General Biology I: Midterm I Review Study Notes

Levels of Biological Organization

Hierarchy from Smallest to Largest

Biological systems are organized in a hierarchy from the simplest to the most complex levels. Understanding this order is fundamental to studying biology.

• Molecules: Chemical structures consisting of two or more atoms bonded together (e.g., H2O, DNA).

• Organism: An individual living entity (e.g., a single gray squirrel).

• Population: All individuals of a species living in a specific area (e.g., all gray squirrels in an oak forest).

• Communities: All populations of different species living and interacting in an area.

• Biosphere: The global ecosystem; the sum of all Earth's ecosystems.

Correct order (from small to large): molecules → organism → population → communities → biosphere

Ecological Definitions

Population vs. Community

Ecological terms describe groups of organisms and their environments.

• Population: A group of individuals of the same species living in a particular area (e.g., gray squirrels in an oak forest).

• Community: All populations of all species in a given area.

• Ecosystem: The community plus the physical environment.

• Biosphere: All ecosystems on Earth.

Example: The gray squirrels that inhabit an oak forest represent a population.

Form and Function in Biology

Relationship Between Structure and Function

In biology, the structure of an organism or its parts is closely related to its function.

• Cells in the intestinal lining have projections (microvilli) to increase surface area for nutrient absorption.

• Plants in dry areas have large roots to absorb more water.

• Seeds dispersed by wind are light for easier transport.

• Fish that swim rapidly have streamlined bodies to reduce resistance.

Note: If asked which example does not exemplify this relationship, "none of the above" may be correct if all examples do show form-function relationships.

Evolutionary Relationships and Cellular Structures

Cilia and Evolution

The presence of certain cellular structures can indicate evolutionary relationships.

• Cilia: Hair-like structures used for movement in some eukaryotic cells (e.g., Paramecium).

• Shared structures suggest a common ancestor among diverse organisms.

Example: The presence of cilia in a new organism suggests it shares a common ancestor with both Paramecium and humans.

Scientific Method and Experimental Design

Variables in Experiments

Understanding variables is essential for designing and interpreting experiments.

• Independent Variable: The factor that is changed or controlled by the experimenter.

• Dependent Variable: The factor that is measured; it responds to changes in the independent variable.

Example: In a study testing a new drug for blood pressure, the change in systolic and diastolic blood pressure is the dependent variable.

Additional info:

• These notes are based on midterm review questions for a General Biology I course, covering foundational concepts in biological organization, ecology, structure-function relationships, evolution, and scientific methodology.