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Questions and Answers
What is the main purpose of staining in microscopy?
Which type of microscope is known for using a single convex lens?
Which component provides support and stability to a microscope?
What is the maximum magnification that typical light microscopes achieve in a college lab?
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What distinguishes electron microscopes from light microscopes?
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What does the coarse adjustment knob do on a microscope?
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What is the resolution of typical light microscopes used in college labs?
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What is a major downside of using electron microscopes?
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What is the primary function of the condenser lens in a microscope?
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Which component of a microscope adjusts the amount of light reaching the specimen?
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Which type of microscopic slide is most suitable for observing motile specimens?
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What is the role of staining in microscopy?
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What does the field diaphragm control in a microscope?
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Which part of the microscope directly enlarges the image of the specimen first?
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What is the simplest way to mount a slide for observation?
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Which type of illuminator is NOT commonly used in microscopes?
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What is primarily contained in the nucleus of an atom according to the Bohr model?
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Which of the following statements about electrons is true in the Bohr model?
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What is the formula representation for carbohydrates?
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According to the octet rule, how many electrons in the outer shell are generally required for stability?
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Which of the following is NOT a major class of biological macromolecules?
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What role do carbohydrates primarily serve in living organisms?
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Which of the following statements about the arrangement of electrons is accurate?
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What is the importance of biological macromolecules in living organisms?
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What color does iodine stain starch?
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What process involves the removal of water from tissue samples?
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Who is credited with coining the term 'cell' after observing cork tissue?
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What does the Unified Cell Theory propose about living organisms?
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What is the purpose of the cryostat in tissue preparation?
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Which stain is used primarily for staining the cytoplasm of cells?
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What is the final step in the preparation of tissues to expose them for study?
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Which of the following is NOT part of the tissue preparation process?
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What is the primary function of mitochondria in eukaryotic cells?
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What distinguishes Rough Endoplasmic Reticulum (ER) from Smooth ER?
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Which organelle is responsible for sorting, tagging, packaging, and distributing proteins and lipids?
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What function do peroxisomes serve in the cell?
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Which of the following is a structural feature exclusive to plant cells?
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What role does the Large Central Vacuole play in plant cells?
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What is the primary difference between plant and animal cells regarding specific organelles?
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Which of the following statements about the nucleus is correct?
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Study Notes
Electron Shells and Niels Bohr Model
- In the Bohr model, atoms consist of a positively charged nucleus containing protons and neutrons, surrounded by negatively charged electrons.
- Electrons occupy specific energy levels called electron shells, defined by their principal quantum number.
- Electrons fill lower energy orbitals first, followed by higher energy orbitals until all electrons are placed.
- Atoms tend to be most stable with a full outer shell (containing 8 electrons), leading to the "octet rule."
Biological Macromolecules
- Large, complex molecules essential for life.
- Built from smaller organic molecules.
- Play crucial roles in structure, function, and regulation of living organisms.
- Four major classes: carbohydrates, lipids, proteins, and nucleic acids.
Carbohydrates
- Formula: (CH2O)n, where n is the number of carbons.
- Provide energy and structural support.
- Examples: Glucose, starch, and cellulose.
Microscopy
- Microscopes magnify objects, making them appear larger.
- Light microscopes use visible light.
- Electron microscopes use a beam of electrons.
- Magnification refers to the enlargement of an object's appearance.
- Resolution refers to the ability to distinguish between two closely spaced objects.
- Light microscopes typically magnify up to 400x with a resolution of 200 nanometers.
- Electron microscopes provide much higher magnification (100,000x) and a resolution of 50 picometers.
Compound Microscope
- Invented by Zacharias Janssen and Hans Janssen.
- Uses multiple lenses for magnification.
Electron Microscopes
- Use a beam of electrons to image specimens.
- Higher magnification and detail compared to light microscopes.
- Preparation kills specimens due to the vacuum requirement.
Microscope Components
- Base: Provides stability and support.
- Arm: Connects the base to the head, used for carrying.
- Stage: Platform for holding microscope slides.
- Stage Clips: Secure the slide in place.
- Coarse Adjustment Knob: Moves the stage up and down for initial focusing.
- Fine Adjustment Knob: Used for precision focusing after using the coarse knob.
- High-Power Eyepiece: Magnifies the image from the objective lens, typically 15x or 20x.
- Objective Lens: Magnifies the specimen initially.
- Condenser Lens: Focuses light onto the specimen.
- Illuminator: Provides the light source for viewing.
- Field Diaphragm: Controls the light beam diameter, improving image quality.
Microscope Slide Presentation
- Thought-out methodology for clear sample explanation.
- Slide Mount: The way a specimen is placed on a slide.
- Dry Mount: Simple mount for specimens.
- Wet Mount: Used for observing motile specimens.
- Smear Mount: Used for examining blood samples.
Staining Media
- Enhances contrast of specimens for easier visualization.
- Iodine: Stains starch black-blue.
- Methylene Blue: Stains nuclei blue.
- Crystal Violet: Used in Gram staining, results in deep violet or purple.
- Eosin Y: Stains cytoplasm bright pink-red.
- Toluidine Blue: Stains acidic tissues like nucleic acids blue.
Tissue Preparation for Study
- Fixation: Prevents putrefaction and degradation.
- Dehydration: Removes water from the tissue.
- Clearing: Alcohol is removed.
- Infiltration and Embedding: Tissue is placed in paraffin wax to provide support for sectioning.
- Sectioning or Trimming: Thin slices of tissue are obtained for observation.
- Cryostat: Used for long-term tissue storage.
Intracellular and Extracellular Matrix
- Intracellular Matrix: Supports internal cellular processes.
- Extracellular Matrix: Provides external support and facilitates cell-to-cell communication.
Cell Theory
- Proposed by Matthias Schleiden and Theodor Schwann.
- States that all living things are made of one or more cells, the cell is the basic unit of life, and new cells arise from existing cells.
Eukaryotic Cells
- Have a true nucleus and specialized organelles.
- Nucleus: Contains the cell's DNA and controls protein and ribosome production.
- Mitochondria: Powerhouses of the cell, generate ATP through cellular respiration.
- Endoplasmic Reticulum (ER): Rough ER synthesizes proteins, smooth ER synthesizes lipids.
- Golgi Apparatus: Sorts, tags, packages, and distributes lipids and proteins.
- Peroxisomes: Break down fatty acids and amino acids, detoxify poisons.
- Vesicles and Vacuoles: Membrane-bound sacs for storage and transport, vacuoles are larger than vesicles.
Plant Cells
- Have cell walls, large central vacuoles, and chloroplasts.
- Cell Wall: Provides protection, structural support, and shape.
- Large Central Vacuole: Regulates water content, especially in different environments.
- Chloroplasts: Carry out photosynthesis, converting sunlight into energy.
Animal vs. Plant Cells
- Both have common organelles such as the nucleus, mitochondria, ER, Golgi apparatus.
- Animal cells have centrosomes and lysosomes.
- Centrosomes: Organize microtubules near the nucleus.
- Lysosomes: Break down waste materials and cellular debris.
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Description
Explore the fundamental concepts of electron shells according to the Niels Bohr model and the importance of biological macromolecules. This quiz covers electron configurations, the stability of atoms with full outer shells, and the primary classes of macromolecules essential for life. Test your knowledge on carbohydrates, lipids, proteins, and nucleic acids!
