Biology Chapter on Evolution and Life Origins

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Questions and Answers

What evidence suggests chloroplasts originated from cyanobacteria?

  • The presence of a double membrane and their own DNA and ribosomes. (correct)
  • Their capacity to infect a wide range of organisms.
  • Their requirement for a host cell to reproduce.
  • The ability to exist in a dormant state for extended periods.

Which feature is NOT considered a characteristic of viruses?

  • The ability to reproduce independently. (correct)
  • The presence of either DNA or RNA as their genetic material.
  • Their role as obligate intracellular parasites.
  • The presence of a protein coat surrounding the nucleic acid.

What is the primary significance of sexual reproduction in the context of evolution?

  • It reduces the overall genetic diversity of a population.
  • It enhances genetic diversity through meiosis and random fertilization. (correct)
  • It allows for rapid reproduction under optimal conditions.
  • It ensures genetic uniformity, leading to a more stable lineage.

What key adaptation was necessary for life to transition from water to land?

<p>Methods to prevent desiccation and maintain water balance. (C)</p> Signup and view all the answers

What was a major feature of the Cambrian explosion?

<p>The rapid increase in the diversity of multicellular animal life. (A)</p> Signup and view all the answers

Which of the following best describes the concept of 'tissue tropism' in viruses?

<p>The preference of a virus to infect certain cell types within a host. (C)</p> Signup and view all the answers

How do multicellular organisms benefit from cell specialization?

<p>It allows for more complex interactions and functions through differentiation. (A)</p> Signup and view all the answers

Approximately how many years ago did the Cambrian explosion occur, according to the geological timescale?

<p>500 million years ago (D)</p> Signup and view all the answers

What is the role of the ozone layer in the context of life's transition to land?

<p>It protected organisms from harmful UV radiation. (C)</p> Signup and view all the answers

Which of the following best describes a key characteristic of the early Earth's atmosphere as described in the chapter?

<p>Rich in carbon dioxide, nitrogen gas, water vapor, and hydrogen gas. (C)</p> Signup and view all the answers

What was the primary focus of the Miller-Urey experiment in the context of the origin of life?

<p>To simulate early Earth conditions and produce organic monomers. (D)</p> Signup and view all the answers

What is thought to be the likely original genetic material, according to the chapter?

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

Which of the following is a characteristic of stromatolites?

<p>They are mat-like structures formed by mineral deposits and trapped by cells. (A)</p> Signup and view all the answers

Which of the following processes is associated with the theory of endosymbiosis in the origin of eukaroytes?

<p>The engulfment of one organism by another, leading to organelles. (D)</p> Signup and view all the answers

Which characteristic is typically associated with lytic viruses?

<p>The virus replicates and causes the host cell to rupture. (B)</p> Signup and view all the answers

What is a significant effect of the movement of continents over geological time?

<p>The formation of supercontinents and subsequent evolutionary lineages. (D)</p> Signup and view all the answers

What is the key difference between inductive and deductive reasoning?

<p>Deductive reasoning moves from general principles to specific conclusions while inductive reasoning uses specific observations to identify a more general pattern or trend. (B)</p> Signup and view all the answers

What is a defining feature of a positive-strand RNA virus?

<p>Its RNA directly serves as mRNA for protein synthesis. (D)</p> Signup and view all the answers

A virus that uses reverse transcriptase to convert RNA to DNA is classified as a:

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

What is a key characteristic of emerging viruses?

<p>They originate in one organism and then spread to another, causing disease. (A)</p> Signup and view all the answers

What role do prions play in disease?

<p>They convert normal host proteins into a misfolded form that causes disease. (A)</p> Signup and view all the answers

What is the primary function of Koch's postulates?

<p>To establish a causal relationship between a microorganism and a disease. (B)</p> Signup and view all the answers

Where does replication typically occur for most RNA viruses?

<p>In the cytoplasm of the host cell (D)</p> Signup and view all the answers

What is a distinguishing characteristic of viroids?

<p>They are tiny, naked molecules of circular RNA. (A)</p> Signup and view all the answers

Which characteristic is NOT typically associated with prokaryotic cells?

<p>Membrane-bound organelles (C)</p> Signup and view all the answers

Which of the following is the primary method of reproduction for prokaryotes?

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

What is the role of the F pilus in bacterial conjugation?

<p>To fuse the cell membranes to create a conjugation bridge (B)</p> Signup and view all the answers

What is the primary function of peptidoglycan in bacterial cell walls?

<p>Providing structural support and maintaining cell shape (C)</p> Signup and view all the answers

How does generalized transduction differ from specialized transduction?

