🌿 BIOLOGY – SUMMARY NOTES
🧠 1. What is Biology?
Biology is the study of living organisms — their structure, function, growth, evolution, and interactions.
Word origin: Bio = life, Logy = study
Main Branches of Biology
| Branch | Study Area |
|---|---|
| Botany | Plants |
| Zoology | Animals |
| Microbiology | Microorganisms |
| Anatomy | Internal structure |
| Physiology | Functions of body parts |
| Genetics | Heredity and variation |
| Ecology | Relationship between organisms and environment |
| Evolution | Origin and development of life |
🧬 2. The Cell – Basic Unit of Life
- Discovered by Robert Hooke (1665) in cork.
- Cell Theory: All living beings are made of cells (Schleiden & Schwann).
- Rudolf Virchow: “All cells arise from pre-existing cells.”
Types of Cells
| Type | Example | Features |
|---|---|---|
| Prokaryotic | Bacteria | No nucleus, simple structure |
| Eukaryotic | Plants, animals | True nucleus, membrane-bound organelles |
Cell Organelles
| Organelle | Function |
|---|---|
| Nucleus | Control center; contains DNA |
| Mitochondria | Powerhouse; ATP production |
| Ribosomes | Protein synthesis |
| Endoplasmic Reticulum (ER) | Transport system (Rough ER – proteins, Smooth ER – lipids) |
| Golgi Apparatus | Packaging and secretion |
| Lysosomes | Digestion (“suicidal bags”) |
| Plastids (in plants) | Chloroplast – photosynthesis |
| Cell Wall | Protection in plant cells |
| Cell Membrane | Controls entry/exit of substances |
🌱 3. Tissues
Plant Tissues
| Type | Function |
|---|---|
| Meristematic | Growth (apical, intercalary, lateral) |
| Permanent | Support and transport (parenchyma, collenchyma, sclerenchyma, xylem, phloem) |
Animal Tissues
| Type | Example | Function |
|---|---|---|
| Epithelial | Skin, lining organs | Protection |
| Connective | Bone, blood, cartilage | Support, connection |
| Muscular | Skeletal, smooth, cardiac | Movement |
| Nervous | Neurons | Transmission of impulses |
🍽️ 4. Life Processes
Main Processes:
- Nutrition
- Autotrophic: Plants (photosynthesis)
- Heterotrophic: Animals (ingestion, digestion)
- Respiration
- Breakdown of food to release energy (ATP).
- Aerobic: Uses oxygen
- Anaerobic: Without oxygen
- Transportation
- Plants: Xylem (water), Phloem (food)
- Humans: Heart, blood, and blood vessels
- Excretion
- Humans: Kidneys remove urea via urine
- Plants: Gases via stomata, waste via leaves
❤️ 5. Human Body Systems
| System | Major Organs | Function |
|---|---|---|
| Digestive | Mouth → Stomach → Intestine | Food breakdown and absorption |
| Respiratory | Lungs, trachea | Exchange of gases |
| Circulatory | Heart, blood, vessels | Transport of materials |
| Excretory | Kidneys, bladder | Removal of wastes |
| Nervous | Brain, spinal cord | Control and coordination |
| Endocrine | Glands (thyroid, adrenal) | Hormonal regulation |
| Reproductive | Ovaries, testes | Continuation of species |
| Skeletal | Bones, joints | Structure, protection, movement |
🧬 6. Genetics and Heredity
| Concept | Description |
|---|---|
| Genes | Units of heredity on chromosomes |
| DNA | Genetic material (double helix by Watson & Crick) |
| Chromosomes | Carriers of genes (Humans: 46 = 23 pairs) |
| Mendel’s Laws | Law of Dominance, Segregation, Independent Assortment |
Key Terms
- Genotype: Genetic makeup
- Phenotype: Physical appearance
- Mutation: Sudden change in gene or chromosome
🧪 7. Evolution
The process by which modern organisms evolved from ancient ancestors.
- Charles Darwin’s Theory: Natural Selection
- Lamarck’s Theory: Inheritance of acquired characters
- Fossils, DNA, and comparative anatomy provide evidence for evolution.
🌎 8. Ecology and Environment
Levels of Organization:
Individual → Population → Community → Ecosystem → Biosphere
Ecosystem = Biotic (living) + Abiotic (non-living) components
Energy Flow:
Sun → Producers → Consumers → Decomposers
Food Chain Example:
Grass → Deer → Tiger → Decomposers
Food Web: Interconnected food chains
🌾 9. Plant Physiology
| Process | Function |
|---|---|
| Photosynthesis | Converts sunlight into food |
| Transpiration | Water loss via stomata |
| Respiration | Energy release from glucose |
| Transport | Xylem (water) & Phloem (food) |
🧍♂️ 10. Human Reproduction
| Stage | Description |
|---|---|
| Male Reproductive System | Testes produce sperms |
| Female Reproductive System | Ovaries produce ova |
| Fertilization | Fusion of sperm and ovum |
| Zygote → Embryo → Fetus → Baby |
Puberty: Period of physical and hormonal changes.
🧫 11. Microorganisms
| Type | Example | Importance |
|---|---|---|
| Bacteria | Lactobacillus | Decomposition, curd making |
| Virus | HIV, Influenza | Cause diseases |
| Fungi | Yeast, Moulds | Decomposition, food |
| Algae | Spirogyra | Oxygen production |
🧍 12. Health and Diseases
| Type | Example | Cause |
|---|---|---|
| Infectious | Tuberculosis, Malaria | Pathogens |
| Non-Infectious | Diabetes, Cancer | Genetic or lifestyle |
| Deficiency | Anemia, Goiter | Lack of nutrients |
Prevention: Vaccination, hygiene, balanced diet.
🌍 13. Environment and Pollution
| Type | Cause | Effect |
|---|---|---|
| Air Pollution | Vehicles, industries | Respiratory diseases |
| Water Pollution | Sewage, chemicals | Waterborne diseases |
| Soil Pollution | Fertilizers, waste | Soil infertility |
| Noise Pollution | Machines, traffic | Stress, hearing loss |
Control: Reduce, Reuse, Recycle (3Rs)
🌱 14. Biotechnology
Use of living organisms to develop useful products.
Applications:
- Genetically modified crops
- Insulin production
- DNA fingerprinting
- Cloning (e.g., Dolly the sheep)
📈 15. Classification of Living Organisms
Five Kingdoms (R.H. Whittaker):
- Monera – Bacteria
- Protista – Amoeba
- Fungi – Yeast, Mould
- Plantae – Plants
- Animalia – Animals
Binomial Nomenclature (Linnaeus):
Each organism has two names – Genus species (e.g., Homo sapiens)
📚 16. Summary at a Glance
| Topic | Key Point |
|---|---|
| Biology | Study of life |
| Cell | Basic unit of life |
| Tissue | Group of similar cells |
| Life Processes | Nutrition, respiration, excretion, etc. |
| Genetics | Study of heredity |
| Evolution | Change over time |
| Ecology | Organisms & environment |
| Reproduction | Creation of new life |
| Health | Balance of body & environment |