Biology Core Concepts - Life Chapter 1

Definition of Biology

• Biology is the natural science that studies life and living organisms, encompassing their structure, function, development, interactions, evolution, distribution, and taxonomy.

Relationship with Other Disciplines

• Biology interrelates with various scientific fields, enhancing understanding and collaborative research.

Levels of Study in Biology

• Biology can be examined on multiple hierarchical levels, from atoms to entire ecosystems, reflecting the complexity of life.

Existence of Life on Earth

• Life thrives in diverse environments, from polar regions to equatorial zones, indicating its adaptability.

Size Range of Organisms

• Organisms vary drastically in size, from microscopic single-celled algae to towering trees measuring over 115 meters.

Hierarchical Organization in Biology

• Biological organization ranges from small-scale atomic levels to large-scale biospheric levels:
  • Atoms
  • Molecules
  • Cells
  • Tissues
  • Organs
  • Organ Systems
  • Organisms
  • Populations
  • Communities
  • Biosphere

Emergent Properties

• Each level of biological organization exhibits unique emergent properties not present in the constituent parts, emphasizing the concept of complexity.

Atomic Level

• Atoms represent the foundational level of biology; the arrangement and types of atoms affect biological structure and function.
• Six essential elements constitute about 99% of the human body's composition:
  • Oxygen (65%)
  • Carbon (18%)
  • Hydrogen (10%)
  • Nitrogen (3%)
  • Calcium (1.5%)
  • Phosphorus (1.0%)

Molecular Level

• Molecules, formed from bonded atoms, are vital for biological functions, including proteins, carbohydrates, lipids, nucleic acids, hormones, and enzymes.

Cellular Level

• Cells are recognized as the basic units of life; organisms can be unicellular (e.g., Amoeba, Euglena).

Tissue Level

• Tissues consist of grouped cells working together for similar functions, such as muscle, blood, xylem, and epithelium.

Organ Level

• Organs are complex structures formed from various tissues, performing specific functions (e.g., photosynthesis in leaves, blood circulation by the heart).

Organ System Level

• Organ systems are groups of organs that cooperate to achieve common physiological goals (e.g., digestive, circulatory, and reproductive systems).

Organism Level

• An organism is a self-contained entity, which may be unicellular or composed of multiple cells organized into tissues and organs.

Population Level

• A population is a collection of organisms of the same species residing in a specific geographical area and capable of interbreeding.

Community Level

• A community includes multiple populations of different species interacting within a shared environment, forming a complex biological network.