Evolution and the Themes of Biology

Introduction

This study guide covers the foundational concepts in general biology, focusing on the properties of life, biological organization, emergent properties, cellular organization, and the core theme of evolution. It also includes practice questions and exercises to reinforce understanding of these key topics.

The Study of Life Reveals Common Themes

Definition of Biology

• Biology is the scientific study of life and living organisms, including their structure, function, growth, evolution, distribution, and taxonomy.

Properties that Distinguish Living Things from Non-Living Things

• Order: Living things exhibit complex but ordered organization.

• Regulation: Organisms can regulate their internal environment (homeostasis).

• Energy Processing: Living things acquire and use energy.

• Response to Environment: Organisms respond to environmental stimuli.

• Reproduction: Living things can reproduce their own kind.

• Growth and Development: Organisms grow and develop according to specific instructions coded in their DNA.

• Evolutionary Adaptation: Populations evolve over generations through adaptations.

Theme 1: Organization of Biological Information

Biological organization is hierarchical, with each level building on the previous one. Understanding these levels helps in studying the complexity of life.

• Hierarchical Levels of Biological Organization (smallest to largest):

  • Molecule → Organelle → Cell → Tissue → Organ → Organ System → Organism

• Cellular Hierarchy: Atom → Molecule → Organelle → Cell

• Organismal Hierarchy: Cell → Tissue → Organ → Organ System → Individual Organism

Emergent Properties

• Emergent Properties are characteristics that arise at each new level of biological organization, which are not present at the preceding level.

• They are revealed when a system goes from the level of its parts to the whole system.

• Example (Biological): The heart is made of heart cells, but heart cells alone cannot pump blood; the whole heart can.

• Example (Non-biological): A functioning bicycle emerges only when all the necessary parts are correctly assembled.

Approaches to Biological Problems

Cellular Organization: Prokaryotes vs. Eukaryotes

Cells are the basic units of life, and they can be classified as prokaryotic or eukaryotic based on their structure.

Domains and Kingdoms

• Three Domains of Life:

  • Bacteria (prokaryotic)

  • Archaea (prokaryotic)

  • Eukarya (eukaryotic)

• Kingdoms within Eukarya: Plantae, Animalia, Fungi, Protista

The Core Theme: Evolution Accounts for the Unity and Diversity of Life

Descent with Modification

• All organisms are related through descent from a common ancestor but have accumulated adaptations that fit them to specific ways of life.

Theory of Natural Selection

• Natural selection is the process by which organisms with advantageous traits survive and reproduce more successfully.

• Three Requirements:

  1. Variation in traits within a population

  2. Heritability of traits

  3. Differential survival and reproduction

• Equation (for population genetics):

Where is the change in allele frequency, is the allele frequency, and is the selection coefficient.

Phylogenetic Trees

• Phylogenetic trees show evolutionary relationships among species.

• Branches represent lineages; nodes (branch points) represent common ancestors.

• Species that share a recent common ancestor are more closely related.

• The arrow typically represents the passage of time.

• Closed circles (nodes) represent common ancestors.

• The star may represent the root or the most recent common ancestor of all taxa in the tree.

Practice Questions and Applications

Properties of Life

• Do all living things move and breathe? No; for example, plants do not breathe in the same way animals do, and some organisms are sessile.

• Two properties all living things have in common: Cellular organization and the ability to reproduce.

Domains and Classification

• Both cats and bacteria belong to the same domain (Eukarya for cats, Bacteria for bacteria), but not the same domain. Additional info: Both are living, but only share higher taxonomic categories at the level of 'life' or 'cellular organization.'

Evolution and Antibiotic Resistance

• Antibiotic resistance in bacteria is an example of natural selection: bacteria with mutations that confer resistance survive and reproduce.

• antibiotic resistance in bacteria is an example of natural selection: bacteria with mutations that confer resistance survive and reproduce.

Galapagos Finches Example

• On a phylogenetic tree, the common ancestor of all Galapagos finches is at the root of the tree.

• The most recent common ancestor of two species is found at the node where their branches meet.