Biology Chapter 5: Evolution and Cells

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Questions and Answers

What is the smallest unit that can evolve over time?

  • An individual organism
  • A population (correct)
  • A community
  • A species

What does 'natural selection' act directly on?

  • Both genotype and phenotype
  • Phenotype (correct)
  • Environment
  • Genotype

What is the relationship between genotype and phenotype?

  • Genotype and phenotype are independent of each other
  • Genotype determines phenotype (correct)
  • Phenotype determines genotype
  • Genotype and phenotype are both determined by the environment

Which of the following is NOT a component of Darwinian evolution?

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

What is the relationship between microevolution and macroevolution?

<p>Macroevolution occurs over a longer period of time than microevolution (A)</p> Signup and view all the answers

Why does a species need to adapt to change?

<p>All of the above (D)</p> Signup and view all the answers

In the context of Darwinian evolution, the term 'fitness' refers to:

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

Why is the vastness of evolutionary time important for understanding macroevolution?

<p>It allows for enough time for small changes to accumulate into major changes (A)</p> Signup and view all the answers

What is the approximate size of a strand of human hair in micrometers?

<p>20- 180 μm (C)</p> Signup and view all the answers

What is the primary reason for studying cells?

<p>To understand the basic functional unit of all living things (D)</p> Signup and view all the answers

Which of the following is NOT a basic feature of ALL cells?

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

What is the primary function of ribosomes within a cell?

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

What is the unit of measure used to describe the size of atoms and bond lengths?

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

How many micrometers are there in one meter?

<p>1,000,000 (A)</p> Signup and view all the answers

What is the approximate range of wavelengths for visible light?

<p>400-700 nm (D)</p> Signup and view all the answers

According to the content, what is the main unifying theme in biology, alongside cell theory?

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

Which of the following is NOT a class of biological macromolecules found in living things?

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

What is the main difference between prokaryotes and eukaryotes?

<p>Eukaryotes have a nucleus, prokaryotes do not. (B)</p> Signup and view all the answers

What is the significance of the RNA world hypothesis?

<p>All of the above. (D)</p> Signup and view all the answers

What is the role of liposomes in protocell formation?

<p>They provide a membrane-like barrier that separates the protocell's interior from the external environment. (D)</p> Signup and view all the answers

Which of the following events is NOT a major step in the evolution of cells?

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

What event is believed to have led to the evolution of eukaryotic cells?

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

Which of the following correctly describes the order of the major events in the evolution of cells?

<p>Abiogenesis, Protocells, RNA world, Prokaryotes, Endosymbiosis, Eukaryotes, Multicellularity (A)</p> Signup and view all the answers

Which of the following biochemical processes evolved during the time when prokaryotes were the dominant form of life?

<p>All of the above. (D)</p> Signup and view all the answers

Which of the following is NOT a major unifying concept of biology as presented in the content?

<p>Big Bang Theory (B)</p> Signup and view all the answers

According to the content, how does the everyday use of the word "theory" differ from its scientific meaning?

<p>In everyday usage, a theory is a guess, while in science, it is a well-supported explanation backed by evidence. (D)</p> Signup and view all the answers

Which of the following is NOT a part of the Modern Cell Theory as presented in the content?

<p>All cells have a nucleus. (C)</p> Signup and view all the answers

How does the content describe the relationship between all species?

<p>All species share a common ancestor and are related through evolution. (B)</p> Signup and view all the answers

What is the mechanism by which the characteristics of a population change over time, according to the Theory of Evolution by Natural Selection?

<p>Individuals with certain heritable traits produce more offspring than those without those traits. (D)</p> Signup and view all the answers

What is the main advantage of eukaryotic cells over prokaryotic cells?

<p>Eukaryotic cells have a more complex internal organization with membrane-bound organelles. (D)</p> Signup and view all the answers

Which of the following is NOT mentioned in the content as a unifying concept related to cells?

<p>Cells can be created spontaneously from non-living matter. (A)</p> Signup and view all the answers

How does the content explain the relationship between cells in a multicellular organism?

