Biology Notes PDF

Biology Cell Biology Cell Structure: ○ Prokaryotic Cells: Characteristics: Simple structure, lack membrane-bound organelles. Examples: Bacteria and Archaea. ○ Eukaryotic Cells: Characteristics: Complex structure wit...

Biology Cell Biology Cell Structure: ○ Prokaryotic Cells: Characteristics: Simple structure, lack membrane-bound organelles. Examples: Bacteria and Archaea. ○ Eukaryotic Cells: Characteristics: Complex structure with membrane-bound organelles. Examples: Plant cells, animal cells, fungi, and protists. ○ Organelles: Nucleus: Contains DNA; controls cell activities. Mitochondria: Site of cellular respiration; produces ATP (energy). Chloroplasts: Found in plant cells; site of photosynthesis, converts solar energy into chemical energy (glucose). Endoplasmic Reticulum (ER): Rough ER: Studded with ribosomes; synthesizes proteins. Smooth ER: Lacks ribosomes; synthesizes lipids and detoxifies toxins. Golgi Apparatus: Modifies, sorts, and packages proteins for secretion or use within the cell. Lysosomes: Contain digestive enzymes to break down waste and cellular debris. Cell Division: ○ Mitosis: Purpose: Growth and repair; results in two identical daughter cells. Phases: Prophase: Chromatin condenses into visible chromosomes. Metaphase: Chromosomes align at the cell's equatorial plane. Anaphase: Sister chromatids are pulled apart to opposite poles. Telophase: Nuclear membranes reform; chromosomes de-condense. ○ Meiosis: Purpose: Producing gametes (sperm and egg); results in four genetically diverse daughter cells. Phases: Meiosis I: Homologous chromosomes separate (reduction division). Meiosis II: Similar to mitosis; sister chromatids separate. Transport Mechanisms: ○ Diffusion: Movement of molecules from an area of high concentration to low concentration; does not require energy (passive).  ○ Osmosis: Specific case of diffusion involving water; occurs across a semi-permeable membrane. ○ Active Transport: Movement of molecules against their concentration gradient, requiring energy (ATP); examples include sodium-potassium pump. Human Body Systems Circulatory System: ○ Components: Heart: Muscular organ with four chambers (right atrium, right ventricle, left atrium, left ventricle); pumps blood throughout the body. Blood Vessels: Arteries: Carry oxygenated blood away from the heart (except pulmonary artery). Veins: Carry deoxygenated blood toward the heart (except pulmonary veins). Capillaries: Microscopic vessels where gas and nutrient exchange occurs. ○ Blood Composition: Red Blood Cells: Carry oxygen (hemoglobin). White Blood Cells: Part of the immune system. Platelets: Involved in blood clotting. Plasma: Liquid component that carries cells, nutrients, hormones, and waste. Respiratory System: ○ Components: Nasal Cavity: Filters, warms, and humidifies air. Trachea: Windpipe that conducts air to the lungs. Bronchi and Bronchioles: Branches that lead into the lungs; further divide into smaller airways. Alveoli: Tiny air sacs where gas exchange occurs; surrounded by capillaries. ○ Gas Exchange Process: Oxygen diffuses from alveoli into the blood, while carbon dioxide diffuses from blood into alveoli to be exhaled. Digestive System: ○ Organs: Mouth: Mechanical digestion (chewing) and chemical digestion (saliva). Esophagus: Muscular tube that transports food to the stomach via peristalsis. Stomach: Acidic environment (HCl) that breaks down food; enzymes aid in digestion. Small Intestine: Major site of nutrient absorption; lined with villi to increase surface area.  Large Intestine: Absorbs water and forms waste (feces); includes the colon and rectum. ○ Digestive Enzymes: Amylase: Breaks down carbohydrates. Pepsin: Breaks down proteins in the stomach. Lipase: Breaks down fats. Ecology Ecosystems: ○ Definition: A biological community of interacting organisms and their physical environment. ○ Components: Biotic Factors: Living organisms (plants, animals, fungi). Abiotic Factors: Non-living elements (water, soil, climate). Food Chains and Webs: ○ Food Chain: Linear sequence of energy transfer (e.g., grass → grasshopper → frog → snake). ○ Food Web: Interconnected food chains showing complex feeding relationships. Biodiversity: ○ Definition: Variety of life forms within an ecosystem; includes genetic, species, and ecosystem diversity. ○ Importance: Ecosystem resilience, stability, and potential for new resources (medicinal). Chemistry Basic Chemistry Concepts Atoms and Molecules: ○ Atoms: Smallest unit of matter, consisting of a nucleus (protons and neutrons) surrounded by electrons. ○ Molecules: Formed when two or more atoms bond together (e.g., H₂O, CO₂). Periodic Table: ○ Structure: Organized by increasing atomic number; groups indicate similar chemical properties. ○ Trends: Atomic Radius: Decreases across a period; increases down a group. Electronegativity: Ability of an atom to attract electrons; increases across a period; decreases down a group. Chemical Reactions  Types of Reactions: ○ Synthesis (Combination): A + B → AB. ○ Decomposition: AB → A + B. ○ Single Replacement: A + BC → AC + B. ○ Double Replacement: AB + CD → AD + CB. Balancing Chemical Equations: ○ Ensure that the number of atoms for each element is the same on both sides of the equation (conservation of mass). Acids and Bases Properties of Acids and Bases: ○ Acids: Sour taste, pH < 7, turn blue litmus paper red, produce H⁺ ions in solution. ○ Bases: Bitter taste, pH > 7, turn red litmus paper blue, produce OH⁻ ions in solution. pH Scale: ○ Ranges from 0 (strong acids) to 14 (strong bases), with 7 being neutral; each unit change represents a tenfold change in acidity/basicity. Physics Forces and Motion Newton’s Laws of Motion: ○ First Law (Law of Inertia): An object at rest remains at rest, and an object in motion remains in motion unless acted upon by an external force. ○ Second Law (F = ma): The acceleration of an object depends on the mass of the object and the amount of force applied. ○ Third Law: For every action, there is an equal and opposite reaction. Motion Concepts: ○ Speed: Distance traveled per unit time (s = d/t). ○ Velocity: Speed with a direction; includes displacement over time. ○ Acceleration: Change in velocity over time (a = Δv/Δt). Energy Types of Energy: ○ Kinetic Energy (KE): Energy of motion, calculated using KE = 1/2 mv², where m is mass and v is velocity. ○ Potential Energy (PE): Stored energy based on position, calculated using PE = mgh, where m is mass, g is gravitational acceleration, and h is height. Energy Transformation: Energy can change from one form to another (e.g., potential to kinetic energy in a falling object). Waves Types of Waves: ○ Mechanical Waves: Require a medium to travel (e.g., sound waves). ○ Electromagnetic Waves: Do not require a medium; travel at the speed of light (e.g., light waves, radio waves). Wave Properties: ○ Wavelength (λ): Distance between two consecutive crests or troughs. ○ Frequency (f): Number of waves that pass a point in one second (measured in Hertz). ○ Amplitude: Maximum displacement from the rest position. Mathematics Algebra Basic Operations: Mastery of addition, subtraction, multiplication, and division involving variables (e.g., simplifying expressions). Solving Equations: ○ Techniques for linear equations include isolating the variable, using inverse operations, and substituting values. Functions: ○ Defined as a relation where each input has one output; can be represented as equations, graphs, or tables. Geometry Shapes and Properties: ○ Triangles: Types (isosceles, equilateral, right); properties include the Pythagorean theorem. ○ Circles: Key formulas for circumference (C = 2πr) and area (A = πr²). Theorems: ○ Pythagorean Theorem: For right triangles, a² + b² = c², where c is the hypotenuse. ○ Properties of Angles: Complementary (sum to 90°) and supplementary (sum to 180°). Data Handling Statistics: ○ Mean: Average of a set of numbers; calculated by summing values and dividing by the number of values.  ○Median: Middle value in an ordered list; if even, average the two middle numbers. ○ Mode: Most frequently occurring value in a dataset. Data Representation: ○ Bar Graphs: Used for categorical data; compares different groups. ○ Line Graphs: Used for continuous data; shows trends over time. ○ Pie Charts: Shows proportions of a whole; each slice represents a category's contribution to the total. Environmental Science Ecosystems and Biodiversity Ecosystem Components: ○ Producers: Organisms that produce their own food (e.g., plants via photosynthesis). ○ Consumers: Organisms that rely on others for food (herbivores, carnivores, omnivores). ○ Decomposers: Break down dead organic matter (fungi, bacteria). Threats to Biodiversity: ○ Habitat Loss: Deforestation, urbanization; disrupts ecosystems. ○ Pollution: Contaminates air, water, and soil; affects wildlife and human health. ○ Climate Change: Alters habitats and species distributions; leads to extinction of vulnerable species. Pollution Types of Pollution: ○ Air Pollution: Caused by emissions from vehicles and industries; effects include respiratory issues and global warming. ○ Water Pollution: Result of industrial waste, agricultural runoff, and plastics; impacts aquatic life and drinking water quality. Pollution Solutions: ○ Recycling: Reduces waste and conserves resources. ○ Waste Reduction: Minimizing single-use plastics and promoting reusable items. ○ Renewable Energy Adoption: Solar, wind, and hydroelectric energy sources to reduce fossil fuel dependence. Sustainability Resource Types: ○ Renewable Resources: Can be replenished naturally (e.g., solar, wind, geothermal).  ○ Non-Renewable Resources: Finite resources that cannot be replenished (e.g., coal, oil, natural gas). Conservation Strategies: ○ Protecting Habitats: Establishing reserves and protected areas to conserve wildlife. ○ Sustainable Agriculture: Practices that minimize environmental impact while maintaining productivity (e.g., crop rotation, organic farming).