Revision sheet: Biology Fundamentals and Disease Mechanisms

SBI 3C1 Final Exam Sheet

1. 📌 Essentials

• Cells are the basic units of life, composed of organelles like mitochondria and nucleus.
• DNA carries genetic information; genes are segments coding for proteins.
• Enzymes are biological catalysts that speed up reactions; by pH and temperature.
• Mitochondria produce ATP via aerobic respiration; known as the cell's powerhouses.
• The cell membrane is a phospholipid bilayer with embedded proteins, controlling substance movement.
• Cell cycle includes G1, S, G2 phases, mitosis (prophase to telophase), and cytokinesis.
• Carbohydrates include monosaccharides, disaccharides, and polysaccharides; primary energy source.
• Bacterial and viral infections differ in structure, transmission, and treatment; antibiotics target bacteria.
• Human body systems (circulatory, respiratory, digestive) work together to sustain life.
• Cancer involves uncontrolled cell division, leading to tumors and metastasis.
• Flagella are microtubule-based structures aiding cell movement.
• Pedigree analysis helps trace inheritance patterns; symbols denote carriers and affected individuals.
• Algal blooms are rapid algae growth causing oxygen depletion in water bodies.
• Good bacteria aid digestion, immunity, and are part of the microbiome.
• Food absorption mainly occurs in the small intestine via villi.
• Structures like the pharynx, epiglottis, and trachea are vital for respiration.

2. 🧩 Key Structures & Components

• Cell membrane — controls entry/exit of substances, fluid mosaic model.
• Mitochondria — produce ATP through aerobic respiration.
• DNA — double helix with complementary base pairing (A-T, G-C).
• Genes — segments of DNA coding for specific proteins.
• Flagella — microtubule-based structures for movement.
• Villi — finger-like projections in small intestine for nutrient absorption.
• Chromosomes — carry genetic material, visible during cell division.
• Bacteria — prokaryotic organisms, some pathogenic.
• Viruses — non-living infectious agents requiring host cells.
• Body systems — circulatory (heart, vessels), respiratory (lungs, trachea), digestive (stomach, intestines).

3. 🔬 Functions, Mechanisms & Relationships

• DNA → Genes → Proteins: genetic information flows from DNA to proteins via transcription and translation.
• Enzymes: bind specific substrates; activity affected by pH and temperature.
• Cell cycle: G1 (growth), S (DNA replication), G2 (preparation), mitosis (cell division).
• Mitochondria: convert glucose and oxygen into ATP; essential for energy.
• Respiratory pathway: air passes from pharynx → epiglottis → trachea → lungs.
• Infections: bacteria produce toxins; viruses hijack host cells.
• Bacterial vs viral: bacteria are alive, treatable with antibiotics; viruses are not, require vaccines.
• Pedigree symbols: squares = males, circles = females, shaded = affected, half-shaded = carriers.
• Algal bloom: rapid algae growth depletes oxygen, harming aquatic life.
• Good bacteria: produce vitamins, aid digestion, prevent pathogen colonization.

4. Comparative Table

Item	Key Features	Notes / Differences
Bacteria	Prokaryotic, no nucleus, reproduce via binary fission	Treated with antibiotics
Viruses	Non-living, require host, DNA or RNA genome	Vaccines available, no antibiotics
Enzymes	Biological catalysts, specific, affected by pH/temperature	Speed up reactions, e.g., digestion
Carbohydrates	Monosaccharides, disaccharides, polysaccharides	Energy source, structural roles
Cell types	Prokaryotic vs eukaryotic	Eukaryotic have nucleus, larger

5. 🗂️ Hierarchical Diagram

Cell
 ├─ Nucleus
 │    └─ Contains DNA
 ├─ Cytoplasm
 │    └─ Site of metabolic reactions
 ├─ Mitochondria
 │    └─ ATP production
 ├─ Cell membrane
 │    └─ Controls substance movement
 └─ Flagella
      └─ Movement aid
Organism
 ├─ Tissues
 │    └─ Groups of similar cells
 ├─ Organs
 │    └─ Different tissues working together
 └─ Systems
      └─ Multiple organs (e.g., circulatory system)

6. ⚠️ High-Yield Pitfalls & Confusions

• Confusing DNA base pairing: A-T and G-C.
• Mistaking bacterial and viral infections; antibiotics only treat bacteria.
• Overlooking the role of enzymes' specificity and environmental effects.
• Misidentifying stages of mitosis; remember the order: prophase → metaphase → anaphase → telophase.
• Forgetting that antibiotics are ineffective against viruses.
• Confusing homozygous (same alleles) with heterozygous (different alleles).
• Assuming all bacteria are harmful; many are beneficial.
• Misinterpreting pedigree symbols; shaded = affected, half-shaded = carrier.
• Overlooking the environmental impact of algal blooms on aquatic ecosystems.

7. ✅ Final Exam Checklist

• Understand cell structure and organelles (nucleus, mitochondria, membrane).
• Know DNA structure, base pairing rules, and gene function.
• Differentiate between bacteria and viruses; treatment and characteristics.
• Describe the cell cycle phases and mitosis.
• Explain enzyme function and factors affecting activity.
• Recognize the role of carbohydrates in energy and structure.
• Identify the main body systems and their functions.
• Interpret pedigree charts and inheritance patterns.
• Describe how infections spread and prevention methods.
• Understand the process of food absorption in the small intestine.
• Recognize environmental issues like algal blooms.
• Know the differences between prokaryotic and eukaryotic cells.
• Recall the significance of flagella and other cell structures.
• Be familiar with common diseases: cancer, laryngitis, respiratory issues.
• Review the hierarchy from cells to systems for organization understanding.