Unit 1: Foundations of Biology

Levels of Biological Organization

Biology studies life at multiple levels of organization, from the smallest chemical units to the complexity of ecosystems.

• Atom: The smallest unit of matter that retains the properties of an element.

• Molecule: Two or more atoms bonded together.

• Macromolecule: Large molecules, often polymers, such as proteins, nucleic acids, carbohydrates, and lipids.

• Cell: The basic unit of life.

• Tissue: Groups of similar cells performing a specific function.

• Organ: Structures composed of different tissues working together.

• Organ System: Groups of organs that perform related functions.

• Organism: An individual living entity.

• Population: A group of organisms of the same species living in a particular area.

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

• Ecosystem: The community plus the nonliving environment.

• Biosphere: All ecosystems on Earth.

Energy Flow and Producers

Energy flows through ecosystems, primarily entering via photosynthesis.

• Producers (autotrophs) convert solar energy to usable energy through photosynthesis.

• Consumers (heterotrophs) obtain energy by eating producers or other consumers.

• Example: Plants (producers) use sunlight to make food, which is then consumed by animals (consumers).

Homeostasis

Homeostasis is the maintenance of a stable internal environment despite external changes.

• Example: Humans maintain a body temperature around 37°C.

Scientific Method and Experimental Design

The scientific method is a systematic approach to understanding the natural world.

• Hypothesis: A testable explanation for an observation.

• Independent Variable: The variable that is changed or controlled in an experiment.

• Dependent Variable: The variable being tested and measured.

• Control Group: The group not receiving the experimental treatment, used for comparison.

• Experimental Group: The group receiving the treatment.

• Statistical Significance: Results are statistically significant if it is unlikely they occurred by chance.

Unit 2: Basic Chemistry for Biology

Atoms and Elements

All matter is composed of atoms, which are the building blocks of elements.

• Atom: Consists of protons, neutrons, and electrons.

• Element: A substance that cannot be broken down into simpler substances by chemical means.

• Isotope: Atoms of the same element with different numbers of neutrons.

• Atomic Number: Number of protons in an atom.

• Mass Number: Sum of protons and neutrons.

• Ions: Atoms that have gained or lost electrons, becoming charged.

Chemical Bonds

Atoms combine through chemical bonds to form molecules.

• Covalent Bond: Atoms share electrons.

• Ionic Bond: Transfer of electrons from one atom to another, resulting in oppositely charged ions.

• Hydrogen Bond: Weak attraction between a hydrogen atom and an electronegative atom (e.g., oxygen or nitrogen).

Properties of Water

Water is essential for life due to its unique chemical properties.

• Polarity: Water is a polar molecule, with a partial negative charge near the oxygen atom and a partial positive charge near the hydrogen atoms.

• Cohesion: Water molecules stick to each other via hydrogen bonds.

• Adhesion: Water molecules stick to other substances.

• High Specific Heat: Water can absorb a lot of heat before changing temperature.

• Solvent Properties: Water dissolves many substances, making it the "universal solvent."

pH and Buffers

pH measures the concentration of hydrogen ions in a solution.

• pH Scale: Ranges from 0 (acidic) to 14 (basic), with 7 being neutral.

• Acids: Substances that increase the concentration of H+ ions.

• Bases: Substances that decrease the concentration of H+ ions (or increase OH-).

• Buffer: A substance that minimizes changes in pH.

Unit 3: Biological Macromolecules

Carbohydrates

Carbohydrates are organic molecules made of carbon, hydrogen, and oxygen, and serve as energy sources and structural components.

• Monosaccharides: Simple sugars (e.g., glucose, fructose).

• Disaccharides: Two monosaccharides joined together (e.g., sucrose, lactose).

• Polysaccharides: Long chains of monosaccharides (e.g., starch, glycogen, cellulose).

• Hydrolysis: The process of breaking down polymers into monomers by adding water.

• Dehydration Synthesis (Condensation): The process of joining monomers by removing water.

Lipids

Lipids are hydrophobic molecules, including fats, oils, phospholipids, and steroids.

• Triglyceride: Composed of one glycerol and three fatty acids.

• Saturated Fatty Acids: No double bonds between carbon atoms; solid at room temperature.

• Unsaturated Fatty Acids: One or more double bonds; liquid at room temperature.

• Phospholipids: Major component of cell membranes; contain a hydrophilic head and two hydrophobic tails.

• Steroids: Lipids with a structure of four fused carbon rings (e.g., cholesterol).

Proteins

Proteins are polymers of amino acids and perform a wide variety of functions in cells.

• Amino Acid: The monomer of proteins, containing an amino group, carboxyl group, hydrogen atom, and R group (side chain).

• Peptide Bond: Covalent bond linking amino acids.

• Primary Structure: Sequence of amino acids in a polypeptide.

• Secondary Structure: Local folding (e.g., alpha helix, beta sheet) due to hydrogen bonding.

• Tertiary Structure: Overall 3D shape of a polypeptide.

• Quaternary Structure: Association of multiple polypeptide chains.

Nucleic Acids

Nucleic acids store and transmit genetic information.

• DNA (Deoxyribonucleic Acid): Stores genetic information.

• RNA (Ribonucleic Acid): Involved in protein synthesis.

• Nucleotide: Monomer of nucleic acids, composed of a sugar, phosphate group, and nitrogenous base.

Tables and Data Interpretation

Distribution of Slugs Within a Ten-Meter Square Plot

This table shows the average distance between individual sea slugs at different times of day, which can be used to analyze behavioral patterns and environmental influences.

Main Purpose: This table is used to analyze the behavioral ecology of sea slugs, specifically how their spacing changes throughout the day, possibly in response to environmental or biological factors.

Sample Practice Questions and Applications

Triglyceride Structure and Properties

• Common Property of Lipids: All lipids are hydrophobic (insoluble in water).

• Formation of Triglycerides: Formed by condensation (dehydration synthesis) reactions between one glycerol and three fatty acids, releasing three water molecules.

• Phospholipids vs. Triglycerides: Phospholipids have two fatty acids and a phosphate group attached to glycerol, making them amphipathic (hydrophilic head, hydrophobic tails), while triglycerides have three fatty acids and are entirely hydrophobic.

Water's Role in Life

• Structure: Water is made of two hydrogen atoms and one oxygen atom (H2O). The molecule is polar, with a partial negative charge on the oxygen and a partial positive charge on the hydrogens.

• Life-Giving Properties: Water's polarity allows it to dissolve many substances, support chemical reactions, and regulate temperature in living organisms.

Enzyme Activity and pH

• Bromelain: An enzyme found in pineapples that digests proteins.

• Enzyme Function: Enzymes catalyze reactions by lowering activation energy. Their activity is affected by pH, temperature, and substrate concentration.

• pH Effect: Each enzyme has an optimal pH. For bromelain, activity decreases as pH moves away from its optimum (3.5 to 5.1). At pH 11, activity would be greatly reduced.

Key Terms and Concepts

• Organic Molecule: Contains carbon and is found in living things.

• Functional Group: Specific groups of atoms within molecules that determine their chemical properties (e.g., hydroxyl, carboxyl, amino, phosphate).

• Macromolecule: Large, complex molecules (carbohydrates, lipids, proteins, nucleic acids).

• Enzyme: A protein that speeds up chemical reactions in cells.

• ATP: Adenosine triphosphate, the main energy currency of the cell.

Additional info:

• Some content was inferred and expanded for clarity and completeness, such as the detailed explanations of macromolecules and the scientific method.

• Practice questions and data interpretation were included to provide context and application of biological concepts.