<p>All cells in a multicellular organism descend from an ancestral cell, forming a lineage through development. (C)</p> Signup and view all the answers

What is the primary role of endosymbiosis in the evolution of cells?

<p>Endosymbiosis led to the formation of eukaryotic cells from prokaryotic cells. (A)</p> Signup and view all the answers

Which of the following is NOT a significant advantage offered by multicellular organisms?

<p>The ability to reproduce sexually, which is crucial for genetic diversity and adaptation. (B)</p> Signup and view all the answers

What is the primary significance of the statement that "All organisms are made from cells" as highlighted in the content?

<p>It emphasizes the underlying unity of all organisms and provides a foundational concept in biology. (B)</p> Signup and view all the answers

What is the significance of the "Cambrian Explosion" in relation to multicellularity?

<p>The Cambrian Explosion is the period where a rapid diversification of multicellular organisms occurred. (C)</p> Signup and view all the answers

Which statement about the timeline of evolution of cells is accurate?

<p>The RNA world existed before the evolution of prokaryotic cells. (B)</p> Signup and view all the answers

What is the primary reason for the increased complexity of eukaryotic cells compared to prokaryotic cells?

<p>Eukaryotic cells have developed specialized membrane-bound organelles with specific functions. (D)</p> Signup and view all the answers

Which of these is NOT a direct consequence of the evolution of multicellularity?

<p>Evolution of the first photosynthetic organisms. (B)</p> Signup and view all the answers

What is the BEST explanation for why Simon Conway Morris describes the eukaryotic cell as "evolution's major achievement"?

<p>Eukaryotic cells are the basis for the development of all complex life forms. (D)</p> Signup and view all the answers

Which of the following is a correct explanation for the presence of a vestigial hemoglobin gene in icefish?

<p>The icefish ancestor possessed hemoglobin, and the gene has been passed down but is no longer needed. (C)</p> Signup and view all the answers

What is a vestigial structure?

<p>A structure that is present in an organism but has no known function. (D)</p> Signup and view all the answers

What evidence supports the fusion of two ancestral chromosomes to form human chromosome 2?

<p>The presence of extra telomeres on chromosome 2. (B)</p> Signup and view all the answers

The presence of vestigial structures in organisms provides evidence for which of the following?

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

What is the most likely reason for the absence of hemoglobin in icefish?

<p>Icefish live in cold water where oxygen is readily available. (C)</p> Signup and view all the answers

The presence of the hemoglobin gene in icefish, despite its non-functionality, can be described as an example of:

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

The absence of hemoglobin in icefish is an example of:

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

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Flashcards

Theory of Evolution by Natural Selection

A scientific explanation that species change over time through natural selection of heritable traits.

Cell Theory

A fundamental concept stating that all living organisms are composed of cells and that all cells arise from pre-existing cells.

Darwinian Evolution

The theory that species evolve over time due to natural selection, emphasizing adaptation and survival.

Homeostasis

The ability of an organism to maintain stable internal conditions despite changes in the external environment.

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Modern Cell Theory

A refined version of cell theory that includes seven principles outlining the role of cells in life.

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Genetics

The study of heredity and the variation of inherited characteristics.

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Natural Selection

The process where organisms with favorable traits reproduce more successfully, leading to evolutionary changes.

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Common Ancestor

A species from which two or more species have evolved over time.

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Shared Chemical Composition

Cells of similar organisms share a similar chemical makeup.

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Basic Features of Cells

All cells have a plasma membrane, cytosol, genetic material, and ribosomes.

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Plasma Membrane

The barrier that surrounds and protects the cell.

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Cytosol

The semifluid substance within a cell, where organelles reside.

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Units of Measure: Micrometer

A micrometer (μm) is one millionth of a meter.

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Units of Measure: Nanometer

A nanometer (nm) is one billionth of a meter.

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Evolution in Biology

Evolution is a unifying theme that explains biological facts.

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Icefish

A group of fish species living in Antarctic waters that lack hemoglobin.

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Thinner Blood

Adaptation of icefish to frigid environments, lacking hemoglobin leads to reduced oxygen transport capacity.

