Tree of Life: Domains and Evolution
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Questions and Answers

What is the primary structure that forms sexual spores in Basidiomycetes?

  • Basidia (correct)
  • Hyphae
  • Sporangia
  • Zygospores

Which of the following best describes zygote formation in Zygomycota?

  • Is independent and does not involve hyphal structures
  • Involves the formation of basidiospores from basidia
  • Occurs through asexual spores called conidiospores
  • Results from the fusion of gametangia producing zygospores (correct)

What distinguishes a fairy ring in fungal growth?

  • It occurs exclusively in Zygomycetes
  • It indicates the age of the underground mycelium (correct)
  • It is formed from asexual spore production
  • It only occurs in dry, arid regions

Which of the following statements is true regarding protists?

<p>They lack a common evolutionary heritage and are a diverse group (C)</p> Signup and view all the answers

Which organism's life cycle is characterized by causing intestinal infections in humans?

<p>Giardia intestinalis (C)</p> Signup and view all the answers

What reproductive process occurs in Giardia intestinalis to produce genetically distinct progeny?

<p>Sexual reproduction (B)</p> Signup and view all the answers

Which structure in Giardia intestinalis is responsible for survival outside the host's body?

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

Which of the following characteristics correctly describe protists?

<p>Some are free-living; others are symbiotic or parasitic (C)</p> Signup and view all the answers

What is a distinct feature of the life cycle of cellular slime molds (e.g., Dictyostelia discoideum)?

<p>They develop stalked sporangia when stressed (D)</p> Signup and view all the answers

In the context of Amoebozoa, how do these organisms typically move and feed?

<p>With pseudopodia (A)</p> Signup and view all the answers

What characteristic is common among all members of the SAR super group?

<p>Cellulose-containing cell walls (A)</p> Signup and view all the answers

Which form of Giardia intestinalis causes disease in humans?

<p>Trophozoite form (C)</p> Signup and view all the answers

What is the primary function of the oral feeding groove in Excavata protists?

<p>Capturing prey (B)</p> Signup and view all the answers

Which characteristic is NOT associated with bacterial endospores?

<p>High water content (C)</p> Signup and view all the answers

Which of the following bacteria is classified as an obligate anaerobe?

<p>Clostridium tetani (A)</p> Signup and view all the answers

What is the estimated impact of the Plague on Europe's population during the 14th century?

<p>Killed approximately 75-200 million people. (B)</p> Signup and view all the answers

What process is primarily responsible for bacterial cell division?

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

Which bacterial genus is known to form spores?

<p>Clostridium (A)</p> Signup and view all the answers

Which type of photosynthesis does green sulfur bacteria perform?

<p>Anoxygenic photosynthesis (B)</p> Signup and view all the answers

What is a key feature of the stationary phase in bacterial growth?

<p>Cell growth ceases (D)</p> Signup and view all the answers

What is the primary way humans serve as hosts in the case of the Yersinia pestis bacterium?

<p>They are incidental hosts. (A)</p> Signup and view all the answers

What distinguishes Archaea from Bacteria?

<p>Archaea have a circular chromosome. (C)</p> Signup and view all the answers

Which statement about penicillin is accurate?

<p>Penicillin was discovered by Sir Alexander Fleming in 1928. (B)</p> Signup and view all the answers

What role does lysozyme play in the human body?

<p>It serves as an antibacterial enzyme present in tears. (A)</p> Signup and view all the answers

What is the significance of the discovery of lysozyme by Sir Alexander Fleming?

<p>It revealed a natural antibacterial agent in human tears. (A)</p> Signup and view all the answers

What describes the oldest forms of life on Earth?

<p>They are prokaryotes that can inhabit diverse habitats. (A)</p> Signup and view all the answers

What is a defining characteristic of prokaryotic cells?

<p>Lack of cell organelles (B)</p> Signup and view all the answers

Which component is found in the cell wall of bacteria?

<p>Peptidoglycan (C)</p> Signup and view all the answers

What is the function of plasmids in bacteria?

<p>Transfer antibiotic resistance genes (A)</p> Signup and view all the answers

Which type of microscopy allows for visualization of bacteria at high magnification?

