Micro Exam 1 Answers

Why does horizontal gene transfer (HGT) make it difficult to classify bacteria?

It allows bacteria to inherit traits from unrelated species

Which of the following correctly matches the typical size range of each type of biological entity?

Virus (20-300 nm), Bacterium (1-10 um), Plant/Animal Cell (10-100 um)

Which of the following is a correct usage of binomial nomenclature?

Myxococcus xanthus

Which of the following statements about refraction is true?

Light waves bend due to changes in speed when entering a new medium

Which factor does NOT increase resolution in microscopy?

Increasing magnification aperture

What is the purpose of immersion oil in microscopy?

To reduce light scattering and increase resolution

Which microscope technique is best for viewing unstained live cells?

Phase-contrast microscopy

What is taxonomy?

The classification of organisms based on evolutionary relationships

Which of the following is NOT a prokaryotic microorganism?

Protozoa

Which group of microorganisms includes only photosynthetic members?

Algae

What characteristic distinguishes archaea from bacteria?

Archaea have different membrane lipids and genetic sequences

Which of the following microorganisms are most closely related to humans?

Fungi

What is the primary difference between TEM and SEM?

TEM uses transmitted electrons, while SEM uses scattered electrons

Which staining technique differentiates bacteria based on cell wall composition?

Gram staining

What is the function of a mordant in staining?

To help fix the primary stain onto the target structure

What is the primary difference between direct and indirect immunofluorescence?

Direct uses a primary antibody tagged with a fluorochrome, while indirect uses a secondary antibody tagged with a fluorochrome

Why must samples for fluorescence microscopy be stained with flurochromes?

Fluorochromes bind to cellular components and emit visible light when excited

Which of the following best describes numerical aperture in microscopy?

It is a measure of a len’s ability to gather light

Which phenomenon occurs when light waves bend around small objects or openings?

Diffraction

Which type of microscope uses a cone of light so that light only hits the specimen indirectly, producing a bright image on a dark background?

Darkfield microscope

Which type of microscope uses multiple lenses to magnify a specimen?

Compound microscope

Ziehl-Neelsen staining, a type of ____ staining, is used to diagnose Mycobacterium tuberculosis

acid-fast staining

What is the main function of the eukaryotic Golgi apparatus?

Protein modification and transport

How do prokaryotic ribosomes differ from eukaryotic ribosomes?

Prokaryotic ribosomes are smaller (70s) than eukaryotic ribosomes (80s)

What is the primary component of bacterial cell walls?

Peptidoglycan

Why do mitochondria and chloroplasts suport the endosymbiotic theory?

They have their own DNA and ribosomes similar to bacteria

What distinguishes Gram-negative bacteria from Gram-positive bacteria?

Gram-negative bacteria have an outer membrane containing lipopolysaccharides

What happens to a bacterial cell placed in a hypertonic solution?

It undergoes plasmolysis as water leaves the cytoplasm

What is the main function of lysosomes in eukaryotic cells?

Digestion of cellular waste and foreign materials

What distinguishes archaeal cell walls from bacterial cell walls?

Archaeal cell walls do not contain peptidoglycan

Which bacterial structure is involved in horizontal gene transfer

Pili

What is the function of bacterial capsules?

Protection against desiccation and immune evasion

Which of the following cell wall components is unique to gram-negative cells?

Lipopolysaccharide

Which bacterial structure is important for adherence to surfaces?

Fimbriae

Which of the following organelles is not part of the endomembrane system?

Peroxisome

What role do prokaryotes play in nitrogen fixation?

They convert atmospheric nitrogen into ammonia

Which of the following is an example of mutualism?

A bacterium in the human gut that helps digest complex carbohydrates

What differentiates Gram-positive from Gram-negative bacteria?

Gram-positive bacteria have a thick peptidoglycan layer

Which of the following genera includes nitrogen-fixing bacteria?

Rhizobium

Which of the following is NOT a form of horizontal gene transfer in bacteria?

Binary fission

What is the primary function of bacterial endospores?

Long-term survival under harsh conditions

Which of the following is the organelle that spirochetes use to propel themselves?

Axial filament

Which of the following refers to photosynthesis performed by bacteria with the use of water as a donor of electrons?

Oxygenic

Why are Mycoplasma and Chlamydia classified as obligate intracellular pathogens?

They lack the ability to replicate outside a host cell

Which genus of Archaea thrives at an optimal temperature of 70-80 degrees C, an optimal pH of 2-3, and oxidizes sulfur to produce sulfuric acid?

Sulfolobus

Which of the following best describes schizogony in protozoa?

A type of multiple fission that produces merozoites

Which structures do protists use for movement?

Cilia, Flagella, and Pseudopodia

What is the purpose of encystment in protists?

Protection from harsh conditions

Which protist is a concern because of its ability to contaminate water supplies and cause diarrheal illness?

Giardia lamblia

Mushrooms are a type of which of the following?

Basidiocarp

What is the plasma membrane of a protist called?

Plasmalemma

What are kinetoplastids?

A group of protists that have a large, modified mitochondrion containing a unique DNA structure

What are septate hyphae?

Hyphae that contain cross-walls (septa) separating individual cells

Why are fungal infections difficult to treat in humans?

Fungal cells are prokaryotic

Which fungal structure is responsible for sexual spore production in Ascomycota?

Ascus

Protists are a diverse, polyphyletic group of eukaryotic organisms. Which of the following best explains why protists are considered polyphyletic?

They do not share a single evolutionary origin but are grouped based on similarities

Harmful algal blooms can release neurotoxins that affect marine life and humans. Which algal group is responsible for red tides?

Dinoflagellates

Which of the following best describes a trophozoite?

The feeding and growing stage of a protozoan

What is the purpose of an apical complex in apicomplexan protozoa?

It enables the organism to enter host cells

What is the primary structural component of fungal cell walls?

Chitin