produces a reversed image, so the specimen appears to move opposite to the direction of slide movement.
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39Which observation would provide the strongest evidence that a dark spot is a nucleus rather than debris?
Observation of human cheek epithelial cells
Medium
A.It lies within a visible cell boundary
B.It has exactly the same color as the slide
C.It appears only where air bubbles are present
D.It is located outside every cell
Correct Answer: It lies within a visible cell boundary
Explanation:
A nucleus should be located inside the cell, whereas debris is often outside cell boundaries or distributed irregularly.
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40Why should the microscope slide be labeled before preparing the cheek-cell sample?
Observation of human cheek epithelial cells
Medium
A.To make the coverslip adhere chemically
B.To prevent all cells from changing shape
C.To increase the brightness of the lamp
D.To identify the specimen and prevent mix-ups
Correct Answer: To identify the specimen and prevent mix-ups
Explanation:
Labeling helps track the sample and distinguish it from other slides during observation and recording.
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41A student observes cheek cells with a compound microscope. The cells appear nearly transparent, and increasing the lamp intensity makes the entire field brighter but does not improve the visibility of the nuclei. Which adjustment would most directly improve nuclear contrast?
Observation of human cheek epithelial cells
Hard
A.Adjust the condenser and diaphragm
B.Increase the ocular lens diameter
C.Increase total magnification
D.Use the coarse-adjustment knob
Correct Answer: Adjust the condenser and diaphragm
Explanation:
Condenser height and diaphragm opening control illumination contrast. Proper adjustment can make stained nuclei more distinct without merely increasing brightness.
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42A cheek-cell smear contains several overlapping cells, making it difficult to determine individual cell boundaries. Which preparation change would best reduce this problem while preserving the cells for observation?
Observation of human cheek epithelial cells
Hard
A.Increase the stain concentration substantially
B.Press the coverslip firmly onto the smear
C.Collect less material and spread it thinly
D.Use the coarse focus at high magnification
Correct Answer: Collect less material and spread it thinly
Explanation:
A thin, even smear reduces overlap and allows cell boundaries to be distinguished. Excessive scraping or pressure can damage or distort the cells.
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43When switching from a objective to a objective, a student loses the image because the specimen moves out of focus. Which interpretation is most accurate?
Observation of human cheek epithelial cells
Hard
A.The ocular lens has produced chromatic aberration
B.The stain has chemically dissolved the cell membrane
C.The microscope has insufficient numerical aperture
D.The microscope is not parfocal or was improperly focused
Correct Answer: The microscope is not parfocal or was improperly focused
Explanation:
A parfocal microscope keeps the specimen nearly focused when objectives are changed. A large focus shift indicates improper initial focusing, incorrect instrument alignment, or a parfocality problem.
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44A student records a cheek cell as measuring 58 ocular divisions with a objective. Calibration shows that one ocular division at this objective equals . What is the estimated cell length?
Observation of human cheek epithelial cells
Hard
A.
B.
C.
D.
Correct Answer:
Explanation:
The estimated length is . The ocular scale must be calibrated separately for each objective.
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45A student calculates cheek-cell size using a calibration factor obtained with the objective but applies it to measurements made with the objective. What is the primary consequence?
Observation of human cheek epithelial cells
Hard
A.The calculated cells will have correct sizes but wrong colors
B.The calculated cells will have random sizes only
C.The calculated cells will be systematically too large
D.The calculated cells will be systematically too small
Correct Answer: The calculated cells will be systematically too large
Explanation:
At higher magnification, each ocular division represents a smaller actual distance. Using the lower-magnification calibration overestimates the specimen dimensions.
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46A cheek-cell preparation shows dark blue granules scattered throughout the cytoplasm, but the nucleus remains poorly defined. Which explanation is most consistent with this observation?