<p>Generalized transduction occurs by accidents in the lytic cycle, while specialized transduction results from accidents in the lysogenic cycle (A)</p> Signup and view all the answers

Which of the following describes the method of genetic recombination in prokaryotes?

<p>Horizontal gene transfer (B)</p> Signup and view all the answers

What makes endospores particularly resistant to environmental stress?

<p>Their thick cell wall surrounding the genome (B)</p> Signup and view all the answers

What distinguishes the plasma membrane of Archaea from that of Bacteria and Eukaryotes?

<p>Ether linkage in the membrane lipids (A)</p> Signup and view all the answers

Which of the following is NOT a typical shape of a prokaryotic cell?

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

Which process involves a bacterial cell picking up DNA directly from its surroundings (environment)?

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

What is the significance of the Gram stain in bacterial classification?

<p>It differentiates bacteria based on the thickness of their cell wall's peptidoglycan layer. (B)</p> Signup and view all the answers

Which statement is true regarding the relationship between F plasmid and the bacterial chromosome in Hfr cells?

<p>The F plasmid integrates into the bacterial chromosome (C)</p> Signup and view all the answers

What is the main function of pili in prokaryotic cells?

<p>Attachment to surfaces (A)</p> Signup and view all the answers

What is a key characteristic that distinguishes prokaryotic ribosomes from eukaryotic ribosomes?

<p>They are targeted by different antibiotics. (D)</p> Signup and view all the answers

What is the role of R plasmids in bacteria?

<p>To encode for antibiotic resistance genes (C)</p> Signup and view all the answers

In early classification schemes for prokaryotes, what feature would be considered a primary characteristic for grouping organisms?

<p>Nutritional mode (photosynthetic or non-photosynthetic) (C)</p> Signup and view all the answers

Flashcards

Endosymbiosis

The process of a smaller cell living inside a larger cell, with the smaller cell eventually becoming an essential part of the larger cell. This is how chloroplasts and mitochondria are believed to have originated.

Endosymbiotic Theory

The theory that mitochondria and chloroplasts originated from bacteria that were engulfed by eukaryotic cells.

Eukaryotic Cell

A single-celled organism with a nucleus and other membrane-bound organelles.

Multicellular Organism

An organism made up of multiple cells that work together, forming tissues and organs.

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Cell Differentiation

The process where cells in a multicellular organism specialize in specific functions.

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Chloroplast

A cell type found in plants that is responsible for photosynthesis.

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Mitochondrion

A cell type found in both plants and animals that is responsible for cellular respiration.

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Virus

A biological agent that can only replicate inside a host cell.

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Archean Eon

The first eon in Earth's history, marked by the appearance of the first life forms, primarily single-celled prokaryotes.

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Cambrian Period

The time period characterized by a rapid diversification of multicellular life forms, including the emergence of many animal phyla, seen in the fossil record.

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Deductive Reasoning

A type of reasoning that starts with a general statement and applies it to specific cases, such as drawing conclusions about the evolution of life based on the fossil record.

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Inductive Reasoning

A type of reasoning that observes specific patterns and trends to form a general conclusion, such as identifying the emergence of prokaryotes based on ancient microfossil evidence.

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Mass Extinction

A major evolutionary event where a large number of species become extinct in a relatively short period of time.

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Weathering

The process of converting silicate rock into soil, influencing atmospheric CO2 levels and Earth's climate over geological time.

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Stromatolites

Fossil evidence of ancient microbial mats composed of layers of bacteria and sediment, providing insights into early life forms.

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Lytic Infection

Viral infection where the virus replicates rapidly within the host cell, leading to the cell's destruction.

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Positive-Strand RNA Virus

A type of virus that carries its genetic material in the form of RNA, which directly acts as messenger RNA (mRNA) upon entering a host cell.

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Negative-Strand RNA Virus

A type of virus that carries its genetic material in the form of RNA, but its RNA is complementary to the viral mRNA, meaning it needs to be transcribed into mRNA first.

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Retrovirus

A type of virus that uses reverse transcriptase to convert its RNA genome into DNA, which can then integrate into the host cell's genome.

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Cancer-Causing Virus

A virus that can contribute to the development of cancer by altering the growth properties of human cells.

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Prions

Infectious particles composed solely of misfolded proteins. They cause transmissible spongiform encephalopathies (TSEs), brain diseases.

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Viroids

Tiny, circular RNA molecules that can infect plants. They don't encode proteins, but they can interfere with the host's RNA.

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Prokaryotes

Small, single-celled organisms that lack a nucleus and other membrane-bound organelles. They are incredibly diverse and abundant.