<p>Light microscopy (B)</p> Signup and view all the answers

What is a unique feature of Gram-positive bacterial cell walls?

<p>Up to 40 layers of peptidoglycan (D)</p> Signup and view all the answers

Which is true regarding the bacterial chromosome?

<p>It is circular and located in the nucleoid (B)</p> Signup and view all the answers

Which of the following correctly describes the peptidoglycan structure in bacteria?

<p>Features a sugar backbone linked by peptide chains (A)</p> Signup and view all the answers

Which type of bacterial cell wall contains an outer membrane?

<p>Gram-negative (D)</p> Signup and view all the answers

Which statement about viruses is true concerning their ability to reproduce?

<p>Viruses reproduce by hijacking the host's cellular machinery. (A)</p> Signup and view all the answers

How do viruses typically exit a host cell?

<p>Via budding or lysis. (A)</p> Signup and view all the answers

Which characteristic indicates that viruses do not meet the definition of living things?

<p>Viruses do not maintain homeostasis. (B)</p> Signup and view all the answers

What is one reason that suggests viruses might be considered lifelike?

<p>Viruses can adapt and evolve through mutation. (C)</p> Signup and view all the answers

Which of the following best describes the composition of viral genomes?

<p>Viral genomes can be made from either RNA or DNA. (D)</p> Signup and view all the answers

Which method of virus transmission is NOT recognized?

<p>Viral transmission through food consumption. (C)</p> Signup and view all the answers

What verdict describes the ability of viruses to use energy?

<p>Viruses rely on host cells for energy when replicating. (A)</p> Signup and view all the answers

What is the primary function of the capsid in a virus?

<p>To protect the viral genome from environmental conditions. (C)</p> Signup and view all the answers

What type of structure do enveloped viruses possess?

<p>Lipid membrane (C)</p> Signup and view all the answers

Which viral structure is characterized by a spherical shape formed from multiple copies of a single protein?

<p>Icosahedral (C)</p> Signup and view all the answers

What is the primary way RNA viruses can differ in their genomes?

<p>Whether they are double or single stranded (A)</p> Signup and view all the answers

Which component is essential for the retrovirus lifecycle where RNA is reverse transcribed into DNA?

<p>Reverse transcriptase (C)</p> Signup and view all the answers

What characteristic distinguishes complex virion structures?

<p>Combination of helical and icosahedral components (B)</p> Signup and view all the answers

Which type of genome cannot be translated into protein immediately?

<p>Negative-sense RNA (B)</p> Signup and view all the answers

Which type of microorganisms are known to differ significantly in the gut microbiomes of obese and lean mice?

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

What type of viral genome is typical for an enveloped virus like Varicella zoster virus?

<p>Linear ds DNA (B)</p> Signup and view all the answers

In what form do viruses gain their envelopes during replication?

<p>Via budding from the plasma membrane (A)</p> Signup and view all the answers

What role do fungi primarily play in ecosystems?

<p>Recyclers of nutrients (A)</p> Signup and view all the answers

What type of relationship exists between mycorrhizae and plant roots?

<p>Mutualism (B)</p> Signup and view all the answers

Which organism is specifically noted for its unicellular structure among fungi?

<p>Saccharomyces cerevisiae (B)</p> Signup and view all the answers

What ecological benefit do lichens provide to barren areas?

<p>Create soil from decay (D)</p> Signup and view all the answers

What is a characteristic feature of viruses?

<p>They are obligate parasites that replicate within host cells. (D)</p> Signup and view all the answers

Which of the following contributions to global biomass is mainly attributed to microbes?

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

What process allows certain bacteria to convert atmospheric nitrogen into ammonia?

<p>Nitrogen fixation (A)</p> Signup and view all the answers

In plant-bacterial mutualism, which statement about root nodules and rhizobia bacteria is correct?

<p>The bacteria supply nitrogen to the plant. (C)</p> Signup and view all the answers

What is the estimated ratio of human cells to bacterial, fungal, and protist cells in the human microbiome?

<p>1:10 (A)</p> Signup and view all the answers

How do microorganisms affect the Tree of Life?

