Biology Basics: Homeostasis & Cell Theory

Homeostasis

• Maintains relatively constant internal conditions
• Examples include body temperature, blood glucose levels, heart rate

Hierarchy of Life

• Atom
• Molecule
• Organelle
• Cell
• Tissue
• Organ
• Organ System
• Organism
• Population
• Community
• Ecosystem
• Biosphere

Original Cell Theory

• All organisms are made up of one or more cells
• The cell is the fundamental unit of life
• All cells come from preexisting cells

Atomic Structure

• Atoms consist of protons, electrons, and neutrons.
• Protons have a positive charge and are located in the nucleus.
• Electrons have a negative charge and are located in shells surrounding the nucleus.
• Neutrons have no charge and are located in the nucleus.
• First electron shell holds up to 2 electrons
• Second electron shell holds up to 8 electrons
• Third electron shell holds up to 8 electrons

Periodic Table of Elements

• The number of protons in an element is its atomic number.
• The atomic number defines the element.
• Atomic mass is the atomic number plus the number of neutrons.

Bulk Elements in Living Organisms

• Oxygen
• Nitrogen
• Carbon
• Hydrogen

Acids and Bases

• Acids have a high concentration of hydrogen ions (H+) and a low concentration of hydroxide ions (OH-).
• Bases have a low concentration of hydrogen ions (H+) and a high concentration of hydroxide ions (OH-).
• Neutral solutions have equal concentrations of hydrogen and hydroxide ions.
• The pH scale measures the acidity or alkalinity of a solution.
• A pH of 1-6 is acidic, 7 is neutral, and 8-14 is basic.

Chemical Bonds

• Atoms form chemical bonds to fill their outer electron shell.
• Covalent bonds involve the sharing of electrons between atoms.
• Ionic bonds involve the transfer of electrons between atoms.
• Hydrogen bonds are weak attractions between a hydrogen atom and an electronegative atom, such as oxygen or nitrogen.

Properties of Water

• Cohesion: Water molecules are attracted to each other due to hydrogen bonding. This property helps water move from plant roots to leaves.
• Adhesion: Water molecules are attracted to non-water substances. This property helps water adhere to surfaces.
• Temperature Regulation: Water can absorb and release a lot of heat without changing temperature drastically. This helps organisms maintain a stable body temperature.
• Solvent: Water is a good solvent because it is a polar molecule. This allows it to dissolve many substances, which is important for transporting solutes in the bloodstream.
• Density: Water is less dense as a solid than as a liquid. This is why ice floats, which allows life to exist in water even during cold temperatures.

Organic Molecules

• Carbohydrates
• Proteins
• Lipids
• Nucleic Acids

Carbohydrates

• The monomer of carbohydrates is a monosaccharide.
• Carbohydrates are the main source of energy for living organisms.
• Examples include sugars, starches, and cellulose.

Proteins

• The monomer of proteins is an amino acid.
• Proteins have a variety of functions in living organisms, including:
  • Structural support
  • Enzyme catalysis
  • Hormone regulation
  • Storage
  • Transport
  • Cell signaling

Lipids

• Contain fats, oils, waxes, and steroids.
• Important for energy storage.
• Phospholipids are a major component of cell membranes.

Nucleic Acids

• The monomers of nucleic acids are nucleotides.
• DNA and RNA are examples of nucleic acids.
• Nucleic acids store and transmit genetic information.

Enzymes

• Enzymes are proteins that speed up chemical reactions.
• Anabolic reactions join smaller molecules to create larger molecules.
• Catabolic reactions break down larger molecules into smaller molecules.
• Enzymes have a specific shape that only fits the substrate it acts on, called enzyme-substrate specificity.

Test your knowledge on fundamental biological concepts including homeostasis, the hierarchy of life, and the original cell theory. This quiz covers essential topics such as atomic structure and the periodic table of elements, providing a comprehensive overview of biology fundamentals.