Basic Biology — Study Notes for UPSSSC PET

Overview

Basic Biology is a core component of the General Science section in UPSSSC PET, typically contributing 8–12 questions. This topic covers the fundamental building blocks of life (cells), classification of living organisms (plant and animal kingdoms), major human body systems (digestive, circulatory, respiratory, nervous, excretory), and common diseases with their causative agents and prevention methods.

Understanding these concepts is crucial because questions often test your ability to identify cell organelles, distinguish between plant and animal characteristics, name organs and their functions, and recognize disease-causing pathogens. Many questions are straightforward recall-based, asking "Which vitamin deficiency causes scurvy?" or "What is the function of the mitochondria?" Focus on memorizing functions, systems, and disease associations rather than deep biochemical pathways. Diagrams of the cell, human organs, and disease transmission cycles are frequently tested indirectly through descriptive questions.

The syllabus expects you to know basic life processes, classification systems up to major phyla, all major human organ systems, and the top 15–20 common diseases. Strong preparation here can fetch you 7–10 marks reliably if you master definitions, functions, and factual associations.

Key Concepts

• **Cell as the Basic Unit**: All living organisms are made of cells; cells contain organelles that perform specialized life functions such as energy production, protein synthesis, and waste removal.
• **Plant vs. Animal Cells**: Plant cells have a rigid cell wall, chloroplasts for photosynthesis, and large central vacuoles; animal cells lack these structures but have centrioles for cell division.
• **Five-Kingdom Classification**: Living organisms are classified into Monera (bacteria), Protista (algae, protozoa), Fungi (mushrooms, yeasts), Plantae (mosses to flowering plants), and Animalia (sponges to mammals).
• **Human Body Systems Work Together**: The digestive system breaks down food; circulatory system transports nutrients and oxygen; respiratory system exchanges gases; nervous system coordinates responses; excretory system removes waste.
• **Blood Composition and Function**: Blood contains red blood cells (oxygen transport), white blood cells (immunity), platelets (clotting), and plasma (liquid medium); human blood groups are A, B, AB, O based on antigens.
• **Nutrition and Vitamins**: Carbohydrates, proteins, fats, vitamins, and minerals are essential nutrients; specific vitamin deficiencies cause distinct diseases (e.g., Vitamin C deficiency → scurvy).
• **Pathogens Cause Diseases**: Bacteria cause tuberculosis, cholera, typhoid; viruses cause polio, AIDS, COVID-19; protozoans cause malaria, amoebic dysentery; fungi cause ringworm; worms cause ascariasis.
• **Vaccination and Immunity**: Vaccines introduce weakened pathogens to train the immune system; active immunity develops from infection or vaccination; passive immunity comes from antibodies transferred from mother or serum.

Formulas / Key Facts

**Cell Structure:**

• **Nucleus**: Contains DNA; controls cell activities; found in eukaryotes.
• **Mitochondria**: Powerhouse of the cell; site of ATP production (cellular respiration).
• **Ribosomes**: Site of protein synthesis; found free in cytoplasm or attached to ER.
• **Endoplasmic Reticulum (ER)**: Rough ER has ribosomes (protein transport); Smooth ER synthesizes lipids.
• **Golgi Apparatus**: Packages and modifies proteins for secretion.
• **Chloroplasts**: Present only in plant cells; site of photosynthesis (converting light energy to glucose).
• **Cell Wall**: Rigid outer layer in plants made of cellulose; provides shape and support.
• **Vacuoles**: Large central vacuole in plants stores water and maintains turgor pressure.

**Human Body Systems:**

• **Digestive System Organs**: Mouth → Oesophagus → Stomach → Small Intestine → Large Intestine → Rectum → Anus. Liver produces bile; pancreas secretes digestive enzymes and insulin.
• **Circulatory System**: Heart has 4 chambers (2 atria, 2 ventricles); double circulation (pulmonary and systemic); arteries carry oxygenated blood (except pulmonary artery); veins carry deoxygenated blood (except pulmonary vein).
• **Respiratory System**: Air enters through nostrils → pharynx → larynx → trachea → bronchi → bronchioles → alveoli (gas exchange site in lungs).
• **Excretory System**: Kidneys filter blood to form urine; nephron is the functional unit; urine stored in bladder.
• **Nervous System**: Central Nervous System (brain and spinal cord) and Peripheral Nervous System (nerves); neurons transmit electrical impulses; reflex actions bypass the brain.