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Endospore

A thick, protective layer that forms around the genome of some bacteria when they are exposed to environmental stress, making them highly resistant to heat and other harsh conditions.

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Nucleoid Region

The region within a prokaryotic cell where the single, circular chromosome is located. It is not enclosed by a membrane like the nucleus in eukaryotic cells.

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Plasmids

Small, circular DNA molecules found in some prokaryotic cells. They often carry genes that give the bacteria a selective advantage, such as antibiotic resistance.

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Binary Fission

The primary mode of reproduction in prokaryotes, where a single cell divides into two identical daughter cells.

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Horizontal Gene Transfer

The transfer of genetic material between prokaryotic cells without involving sexual reproduction.

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Conjugation

A type of horizontal gene transfer in which a bacterial cell with a plasmid (F+) transfers the plasmid to another bacterial cell (F-) through direct contact.

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Transduction

A type of horizontal gene transfer in which bacterial DNA is transferred to another bacteria by a virus.

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Transformation

A type of horizontal gene transfer in which bacteria take up DNA from their environment.

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Lack of Internal Compartmentalization

Prokaryotic cells are characterized by the absence of internal membrane-bound organelles, meaning they have no nucleus or other distinct internal compartments.

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Cell Wall Difference

Both bacteria and archaea have a cell wall, but while bacteria use peptidoglycan as a key component, archaea lack this specific molecule.

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Prokaryotic DNA

The genetic material of most prokaryotes is a single, circular molecule of DNA located in a region called the nucleoid. They can also have extra-chromosomal DNA in the form of plasmids.

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Metabolic Diversity in Prokaryotes

Prokaryotes have a remarkably diverse range of metabolic processes. They can be photosynthetic, chemosynthetic, or utilize a variety of energy sources and carbon sources.

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Prokaryotic Flagella

In contrast to eukaryotic flagella, which are complex structures, the flagella of prokaryotes are simpler, and they use a different mechanism for rotation and movement.

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Gram Staining

The Gram stain is a widely used method to differentiate bacteria based on their cell wall structure. Gram-positive bacteria have a thicker peptidoglycan layer and stain purple, while Gram-negative bacteria have a thinner layer and stain pink or red.

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Study Notes

Chapter 25: Origin & Diversity of Life

  • Geological time is divided into 4 eons, eras, and periods
  • Cambrian period (500 million years ago) marked an explosion of fossil records
  • Carboniferous period is when fossil fuels formed
  • No life existed until 3.6-3.8 billion years ago (prokaryotes)
  • Eukaryotes evolved 2.7 billion years later
  • CO2 levels shifted and affected temperature
  • Increased weathering converted silicate rock to soil
  • Tectonic plates moved over geologic time; Pangea formed as a supercontinent
  • Life emerged in the Archean eon
  • Cambrian period showed diversification of multicellular organisms
  • Early organic molecules formed are unknown

Chapter 25: Earth's Atmosphere

  • Earth's atmosphere comprised of carbon dioxide (CO2), nitrogen gas (N2), water vapor (H2O), and hydrogen gas (H2)
  • Miller-Urey experiment attempted to recreate early Earth conditions to produce organic molecules
  • Emergence of metabolic pathways: primitive organisms were autotrophic (self-feeding)
  • RNA may have been the first genetic material
  • Fossil evidence of life during Archaean in the form of microfossils; 3.5 billion years old resembling prokaryotes

Chapter 25: Stromatolites & Mass Extinctions

  • Stromatolites are mats of cyanobacteria that trap mineral deposits
  • Earth's changing system (temperature and water availability) and mass extinctions influenced evolution
  • Deductive reasoning: uses general statements
  • Inductive reasoning: uses patterns and trends

Chapter 25: Compartmentalization of Cells

  • Three domains: prokaryotic (bacteria and archaea) and eukaryotic (fungi, plants, animals, and protists)
  • All eukaryotic cells have compartmentalizations (organelles, membranes, etc.)
  • Bacteria and archaea do not have internal compartmentalization

Chapter 25: Endosymbiosis

  • Mitochondria and chloroplasts are unique compared to other components because they have their own DNA and ribosomes; double membrane
  • Endosymbiosis: mitochondria and chloroplasts were once free-living prokaryotes that were engulfed by a larger cell
  • Ribosomes match Archean sizes
  • Chloroplast came from cyanobacteria
  • Only protists and plantae have both mitochondria and chloroplasts

Chapter 25: Multicellularity

  • Unicellular body plans are successful; multicellularity allows organisms to respond to the environment in more ways
  • Sexual reproduction increases genetic diversity
  • Meiosis & crossing over occur, and random fertilization occurs
  • First eukaryotes were probably haploid

