Fundamental Concepts in Biology

Posted on Mar 11, 2025 in Biology

Two Basic Types of Science

Science can be broadly categorized into two main types:

• Discovery Science: This type of science is primarily based on observation and data analysis. It involves describing the natural world through verifiable data.
  • Example: Jane Goodall’s decades-long observation of chimpanzees in their natural habitat.
• Hypothesis-Driven Science: This approach involves formulating a tentative answer to a well-framed question (a hypothesis) and then testing predictions through experiments.
  • Example: Investigating why a remote control is not working. A tentative answer (hypothesis) might be that the battery is dead. This can be tested by replacing the battery and observing the result.

Seven Properties of Life

All living organisms share seven key characteristics:

1. Evolution
2. Energy processing
3. Order
4. Growth and development
5. Regulation
6. Response to the environment
7. Reproduction

Two Major Types of Cells and the Three Domains of Life

There are two fundamental types of cells:

• Prokaryotic Cells: These are typically single-celled and smaller than eukaryotic cells. They lack a membrane-bound nucleus and other internal organelles.
  • Domain Archaea
  • Domain Bacteria
• Eukaryotic Cells: These cells are generally larger and more complex, containing a membrane-bound nucleus and other organelles. They can be unicellular or multicellular.
  • Domain Eukarya
    • Kingdom Plantae (plants)
    • Kingdom Fungi (fungus)
    • Kingdom Animalia (animals)
    • Protists (e.g., seaweed)

Four Main Groups Within Domain Eukarya

The domain Eukarya is further divided into four main groups:

Five Major Themes in Biology

Five unifying themes are central to the study of biology:

1. Evolution: The process of change over time, driven by natural selection.
2. Structure/Function: The relationship between the structure of a biological component and its function. Changes in structure often lead to changes in function.
3. Information Flow: Genetic information is stored in DNA, transmitted, and used by cells.
4. Energy Transformation: Energy flows through ecosystems, typically entering as sunlight and exiting as heat.
5. Interconnections within Systems: Biological systems are interconnected and interact at multiple levels.

Natural Selection vs. Artificial Selection

• Natural Selection: This process occurs when organisms with traits better suited to their environment are more likely to survive and reproduce. This leads to:
  • Overproduction of offspring.
  • Competition for limited resources.
  • Individual variation within a population.
  • Adaptation: Over time, populations can adapt to their environment. Example: The change in finch beak size over generations, depending on the available seed sizes.
• Artificial Selection: In contrast, artificial selection is driven by human intervention. Humans select desirable traits and breed organisms to enhance those traits. Example: Breeding dogs for specific physical characteristics or behaviors.

Two Main Processes of an Ecosystem

Ecosystems function through two key processes:

• Nutrient Cycling: Nutrients are recycled within the ecosystem.
  • Decomposers break down dead organisms, releasing nutrients.
  • Plants take up these nutrients through their roots.
  • Nutrients are passed to consumers when they eat plants or other consumers.
  • The cycle repeats when organisms die and decompose.
• Energy Flow: Energy flows into an ecosystem (usually as sunlight) and is converted to chemical energy by producers (plants). This energy is then transferred to consumers, and some energy is lost as heat at each step. Energy flows through the system, it is not recycled.

Ten Levels of Biological Organization

Life can be organized into ten hierarchical levels, from the largest to the smallest:

1. Biosphere: The entire portion of Earth inhabited by life. Example: All ecosystems on Earth.
2. Ecosystems: All the living and non-living components in a particular area. Example: A desert, a forest, or a coral reef.
3. Communities: All the living organisms in an ecosystem.
4. Populations: A group of individuals of the same species living in a particular area. Example: A group of iguanas.
5. Organisms: An individual living thing. Example: A single iguana.
6. Organs: A body part consisting of two or more tissues that performs a specific function. Example: An iguana’s heart.
7. Tissues: A group of similar cells performing a specific function.
8. Cells: The fundamental unit of life.
9. Organelles: A membrane-bound structure within a cell that performs a specific function.
10. Atoms and Molecules: The chemical building blocks of all matter.