<p>They contribute significantly to global biomass. (D)</p> Signup and view all the answers

Which statement correctly describes the relationship of viruses with living organisms?

<p>Viruses can infect a variety of living organisms. (B)</p> Signup and view all the answers

What distinguishes viruses from living cells?

<p>Viruses lack cellular structures and means of independent replication. (A)</p> Signup and view all the answers

Flashcards

Giardia intestinalis

A parasitic protist that causes giardiasis, a diarrheal illness.

Protists

A diverse group of eukaryotic organisms, often microscopic, that includes both free-living and parasitic species.

Asexual Reproduction in Protists

A type of reproduction in protists where a single organism divides to produce identical offspring.

Amoebozoa

Supergroup of protists that move and feed using pseudopodia.

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Plasmodium

Multinucleated mass of cytoplasm in some acellular slime molds.

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Sporangia

Structures that produce spores, the reproductive cells in some slime molds.

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Supergroups

Major groups of eukaryotes, distinguished by shared evolutionary features.

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SAR

Supergroup of protists with shared characteristics of plastids and cellulose cell walls.

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Budding Yeast

A type of yeast that reproduces asexually by forming a bud that grows into a new individual.

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Fission Yeast

A type of yeast that reproduces asexually by dividing into two equal daughter cells.

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Zygomycetes

A group of fungi that produce distinctive thick-walled resting spores called zygospores during sexual reproduction. Their hyphae are coenocytic, meaning they lack cross walls.

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Basidiomycetes

A group of fungi that produce sexual spores called basidiospores on specialized structures called basidia, often found in mushrooms. Their hyphae are septate, meaning they have cross walls.

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Fairy Ring

A circular pattern of mushroom growth caused by the outward expansion of an underground fungal mycelium.

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Bacterial Growth Phases

The stages of bacterial growth, which include the lag phase, exponential (log) phase, stationary phase, and death phase.

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Stationary Phase

A phase in bacterial growth where the number of viable cells remains constant, due to balanced rates of cell division and cell death.

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Death Phase

The stage in bacterial growth where the number of viable cells declines, usually due to nutrient depletion and waste accumulation.

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Endospore

A resistant, dormant form of some bacteria that allows them to survive harsh conditions.

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Types of Bacterial Metabolism

Bacteria utilize diverse metabolic strategies, including aerobic (using oxygen), anaerobic (without oxygen), and photosynthetic (converting light energy into chemical energy).

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Obligate Anaerobe

A bacteria that can only grow without the presence of oxygen. It is poisoned by oxygen and dies if exposed to it.

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Facultative Anaerobe

A bacteria that can grow with or without oxygen, but prefers oxygen to other energy sources.

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The Microbiome

The vast assemblage of microbes (mostly bacteria) that inhabit a specific environment, particularly the human body, influencing health and disease.

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Antibiotics

Medicines that kill or inhibit the growth of bacteria, often by targeting bacterial cell wall synthesis.

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Penicillin

A famous antibiotic that was discovered by Alexander Fleming from a Penicillium fungus. It targets the cell wall of bacteria, inhibiting its synthesis.

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Gram-positive bacteria

Bacteria with a thick peptidoglycan layer in their cell wall, which stains purple with Gram staining.

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Gram-negative bacteria

Bacteria with a thin peptidoglycan layer in their cell wall, which stains pink with Gram staining.

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Archaea

A distinct domain of life, primarily prokaryotes, known for their unique adaptations to extreme environments.

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What are the 3 domains of life?

The three domains of life are Bacteria, Archaea, and Eukarya. This classification is based on fundamental differences in their cellular structure and evolutionary history.

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What are the defining characteristics of prokaryotes?

Prokaryotes are organisms that lack a membrane-bound nucleus and other membrane-bound organelles. They have a cell wall that contains peptidoglycan.

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What is a plasmid?

A plasmid is a small, circular piece of DNA found in bacteria. It replicates independently of the bacterial chromosome and can carry genes for antibiotic resistance, virulence factors, or other traits.

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What is the difference between gram-positive and gram-negative bacteria?

Gram-positive bacteria have a thick layer of peptidoglycan in their cell wall, while gram-negative bacteria have a thin layer of peptidoglycan and an outer membrane.

