Cell Structure Comparison Quiz

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Questions and Answers

What type of ribosomes are found in eukaryotic cells compared to bacterial cells?

80S in eukaryotes and 70S in bacteria (correct)

50S in eukaryotes and 70S in bacteria

60S in eukaryotes and 80S in bacteria

70S in eukaryotes and 60S in bacteria

Which structure is absent in bacterial cells but present in eukaryotic cells?

Cell membrane

Ribosomes

Mitochondria (correct)

Cell wall

What term describes bacteria that lack a cell wall?

Cocci

Mycoplasmas (correct)

Obligate intracellular parasites

Spirilla

Which type of bacteria is known to reproduce asexually through binary fission?

Bacteria Signup and view all the answers

What component in bacterial cell walls provides resistance to osmotic stress?

Peptidoglycan Signup and view all the answers

Which of the following statements about flagella in bacteria is correct?

They are simple in structure. Signup and view all the answers

Which of the following antibiotics targets bacterial ribosomes?

Tetracycline Signup and view all the answers

What is the average size range of bacteria?

0.5-5.0 mm Signup and view all the answers

What does viable count represent in microbiology?

The concentration of living cells only. Signup and view all the answers

Which of the following best describes the total viable count?

It identifies living cells regardless of species type. Signup and view all the answers

What is a characteristic of the traditional method for viable count?

It tends to be labor-intensive and slow. Signup and view all the answers

In the pour plate method, what is the acceptable range of colony-forming units (CFU) per mL for accurate counting?

30-300 CFU/mL Signup and view all the answers

Which part of a mould colony represents its oldest and most mature region?

The central area of the colony. Signup and view all the answers

What type of growth refers to microorganisms that are attached to a surface?

Sessile growth Signup and view all the answers

Which of the following statements about yeast colonies is true?

Yeast colonies are usually larger and can be colored. Signup and view all the answers

Which of the following factors defines the need for traditional methods of viable count?

They need to analyze large volumes of culture media. Signup and view all the answers

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

Cell wall composition Signup and view all the answers

Which of the following describes strict anaerobes?

Cannot grow in the presence of oxygen Signup and view all the answers

What is a primary characteristic of fungi?

Form spores that resist drying Signup and view all the answers

Which of the following is true about most protozoa?

Most are harmless and free-living Signup and view all the answers

What is a common method of reproduction in yeast?

Budding or binary fission Signup and view all the answers

What type of bacteria are most saprophytes classified as?

Non-photosensitizing Signup and view all the answers

Which group of microorganisms is primarily unicellular and regarded as animals?

Protozoa Signup and view all the answers

In what environment are most protozoa commonly found?

Aquatic environments Signup and view all the answers

What is a major characteristic of yeast as fungi?

They reproduce asexually through the formation of asexual spores. Signup and view all the answers

What is the correct way to denote the scientific name of an organism?

Italics for the genus and species but not for collective names. Signup and view all the answers

What does the term 'collective' refer to in microbiology nomenclature?

A whole group of microbes. Signup and view all the answers

Which of the following describes anaerobic organisms?

They prefer low redox potential environments. Signup and view all the answers

What is the main structure of yeast as fungi?

A tangled mass of filaments called mycelium. Signup and view all the answers

When discussing microbial metabolism, what is essential for food breakdown?

Oxidation of food to release energy. Signup and view all the answers

What is a characteristic of the threads or filaments of fungi?

They are called hyphae and can vary in width. Signup and view all the answers

Which of the following statements is true regarding the reproduction of yeast?

They primarily reproduce asexually via spores. Signup and view all the answers

What is the primary function of yeast extract in microbial cultivation?

To provide B-group vitamins Signup and view all the answers

What is the effect of agar concentration of 1-1.5% in culture media?

It provides a firm gel that cannot be liquefied by bacterial enzymes Signup and view all the answers

At what temperature does agar begin to liquefy?

90°C Signup and view all the answers

Which of the following is NOT a purpose of special culture media?

To enhance microbial growth Signup and view all the answers

What role does adding bile to culture media serve?

To suppress organisms other than those found in the gastrointestinal tract Signup and view all the answers

Which of the following statements is true regarding the use of carbohydrates in culture media?

They may be added for diagnostic purposes Signup and view all the answers

Why is it important for agar to remain liquid at 45°C during incubation?

To facilitate pour plate counting methods Signup and view all the answers

What is a characteristic of tryptone soya medium?

It is rich in peptones and supports a wide range of microorganisms Signup and view all the answers

Study Notes

Cell Structures and Characteristics

Mitochondria and chloroplasts are present in eukaryotic cells, absent in prokaryotic cells.
Cell membrane contains sterols in eukaryotes; prokaryotic membranes lack sterols.
Cell walls of eukaryotes consist of cellulose or chitin; bacteria have peptidoglycan.
Eukaryotic ribosomes are 80S, whereas prokaryotic ribosomes are 70S.
Flagella in eukaryotes are complex, while bacterial flagella are simple.
Pili are absent in eukaryotes but present in some bacteria.
Bacterial fimbriae are often present and help in attachment.

Bacterial Features

Bacteria can cause contamination and spoilage, particularly in pharmaceuticals.
Bacterial cell walls resist osmotic stress and drying; some are targeted by antibiotics like penicillins.
Bacteria prefer temperatures between ambient and human body temperature, can tolerate varying oxygen levels.
Structural differences between bacterial and eukaryotic cells lead to selective antibiotic toxicity.
Bacteria reproduce asexually, primarily through binary fission, with genetic variation mainly due to mutations.

Viable Cell Count

Total viable count assesses living microorganisms across species in a sample, including bacteria and fungi.
Solid medium yeast colonies are larger with pigmentation; molds display a mycelium structure revealing a central (oldest) area with spore pigmentation.
Traditional viable count methods are labor-intensive, slow, and require considerable culture media and incubation space.

Growth Methods

Pour plate method is used for viable count; 30-300 CFU/mL is considered an acceptable range.
Involves mixing a small sample with molten agar at 45°C and counting colony formations after incubation.

Types of Bacteria

Distinction between Gram-positive and Gram-negative bacteria.
Bacteria can be saprophytes, strict aerobes, or anaerobes, with varying oxygen dependencies.
Examples of obligate intracellular parasites include Rickettsia and Chlamydia.
Mycoplasmas lack cell walls, making them unique among bacteria.

Fungi and Yeasts

Fungi form spores resistant to drying; they are often contaminants in raw pharmaceutical materials.
Most fungi are saprophytes, some can cause severe illness in immunocompromised individuals.
Yeasts are unicellular and generally larger than bacteria, utilizing binary fission or budding for reproduction, with a size range of 10-50 μm.

Protozoa

Predominantly unicellular, protozoa are regarded as animals rather than plants.
Many are free-living and motile, found in water and soil; only a few are pathogenic, notably causing diseases like malaria.

Naming of Organisms

Scientific names of organisms are italicized to denote their status as proper names; collective terms are not italicized.

Microbial Metabolism and Cultivation

Anaerobic organisms prefer low redox potential environments, indicating their oxygen requirements.
Cultivation methods can use specific media, such as tryptone soya medium, to enhance microbial growth.

Solid Culture Media

Agar, utilized in culture media, creates a firm gel that withstands bacterial enzymes, solidifying at about 40°C.
Carbohydrates may be included in culture media for diagnostic purposes, restricting growth of certain microorganisms.

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Description

Test your knowledge on the differences between various cell structures. This quiz covers cell membrane components, ribosome types, and the presence of organelles in different types of cells. Perfect for biology students looking to deepen their understanding of cellular biology.