All flashcards
Flashcard 1: What is the cell theory statement that links cells to the structure of living things?
Answer: All living things are made of one or more cells. This is the first principle of cell theory, established by Schleiden and Schwann.
Flashcard 2: What is the correct definition of a cell in life science?
Answer: The smallest unit of life that carries out life processes. Cells perform all functions necessary for life, from metabolism to reproduction.
Flashcard 3: Which tool is most appropriate for collecting evidence that cells exist in a tissue sample?
Answer: A microscope. Cells are too small to see with the naked eye, requiring magnification.
Flashcard 4: What is the correct order of microscope magnifications from lowest to highest power?
Answer: Scanning, low, high. Scanning (4x) provides overview, low (10x) locates cells, high (40x) shows details.
Flashcard 5: Which step should you do first when focusing a microscope to find cells on a slide?
Answer: Start on lowest power and use the coarse focus knob. Low power gives widest field of view; coarse knob moves stage quickly.
Flashcard 6: What is the independent variable in an investigation comparing plant and animal slides?
Answer: The type of specimen (plant versus animal). Independent variables are what you deliberately change or compare.
Flashcard 7: What is one controlled variable when comparing cell observations across multiple slides?
Answer: The magnification used. Controlled variables must stay constant to ensure fair comparison.
Flashcard 8: Which observation is the strongest evidence that a sample is living tissue: crystals or cells?
Answer: Cells. Only living things have cells; crystals are non-living mineral structures.
Flashcard 9: What is the correct conclusion if you observe many repeating, membrane-bounded units in a leaf sample?
Answer: The leaf is composed of cells. Membrane-bounded units are cells, confirming the tissue is living.
Flashcard 10: What structure is present in plant cells but not in typical animal cells and supports evidence of cells?
Answer: A cell wall. Cell walls provide rigid support and protection unique to plants.
Flashcard 11: What organelle contains green pigment and is commonly observed in plant cells during investigations?
Answer: Chloroplast. Chloroplasts contain chlorophyll for photosynthesis in plant cells.
Flashcard 12: What cell structure forms the outer boundary of both plant and animal cells?
Answer: Cell membrane. This flexible barrier controls what enters and exits all cells.
Flashcard 13: Which cell structure is commonly visible as a darker, round region in stained animal cells?
Answer: Nucleus. The nucleus contains DNA and appears dark when stained.
Flashcard 14: What is the main purpose of staining a microscope slide in a cell investigation?
Answer: To increase contrast so cell structures are easier to see. Stains bind to cell parts, making transparent structures visible.
Flashcard 15: Identify the best evidence-based claim if onion cells and cheek cells both show boundaries and nuclei.
Answer: Both plant and animal tissues are made of cells. Observing cells in different organisms supports cell theory universality.
Flashcard 16: Which observation best distinguishes a plant cell from a cheek cell in microscope evidence?
Answer: A rigid cell wall forming box-like shapes. Animal cells lack walls, so they appear round or irregular.
Flashcard 17: What is the correct term for a group of similar cells working together, often sampled in investigations?
Answer: Tissue. Cells organize into tissues for specialized functions.
Flashcard 18: What is the correct term for a single-celled living thing that can be observed as one cell under a microscope?
Answer: Unicellular organism. Examples include bacteria and amoebas that live as single cells.
Flashcard 19: Which investigation result best supports cell theory: all samples show cells or only one sample shows cells?
Answer: All living samples show cells. Universal presence of cells confirms all life is cellular.
Flashcard 20: Identify the dependent variable in an investigation testing whether stain improves cell visibility.
Answer: Visibility/contrast of cell structures under the microscope. The dependent variable is what you measure in response to the treatment.
Flashcard 21: Find the correct conclusion: You observe no cells at high power; what is the most likely investigation error?
Answer: The specimen was not centered/focused at low power first. High power has a narrow field; specimens must be centered at low power first.
Flashcard 22: What is the best reason to make a wet mount when viewing cells under a light microscope?
Answer: To keep the specimen hydrated and improve viewing clarity. Water prevents drying and helps light pass through the specimen.
Flashcard 23: Which observation best distinguishes cells from nonliving crystals under a microscope?
Answer: Cells show membrane boundaries and internal structures like nuclei. Living cells have membranes and organelles; crystals lack these features.
Flashcard 24: What is the correct evidence-based conclusion after observing many similar units with membranes in tissue?
Answer: The tissue is composed of cells. Repeated membrane-bound units are the defining characteristic of cellular tissue.
Flashcard 25: Which practice best ensures a fair test when comparing two microscope slides of different tissues?
Answer: Keep magnification and lighting the same for both slides. Controlling variables ensures differences are due to tissue type only.
Flashcard 26: What is the best control condition when testing whether stain improves visibility of nuclei?
Answer: An unstained slide prepared the same way. Controls differ only in the tested variable, keeping all else constant.
Flashcard 27: Identify the independent variable in an investigation comparing stained vs unstained cheek cell slides.
Answer: Presence of stain (stained vs unstained). The independent variable is what the experimenter changes (stain/no stain).
Flashcard 28: Which stain is commonly used to increase contrast in plant tissue such as onion cells?
Answer: Iodine solution (Lugol’s iodine). Iodine stains cellulose and starch, enhancing plant cell visibility.
Flashcard 29: Which stain is commonly used to make cheek cell nuclei easier to see in a classroom investigation?
Answer: Methylene blue. This blue dye binds to nucleic acids, highlighting nuclear structures.
Flashcard 30: Which visible feature best supports that cheek tissue is made of cells when viewed under a microscope?
Answer: Many repeated membrane-bound units (individual cells). Multiple distinct cellular units prove tissue is composed of individual cells.