General Biology Study Guide: Chapters 1, 26, 27, 28

Chapters Covered: 1, 26, 27, 28

This study guide summarizes key concepts and terms from the specified chapters, focusing on material defined in lecture slides and homework questions. It is organized by main topics and subtopics for effective exam preparation.

Chapter 1: Introduction to Biology

Biological Hierarchy

The biological hierarchy organizes living things from simplest to most complex levels.

• Levels: Atom → Molecule → Organelle → Cell → Tissue → Organ → Organ System → Organism → Population → Community → Ecosystem → Biosphere

• Definitions: Each level represents increasing complexity and organization.

• Example: Humans are multicellular organisms composed of organ systems, which are made of organs, tissues, and cells.

Overview of Scientific Method

The scientific method is a systematic approach to inquiry in biology.

• Key Terms: Observation, Hypothesis, Experiment, Data Collection, Analysis, Conclusion

• Types of Inquiry: Descriptive, Experimental, Comparative

• Requirements: Hypotheses must be testable and falsifiable.

• Example: Testing the effect of light on plant growth by comparing plants grown in light and dark conditions.

Darwinian Evolution

Darwinian evolution explains the diversity of life through natural selection and genetic variation.

• Darwin's Observations: Variation exists within populations; more offspring are produced than can survive; traits that enhance survival are more likely to be passed on.

• Driving Forces: Natural selection, mutation, genetic drift, gene flow

• Example: The finches of the Galápagos Islands evolved different beak shapes to exploit different food sources.

Mouse Video

Understanding genetic variation and adaptation through a case study.

• Application: Be able to answer questions about the mouse video discussed in class, focusing on how genetic variation leads to adaptation in populations.

Chapter 26: Diversity and Systematics

Diversity of Life

Biologists classify and study the diversity of living organisms.

• Known Species vs. Actual Number: The number of described species is much lower than the estimated total.

• What Defines Life? Organization, metabolism, growth, adaptation, response to stimuli, reproduction

Systematics

Systematics is the study of the diversity and relationships among organisms.

• Domains of Life: Bacteria, Archaea, Eukarya

• Characteristics: Each domain has unique cellular and genetic features.

• Example: Eukarya includes plants, animals, fungi, and protists.

Taxonomy and Nomenclature

Taxonomy is the science of naming and classifying organisms.

• Binomial Nomenclature: Two-part scientific naming system (Genus species), invented by Carl Linnaeus.

• Classification: Kingdom, Phylum, Class, Order, Family, Genus, Species

Phylogeny

Phylogeny studies evolutionary relationships among organisms.

• Phylogenetic Trees: Diagrams showing evolutionary relationships; branch points represent common ancestors.

• Monophyletic, Polyphyletic, Paraphyletic: Monophyletic groups include all descendants of a common ancestor; polyphyletic groups do not; paraphyletic groups include some but not all descendants.

• Example: Birds and reptiles share a common ancestor, making them part of a monophyletic group.

Homology vs. Analogy

Homology refers to traits inherited from a common ancestor; analogy refers to traits with similar function but different evolutionary origins.

• Convergent Evolution: Unrelated species evolve similar traits due to similar environments.

• Divergent Evolution: Related species evolve different traits.

• Example: Wings of bats (mammals) and birds (aves) are analogous structures.

Phylogenetic Hypotheses

Phylogenetic hypotheses are based on morphological, genetic, and molecular data.

• Key Point: Understand what data is used to construct phylogenetic trees.

Chapter 27: Prokaryotes and Bacteria

Differences Between Prokaryotic and Eukaryotic Cells

Prokaryotic cells lack a nucleus and membrane-bound organelles; eukaryotic cells have both.

• Prokaryotes: Bacteria and Archaea

• Eukaryotes: Plants, animals, fungi, protists

Bacteria vs. Archaea

Bacteria and Archaea are two domains of prokaryotes with distinct characteristics.

• Distinguishing Features: Cell wall composition, membrane lipids, genetic machinery

• Adaptations: Archaea often live in extreme environments (e.g., hot springs, salt lakes).

Bacterial Diversity and Identification

Bacteria are diverse and can be identified by shape, arrangement, and staining.

• Shapes: Cocci (spherical), Bacilli (rod-shaped), Spirilla (spiral)

• Arrangements: Chains, clusters, pairs

• Gram Staining: Differentiates bacteria by cell wall structure (Gram-positive vs. Gram-negative)

Bacterial Symbiosis and Roles

Bacteria play important roles in symbiosis, metabolism, and health.

• Symbiosis: Mutualism, commensalism, parasitism

• Metabolism: Autotrophic, heterotrophic, chemotrophic, phototrophic

• Pathogenic Bacteria: Cause diseases; examples include Streptococcus and Escherichia coli

• Beneficial Bacteria: Gut microbiota, nitrogen fixation

Bacterial Reproduction and Genetic Recombination

Bacteria reproduce asexually by binary fission and can exchange genetic material.

• Binary Fission: Simple cell division

• Genetic Recombination: Transformation, transduction, conjugation

• Example: Antibiotic resistance genes can spread via conjugation.

Energy Acquisition in Bacteria

Bacteria use various methods to obtain energy.

• Types: Photosynthesis, chemosynthesis, fermentation, respiration

Pathogenic Bacteria and Disease

Pathogenic bacteria cause disease through toxins and infection.

• Gram-Positive vs. Gram-Negative: Gram-negative bacteria often produce endotoxins; Gram-positive bacteria may produce exotoxins.

• Examples: Clostridium botulinum (botulism), Mycobacterium tuberculosis (tuberculosis)

Chapter 28: Protists

Defining Protists

Protists are a diverse group of mostly unicellular eukaryotes.

• Polyphyletic Group: Protists do not share a single common ancestor; they are classified based on convenience.

• Roles: Symbionts, parasites, producers

• Examples: Amoeba, Paramecium, Plasmodium

Protist Nutritional Diversity

Protists exhibit a wide range of nutritional strategies.

• Autotrophs: Photosynthetic protists (e.g., algae)

• Heterotrophs: Ingest or absorb food (e.g., protozoa)

• Mixotrophs: Combine photosynthesis and heterotrophy

Complexity of Protists

Protists are considered complex due to their diverse life cycles and cellular structures.

• Life Cycles: Alternation of generations, sexual and asexual reproduction

• Cellular Features: Nucleus, organelles, sometimes multicellularity

Endosymbiotic Theory

The endosymbiotic theory explains the origin of mitochondria and chloroplasts in eukaryotes.

• Key Evidence: Double membranes, own DNA, similarities to prokaryotes

• Example: Mitochondria originated from engulfed aerobic bacteria.

Survey of Protist Groups

Protists are classified into major supergroups based on morphology and genetics.

• Supergroups: Excavata, SAR, Archaeplastida, Unikonta

• Features: Each supergroup has unique morphological and genetic traits.

• Examples: Euglena (Excavata), Plasmodium (SAR), Chlamydomonas (Archaeplastida), Amoeba (Unikonta)

Ecological Significance of Protists

Protists play vital roles in ecosystems as producers, decomposers, and symbionts.

• Producers: Algae contribute to oxygen production and food webs.

• Decomposers: Some protists break down organic material.

• Symbionts: Protists can form mutualistic or parasitic relationships with other organisms.