Taxonomy Fundamentals

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Questions and Answers

What process allows the transfer of DNA between bacterial cells through a bridge?

Binary fission

Transformation

Transduction

Conjugation (correct)

What is the role of endospores in bacteria?

To enhance nutrient absorption

To increase motility

To protect DNA in unfavorable conditions (correct)

To facilitate reproduction

Which human use of bacteria does NOT contribute to environmental management?

Cleaning up oil spills

Food production (correct)

Sewage treatment

Production of vitamins in intestines

What is one of the primary causes of bacterial resistance to antibiotics?

Overuse or misuse of antibiotics Signup and view all the answers

Which method is NOT effective for food preservation against bacterial growth?

Allowing food to sit at room temperature Signup and view all the answers

Which of the following statements is true concerning Gram-negative bacteria?

They have a complex cell wall structure with three layers. Signup and view all the answers

What are the shapes of bacteria classified as bacilli?

Rod shaped Signup and view all the answers

How do extreme thermohalophiles typically thrive?

In high-temperature environments such as hot springs Signup and view all the answers

What is the primary method through which bacteria reproduce asexually?

Binary fission Signup and view all the answers

Which grouping characterizes bacteria that form chains?

Streptococcus Signup and view all the answers

What is a distinguishing characteristic of Gram-positive bacteria?

They retain the crystal violet stain and appear purple. Signup and view all the answers

What is the process through which plasmids are exchanged between bacteria?

Conjugation Signup and view all the answers

Which type of mobility mechanism do some bacteria use to move through environments?

Flagella Signup and view all the answers

Which kingdom is known for having a cell wall that lacks peptidoglycan?

Kingdom Archaebacteria Signup and view all the answers

In which kingdom do most organisms absorb their food from the environment?

Kingdom Fungi Signup and view all the answers

What type of organisms can be found in the Kingdom Protista?

Both autotrophic and heterotrophic organisms Signup and view all the answers

Which kingdom includes organisms that reproduce both sexually and asexually?

All of the above Signup and view all the answers

Which of the following characteristics distinguishes Kingdom Animalia from other kingdoms?

Absence of cell walls Signup and view all the answers

Which of the following kingdoms contains both unicellular and multicellular organisms?

Kingdom Protista Signup and view all the answers

Which statement is true about Kingdom Eubacteria?

They are found in nearly every environment. Signup and view all the answers

What is a common habitat for organisms in the Kingdom Archaebacteria?

Volcanic hot springs Signup and view all the answers

What is the primary purpose of taxonomy in biology?

To accurately and uniformly name organisms Signup and view all the answers

Which part of the scientific name identifies the genus to which an organism belongs?

The first part of the name Signup and view all the answers

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

Italicized with the genus capitalized and species in lowercase Signup and view all the answers

Which of the following statements regarding taxonomic categories is true?

Linnaeus established a system with eight taxonomic ranks Signup and view all the answers

Which scientist is credited with developing the binomial nomenclature system?

Carolus Linnaeus Signup and view all the answers

Why was the Kingdom Monera split into two different taxa?

Because of large differences in cellular structure Signup and view all the answers

What does molecular analysis in taxonomy primarily focus on?

DNA sequence comparisons among species Signup and view all the answers

How does the new domain system categorize organisms?

Into three broad groups reflecting molecular evidence Signup and view all the answers

Which of the following is NOT a taxonomic category in the hierarchy?

Ecosystem Signup and view all the answers

Which organism’s scientific name is correctly matched with its common name?

Ursus arctos - Grizzly Bear Signup and view all the answers

What is the primary function of a dichotomous key?

To identify unfamiliar organisms through observable traits Signup and view all the answers

Which structure is NOT part of the general structure shared by both domains of bacteria?

Nucleus Signup and view all the answers

What type of Archaebacteria are methanogens, and where can they be commonly found?

They are chemoautotrophic anaerobes found in swamps and landfills. Signup and view all the answers

Which of the following characteristics describes thermophiles?

They can grow at temperatures above boiling point. Signup and view all the answers

Which statement about halophiles is true?

They are aerobic organisms living in saline conditions. Signup and view all the answers

What does the term 'plasmid' refer to in bacteria?

Circular DNA used for sexual reproduction Signup and view all the answers

Which observable trait might lead to identifying an organism as belonging to the BB classification in a dichotomous key?

The organism is round and orange. Signup and view all the answers

Which is a key characteristic of the capsule surrounding some bacterial cells?

It protects the bacteria from harsh environmental conditions. Signup and view all the answers

Study Notes

Taxonomy

The science of classifying organisms
Around 1.7 million species identified and named
Estimated 8 million more unknown species
Aristotle first classified organisms into land, sea, and air dwellers
Organisms need a name and organization
Uses Latin for consistent naming
Each species has only one scientific name
Same name not used for different species
Shows evolutionary relationships

Taxonomic Categories & Hierarchy

Linnaeus grouped organisms into taxa based on structure and function (morphology)
Eight taxa within taxonomy: Domain, Kingdom, Phylum, Class, Order, Family, Genus, Species
Classification is organized from smallest to largest
Each level groups organisms with more shared characteristics than the level before

Binomial Nomenclature

Developed by Carl Linnaeus
A two-part scientific name for each species
First part identifies the genus (group of closely related species)
Second part is unique to each species within the genus
Scientific names are always written in italics when typed
The first letter of the genus is capitalized, and the second word is lowercase
Example: Ursus arctos (Grizzly Bear)
Can be underlined when handwriting

