Microbiology
See correct answers immediately with detailed explanations after each question.
Answer all questions, then review your results with feedback at the end.
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Below are sample questions from this exam to help you understand the content and format.
Q1: While in the same family as a disease that was killing millions, this disease is not deadly and was used by Edward Jenner as a vaccination
Answer Choices:
◆ Edward Jenner noticed that milkmaids who had previously been infected with cowpox, a mild viral infection, were protected from contracting smallpox, a deadly and widespread disease at the time.
◆ Cowpox belongs to the same family of poxviruses as smallpox, which meant that the immune system could cross-react and provide protection.
◆ Because cowpox infections were not deadly, Jenner was able to use it safely as the basis for his vaccination experiment.
◆ This discovery became the foundation of immunization practices, proving that exposure to a weaker pathogen could protect against a more dangerous one.
Q2: This lens on the compound microscope can be changed to view specimens at varying magnifications
Answer Choices:
◈ The objective lens is the part of the compound microscope that can be rotated to change the level of magnification when viewing a specimen.
◈ Objective lenses are available in different powers (e.g., 4x, 10x, 40x, 100x), allowing the observer to increase or decrease the level of detail and clarity of the image.
◈ The ocular lens or eyepiece usually has a fixed magnification, typically 10x, and is not interchangeable in the same way.
◈ The objective lens is the correct answer because it directly determines how magnified the specimen appears under the microscope.
Q3: Which is NOT a characteristic of the plasma membrane?
Answer Choices:
» The plasma membrane is primarily responsible for selective permeability, which means it controls the substances entering and leaving the cell.
» It is also composed of a phospholipid bilayer with embedded proteins, which participate in transport, signaling, and structural support.
» Some antibiotics target the plasma membrane, making it a key site for antimicrobial action.
» Maintaining cell shape is the role of the cell wall in bacteria or the cytoskeleton in eukaryotes, not the plasma membrane, which is why “maintains cell shape” is not correct.
Q4: Protection of a disease provided by vaccination is called ________ and was discovered thanks to the work of____________
Answer Choices:
⨠ The protection provided by vaccination is called immunity, which refers to the body’s ability to resist or fight infection.
⨠ Edward Jenner’s experiments using cowpox demonstrated that the immune system could be trained to defend against smallpox.
⨠ Jenner’s discovery was groundbreaking because it showed that deliberate exposure to a safe antigen could provide long-lasting protection without causing serious disease.
⨠ His work became the basis of the modern vaccination system, which is now used globally to prevent infectious diseases.
Q5: A bacterial cell is placed in an isotonic solution. Describe the movement of water specifically in this type of solution.
Answer Choices:
◉ An isotonic solution has the same solute concentration as the inside of the bacterial cell, meaning there is no concentration gradient for water.
◉ In this condition, water molecules still move across the membrane, but their movement is balanced in both directions, so there is no net change in volume.
◉ Because of this equilibrium, the bacterial cell maintains its normal size and does not swell (as in hypotonic solutions) or shrink (as in hypertonic solutions).
◉ This demonstrates the principle of osmotic balance, which is critical for maintaining cell stability in laboratory and clinical settings.
