Biology Basics Questions for RRB GROUP D

Cell: The Basic Unit of Life

Every living thing is made of cells. Think of a cell like a small factory — it has a control room (nucleus), power generators (mitochondria), and boundary walls (cell membrane). Plant cells have an extra outer wall called the cell wall and a green component called chloroplast for making food. Animal cells do not have cell walls or chloroplasts.

• Cell was discovered by Robert Hooke in 1665 using a cork slice.
• Nucleus controls all cell activities — it is the brain of the cell.
• Mitochondria produce energy (ATP) — called the powerhouse of the cell.
• Ribosomes make proteins — called the protein factory.
• Chloroplast is found only in plant cells — responsible for photosynthesis.
• Lysosomes are called the suicide bags — they digest waste and dead cells.

Classification of Living Organisms

Living things are grouped into 5 kingdoms: Monera (bacteria), Protista (amoeba), Fungi (mushroom), Plantae (plants), Animalia (animals). For exam purposes, remember which organism belongs to which kingdom. Viruses are NOT placed in any kingdom — they are considered non-living outside a host.

• Bacteria belong to Monera — they are prokaryotes (no proper nucleus).
• Fungi are neither plants nor animals — they are decomposers.
• Virus causes diseases like flu, dengue, HIV, COVID-19.
• Lichens are a combination of algae and fungi living together (symbiosis).
• Scientific naming follows Binomial Nomenclature given by Carolus Linnaeus.

Human Body Systems

RRB Group D frequently asks about organ functions and diseases linked to specific systems. Think of the body as departments in a company — each system has a fixed job. Knowing which organ does what, and what goes wrong when it fails, is the key strategy.

• Digestive system: Digestion starts in mouth. Liver produces bile. Small intestine absorbs nutrients.
• Circulatory system: Heart pumps blood. RBC carries oxygen using hemoglobin. Blood group discovered by Karl Landsteiner.
• Respiratory system: Lungs exchange gases. Diaphragm helps in breathing.
• Nervous system: Brain is control center. Neurons are nerve cells. Reflex action is controlled by spinal cord.
• Excretory system: Kidneys filter blood and produce urine. Nephron is the functional unit of kidney.
• Endocrine system: Glands release hormones. Insulin is released by pancreas — controls blood sugar.

Nutrition and Vitamins

Vitamins and minerals are small in quantity but big in importance for exam marks. Each vitamin has a deficiency disease linked to it. Think of vitamins as keys — without the right key, a specific lock (body function) breaks down. Carbohydrates, proteins, fats, vitamins, minerals, and water are the six nutrients.

• Vitamin A deficiency: Night blindness. Source: Carrots, milk.
• Vitamin B12 deficiency: Anaemia. Source: Meat, eggs.
• Vitamin C deficiency: Scurvy. Source: Citrus fruits.
• Vitamin D deficiency: Rickets (in children). Source: Sunlight, fish oil.
• Vitamin K is needed for blood clotting.
• Iron deficiency causes anaemia. Iodine deficiency causes goitre.

Photosynthesis and Plant Biology

Plants make their own food using sunlight, water, and carbon dioxide — this process is called photosynthesis. It happens in chloroplasts. The green pigment chlorophyll absorbs sunlight. Plants release oxygen during this process, which is why they are called producers.

• Equation: CO2 + H2O + sunlight → Glucose + O2 (happens in chloroplast).
• Transpiration is loss of water through leaves.
• Pollination is transfer of pollen — by wind (anemophily) or insects (entomophily).
• Xylem carries water upward. Phloem carries food downward — remember XUP, PDOWN.
• Root pressure and capillary action help water rise in plants.

Common Diseases and Causative Agents

RRB Group D loves to ask which disease is caused by which organism — bacteria, virus, fungi, or protozoa. This is a pure memory section. Group them by agent to avoid confusion.

• Bacterial diseases: Tuberculosis (TB), Typhoid, Cholera, Plague.
• Viral diseases: Dengue, Malaria (No — malaria is protozoan!), Polio, Rabies, HIV.
• Protozoan diseases: Malaria (Plasmodium via Anopheles mosquito), Amoebic dysentery.
• Fungal diseases: Ringworm, Athlete's foot.
• Malaria vector is female Anopheles mosquito. Dengue vector is female Aedes mosquito.

• Confusing Malaria as a viral disease — it is caused by Plasmodium, a protozoan, spread by Anopheles mosquito.
• Mixing up Xylem and Phloem — Xylem carries water UP, Phloem carries food DOWN (remember XUP PDOWN).
• Thinking viruses are living organisms placed in a kingdom — viruses are acellular and not classified in any kingdom.
• Confusing Vitamin D deficiency (Rickets in children, Osteomalacia in adults) with Vitamin C deficiency (Scurvy).
• Assuming the spinal cord only connects brain to body — it also independently controls reflex actions without brain involvement.

• MNPFA kingdoms: Monera, protista, Fungi, Plantae, Animalia — My Pretty Flowers Planted Anywhere.
• Vitamin deficiency trick: A=eyes (bAd sight), C=skin (sCurvy), D=bones (D for Dense bones needed), K=Klotting (K for Klot).
• XUP PDOWN: Xylem UP, Phloem DOWN — like X goes up in algebra class and P goes down on a piano.
• Powerhouse = Mitochondria, Suicide bag = Lysosome, Protein factory = Ribosome, Brain = Nucleus — remember the Cell Factory analogy.

• RRB Group D biology questions are almost always one-line fact type — no analysis needed. Read options carefully as they often swap organ names or disease agents.
• Diseases and their causative agents are the single most repeated biology topic in RRB Group D papers — spend extra revision time here.
• Vitamin deficiency diseases appear in almost every paper — at least 1 question guaranteed. Learn all 5 fat-soluble and water-soluble vitamins.
• Cell organelle questions appear regularly — especially powerhouse (mitochondria), suicide bag (lysosome), and differences between plant and animal cells.
• Do not spend more than 30-40 seconds per biology question — these are scoring quick-win questions. If unsure, use elimination of obviously wrong options.