Biology Overview and Basics

Biology Notes

• Biology is the study of life, encompassing various branches like biochemistry, cell biology, genetics, evolutionary theory, microbiology, botany, and zoology.
• Living organisms share six key characteristics: they are made of cells, obtain and use energy, grow and develop, reproduce, respond and adapt to their environment, and eliminate waste.
• Lab equipment includes glassware like Erlenmeyer flasks, Griffin beakers, graduated cylinders and graduated pipets.
• Homeostasis is critical for organisms, especially higher vertebrates, to maintain a steady and balanced internal environment, promoting optimal conditions.
• Metric conversions are essential, using multiplication factors (e.g., kilometers to meters: x 1000).
• A law is a widely accepted idea about a phenomenon that doesn't change, exemplified by the Law of Conservation of Mass.
• A theory is a broad explanatory idea backed by numerous experiments, like Cell Theory (which can evolve with new technology). A hypothesis is a proposed testable explanation for observations.
• The scientific method involves careful observation, forming a testable hypothesis, conducting experiments, and gathering results using the metric system.
• Controlled experiments isolate one variable at a time to study its effect.
• The independent variable is manipulated, graphed on the X-axis, while the dependent variable is measured, graphed on the Y-axis. An Experimental group is tested and compared to a Control Group which isn't changed.
• Atoms are composed of protons, neutrons, and electrons. The atomic number is the number of protons, and atomic mass is the number of protons plus neutrons.
• Chemical bonds include covalent (electrons are shared), ionic (electrons are transferred), and hydrogen bonds (weak bonds between polar molecules).
• Water is a polar molecule due to the positive hydrogen and negative oxygen, leading to properties like adhesion (to surfaces) and cohesion (attraction between water molecules).
• A solution is a homogeneous mixture at a molecular level; water is a common solvent, and dissolved substances are solutes.
• Carbon is the base element of organic molecules. Polymers (carbohydrates: short-term energy; lipids: long-term energy; nucleic acids: genetic material; and proteins: enzymes), are made of monomers.
• Amino acids contain an amino group (NH2) and a carboxyl group (COOH), with a variable side chain.
• Specific chemical tests exist for different biomolecules: proteins (Biuret), complex carbohydrates (Lugol's), simple sugars (Benedict's), and lipids (Sudan III).
• Transport across membranes includes passive transport (no ATP needed; includes diffusion and facilitated diffusion) and active transport (requires ATP; moves substances against their concentration gradient). Examples include the sodium-potassium pump and calcium pump in muscles.
• Endocytosis and exocytosis are active transport mechanisms for bulk material movement in and out of cells
• The Cell Theory states that all organisms are composed of cells, cells are the basic unit of life, and all cells arise from pre-existing cells.
• Cells are classified as prokaryotic (no nucleus) or eukaryotic (with a nucleus). Prokaryotic examples are bacteria; Eukaryotic examples include animals, plants, fungi, and protists.
• Cell components like cytoplasm, mitochondria (cellular respiration), cell membrane (regulation), lysosomes (digestion), cell wall (protection), ribosomes (protein synthesis), chloroplasts (photosynthesis), and nucleus (DNA storage) are crucial.
• Plant and animal cells differ; plant cells have chloroplasts and cell walls, while animal cells have centrioles.
• Photosynthesis (reactants: CO2, H2O; products: C6H12O6, O2) takes place in chloroplasts and involves light reactions and Calvin cycle.
• Cellular respiration (reactants: C6H12O6, O2; products: CO2, H2O, ATP) utilises mitochondria; ATP is produced during the electron transport chain.
• Organisms that make their own food are autotrophs. Heterotrophs consume food produced by autotrophs.
• The products of photosynthesis are the reactants for cellular respiration, illustrating the interconnectedness of these processes.
• Anaerobic respiration occurs without oxygen.
• Aerobic respiration occurs with oxygen.