Cell Biology Quiz
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Questions and Answers

What is the primary function of the nucleus in a cell?

  • Protein synthesis
  • Transporting molecules via vesicles
  • Controlling cellular activities through DNA (correct)
  • ATP production

Which cellular structure is directly involved in protein synthesis?

  • Nucleus
  • Mitochondria
  • Ribosomes (correct)
  • Vesicles

If a cell has a high rate of protein synthesis, it will likely have a higher amount of which organelle?

  • Nuclei
  • Ribosomes (correct)
  • Mitochondria
  • Vesicles

What is a key structural difference between eukaryotic and prokaryotic cells?

<p>Eukaryotic cells have a nucleus and membrane-bound organelles, while prokaryotic cells lack these (C)</p> Signup and view all the answers

Besides bacteria, which of the following is a prokaryotic organism?

<p>Archaea (D)</p> Signup and view all the answers

Which structure, found in eukaryotic cells, is NOT present in prokaryotic cells?

<p>Membrane-bound organelles (B)</p> Signup and view all the answers

What is the general role of vesicles within a cell?

<p>To transport molecules to specific locations (C)</p> Signup and view all the answers

What is the full name for 'rER'?

<p>Rough Endoplasmic Reticulum (A)</p> Signup and view all the answers

What is the primary limitation imposed by the phospholipid bilayer on substance movement?

<p>It restricts the movement of water-soluble and large substances. (A)</p> Signup and view all the answers

Which of the following best describes the movement of substances during facilitated diffusion?

<p>Substances move down a concentration gradient through carrier or channel proteins, without ATP. (C)</p> Signup and view all the answers

How do channel proteins facilitate diffusion across a cell membrane?

<p>By forming a hydrophilic pore that allows passage of water-soluble substances. (D)</p> Signup and view all the answers

What is the primary role of carrier proteins in facilitated diffusion?

<p>To bind to specific molecules, change shape, and transport them down their concentration gradient. (C)</p> Signup and view all the answers

Which of the following is MOST accurate regarding water potential (ψ)?

<p>Pure water has the highest possible ψ. (A)</p> Signup and view all the answers

How does osmosis differ from facilitated diffusion?

<p>Osmosis involves the movement of water, while facilitated diffusion involves the movement of other solutes. (B)</p> Signup and view all the answers

What is the key characteristic of active transport that distinguishes it from passive transport processes?

<p>Movement of substances up a concentration gradient requiring ATP. (B)</p> Signup and view all the answers

What is the direct role of ATP hydrolysis in active transport?

<p>To provide the energy to change the shape of the carrier protein, which allows it to transport substances against their concentration gradient. (B)</p> Signup and view all the answers

Which of the following is a characteristic of prokaryotic cells?

<p>Presence of 70S ribosomes (C)</p> Signup and view all the answers

Why are viruses considered acellular?

<p>They are not made of cells and lack cell organelles. (C)</p> Signup and view all the answers

What is the definition of magnification?

<p>The number of times an image is larger than the actual object. (D)</p> Signup and view all the answers

Which type of microscope uses electrons that bounce off the surface of a specimen to generate a 3D image?

<p>Scanning electron microscope (SEM) (C)</p> Signup and view all the answers

Which of the following is a limitation of optical microscopes?

<p>They have low resolution due to the long wavelength of light. (C)</p> Signup and view all the answers

Which type of microscope allows visualization of the internal structures of organelles?

<p>Transmission electron microscope (TEM) (A)</p> Signup and view all the answers

What is a major limitation of using electron microscopes?

<p>They require complex specimen preparation which can lead to artefacts. (A)</p> Signup and view all the answers

Which microscope provides a 2D cross-sectional image of a specimen?

<p>Transmission electron microscope (B)</p> Signup and view all the answers

A student observes a specimen under a microscope where it appears larger than its actual size. This is an example of:

<p>high magnification (D)</p> Signup and view all the answers

Which of the following is NOT a characteristic of a transmission electron microscope?

<p>Can show colour in the image (B)</p> Signup and view all the answers

What is the primary purpose of squashing the cells under a coverslip during slide preparation?

<p>To create a single layer of cells for clearer observation under a microscope. (C)</p> Signup and view all the answers

What is the main reason for using root tips in the preparation of cell squashes?

<p>The cells in root tips are rapidly dividing, allowing viewing of mitosis stages. (B)</p> Signup and view all the answers

What is NOT a purpose of soaking root tips in hydrochloric acid

<p>To fix the DNA in situ. (B)</p> Signup and view all the answers

Why is it important to lower the coverslip at a 45-degree angle during slide preparation?

<p>To prevent the formation of air bubbles under the coverslip. (C)</p> Signup and view all the answers

Why should the coverslip not be pushed sideways during the squashing process?

<p>To prevent rolling cells together or breaking the chromosomes. (D)</p> Signup and view all the answers

What is the purpose of staining cells, using a stain such as toluidine blue, before observation under an optical microscope?