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Vestigial Gene

A genetic remnant from ancestors that is no longer functional, like icefish hemoglobin gene.

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Chromosome Count in Apes

Great apes have 24 pairs of chromosomes except humans, who have 23 pairs.

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Missing Chromosome Theory

The assumption that humans lost a chromosome pair during evolution, unlikely due to genetic information importance.

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Fusion of Chromosomes

Human chromosome 2 formed through the fusion of two ancestral chromosomes, involving vestigial elements.

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Telomeres

Protective ends of chromosomes, often vestigial in cases of chromosome fusions.

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Common Ancestor Evidence

Genetic similarities and remnants provide evidence of common ancestors among species, such as humans and great apes.

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Population

The smallest group capable of evolving, consisting of individuals of the same species.

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Heritable Traits

Characteristics that can be passed from parents to offspring, influencing evolution.

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Phenotype

The observable characteristics of an organism resulting from the interaction of its genotype and environment.

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Genotype

The genetic constitution of an individual organism.

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Macroevolution

Large-scale evolutionary changes that take place over long periods of time.

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Climbing Mount Improbable

A metaphor for how evolution results from many small changes over time leading to significant adaptations.

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Evolutionary Time

The vast timescales over which evolution occurs, often measured in millions or billions of years.

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Abiogenesis

The spontaneous formation of life's molecules under prebiotic conditions.

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Protocells

Early forms of cells formed from lipids creating structures in water.

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RNA World

The hypothesis that RNA was the first genetic material, capable of storing information and catalyzing reactions.

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Prokaryotes

Simple cells without a nucleus, existing for over 2 billion years.

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Eubacteria

A major group of prokaryotes characterized by their simple cell structure.

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Archaea

A group of prokaryotes distinct from eubacteria, often extremophiles.

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Endosymbiogenesis

The process by which eukaryotic cells evolved from symbiotic relationships between prokaryotic cells.

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Multicellularity

The condition of organisms composed of multiple cells working together.

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Eukaryotes

Complex cells with membrane-bound organelles and a nucleus, which include all multicellular organisms.

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Cambrian Explosion

A period around 541 million years ago when most major animal phyla appeared in the fossil record, marking a significant increase in biodiversity.

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Study Notes

Course Information

  • Course title: Biology 1 – Cells, Molecular Biology and Genetics
  • Course code: Biol 1000
  • Professor: Dr. Michael Cardinal-Aucoin
  • Semester: Winter 2025
  • Institution: York University

Evolution

  • Major unifying theories in biology
  • Darwinian evolution
  • Natural selection
  • Evidence and examples of evolution

Unifying Concepts of Biology

  • Theory of Evolution by Natural Selection
  • Cell Theory
  • Genetics
  • Homeostasis

Theories in Science

  • Everyday use of "theory": a guess, speculation
  • Scientific theory: a broad explanation supported by many lines of evidence, aids in creating new hypotheses, withstands scientific scrutiny

Theory of Evolution by Natural Selection

  • Characteristics of a population change over time (pattern)
  • Individuals with heritable traits produce more offspring than those without (mechanism)
  • All species are related through common ancestry
  • All species descend from pre-existing species

Cell Theory

  • All organisms are made of cells (pattern)
  • All cells come from pre-existing cells (mechanism)
  • All cells in a multicellular organism descend from an ancestral cell
  • All single-celled organisms in a population are related to a common ancestor

Modern Cell Theory

  • A cell is the smallest self-reproducing unit of life
  • Cells make up all living things
  • New cells arise from pre-existing cells
  • Organism's activity depends on the total activity of independent cells
  • Energy flow (metabolism & biochemistry) occurs within cells
  • Cells contain hereditary information (DNA and RNA)
  • Cells of similar organisms share similar chemical composition

Cells

  • All cells share certain properties but are not identical
  • Plant, animal, and bacterial cells are different sizes and structures

Different Types of Cells

  • Four basic features of all cells: plasma membrane, semifluid cytosol, genetic material, ribosomes
  • Plus metabolism (chemical pathways) to convert various energy forms into biochemical work

Units of Measurement

  • Micrometer (µm): 1,000,000 µm = 1 meter; strand of hair ~20-180 µm
  • Nanometer (nm): 1,000,000,000 nm = 1 meter; wavelength of visible light ~400-700 nm
  • Angstrom (Ã…): 10,000,000,000 Ã… = 1 meter; used to measure atomic/bond lengths; C-H bond in methane ~1 Angstrom

Introduction to the Cell

  • The human body has ~37 trillion cells
  • Cells vary greatly in size, as seen in the graphic

Why Study Cells?

