Scientific Method and Biology: Key Concepts Explained
The Scientific Method
The scientific method is a process used across all sciences. The steps include:
- Observation of events
- Formulation of a hypothesis
- Corroboration of hypotheses through testing
- Development of a theory
Scientific Knowledge
Scientific knowledge is limited to what can be perceived directly by the senses or through instruments that amplify the senses.
Biology: The Study of Life
Biology is the science that studies living organisms. Fields of study include:
- Descriptive or Structural Biology: Answers the question “who or what?” Focuses on structures and organs.
- Functional Biology: Answers the question “how?” Examines how structures and organs work.
- Evolutionary Biology: Addresses the question “why?” Investigates the causes of features and diversity.
Signs of Life
Living beings share common characteristics:
- Common Composition: Primarily composed of C, H, O, P, N, S. Includes compounds like carbohydrates, fats, proteins, and nucleic acids.
- Cellular Structure: Organized into living cells.
- Organization: Well-organized structures.
- Homeostasis: Maintenance of a stable internal environment.
- Assimilation: Capture and transformation of energy and materials from the environment for growth and development.
- Response to Stimuli: Consists of related functions that facilitate the realization of other functions.
- Reproduction: Capacity to generate new beings.
Biochemical Methods
Methods Based on Chemical Properties
- Biochemical Analysis Methods:
- Quantitative: Analysis of identical cell masses to determine cellular chemical composition.
- Analysis of cellular fractions to determine the nature and concentration of constituents.
- Cytochemical Localization Methods: Enables the location of chemical components within cells.
Methods Based on Physical Properties
- Spectrophotometric Methods: Determine constituents based on their light absorption properties.
- Fluorescence-Based Methods: Utilize substances that emit light after absorbing radiation (fluorescence). Detects the presence of specific substances within cells.
- Methods Using Radioactive Elements: Detect radiation or particles emitted by radioactive elements.
Bioelements and Biomolecules
Bioelements
Bioelements are elements present naturally in living beings. The most abundant primary elements are H, C, N, and O.
Oligoelements
Oligoelements are found in smaller quantities but play a pivotal role from a biological perspective.
Biomolecules
Biomolecules are formed when bioelements combine. Chemical bonds include:
- Ionic Bonds: Electron transfer.
- Covalent Bonds: Electron sharing.
- Hydrogen Bonds: United by hydrogen.
Water
Water is a major component of living beings and serves as a solvent for nutrients.
Glucids (Carbohydrates)
Glucids are organic molecules formed by C, H, and O.
Monosaccharides
Monosaccharides are simple carbohydrates that cannot be decomposed by hydrolysis. They are usually sugars with reducing power (tendency to donate electrons).
- Aldose: Contains an aldehyde functional group.
- Ketose: Contains a ketose functional group.
- Trioses: 3 carbon atoms.
- Tetroses: 4 carbon atoms.
Osides
Osides are carbohydrates that yield monosaccharides upon hydrolysis, sometimes accompanied by other compounds.
Holosides
Holosides yield only monosaccharides upon hydrolysis. They can be:
- Oligosaccharides: Two to ten monosaccharides linked by O-glycosidic bonds.
- Polysaccharides: More than ten monosaccharides linked by glycosidic bonds, resulting in high molecular weight.
Types of Polysaccharides
- Homopolysaccharides: Composed of only one type of monosaccharide.
- Heteropolysaccharides: Composed of various types of monosaccharides.
Heterosides
Heterosides yield monosaccharides and other substances upon hydrolysis.