Observation of human cheek epithelial cells
Hard
A.The cells were necessarily prokaryotic
B.The specimen contains only cell walls
C.The objective lens lacks magnifying power
D.The cells were stained unevenly or overstained
Correct Answer: The cells were stained unevenly or overstained
Explanation:
Uneven or excessive stain can produce cytoplasmic precipitates and obscure nuclear boundaries. Staining quality must be distinguished from actual cellular structures.
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47A student sees a round, sharply defined structure in every field, including areas without cells. The structure remains stationary when the slide is moved. What is the most likely identification?
Observation of human cheek epithelial cells
Hard
A.A cheek-cell nucleus
B.A mitochondrial cluster
C.A nucleolus in each cell
D.An air bubble under the coverslip
Correct Answer: An air bubble under the coverslip
Explanation:
Air bubbles are usually circular, highly refractile, and present independently of cell distribution. A true nucleus should be located within a cell and move with the specimen.
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48A stained cheek cell appears shrunken with a dense, contracted cytoplasmic region separated from the surrounding boundary. Which preparation condition most likely caused this appearance?
Observation of human cheek epithelial cells
Hard
A.Exposure to a hypotonic solution
B.Exposure to a hypertonic solution
C.Removal of all extracellular solutes
D.Use of an oil-immersion objective
Correct Answer: Exposure to a hypertonic solution
Explanation:
A hypertonic external solution causes water to leave the cell, producing shrinkage and possible separation of the plasma membrane from the cell perimeter.
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49Why is methylene blue particularly useful when observing unstained human cheek epithelial cells?
Observation of human cheek epithelial cells
Hard
A.It converts animal cells into rigid polygonal cells
B.It dissolves the plasma membrane to expose organelles
C.It increases nuclear contrast by binding acidic components
D.It prevents all diffusion across the cell boundary
Correct Answer: It increases nuclear contrast by binding acidic components
Explanation:
Methylene blue preferentially increases contrast in nuclei because it interacts with acidic molecules such as nucleic acids, making nuclear boundaries easier to observe.
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50A student focuses on a visible dust particle on the coverslip and then moves the slide. The particle does not move with the cells. Which method would best verify that it is not part of the specimen?
Observation of human cheek epithelial cells
Hard
A.Switch directly to the highest objective
B.Rotate the ocular lens while holding the slide fixed
C.Move the slide and compare the particle's motion
D.Increase stain exposure until the particle disappears
Correct Answer: Move the slide and compare the particle's motion
Explanation:
Specimen structures move with the slide, whereas particles on the optical surfaces remain stationary relative to the field or move differently. Comparing motion helps locate the artifact.
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51A student reports that cheek epithelial cells possess a cell wall because each cell has a visible outer boundary. Which correction is scientifically appropriate?
Observation of human cheek epithelial cells
Hard
A.The boundary is always a cellulose layer
B.The boundary is the stained central vacuole
C.The boundary is formed by bacterial peptidoglycan
D.The boundary is usually the plasma membrane, not a cell wall
Correct Answer: The boundary is usually the plasma membrane, not a cell wall
Explanation:
Human cheek cells are animal cells and lack cell walls. Their outer limit is the plasma membrane, which may be difficult to resolve directly.
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52A student observes many flat, irregularly shaped cells with a single prominent nucleus and no chloroplasts. Which conclusion is best supported by these observations?
Observation of human cheek epithelial cells
Hard
A.The specimen likely contains human squamous epithelial cells
B.The cells are skeletal muscle fibers in longitudinal section
Correct Answer: The specimen likely contains human squamous epithelial cells
Explanation:
Cheek epithelial cells are flattened animal cells, commonly appearing irregular or polygonal with a prominent nucleus and no chloroplasts.
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53Two students prepare cheek-cell slides from the same donor. Student A sees distinct nuclei, whereas Student B sees mostly dark debris. Which variable is the most direct candidate for explaining the difference?
Observation of human cheek epithelial cells
Hard
A.Staining time and smear thickness
B.The cells' chromosome number
C.The microscope's brand name alone
D.The donor's blood type alone
Correct Answer: Staining time and smear thickness
Explanation:
Differences in stain exposure, sample amount, spreading, and washing can strongly affect contrast and debris. These preparation variables are more direct than unrelated biological traits.
