Biology Supplement 3: Key Concepts

1. Natural Selection:

• Fitness: Refers to an organism’s ability to survive and reproduce in a particular environment.

• Examples:

• Which individual is better adapted to a harsh environment and thus survives and reproduces more?

• Which species is better at competing for food and therefore gains an advantage?

Note: Fitness always focuses on an organism’s adaptability and advantage in the evolutionary process.

2. Ecological Pyramid:

• Pyramid of Energy: The most complete pyramid, as it shows the decreasing amount of energy from lower trophic levels to higher trophic levels.

• Reason: Energy is lost at each trophic level through the organism’s life activities, respiration, and excretion.

Note: Ecological pyramids always demonstrate the decreasing amount of energy, biomass, or number of individuals from lower trophic levels to higher ones.

3. “Real”:

• The letter “R”: Used to differentiate real-world situations from theoretical ones in scientific research.

• Examples:

• Real: Field experiments conducted in a natural setting.

• Theoretical: A theoretical model built upon assumptions.

Note: “Real” is always based on empirical data and direct observation.

4. Fossil:

• Direct: Fossil evidence that directly identifies the existence of an organism in the past.

• Indirect: Fossil evidence that indicates the presence of an organism such as footprints or activity traces.

Note: Fossils are crucial evidence for understanding the history of life and the evolution of organisms.

5. Common Origin:

• Homology: The structural similarity between organs of different species due to their shared ancestry.

• Example: Bird wings, human arms, and fish fins all share similar bone structures.

Note: Homology is evidence of the evolutionary relationship between species.

6. Common Function:

• Analogous Structures: Organs that have similar functions but different structures.

• Example: Bird wings and butterfly wings both function for flight but have different structures.

Note: Analogous structures are a result of adaptive evolution in response to the environment.

7. Appendix, Coccyx:

• Vestigial: The reduction in size and function of organs due to their lack of necessity during evolution.

Note: Vestigial structures are evidence of environmental changes and adaptive responses in organisms.

8. “Primitive”:

• Previously devoid of anything: The state of no life on Earth.

• Example: The period before life arose on Earth.

Note: “Primitive” refers to the origin of life.

9. “Secondary”:

• Previously with an environment: The state where life has already arisen and existed for a period.

• Example: The period after life arose on Earth.

Note: “Secondary” refers to the development of life after its formation.