**Common Diseases:**

• **Tuberculosis (TB)**: Caused by *Mycobacterium tuberculosis* (bacteria); affects lungs; spread by droplets; vaccine = BCG.
• **Malaria**: Caused by *Plasmodium* (protozoan); spread by female *Anopheles* mosquito; symptoms = fever, chills.
• **Typhoid**: Caused by *Salmonella typhi* (bacteria); contaminated food/water; vaccine available.
• **Polio**: Caused by poliovirus; affects nervous system; vaccine = OPV/IPV (Pulse Polio program).
• **AIDS**: Caused by HIV (virus); attacks immune system; spread by blood, sexual contact, mother-to-child.
• **COVID-19**: Caused by SARS-CoV-2 (virus); respiratory infection; spread by droplets and aerosols.
• **Cholera**: Caused by *Vibrio cholerae* (bacteria); severe diarrhea; contaminated water; ORS treatment.

**Vitamin Deficiency Diseases:**

• **Vitamin A**: Night blindness, xerophthalmia.
• **Vitamin B1 (Thiamine)**: Beriberi.
• **Vitamin B3 (Niacin)**: Pellagra.
• **Vitamin C**: Scurvy (bleeding gums).
• **Vitamin D**: Rickets (children), osteomalacia (adults).
• **Vitamin K**: Blood clotting problems.

Worked Examples

**Example 1: Identify the Organelle** *Question*: Which cell organelle is known as the "powerhouse of the cell"? *Solution*: The mitochondria is called the powerhouse of the cell because it produces ATP (adenosine triphosphate) through cellular respiration, which provides energy for all cellular activities. This is a frequently asked direct question in PET. *Answer*: Mitochondria

**Example 2: Blood Group Compatibility** *Question*: A person with blood group AB can receive blood from which donor groups? *Solution*: Blood group AB has both A and B antigens on red blood cells and no antibodies in plasma. Therefore, AB individuals are universal recipients and can receive blood from A, B, AB, and O groups without rejection. *Answer*: A, B, AB, O (all groups)

**Example 3: Disease and Pathogen Matching** *Question*: Malaria is caused by which type of pathogen and transmitted by which vector? *Solution*: Malaria is caused by *Plasmodium* species, which are protozoans (single-celled eukaryotic parasites). The disease is transmitted when an infected female *Anopheles* mosquito bites a human. Prevention includes mosquito nets, eliminating stagnant water, and antimalarial drugs. *Answer*: Protozoan (*Plasmodium*); Vector: Female *Anopheles* mosquito

Common Mistakes

• **Confusing Plant and Animal Cell Structures**: Students often forget that chloroplasts and cell walls are exclusive to plant cells, while centrioles are found only in animal cells. **Fix**: Create a comparison table and memorize the unique structures for each cell type.

• **Mixing Up Arteries and Veins**: Many believe arteries always carry oxygenated blood. **Fix**: Remember arteries carry blood away from the heart (pulmonary artery carries deoxygenated blood to lungs), veins carry blood toward the heart.

• **Misidentifying Disease Causative Agents**: Confusing bacterial diseases (treatable with antibiotics) with viral diseases (not treatable with antibiotics). **Fix**: Memorize 5 bacterial diseases (TB, cholera, typhoid, tetanus, plague) and 5 viral diseases (polio, AIDS, measles, dengue, COVID-19) separately.

• **Forgetting Vitamin-Disease Links**: Students often know vitamins exist but can't match deficiency diseases. **Fix**: Use the mnemonic "A-Night, C-Scurvy, D-Rickets, K-Klotting" to remember Vitamin A → Night blindness, C → Scurvy, D → Rickets, K → Blood clotting.

• **Overlooking the Nephron as Kidney's Functional Unit**: Questions may ask about urine formation at the microscopic level. **Fix**: Remember nephron (not kidney itself) is where filtration, reabsorption, and secretion occur to form urine.

Quick Reference

• **Mitochondria = Powerhouse**; **Nucleus = Control centre**; **Ribosomes = Protein factory**; **Chloroplasts = Photosynthesis (plants only)**.
• **Plant cells have**: Cell wall, chloroplasts, large central vacuole. **Animal cells have**: Centrioles, small vacuoles.
• **Human blood groups**: A, B, AB (universal recipient), O (universal donor).
• **Digestive enzymes**: Amylase (starch), Pepsin (protein in stomach), Lipase (fats), Trypsin (protein in intestine).
• **TB, Cholera, Typhoid = Bacteria**; **Polio, AIDS, COVID-19 = Virus**; **Malaria = Protozoan**; **Ringworm = Fungus**.
• **Vitamins**: A (eyes), B1 (beriberi), C (scurvy), D (bones-rickets), K (clotting).
• **Nephron filters blood in kidneys**; **Alveoli exchange gases in lungs**; **Neurons transmit nerve impulses**.