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What is peptidoglycan?

Peptidoglycan is a polymer that forms the cell wall of bacteria. It consists of a sugar backbone made of N-acetylmuramic acid (NAMA) and N-acetylglucosamine (NAG) linked by peptide chains.

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What is the function of the cell wall in bacteria?

The cell wall provides structural support and rigidity to the bacterial cell, protecting it from osmotic pressure and other environmental stresses.

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How do gram-positive and gram-negative bacteria differ in their susceptibility to antibiotics?

Gram-positive bacteria are generally more susceptible to antibiotics that target peptidoglycan synthesis, such as penicillin, than gram-negative bacteria, because their thicker peptidoglycan layer is more easily targeted by these drugs.

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How do electron microscopy and light microscopy differ?

Light microscopy uses visible light to illuminate and magnify specimens, with lower resolution. Electron microscopy uses a beam of electrons to image specimens, providing much higher resolution and allowing visualization of smaller structures.

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What are viruses?

Viruses are obligate intracellular parasites, meaning they can only replicate inside living cells. They lack the machinery to make their own proteins or generate energy and rely on host cells for these processes.

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What is a capsid?

A capsid is the protein shell that surrounds a virus's genetic material (DNA or RNA). It protects the genome and facilitates the virus's entry into host cells.

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What is the difference between enveloped and non-enveloped viruses?

Enveloped viruses have an additional membrane called an envelope, made of lipids and proteins, that surrounds the capsid. Non-enveloped viruses lack this envelope.

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What is the difference between (+) and (-) RNA strands?

A (+) RNA strand is similar to mRNA, directly translated into proteins by the host's ribosomes. A (-) RNA strand is the complement of the (+) strand and needs to be copied into (+) sense before translation.

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What is a retrovirus?

A retrovirus contains an RNA genome and uses an enzyme called reverse transcriptase to convert RNA into DNA, which then integrates into the host's genome.

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What is reverse transcriptase?

Reverse transcriptase is an enzyme found in retroviruses that copies the viral RNA genome into DNA.

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How do viruses acquire envelopes?

Enveloped viruses gain their envelope by budding from the host cell's membrane. During budding, the virus's proteins embed in the host cell's membrane, creating a new envelope.

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What are the different types of viral genomes?

Viral genomes can be made of DNA or RNA, and they can be single-stranded or double-stranded, linear or circular. Different viruses have different genome types.

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What is a virus?

A non-cellular particle that infects a host cell and replicates within it.

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Symbiosis

A prolonged and intimate relationship between two different organisms.

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Viral Structure

Viruses consist of a nucleic acid genome (DNA or RNA) enclosed in a protective protein coat called a capsid. Some viruses also have an outer lipid and protein envelope.

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Mutualism

A symbiotic relationship where both organisms benefit and may fail to grow independently.

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Nitrogen Fixation

The conversion of atmospheric nitrogen gas (N2) into ammonia (NH3) by certain bacteria, making it usable by other organisms.

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Human Microbiome

The collective community of microbes (mostly bacteria) inhabiting the human body, influencing health and disease.

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Pathogen

Any infectious entity that causes disease in the host.

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Gut Microbiome & Obesity

The composition of gut bacteria in obese mice differs from lean mice, suggesting a potential link between gut microbiota and obesity.

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Faecal Transplant

Transferring gut bacteria from an obese mouse to a lean mouse can induce obesity in the lean mouse. This supports the idea that gut microbiota can influence weight.

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Fungi: Decomposers

Fungi play a vital role in recycling nutrients by breaking down complex organic matter into simpler substances that other organisms can use.

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Lichens: Mutualism

Lichens are a symbiotic relationship between a fungus and an algae or cyanobacterium, where both partners benefit.

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Mycorrhizae: Plant Partners

Mycorrhizae are a mutualistic relationship between fungi and plant roots, where the fungus provides water and nutrients, and the plant provides sugar.

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Viral Genome Replication

The process by which a virus replicates its genetic material using the host cell's machinery.

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Virus Entry: Attachment & Entry

The initial stage of virus infection, where the virus binds to a host cell and gains entry.

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Viral Protein Synthesis

The process by which a virus uses the host cell's ribosomes to produce viral proteins.