<p>To enhance the contrast between cell organelles, particularly chromosomes. (A)</p> Signup and view all the answers

When using an optical microscope, why should the lowest power objective lens typically be selected first?

<p>To initially locate the specimen with a wide field of view. (D)</p> Signup and view all the answers

During the practical to set up an optical microscope, once the slide is clipped to the stage and the low power lens is selected, what is the next critical step?

<p>Adjust the coarse focusing dial to lower the stage until it is close to the objective lens. (B)</p> Signup and view all the answers

Why is it important to regularly shake test tubes containing plant tissue cubes during an experiment?

<p>To ensure all surfaces of the cubes maintain contact with the liquid promoting diffusion. (A)</p> Signup and view all the answers

A high absorbance reading from a sample using a colorimeter suggests which of the following regarding its cell membrane?

<p>The cell membrane has become highly permeable and released a high quantity of a pigment into the surrounding test solution. (A)</p> Signup and view all the answers

What is the primary purpose of creating a calibration curve in a colorimetry experiment?

<p>To establish a relationship between absorbance readings and known concentrations of a substance. (B)</p> Signup and view all the answers

Why is it crucial to control the volume of water used when testing the release of pigment from plant cells?

<p>To avoid excessive dilution of the pigment, which would skew absorbance readings. (C)</p> Signup and view all the answers

What is the main subjective issue when comparing a sample solution to colour standards?

<p>The potential for mismatch in colour perception. (C)</p> Signup and view all the answers

Why would washing beetroot cylinders be done prior to introducing them into water in the test?

<p>To remove any pigment that is not released from within the cell. (B)</p> Signup and view all the answers

How can one ensure that the temperature remains consistent when conducting an experiment involving plant tissue?

<p>By using a digital thermometer or temperature sensor and making corrections as required. (D)</p> Signup and view all the answers

In conducting colorimetric analysis, what is represented on the x-axis of the calibration curve?

<p>The concentration of the standard solutions. (B)</p> Signup and view all the answers

What is the main role of antibodies in the immune response?

<p>To bind to antigens forming antigen-antibody complexes (D)</p> Signup and view all the answers

Which characteristic of antibodies allows them to bind specifically to antigens?

<p>The specific tertiary structure of the binding site (C)</p> Signup and view all the answers

What is the difference between the primary immune response and the secondary immune response?

<p>Antibodies are produced faster and in higher concentration during secondary response (D)</p> Signup and view all the answers

How do vaccines protect individuals against disease?

<p>By stimulating the production of antibodies against the vaccine's antigens (A)</p> Signup and view all the answers

What is the role of phagocytes in the immune response?

<p>To engulf and destroy pathogens marked by antibodies (D)</p> Signup and view all the answers

What happens to B lymphocytes after they bind to an antigen?

<p>They divide by mitosis and form clones (B)</p> Signup and view all the answers

Which statement accurately describes the formation of antibody-antigen complexes?

<p>Antibodies can bind to two pathogens at once, promoting clumping (D)</p> Signup and view all the answers

What initiates the secondary immune response upon re-exposure to an antigen?

<p>The rapid division of B memory cells (A)</p> Signup and view all the answers

Flashcards

What are prokaryotic cells?

Prokaryotic cells are single-celled organisms that lack a nucleus and other membrane-bound organelles.

Describe the general structure of a prokaryotic cell.

Prokaryotic cells have a simple structure, consisting of a cell membrane, cytoplasm, ribosomes, and a single circular DNA molecule (the chromosome).

Compare and contrast the structure of eukaryotic and prokaryotic cells.

Eukaryotic cells have a nucleus and other membrane-bound organelles, while prokaryotic cells lack these structures. Eukaryotic cells are typically larger and more complex than prokaryotic cells.

What are examples of prokaryotic organisms?

Bacteria and archaea are two domains of prokaryotic organisms. They are always unicellular, meaning they consist of a single cell.

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Why is prokaryotic genetic material not enclosed in a nucleus?

The genetic material of prokaryotes is not enclosed within a membrane-bound nucleus like in eukaryotic cells. Instead, it is located in a region called the nucleoid.

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What structures are absent in prokaryotic cells?

Prokaryotic cells lack membrane-bound organelles, such as mitochondria, Golgi apparatus, and endoplasmic reticulum.

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What is the function of ribosomes in prokaryotic cells?

Ribosomes are essential for protein synthesis in prokaryotic cells.

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What is the function of the cell membrane in prokaryotic cells?

The cell membrane encloses the cytoplasm and regulates the passage of substances into and out of the cell.

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Resolution

The ability of a microscope to distinguish between two objects that are very close together.

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Magnification

The number of times larger an image is compared to the actual object.

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Optical Microscope

A microscope that uses light to illuminate a specimen and form an image.

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Transmission Electron Microscope (TEM)

A microscope that uses a beam of electrons to create an image with very high resolution.

