Foundations of Biology: Evolution, Themes, and Scientific Inquiry

What is Biology? Characteristics of Living Things

Cellular Organization

All living organisms are composed of cells, which are the basic units of life. Cells can be unicellular (single-celled organisms) or multicellular (organisms made of many cells).

• Cell: The smallest unit of life, capable of performing all life processes.

• Example: Bacteria are unicellular; humans are multicellular.

Properties of Life

Living things share several key properties that distinguish them from non-living matter.

• Order: Highly organized structures, such as cells and tissues.

• Energy Processing: Ability to obtain and use energy (e.g., photosynthesis in plants, cellular respiration in animals).

• Regulation (Homeostasis): Maintenance of stable internal conditions despite changes in the environment.

• Response to Environment: Reacting to stimuli (e.g., plants growing toward light).

• Evolutionary Adaptation: Populations change over generations to better survive in their environments.

• Reproduction: Ability to produce new individuals.

• Growth and Development: Increase in size and change in form during an organism's life cycle.

Energy Processing and Homeostasis

Energy Utilization

Organisms require energy to carry out life processes. Energy can be obtained from sunlight (autotrophs) or from consuming other organisms (heterotrophs).

• Autotrophs: Organisms that produce their own food (e.g., plants via photosynthesis).

• Heterotrophs: Organisms that consume other organisms for energy (e.g., animals).

Homeostasis

Homeostasis refers to the regulation of internal conditions to maintain a stable state.

• Example: Human body temperature regulation.

Classification and Domains of Life

Taxonomy and Classification

Taxonomy is the science of naming and classifying organisms. The hierarchy includes domain, kingdom, phylum, class, order, family, genus, and species.

• Domain: The highest taxonomic rank. There are three domains: Bacteria, Archaea, and Eukarya.

• Kingdom: Subdivisions within domains (e.g., Animalia, Plantae, Fungi).

The Three Domains of Life

Domain	Characteristics
Prokaryotes	No nucleus; includes Bacteria and Archaea
Eukaryotes	Cells with a nucleus; includes plants, animals, fungi, protists

Evolution: The Unifying Theme of Biology

Concept of Evolution

Evolution is the process by which populations of organisms change over generations. It explains both the unity and diversity of life.

• Natural Selection: The driving force behind evolution, where individuals with advantageous traits survive and reproduce more successfully.

• Adaptation: Traits that improve an organism's ability to survive and reproduce.

Evidence for Evolution

• Molecular Homology: Similarities in DNA and protein sequences among different organisms indicate common ancestry.

• Fossil Record: Fossils provide evidence of past life forms and evolutionary changes over time.

• Similarity of Life: Shared characteristics among living organisms suggest evolutionary relationships.

Key Features of Natural Selection

• Variation exists within populations.

• Some variations are heritable.

• Individuals with advantageous traits are more likely to survive and reproduce.

• If environmental conditions change, natural selection may favor different traits.

Artificial Selection

Humans can influence evolution by selecting for desired traits in plants and animals (e.g., breeding dogs, crops).

Scientific Inquiry and Theory

Nature of Scientific Theories

• Theory: A well-substantiated explanation of some aspect of the natural world, based on a body of evidence.

• Scientific theories are testable, falsifiable, and subject to revision.

Limitations of Science

• Science cannot answer all questions (e.g., those outside the realm of natural phenomena).

• Scientific knowledge is always open to revision with new evidence.

Darwin's Theory of Evolution

Charles Darwin

Darwin proposed that species evolve over time through natural selection. He observed adaptation in various environments and formulated the theory of evolution by natural selection.

• Adaptation: Organisms are suited to their environments due to inherited traits.

• Natural Selection: Mechanism by which evolution occurs.

Vocabulary

• Eukaryote- A single-celled or multicellular organism comprised of eukaryotic cells; eukaryotes include protists, plants, fungi, and animals.

• Prokaryote- A single-celled organism of the domain Bacteria or Archaea

• Adaptation- Inherited characteristic of an organism that enhances its survival and reproduction in a specific environment.

• Homology- Similarity in characteristics resulting from a shared ancestry.

• Natural selection- A process in which individuals that have certain inherited traits tend to survive and reproduce at higher rates than other individuals because of those traits.

• Artificial selection- The selective breeding of domesticated plants and animals to encourage the occurrence of desirable traits.

• Mutation- A change in the nucleotide sequence of an organism's DNA or in the DNA or RNA of a virus.

• Evolution- Descent with modification; the process by which species accumulate differences from their ancestors as they adapt to different environments over time; also defined as a change in the genetic composition of a population from generation to generation.

• Theory- An explanation that is broader in scope than a hypothesis, generates new hypotheses, and is supported by a large body of evidence.

Study Guide: Key Concepts

1. Review the 7 properties found in all living organisms. Cellular organization/order, energy use, homeostasis, response to environment, growth & development, reproduction,evolutionary adaptation.

2. Compare and contrast prokaryotic and eukaryotic cells. Prokaryotes lack a nucleus and are simpler; eukaryotes have a nucleus and are more complex.

3. Name the 3 Domains of living organisms. Name the 6 Kingdoms. Give examples of common organisms found in each. Domains: Bacteria, Archaea, Eukarya Kingdoms: Eubacteria, Archaebacteria, Protista, Fungi, Plantae, Animalia

4. Describe 3 different driving forces behind evolution. Which plays the largest role in nature? Answer: Natural selection (largest role) Mutation, Artificial selection

5. Name 3 pieces of scientific evidence for evolution. Answer: Fossils, DNA similarities, shared traits.

6. Using 1-2 sentences, link these terms: Natural Selection, Adaptation, and Evolution? Natural selection favors individuals with beneficial adaptations, allowing them to reproduce more successfully. Over time, this process leads to evolution within populations.

7. Give examples of species adaptations that Darwin noticed on the Galapagos islands.