Traditional Taxonomy

Two Kingdom System (Linnaeus): Animalia and Plantae
Five Kingdom System: Monera, Protista, Fungi, Plantae, Animalia
Six Kingdom System: Eubacteria and Archaebacteria split from Monera

Molecular Analysis

Similarities on the molecular level indicate common ancestors
Used to determine classification and evolutionary relationships
Shows how species have evolved
DNA sequence comparisons show relatedness: more similar sequences = more recent common ancestry

New Domain System

Reflects understanding of molecular and evolutionary evidence
Three domains: Bacteria, Archaea, Eukarya

3 Domains of Life

Bacteria: Peptidoglycan in cell walls, includes bacteria causing disease, unicellular and prokaryotic
Archaea: No peptidoglycan in cell walls, live in harsh environments
Eukarya: Unicellular and multicellular, eukaryotic, includes Kingdoms Protista, Fungi, Plantae, and Animalia

Kingdom Archaebacteria

“Ancient” bacteria
Prokaryotic and unicellular
Both autotrophs and heterotrophs
Cell wall lacks peptidoglycan
Reproduce asexually
Some are motile (can move)
Live in extreme environments (volcanic hot springs, salt marshes)

Kingdom Eubacteria

“Recent” bacteria
Prokaryotic and unicellular
Both autotrophic and heterotrophic
Reproduce asexually
Some are motile
Cell wall contains peptidoglycan
Live nearly everywhere

Kingdom Protista

Organisms that cannot be classified as animals, plants, or fungi
Great variety among members
Classified into three groups: Animal-like protists, Plant-like protists, Fungi-like protists
Eukaryotic
Most are unicellular, some are multicellular
Autotrophs and heterotrophs
Reproduce sexually and asexually
Some are motile
Some have a cell wall
Live in damp or wet habitats

Kingdom Fungi

Eukaryotic
Mostly multicellular, some unicellular (yeast)
Heterotrophic: Absorb food from the environment
Feed on dead or decaying matter
Have a cell wall made of chitin
Reproduce sexually and asexually
Non-motile
Live as parasites or saprophytes

Kingdom Plantae

Eukaryotic and multicellular
Photosynthetic, autotrophs
Have a cell wall made of cellulose
Reproduce sexually and asexually
Non-motile
Includes cone-bearing and flowering plants, mosses, and ferns

Kingdom Animalia

Eukaryotic and multicellular
Heterotrophic
Mostly reproduce sexually
No cell walls
Motile, except sponges
Very diverse

Dichotomous Key

A tool for identifying unfamiliar organisms
List of observable traits that lead to the organism's name
“Dichotomous” means “divided into two parts”
Each step has two choices (yes or no)

General Structure of Bacteria

DNA: Dictates cell function, including plasmids for sexual reproduction
Ribosomes: Make proteins
Cell wall: Provides structure to the bacterial cell
Capsule: Thick gelatin around the cell wall, protects bacteria, hardens in harsh conditions
Pili: For movement
Flagellum: For movement in some bacteria

Domain Archaea

Live in extremely hot, salty, oxygen-poor, toxic environments
Oldest known organisms
Methanogens, halophiles, and thermophiles are different types of archaea

Methanogens

Chemoautotrophic anaerobes
Produce methane as a waste product
Found in swamps, sewage, landfills, and guts of large mammals
Potential for methane production in sewage treatment and landfills

Halophiles

Salt-loving Archaea
Grow in places like salt ponds and lakes
Large numbers can turn water a dark pink
Aerobic

Thermophiles

Archaebacteria from hot springs and other high-temperature environments
Some can grow above the boiling point of water
Anaerobic
Extreme thermohalophiles grow in high temperatures, like deep-sea hot vents

Domain Bacteria

Found everywhere else
Cocci, bacilli, spirilla are different shapes of Eubacteria
Diplo-, strepto-, staphylo- groupings describe how bacteria cluster
Gram staining helps classify bacteria:
- Gram-positive: Purple stain, one cell layer, thick peptidoglycan
- Gram-negative: Pink stain, three cell layers, thin peptidoglycan, thick lipid layer
Mobility: Flagella, lashing, gliding, or spiraling movements
Reproduction:
- Binary fission: Asexual, bacterium replicates DNA and divides in half, producing two identical cells
- Conjugation: Sexual, transfer of plasmids (small, circular DNA) from one bacteria to another
- Spore formation: In unfavorable conditions, bacteria produce a thick internal wall around DNA and cytoplasm

Importance of Bacteria

Ecological roles: Producers, decomposers, nitrogen fixers
Human uses: Foods and beverages, sewage treatment, cleaning up oil spills, synthesis of drugs and chemicals, production of vitamins in the gut
Pathogenic bacteria: Cause diseases (pneumonia, tetanus)

Defending Against Bacterial Infections

Prevention: Hand washing, active immunity (vaccination), passive immunity
Food preservation: Heat or chemicals to slow down bacterial growth (sterilization, refrigeration, cooking through, canning, freezing, drying)
Antibiotics: Compounds that kill or inhibit bacterial growth

Antibiotic Resistance

Bacteria can develop resistance to antibiotics, which is a growing problem

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Description

Explore the fascinating world of taxonomy, the science of classifying organisms. Learn about the classification hierarchy, taxonomic categories, and the system of binomial nomenclature developed by Carl Linnaeus. This quiz will help you understand how we organize and name the diverse species of our planet.