Introduction to Biology Lecture 1

Introduction to Biology

• Biology combines "bio" (life) and "logy" (study) to denote the scientific study of life.
• Fundamental principles of biology include evolutionary changes and adaptations of life.
• Earth hosts two main types of entities: living organisms (humans, insects, bacteria) and non-living things (rocks).
• Diverse forms of life exist, including animals, bacteria, plants, fungi, and protozoa.

Defining Life

• Life can be classified by types: animals (humans, fish, insects), plants (trees, algae), bacteria (E. coli), fungi (mushrooms, yeast), and protozoa (Amoeba).
• Life is found in various locations: oceans, lakes, rivers, ice, underground, and in the air.
• Organisms can be visible to the naked eye (humans, larger animals) or require a microscope (bacteria, protozoa).
• Nutritional methods vary among life forms: ingestion (humans), absorption (Amoeba), photosynthesis (plants), and diffusion (bacteria).

Criteria of Life

• Reproduction methods include sexual reproduction (humans) and asexual reproduction (binary fission in bacteria, budding in yeast).
• Organisms demonstrate organization, from atoms to the biosphere, with unicellular (e.g., bacteria) and multicellular (e.g., humans) forms.
• Emergent properties arise as complexity increases within biological organization (e.g., nervous cells enabling communication).

Distinguishing Living and Non-Living

• Living organisms display traits such as organization, reproduction, adaptation, and response to environmental changes.
• Non-living entities lack these living characteristics and do not undergo adaptations or evolution.

Evolution and Natural Selection

• Evolution is a key concept in biology, illustrating a common ancestry for all life forms through an evolutionary tree.
• Natural selection, articulated by Charles Darwin, is the mechanism facilitating adaptations and modifications in species.

Taxonomy and Classification

• Taxonomy is the scientific method for classifying and grouping organisms, originated by Carolus Linnaeus.
• Classification categories range from species (least inclusive) to domain (most inclusive), providing a hierarchical structure.

Domains of Life

• Three primary domains exist: Archaea (unicellular prokaryotes in extreme environments), Bacteria (unicellular prokaryotes present in diverse conditions), and Eukarya (unicellular and multicellular organisms with nuclei).
• Prokaryotes lack a membrane-bound nucleus and include organisms from both Archaea and Bacteria domains.
• Eukaryotes possess membrane-bound nuclei and can be unicellular (like yeast) or multicellular (like plants and animals).

Biodiversity and Ecosystem Organization

• Biodiversity encompasses species count, genetic variation, and ecosystem diversity; estimated to include 15 million species, with only 2 million identified.
• Human activities lead to ecosystem destruction, causing rapid species extinction (400 species/day) and threatening 38% of known species.
• Natural ecosystems such as rainforests and coral reefs nurture significant biodiversity, crucial for planetary health.

This quiz covers the basics introduced in the first lecture of biology. Explore the scientific study of life, including definitions and the principles of evolutionary changes and adaptation. Test your understanding of living and non-living entities and their varieties on Earth.