BI-101 Introductory Biology Unit 1.1 & 1.2 Study Guide

What Is Biology?

Biology is defined as the study of life. It encompasses an examination of living organisms, focusing on how they function, evolve, and interact within their environments.

The 8 Properties of Life

The following eight characteristics are essential to understanding what constitutes life:

Made of one or more cells: All living organisms are composed of at least one cell, which is the basic unit of life.
Uses energy (metabolism): Organisms require energy to perform various functions, including growth, reproduction, and maintaining homeostasis.
Maintains homeostasis: Homeostasis refers to the ability of an organism to maintain stable internal conditions irrespective of external changes. For example, organisms regulate their body temperature and blood sugar levels.
Grows and develops: Living beings undergo growth and development, following a specific program dictated by their genes.
Reproduces: Organisms have the ability to reproduce, whether sexually or asexually, ensuring the continuation of their species.
Responds to stimuli: All living organisms have adaptive responses to their environment, which is crucial for survival.
Contains DNA: All organisms possess DNA, which carries genetic information vital for inheritance and the functioning of living cells.
Populations evolve over time: Change in a population's genetic makeup occurs over generations, a process driven by natural selection and other evolutionary mechanisms.

Homeostasis

Homeostasis is the inherent ability of an organism to maintain stable internal conditions. Examples include:

Temperature regulation: Many organisms can regulate their body temperature in response to environmental changes.
Blood sugar control: The body maintains blood glucose levels through various mechanisms involving hormones.

Levels of Biological Organization (Small to Large)

Biological organization spans various levels ranging from the smallest to the largest, as follows:

Atom: The smallest unit of matter.
Molecule: Composed of two or more atoms bonded together.
Macromolecule: Large, complex molecules such as proteins, nucleic acids, carbohydrates, and lipids.
Organelle: Specialized structures within cells, such as mitochondria and chloroplasts.
Cell: The fundamental unit of life; can be prokaryotic or eukaryotic.
Tissue: A group of similar cells that perform a specific function together.
Organ: A structure composed of different types of tissues working together to perform complex functions.
Organ System: Groups of organs that work together for a common purpose.
Organism: A complete individual form of life.
Population: A group of organisms of the same species living in a specific area.
Community: Different populations that interact with each other in a given area.
Ecosystem: A community along with its physical environment, including the interactions among organisms and between organisms and their environment.
Biosphere: The global ecological system integrating all living beings and their relationships.

Types of Cells

Cells can be categorized into two main types:

Prokaryotes: These cells do not possess a nucleus or membrane-bound organelles. Examples include Bacteria and Archaea.
Eukaryotes: These cells have a defined nucleus and membrane-bound organelles. Examples include organisms from the kingdoms Plantae, Animalia, and Fungi.

Domains of Life

There are three primary domains of life:

Bacteria: Unicellular prokaryotic organisms that are found in various environments.
Archaea: Also unicellular prokaryotes, but often found in extreme environments and possessing distinct biochemistry and genetics compared to bacteria.
Eukarya: Organisms with eukaryotic cells, including animals, plants, fungi, and protists.

Basic vs Applied Science

Basic Science: This branch of science is focused on expanding knowledge without an immediate practical application. It aims at understanding fundamental principles.
Applied Science: This branch utilizes the knowledge gained through basic science to address and solve real-world problems.

The Scientific Method

The scientific method is a systematic approach used to conduct scientific research and involves the following steps:

Observation and question: Identify and articulate a specific question based on observations.
Hypothesis: Propose a testable and falsifiable explanation for the observed phenomena.
Experiment: Design and implement an experiment to test the hypothesis.
Data collection and analysis: Gather and analyze data from the experiment, looking for patterns or significant results.
Conclusion and revision if necessary: Draw conclusions based on the data. If findings do not support the hypothesis, revise the hypothesis and retest as needed.

Variables in Experiments

In scientific experiments, there are key types of variables:

Independent variable: This is the factor that is changed or manipulated during the experiment.
Dependent variable: This is the factor that is measured or observed in response to changes made to the independent variable.
Control group: Serves as a standard for comparison within the experiment, as it does not receive the experimental treatment.

Scientific Reasoning

Two forms of scientific reasoning are used to draw conclusions:

Inductive reasoning: This approach begins with specific observations and formulates general conclusions. For example, observing that "all observed swans are white" may lead to the conclusion that all swans are white.
Deductive reasoning: This approach starts with general principles to predict specific outcomes. For example, if all humans are mortal, and Socrates is a human, then Socrates is mortal.

Scientific Hypothesis, Theory, and Law

Hypothesis: A hypothesis is defined as a testable explanation for a phenomenon, which is subject to experimentation.
Theory: A theory is a well-supported explanation grounded in evidence that has stood up to repeated testing and scrutiny.
Law: A scientific law describes phenomena that typically occur in nature, often expressed mathematically, such as Newton's laws of motion.

Key Exam Reminders

It is important to note that viruses are not considered alive because they lack several properties of life.
Prokaryotes are noted for being the most diverse organisms, representing a vast range of forms and functions in ecological systems.