1Which type of tissue is observed in a human cheek cell preparation?
Observation of human cheek epithelial cells
Easy
A.Muscle tissue
B.Nervous tissue
C.Epithelial tissue
D.Connective 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.Glass stirring rod
C.Plastic forceps
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.Surface of the tongue
C.Inside the cheek
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 increase cell size
B.To prevent light from passing
C.To make cells move faster
D.To make cell structures clearer
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.Sudan III
D.Methylene blue
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.Vacuole
B.Cell wall
C.Chloroplast
D.Nucleus
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.Diaphragm
B.Eyepiece
C.Stage
D.Fine adjustment knob
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.Test-tube cap
C.Filter paper
D.Cover slip
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 flatten and protect the sample
B.To increase the sample temperature
C.To stain the sample blue
D.To remove the cell membrane
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.Ribosome
B.Nucleus
C.Cytoplasm
D.Cell membrane
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.Cytoplasm
D.Cell wall
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.Animal cells
B.Fungal cells
C.Plant cells
D.Bacterial 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.Cell wall
C.Cytoplasm
D.Nucleus
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.Lowest-power objective
B.Oil-immersion objective
C.Highest-power objective
D.Special dark-field 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.Heat the microscope
B.Remove the eyepiece
C.Prepare and cover the sample
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.Long and branched
B.Flat and irregular
C.Rectangular and green
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 contain chloroplasts
B.They lack chloroplasts
C.They have a large central vacuole
D.They have a rigid cell wall
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 reduce contamination
B.To produce more nuclei
C.To increase cell division
D.To change the cell shape
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.Fine adjustment knob
B.Light switch
C.Stage clip
D.Revolving nosepiece
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 dissolve the cell membrane
B.To reduce contamination of the sample
C.To make the nucleus disappear
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 stain the nucleus for easier observation
B.To remove excess cytoplasm from the cells
C.To make the slide permanently sterile
D.To increase the magnification of the microscope
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 have rigid cell walls
C.They contain many chloroplasts
D.They form organized vascular bundles
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 increase the cell division rate
B.To change the cells into a cuboidal shape
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.Begin with the lowest-power objective
B.Use only the fine-adjustment knob immediately
C.Add stain while the objective touches the slide
D.Remove the coverslip before focusing
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 remains exactly the same
B.It becomes narrower
C.It becomes completely colorless
D.It becomes wider
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.Chloroplast
B.Cell wall
C.Cell membrane
D.Large central vacuole
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 are easily collected from the mouth
B.They are naturally arranged in leaf tissue
C.They have unusually thick cell walls
D.They contain visible chloroplasts
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.Mitochondrial membranes
B.Cell walls
C.Extracellular mucus layer
D.Nuclei
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 microscope automatically increases contrast
B.Every nucleus becomes perfectly transparent
C.Individual cell boundaries become difficult to distinguish
D.The cells develop rigid walls during observation
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.Scrape the cheek repeatedly until tissue clumps
C.Leave the slide completely unstained
D.Use several coverslips at once
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 may injure the tissue and cause bleeding
B.It causes the microscope lens to lose magnification
C.It converts epithelial cells into plant cells
D.It prevents methylene blue from staining nuclei
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.Increase the amount of immersion oil
B.Return to low power and relocate the specimen
C.Remove the objective and clean the specimen
D.Move the slide rapidly in all directions
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 contains chloroplasts
C.The cheek cell has a large central vacuole
D.The cheek cell lacks a rigid cell wall
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 contain no cytoplasm at all
B.They reflect all light as a metallic surface
C.They have little natural contrast against the background
D.They are too large to fit under a coverslip
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 must be conducting nerve impulses
B.The cells are consistent with squamous epithelial tissue
C.The cells are likely bacterial colonies
D.The cells are specialized for photosynthesis
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 microscope reverses image movement
B.The cells are actively migrating
C.The objective is producing chlorophyll
D.The stain has damaged the nucleus
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 has exactly the same color as the slide
B.It lies within a visible cell boundary
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 prevent all cells from changing shape
B.To increase the brightness of the lamp
C.To identify the specimen and prevent mix-ups
D.To make the coverslip adhere chemically
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.Use the coarse-adjustment knob
B.Adjust the condenser and diaphragm
C.Increase total magnification
D.Increase the ocular lens diameter
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.Collect less material and spread it thinly
B.Increase the stain concentration substantially
C.Use the coarse focus at high magnification
D.Press the coverslip firmly onto the smear
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 microscope has insufficient numerical aperture
C.The microscope is not parfocal or was improperly focused
D.The stain has chemically dissolved the cell membrane
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 be systematically too large
B.The calculated cells will have correct sizes but wrong colors
C.The calculated cells will be systematically too small
D.The calculated cells will have random sizes only
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 specimen contains only cell walls
B.The cells were stained unevenly or overstained
C.The cells were necessarily prokaryotic
D.The objective lens lacks magnifying power
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 nucleolus in each cell
C.A mitochondrial cluster
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.Removal of all extracellular solutes
B.Use of an oil-immersion objective
C.Exposure to a hypertonic solution
D.Exposure to a hypotonic solution
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 increases nuclear contrast by binding acidic components
B.It converts animal cells into rigid polygonal cells
C.It dissolves the plasma membrane to expose organelles
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.Increase stain exposure until the particle disappears
C.Rotate the ocular lens while holding the slide fixed
D.Move the slide and compare the particle's motion
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?
B.The cells are skeletal muscle fibers in longitudinal section
C.The cells are most likely bacterial colonies
D.The specimen likely contains human squamous epithelial cells
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.The donor's blood type alone
B.The microscope's brand name alone
C.The cells' chromosome number
D.Staining time and smear thickness
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.Move the slide so the cell is centered at low power
B.Increase illumination until the cell reaches the center
C.Rotate the nosepiece without securing the slide
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 condenser has become a biological structure
C.The higher-power objective generally transmits less light
D.The cheek cells have stopped absorbing stain
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 necessarily the Golgi apparatus
C.It is likely a coverslip-related optical artifact
D.It is a permanent feature of every nucleus
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 only the largest cells from each slide
B.Measure random intact cells using the same calibration
C.Estimate size by comparing stain darkness
D.Use different objectives without recalibrating
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 objective was correctly centered
B.The sample was not spread evenly before staining
C.The slide was viewed with both eyes open
D.The eyepiece was cleaned before use
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.
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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 appears in every empty field region
B.It remains fixed while the slide moves
C.It lies within a larger stained nuclear region
D.It occurs outside the cell boundary
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.
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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 objective is measuring cell mass directly
B.The cell is changing shape during every focus adjustment
C.The stain is causing reversible chromosome replication
D.The cell has three-dimensional thickness and limited depth of focus
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.
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