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Budding: Virus Exit

A method of virus release where new viral particles bud from the host cell membrane.

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Lysis: Virus Exit

A method of virus release where the host cell bursts open, releasing new viral particles.

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Are Viruses Alive? Reproduction

Viruses can only replicate by using the host cell's machinery. They lack the necessary mechanisms to copy their own genes or make proteins.

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Are Viruses Alive? Growth

Viruses do not grow in the same way that living organisms do. Each virion is fully formed and does not increase in size or complexity.

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Are Viruses Alive? Homeostasis

Viruses are not capable of maintaining a stable internal environment. They rely on the host cell for survival and replication.

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Study Notes

Overview of Lecture

  • The lecture will cover the Tree of Life, focusing on the three domains: Bacteria, Archaea, and Eukaryota.
  • Multicellular life evolved from single-celled organisms.
  • Linnaean classification and phylogenetic analysis are used to categorize organisms.
  • Life is diverse, and microorganisms dominate the Tree of Life.
  • Life evolved from a common ancestor.
  • All cellular life operates via DNA transcription into RNA and translation into proteins via ribosomes.
  • Evolution drives diversity by changing the blueprints over time.
  • Key processes of change result in new species.

The Tree of Life

  • The Tree of Life shows evolutionary relationships among organisms.
  • The fundamental unit of evolutionary classification is a taxon and can be grouped at differing levels.
  • Domains of life were developed by comparison of the genetic information of related organisms (16S rRNA).
  • Three domains of life exist: Bacteria, Archaea, and Eukarya.

Macroorganisms

  • Bacteria are a major form of microbial life.
  • Protists include Paramecium and other single-celled organisms.
  • Archaea are a category of microorganisms.
  • Fungi include Aspergillus and other multicellular organisms
  • Microorganisms dominate the Tree of Life, meaning these organisms are the most numerous life form

Microorganisms

  • Microbial Life evolved from a common ancestor
  • Principles for how life is structured:
  • DNA
  • RNA
  • Protein

Evolution

  • Organisms continually change over time.
  • This change ultimately leads to the creation of new related species.
  • The last universal common ancestor (LUCA) is the theoretical ancestor of all life on Earth.

Classification

  • Linnaean taxonomy is a method for classifying organisms based on shared characteristics.
  • It includes species, genus, family, order, class, phylum and kingdoms.

Phylogenetics

  • A method that studies evolutionary relationships from the perspective of genetic information and biochemical properties.
  • This is done by analyzing similarities in gene sequences and protein structures.

Horizontal Gene Transfer

  • The process by which genes can be passed between unrelated organisms.

Microbial Life in Extreme Environments

  • Extremophiles can survive in extreme conditions (i.e. high temps, pressure, saltwater).
  • These conditions test the limits of life as we know it and often include microorganisms such as bacteria and archaea.

Bacteria and Archaea

  • Archaea and bacteria are prokaryotes, meaning they do not have a nucleus and other membrane-bound organelles.
  • Bacteria and archaea are commonly seen as extremophiles, flourishing in extreme conditions of temperature and salinity.

Cell Structure

  • Bacterial and Archaeal cells have a cell wall made of peptidoglycan (bacteria) or other chemicals (archaea)
  • These cells have a plasma membrane that surrounds the cell, separating it from the external environment.

Bacterial Reproduction

  • Bacteria reproduce asexually by binary fission, creating two identical daughter cells.
  • This rapid rate of reproduction is a reason for their dominance in ecological environments.

Bacterial Metabolism

  • Bacteria exhibit metabolic diversity, including aerobic, anaerobic, and photosynthetic organisms.

Importance of Microorganisms

  • Microorganisms are essential to maintaining the balance of ecosystems.
  • They are involved in nutrient cycles, decomposition, and other vital processes.
  • They have a unique diversity, adaptability and abundance.

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Description

This quiz explores the Tree of Life, focusing on the three domains: Bacteria, Archaea, and Eukaryota. It delves into the evolution of multicellular life from single-celled organisms, the significance of Linnaean classification, and phylogenetic analysis. Test your understanding of how life diversifies through evolutionary processes.

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