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?

Methods to prevent desiccation and maintain water balance. Signup and view all the answers

What was a major feature of the Cambrian explosion?

The rapid increase in the diversity of multicellular animal life. Signup and view all the answers

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

The preference of a virus to infect certain cell types within a host. Signup and view all the answers

How do multicellular organisms benefit from cell specialization?

It allows for more complex interactions and functions through differentiation. Signup and view all the answers

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

500 million years ago Signup and view all the answers

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

It protected organisms from harmful UV radiation. 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?

Rich in carbon dioxide, nitrogen gas, water vapor, and hydrogen gas. Signup and view all the answers

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

To simulate early Earth conditions and produce organic monomers. Signup and view all the answers

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

RNA Signup and view all the answers

Which of the following is a characteristic of stromatolites?

They are mat-like structures formed by mineral deposits and trapped by cells. Signup and view all the answers

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

The engulfment of one organism by another, leading to organelles. Signup and view all the answers

Which characteristic is typically associated with lytic viruses?

The virus replicates and causes the host cell to rupture. Signup and view all the answers

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

The formation of supercontinents and subsequent evolutionary lineages. Signup and view all the answers

What is the key difference between inductive and deductive reasoning?

Deductive reasoning moves from general principles to specific conclusions while inductive reasoning uses specific observations to identify a more general pattern or trend. Signup and view all the answers

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

Its RNA directly serves as mRNA for protein synthesis. Signup and view all the answers

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

retrovirus Signup and view all the answers

What is a key characteristic of emerging viruses?

They originate in one organism and then spread to another, causing disease. Signup and view all the answers

What role do prions play in disease?

They convert normal host proteins into a misfolded form that causes disease. Signup and view all the answers

What is the primary function of Koch's postulates?

To establish a causal relationship between a microorganism and a disease. Signup and view all the answers

Where does replication typically occur for most RNA viruses?

In the cytoplasm of the host cell Signup and view all the answers

What is a distinguishing characteristic of viroids?

They are tiny, naked molecules of circular RNA. Signup and view all the answers

Which characteristic is NOT typically associated with prokaryotic cells?

Membrane-bound organelles Signup and view all the answers

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

Binary fission Signup and view all the answers

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

To fuse the cell membranes to create a conjugation bridge Signup and view all the answers

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

Providing structural support and maintaining cell shape Signup and view all the answers

How does generalized transduction differ from specialized transduction?

Generalized transduction occurs by accidents in the lytic cycle, while specialized transduction results from accidents in the lysogenic cycle Signup and view all the answers

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

Horizontal gene transfer Signup and view all the answers

What makes endospores particularly resistant to environmental stress?

Their thick cell wall surrounding the genome Signup and view all the answers

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

Ether linkage in the membrane lipids Signup and view all the answers

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

Cuboidal Signup and view all the answers

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

Transformation Signup and view all the answers

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

It differentiates bacteria based on the thickness of their cell wall's peptidoglycan layer. Signup and view all the answers

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

The F plasmid integrates into the bacterial chromosome Signup and view all the answers

What is the main function of pili in prokaryotic cells?

Attachment to surfaces Signup and view all the answers

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

They are targeted by different antibiotics. Signup and view all the answers

What is the role of R plasmids in bacteria?

To encode for antibiotic resistance genes Signup and view all the answers

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

Nutritional mode (photosynthetic or non-photosynthetic) Signup and view all the answers

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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Test your understanding of key biological concepts related to evolution, reproduction, and the origins of life. This quiz covers essential topics such as the significance of chloroplasts, the characteristics of viruses, and the adaptations necessary for life to thrive on land. Prepare to explore the fascinating events that have shaped life on Earth.