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54A cell is visible at the edge of the field under a objective. The student wants to center it before switching to a objective. Which action is most appropriate?
Observation of human cheek epithelial cells
Hard
A.Increase illumination until the cell reaches the center
B.Rotate the nosepiece without securing the slide
C.Move the slide so the cell is centered at low power
D.Use the coarse focus while already at high power
Correct Answer: Move the slide so the cell is centered at low power
Explanation:
Centering the specimen before increasing magnification reduces the chance of losing it because the high-power field of view is much smaller.
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55A student's field becomes darker after switching to a higher-power objective, even though the lamp setting is unchanged. Which explanation is most likely?
Observation of human cheek epithelial cells
Hard
A.The ocular lens has reduced specimen thickness
B.The higher-power objective generally transmits less light
C.The cheek cells have stopped absorbing stain
D.The condenser has become a biological structure
Correct Answer: The higher-power objective generally transmits less light
Explanation:
Higher-power objectives often provide a smaller field and may transmit less light, so condenser alignment, diaphragm adjustment, and illumination may need to be optimized.
Incorrect! Try again.
56A cheek-cell image contains a dark crescent along one side of nearly every cell. The crescent changes position when the coverslip is gently shifted. What is the best interpretation?
Observation of human cheek epithelial cells
Hard
A.It is evidence that the cells are undergoing mitosis
B.It is a permanent feature of every nucleus
C.It is likely a coverslip-related optical artifact
D.It is necessarily the Golgi apparatus
Correct Answer: It is likely a coverslip-related optical artifact
Explanation:
A feature that shifts when the coverslip moves is associated with the optical preparation rather than a stable intracellular structure.
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57A student wants to compare the average size of cheek cells from two slides. Which procedure would produce the most defensible comparison?
Observation of human cheek epithelial cells
Hard
A.Measure random intact cells using the same calibration
B.Estimate size by comparing stain darkness
C.Use different objectives without recalibrating
D.Measure only the largest cells from each slide
Correct Answer: Measure random intact cells using the same calibration
Explanation:
Random sampling reduces selection bias, and consistent calibration ensures that measurements from both slides are comparable.
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58A cheek-cell smear has numerous dark particles concentrated near the point where the sample was initially placed. Which procedural error most likely produced this pattern?
Observation of human cheek epithelial cells
Hard
A.The sample was not spread evenly before staining
B.The eyepiece was cleaned before use
C.The objective was correctly centered
D.The slide was viewed with both eyes open
Correct Answer: The sample was not spread evenly before staining
Explanation:
Failure to spread the sample creates a dense deposit at the collection point, increasing overlap, stain accumulation, and debris in that region.
Incorrect! Try again.
59A student identifies a faint circular region inside a stained cheek cell as the nucleolus. Which additional observation would provide the strongest support for that identification?
Observation of human cheek epithelial cells
Hard
A.It remains fixed while the slide moves
B.It occurs outside the cell boundary
C.It lies within a larger stained nuclear region
D.It appears in every empty field region
Correct Answer: It lies within a larger stained nuclear region
Explanation:
A nucleolus is located within the nucleus. Its identification is more credible when a smaller dense region is enclosed by a clearly defined nucleus.
Incorrect! Try again.
60A student observes that the apparent thickness of a cheek cell changes dramatically as the fine-focus knob is adjusted. What does this most strongly indicate?
Observation of human cheek epithelial cells
Hard
A.The stain is causing reversible chromosome replication
B.The cell is changing shape during every focus adjustment
C.The cell has three-dimensional thickness and limited depth of focus
D.The objective is measuring cell mass directly
Correct Answer: The cell has three-dimensional thickness and limited depth of focus
Explanation:
Different focal planes reveal different portions of a cell. Focusing through the specimen can therefore make its apparent thickness and internal features change.
Incorrect! Try again.
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