Chapter 26: Viruses

  • Viruses are not considered living
  • Cannot reproduce on their own
  • Must have a host cell, and cannot utilize energy on their own
  • All viruses have a nucleic acid core surrounded by protein
  • Can have circular or linear DNA/RNA
  • Classified by genome (RNA/DNA virus, etc.)
  • Obligate intracellular parasites which infect every organism type
  • Host range—each type of virus has a limited host range, tissue tropism (viruses may only infect specific tissues)
  • Remain dormant or latent for years

Chapter 26: Viral Genomes

  • Viral genomes vary greatly in nucleic acid type and number of strands (single/double stranded DNA/RNA)
  • Most RNA viruses are single-stranded
  • Replication occurs in the host cell's cytoplasm; mutations occur during replication; difficult to target for immune system
  • RNA viruses: positive-strand viruses act as mRNA, negative-strand viruses are complementary transcripts, retroviruses use reverse transcriptase to convert viral RNA to DNA.

Chapter 26: Human Immunodeficiency Virus (HIV)

  • Some people are resistant to HIV infection
  • Exposure to HIV does not guarantee infection, and exposure does not lead to AIDS
  • Others have little resistance to HIV and progress rapidly from infection to AIDS

Chapter 26: Emerging Viruses

  • Emerging viruses originate in one organism and spread to another; often pose a threat
  • SARS coronavirus is an example
  • Viruses can contribute to some cancers by altering the growth properties of human cells

Chapter 26: Prions & Viroids

  • Prions cause transmissible spongiform encephalopathies (TSEs)
  • Host's normal prion protein misfolds, leading to disease
  • Viroids are tiny naked molecules of circular RNA

Chapter 27: Prokaryotes

  • Size of prokaryotic cells led to their being undiscoverable
  • Antony van Leeuwenhoek first observed and described microbial life
  • Koch's postulates determined causal relationships between a microbe and disease
  • Prokaryotic diversity falls into two domains: Bacteria and Archaea.
  • Prokaryotic cells are unicellular; most are single-celled.
  • Cell size varies significantly; most are smaller than 1 μm in diameter
  • Prokaryotes have a nucleoid region with a single circular DNA chromosome (often plasmids)

Chapter 27: Prokaryotic Genetics, Cell Structure & Diversity

  • Characteristics of prokaryotes include unicellularity, small cell size, variety in shapes, and diverse genetic mechanisms such as plasmid transfer

  • Prokaryotes reproduce primarily by binary fission.

  • Horizontal gene transfer via Conjugation (cell-to-cell contact), Transduction (viruses), and Transformation (environment) occurs

  • Cell walls are rigid and differ between bacteria (peptidoglycan) and archaea (lack peptidoglycan).

  • Plasma membranes differ in structure between bacterial (ester linkages) and archaeal (ether linkages).

Chapter 27: Prokaryotic Classification

  • Early classification characteristics include photosynthesis, motility, cell shape, spore formation, and importance as pathogens
  • Basic shapes of prokaryotic cells (Bacillus: rod-shaped, coccus: spherical, and spirillum: helical) exist.
    1. Arrangements (Streptococcus: chains and Staphylococci: clusters) exist.
  • Cell walls, gram-positive, and gram-negative characteristics are also important.
  • Flagella structure and fimbriae features exist depending on the organism.

Chapter 27: Endospores, Organization Genetic Mechanisms

  • Endospores form when the cell is exposed to stress (often heat)
  • Endospores are highly resistant to stressors such as heat and radiation
  • Nucleoid region contains singular circular chromosomes and may contain plasmids
  • Genetic mechanisms are diverse, encompassing binary fission, conjugation, transduction, and transformation.

Chapter 27: Horizontal Gene Transfer

  • Conjugation involves cell-to-cell contact; plasmid exchange via rolling circle replication
  • Transduction involves viral transfer of genetic material from one cell to another
  • Transformation involves prokaryotic cells taking up DNA from the environment

Chapter 27: Natural Transformation, CRISPR, Symbiosis, and Bacteria in Genetic Engineering

  • Natural transformation is when a bacterium takes up a released DNA fragment from a dead cell.
  • CRISPR is a bacterial adaptive immune system.
  • Symbiosis is an ecological relationship between different species that live in direct contact. This can be mutualistic (both benefit), commensalistic (one benefits, the other is unaffected), or parasitic (one benefits, the other is harmed).
  • Bacteria play a role in genetic engineering (producing chemicals like insulin) and bioremediation (removing pollutants).

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