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Scanning Electron Microscope (SEM)

A type of electron microscope that creates a three-dimensional image of the specimen.

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Acellular

An object that is not a cell, such as a virus.

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Respiration

The process in which a cell breaks down glucose to produce energy in the form of ATP.

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Small/70S Ribosomes

Small (70S) ribosomes found in both prokaryotic cells and the mitochondria and chloroplasts of eukaryotic cells.

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Organelle

A structure within a cell that is enclosed by a membrane.

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Mitochondria

A structure within a eukaryotic cell that breaks down glucose to produce ATP.

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Why are root tips used?

The part of the plant root where cells are actively dividing.

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Why is a stain used?

A stain is used to make chromosomes visible under the microscope.

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Why squash / press down on cover slip?

Squashing the root tip spreads the cells out into a single layer, allowing light to pass through and make chromosomes visible.

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Why not push cover slip sideways?

Pushing the cover slip sideways can disrupt the cells and chromosomes, making them difficult to observe.

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Why soak roots in acid?

Soaking in acid does several things: 1. Separates cells, making them easier to squash. 2. Breaks down cell walls, allowing stain to diffuse into cells. 3. Stops mitosis, allowing you to observe different stages.

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Lowest power objective lens

The objective lens closest to the stage, typically magnifying 4 times.

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Coarse focusing dial

This knob is used to adjust the distance between the stage and the objective lens for coarse focusing.

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Fine focusing knob

This knob is used to make fine adjustments to the focus, achieving sharper images.

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Plasma cells

Plasma cells are immune cells that produce antibodies in response to specific antigens.

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Antibodies

Antibodies are proteins that specifically bind to antigens, forming antigen-antibody complexes.

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Antibody structure

Antibodies have a specific tertiary structure with a binding site (variable region) that recognizes and binds to a complementary antigen.

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Agglutination

Agglutination is the clumping of pathogens by antibodies, which bind to multiple pathogens simultaneously.

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Antibody-phagocyte interaction

Antibodies attract phagocytes, which engulf and destroy pathogens.

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Primary immune response

The primary immune response is the initial exposure to an antigen, characterized by slow antibody production and the development of memory cells.

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Secondary immune response

The secondary immune response is the subsequent exposure to the same antigen, characterized by rapid and high antibody production due to memory cells.

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What is a vaccine?

A vaccine is an injection containing weakened or dead antigens, stimulating the immune system to produce memory cells.

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Passive Transport

The movement of substances across a cell membrane from an area of high concentration to an area of low concentration, without requiring energy from ATP.

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Active Transport

The movement of substances across a cell membrane from an area of low concentration to an area of high concentration, requiring energy from ATP.

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Osmosis

The movement of water molecules across a partially permeable membrane from an area of high water potential to an area of low water potential.

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Water Potential

A measure of the tendency of water to move into a solution, influenced by solute concentration.

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Facilitated Diffusion

A type of passive transport where substances move across the membrane with the help of specific proteins.

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Channel and Carrier Proteins

Proteins embedded in the cell membrane that form channels or act as carriers to facilitate the movement of specific substances.

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Phospholipid Bilayer Limitations

The selective permeability of the phospholipid bilayer, allowing some substances to pass through easily while restricting others.

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Hydrolysis of ATP

The process by which ATP is broken down into ADP and inorganic phosphate, releasing energy that can be used to power cellular processes.

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Color Standard Comparison

Comparing the color of a sample to a set of pre-defined colors, like those found in a color chart.

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Why Wash Beetroot?

Washing the beetroot before adding it to water removes any pigment that may be present on the surface, ensuring that the color released is truly due to the experiment's variable.

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Why Shake Beetroot Tubes?

Regular shaking ensures that all sides of the beetroot cubes are exposed to the water, maintaining a concentration gradient and allowing for consistent diffusion of pigment.

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Why Control Water Volume?

Too much water would dilute the pigment, making the solution appear lighter and reducing the absorbance value measured by the colorimeter. This affects the reliability of results.

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Why Maintain Constant Temperature?

Keeping the temperature stable ensures that any changes in pigment release are due to the experimental variable, not temperature fluctuations.

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High Absorbance, What Does it Mean?

A higher absorbance value indicates that more light is being absorbed by the solution, suggesting a greater amount of pigment has been released from the beetroot, potentially indicating a more permeable cell membrane.

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Colorimeter and Calibration Curve

Using a colorimeter measures the amount of light passing through a solution with a known concentration. This allows us to establish a relationship between absorbance and concentration, which can be used to determine the unknown concentration of a sample.

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Colorimeter

A colorimeter measures the amount of light absorbed by a solution. It is often used in experiments investigating the permeability of cell membranes.

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Description

Test your knowledge on the fundamental concepts of cell biology, including cellular structures, protein synthesis, and the differences between eukaryotic and prokaryotic cells. This quiz covers key roles and functions of various organelles and processes such as facilitated diffusion and osmosis.

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