  • Cells are the fundamental functional unit of all living things
  • Cell theory is a unifying principle in biology
  • Understanding cells helps understand how organisms function (plants, animals, parasites, fungus, etc.)
  • Crucial for understanding human health & disease

Evolution by Natural Selection

  • If a population has differences between individuals that are heritable and result in differential survival and reproduction, then evolution will occur.
  • Differences can form from mutations and meiosis in reproduction

Natural Selection

  • Natural selection is one mechanism driving evolution
  • Artificial and sexual selection, genetic drift, and gene flow are other mechanisms

Evidence for Evolution

  • Extensive evidence supports the theory
  • Homology, fossil record, genomics, insecticide resistance, genetic, biogeography, micro and macro evolution, anatomical features, comparative biochemistry, and embryology

Darwin's Theory

  • Natural selection in action (examples)
  • Homology (anatomy, development, molecular)
  • Convergent evolution (analogous features)
  • Biogeography
  • Fossils

Antibiotic Resistance

  • Drug use can lead to pathogens becoming drug resistant
  • Bacteria and HIV can become drug resistant

Homology: Vestigial Genetic/Molecular

  • Analysis of icefish and other species reveals vestigial genes
  • Icefish genes lack hemoglobin
  • Similar genes and proteins in various organisms support evolutionary links

Convergent Evolution

  • Similar traits in unrelated species that adapt to similar environments
  • Analogous features demonstrate a shared environmental pressure, not a common ancestor

Biogeography

  • Species distribution patterns are linked to evolutionary history
  • Species in the same area tend to be more closely related than those in different areas
  • Continental drift and plate tectonics have influenced species distribution

Fossils

  • Oldest fossils are ~ 4 billion years old
  • Fossils have revealed a progression of life forms over time

How is Evolution Relevant to Cell Biology?

  • Explains cell evolution, diversity, and common features
  • Explains cell structure, function, and adaptation to various environments

Main Events in the Evolution of Cells

  • Abiogenesis
  • Protocells
  • RNA world
  • Prokaryotes
  • Endosymbiosis
  • Eukaryotes
  • Multicellularity

Prebiotic Synthesis

  • Molecules of life can arise spontaneously in prebiotic conditions
  • Lab experiments replicate early Earth conditions to study this

Protocells

  • Lipids form membranes, leading to the formation of micelles and liposomes in water
  • Hydrophilic heads face water and hydrophobic tails face away

RNA World

  • RNA can perform both information storage and enzymatic functions
  • Scientists believe that RNA preceded DNA in the evolution of life forms
  • Recent experiments support this idea

Prokaryotes

  • Small cells lacking internal compartments
  • Evolved most biochemistry found in living things
  • DNA replication, genetic code, protein synthesis (transcription/translation), photosynthesis
  • Included bacteria and archaea

Endosymbiosis

  • Eukaryotic organelles (like mitochondria and chloroplasts) originated from free-living prokaryotes that were engulfed by larger cells
  • This eventually formed a symbiotic relationship between the host cell and the engulfed cell.

Eukaryotes

  • Complex cells with membrane-bound organelles (compartmentalization)
  • Endomembrane system
  • Bigger than prokaryotes
  • True multicellularity
  • Multiple chromosomes
  • Mitosis & meiosis
  • Increased diversity

Multicellularity

  • First multicellular organisms ~2.7 billion years ago
  • Took off around 1 billion years ago
  • A strong selective advantage over unicellular organisms
  • Advantages include size, competition for food, protection from predators, and division of labor; increased complexity, and ability to overcome limits to cell size

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