Biology Past Paper PDF
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This document contains notes on biological topics, including experimental design, classification of organisms, chemistry of life, and macromolecules. The content appears to be study material, potentially for a secondary school level biology class or a similar preparation. The document likely comes from a textbook, work book or educational resource rather than a formal past paper.
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1. Experimental Design and Bias When a properly controlled experiment lacks bias: C ontrol group: Comparison with experimental groups. Random sampling: Ensures subjects are selected withoutbias. Blinded studies: Prevents influence from researchersor pa...
1. Experimental Design and Bias When a properly controlled experiment lacks bias: C ontrol group: Comparison with experimental groups. Random sampling: Ensures subjects are selected withoutbias. Blinded studies: Prevents influence from researchersor participants. Types of Systematic Bias: Measurement bias: Inaccurate tools or methods. ○ Avoidance: Calibrate instruments, and standardizemeasurements. Selection bias: Non-random selection of subjects. ○ Avoidance: Random sampling, stratified sampling. Confirmation bias: Researchers favor data that supportstheir hypothesis. ○ Avoidance: Peer review, open data sharing, objectiveanalysis. Importance of Peer Review: E nsures validity, reliability, and credibility of research. Helps to identify errors, omissions, or biases in the study. 2. Classification of Organisms Taxonomic Ranks (in order of specificity): 1. D omain→ 2.Kingdom→ 3.Phylum→ 4.Class→ 5.Order→ 6.Family→ 7.Genus → 8.Species 3 Domains and Characteristics: A rchaea: Single-celled, no nucleus, extreme environments. Bacteria: Single-celled, no nucleus, common bacteria. Eukarya: Cells with a nucleus, including plants, animals,fungi, and protists. 6 Kingdoms and Characteristics: . A 1 rchaebacteria: Prokaryotic, extremophiles. 2. Eubacteria: Prokaryotic, common bacteria. 3. Protista: Single-celled, eukaryotic, diverse. . F 4 ungi: Multicellular, eukaryotic, absorb nutrients. 5. Plantae: Multicellular, eukaryotic, photosynthetic. 6. Animalia: Multicellular, eukaryotic, heterotrophic. Classifying Using a Dichotomous Key: Use a series of yes/no questions to identify organisms. 3. Chemistry of Life Properties of Water: Polar, high specific heat, cohesive, adhesive, solvent for many substances. Parts of an Atom: P rotons(positive),Neutrons(neutral),Electrons(negative). Atoms are the smallest units of elements, compounds are made of atoms, and mixtures consist of two or more substances combined physically. Types of Bonds: Covalent Bonds: Sharing of electrons. Ionic Bonds: Transfer of electrons. Functional Groups in Molecules: Hydroxyl (-OH), Carboxyl (-COOH), Amino (-NH2), Phosphate (-PO4), etc. 4. Macromolecules Functions of Macromolecules: arbohydrates: Energy storage, structure (e.g., starch,cellulose). C Lipids: Long-term energy storage, cell membranes,signaling (e.g., fats, phospholipids). Proteins: Enzymes, structure, transport, signaling(e.g., enzymes, antibodies). Nucleic Acids: Genetic information (e.g., DNA, RNA). Types of Macromolecules: onosaccharides: Simple sugars (e.g., glucose). M Disaccharides: Two sugar units (e.g., sucrose). Polysaccharides: Multiple sugar units (e.g., starch). Triglycerides: Fats, energy storage. Fatty Acids: Building blocks of lipids. Phospholipids: Cell membrane structure. Peptides/Polypeptides: Short/long chains of aminoacids. DNA/RNA: Genetic material, involved in protein synthesis. Dehydration Synthesis & Hydrolysis: D ehydration: Formation of a bond by removing water(e.g., monosaccharide → disaccharide). Hydrolysis: Breaking of a bond by adding water (e.g.,disaccharide → monosaccharides). 5. Enzyme Activity Enzyme Impact: Lowers activation energy for chemical reactions. Types of Reactions: A nabolic: Build larger molecules (requires energy). Catabolic: Break down molecules (releases energy). Factors Affecting Enzyme Activity: T emperature,pH,Substrate concentration,Enzyme concentration. Competitive Inhibition: Inhibitor competes with substratefor the active site. 6. Digestive System Digestive Organs & Their Roles: M outh: Mechanical digestion (chewing), chemical digestion(saliva). Stomach: Protein digestion (pepsin), acidic environment. Small Intestine: Nutrient absorption (villi). arge Intestine: Water absorption, formation of feces. L Pancreas: Secretes digestive enzymes. Liver: Produces bile. Gallbladder: Stores bile. Rectum/Anus: Expulsion of waste. Enzymes Involved in Digestion: mylase: Breaks down starch (mouth, pancreas). A Pepsin: Breaks down proteins (stomach). Lipase: Breaks down lipids (pancreas). Protease: Breaks down proteins (stomach, pancreas). Lactase: Breaks down lactose (small intestine). 7. Photosynthesis & Cellular Respiration Photosynthesis: E quation: 6CO2 + 6H2O → C6H12O6 + 6O2 Light-dependent reactions: Occur in thylakoid membranes, and produce ATP and NADPH. Light-independent reactions (Calvin Cycle): Occur in the stroma, use ATP and NADPH to synthesize glucose. Cellular Respiration: E quation: C6H12O6 + 6O2 → 6CO2 + 6H2O + ATP Aerobic: Requires oxygen, and produces more ATP (includes Glycolysis, Krebs Cycle, ETC). Anaerobic: No oxygen, less ATP (Fermentation). 8. Biogeochemical Cycles Carbon Cycle: P lants and animals need carbon for energy and growth. Carbon enters the atmosphere through respiration, combustion, and decay. Carbon is removed through photosynthesis. Nitrogen Cycle: N itrogen-fixing bacteria convert atmospheric nitrogen into forms plants can use (nitrates). Denitrifying bacteria convert nitrates back to nitrogen gas. Water Cycle: Water is moved through evaporation, transpiration, condensation, and percolation. Phosphorus Cycle: P hosphorus is found in rocks, soil, and water. Plants absorb phosphate, and it returns to the environment through decay and waste. 9. Root Words Definitions: acro-: Large M Mono-: One Di-: Two Poly-: Many Sacchar-: Sugar -mer: Part Hydr(o)-: Water -lys-: Break Glyc-: Sweet -ose: Sugar -ic: About Syn-: Together Oxy-: Oxygen -phobic: Fear of -Philip: Love of Hem-: Blood
