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Complete Biology Revision for RRB JE

A comprehensive rapid-fire revision of biology covering cytology, genetics, nucleic acids, circulatory, digestive, and endocrine systems. The lecture also details plant physiology, reproduction, taxonomy, and animal classifications with associated diseases and deficiencies.

Railway
Biology
English · 9 topics
Checked against the video on 24 Oct 2026

Made by AI from the YouTube video RRB JE CBT 1 General Science Marathon | Biology One Shot For RRB JE 2025 | RRB JE Science Classes (opens YouTube in a new tab) by Engineers Wallah AE JE, then checked against it. All credit for the teaching goes to the creator. Tap a topic’s time to confirm a fact in the video.

Complete Biology Revision for RRB JE

English9 topics · 8 MCQs · 14 flashcardsWatch the video (opens YouTube in a new tab)

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In short

A comprehensive rapid-fire revision of biology covering cytology, genetics, nucleic acids, circulatory, digestive, and endocrine systems. The lecture also details plant physiology, reproduction, taxonomy, and animal classifications with associated diseases and deficiencies.

Cell Biology & Historical Milestones

Cytology refers to the scientific branch of biology dedicated to studying cell structure, function, composition, and behavior.
Robert Hooke observed dead cells in a thin slice of cork in 1665 and coined the word cell from the Latin word *cella*, which means a small room.
Must knowAnton van Leeuwenhoek was the first scientist to discover and describe living cells like bacteria and protozoa in 1674 using an improved microscope.
Robert Brown discovered the nucleus in 1831, identifying it as the critical cell organelle controlling all cellular activities, also called the brain of the cell.
The Cell Theory was proposed by Matthias Schleiden (1838) and Theodor Schwann (1839), stating all living organisms are made up of one or more cells.
Must knowIn 1855, Rudolf Virchow expanded the Cell Theory with the aphorism *Omnis cellula e cellula*, meaning every cell arises from a pre-existing cell.
Viruses are acellular entities that do not follow the classical cell theory.

Prokaryotic vs Eukaryotic Cells & Cell Organelles

Based on structural organization, cells are categorized into primitive prokaryotic cells and advanced eukaryotic cells.
Prokaryotic cells lack a true nucleus, have naked circular DNA without a nuclear membrane, and lack membrane-bound organelles except ribosomes.
Eukaryotic cells possess a well-defined membrane-bound nucleus and membrane-bound organelles like mitochondria, chloroplasts, Golgi apparatus, and endoplasmic reticulum.
Germ cells (sperm and egg) contain a haploid number of 23 chromosomes, whereas normal somatic diploid human cells contain 46 chromosomes (23 pairs).
The cell wall is a rigid, outermost layer found in plants (made of cellulose), fungi (chitin), and bacteria (peptidoglycan), but is absent in animals.
The plasma or cell membrane follows the Fluid Mosaic Model, composed primarily of a phospholipid bilayer with embedded proteins that act as a selectively semi-permeable barrier.

Feature	Prokaryotes	Eukaryotes
Cell Size	Generally small	Generally large
Nucleus	Absent (no envelope)	Present (well-defined)
Chromosomes	Single, circular	More than one, linear
Cell Division	Fission or budding	Mitosis and meiosis
Organelles	Membrane-bound absent	Membrane-bound present

Organelles and Internal Architecture

The Endoplasmic Reticulum (ER) consists of a network of membranous tubules; Rough ER (RER) has ribosomes on its surface and synthesizes/transports proteins.
Smooth ER (SER) lacks ribosomes and participates in lipid synthesis, detoxification of toxins/drugs, and calcium ion storage.
The Golgi apparatus consists of stacked cisternae that modify, sort, and package proteins and lipids received from the ER, also aiding in forming lysosomes.
Must knowLysosomes contain digestive enzymes and are called suicidal bags or atom bombs of the cell because they digest worn-out cell parts or undergo apoptosis.
Must knowMitochondria possess a double membrane with folded inner cristae and are called the powerhouse of the cell because they generate cellular energy in the form of ATP (adenosine triphosphate).
Mitochondria contain their own independent DNA and ribosomes, allowing them to synthesize some of their own functional proteins.
Plastids are double-membrane organelles found in plants: chloroplasts (contain chlorophyll for photosynthesis), chromoplasts (give colors to flowers and fruits), and leucoplasts (colorless, store starch, oils, and proteins).
Ribosomes lack membranes, are composed of ribosomal RNA (rRNA) and proteins, and serve as the protein-making factories of the cell.

Feature	Plant Cells	Animal Cells
Cell Shape	Rectangular or cubic	Round, oval, or irregular
Cell Wall	Present (cellulose)	Absent
Plastids	Present	Absent
Vacuoles	Large central vacuole	Small, scattered or absent
Centrosomes	Usually absent/less prominent	Present (aid division)
Energy Storage	Stored as starch	Stored as glycogen

The Cell Cycle, DNA, and RNA

The cell cycle consists of Interphase (growth and preparation) and the M Phase (division phase).
Interphase is divided into G1 phase (cell growth, organelle production), S phase (DNA replication/synthesis), and G2 phase (checks errors in DNA replication, prepares for division).
The M phase (mitosis) divides the nucleus via PMAT: Prophase (chromosomes visible), Metaphase (chromosomes line up), Anaphase (chromosomes separate), and Telophase (nuclei reform).
Cytokinesis follows karyokinesis and divides the cytoplasm to yield two distinct daughter cells.
Mitosis produces two genetically identical diploid daughter cells for body growth and repair, while meiosis produces four genetically diverse haploid cells in reproductive organs.
Must knowThe double-helical structure of DNA (deoxyribonucleic acid) was proposed by James Watson and Francis Crick, featuring a sugar-phosphate backbone and paired nitrogenous bases.
DNA contains Adenine (A), Thymine (T), Guanine (G), and Cytosine (C); Adenine pairs with Thymine (A-T) and Guanine pairs with Cytosine (G-C).
RNA (ribonucleic acid) is single-stranded, contains ribose sugar, and replaces Thymine with Uracil (U).
RNA exists as mRNA (messenger RNA), tRNA (transfer RNA), and rRNA (ribosomal RNA) to assist in protein synthesis.

Hematology: Blood and Circulation

Blood is a specialized fluid connective tissue consisting of 55% plasma (liquid matrix containing 90-92% water and solutes) and 45% formed cellular elements.
Must knowErythrocytes (RBCs) are biconcave, non-nucleated discs containing iron-rich hemoglobin to carry oxygen and carbon dioxide, possessing a typical lifespan of 120 days.
RBCs are produced in the red bone marrow through erythropoiesis and are destroyed in the spleen (known as the graveyard of RBCs) and liver.
Leukocytes (WBCs) defend against infections; granulocytes include neutrophils (phagocytose bacteria/fungi), eosinophils (fight parasites/allergies), and basophils (release histamine).
Agranulocytes include lymphocytes (B and T cells producing antibodies) and monocytes (transform into macrophages to engulf pathogens).
Thrombocytes (platelets) are disc-shaped cell fragments produced from megakaryocytes in bone marrow that assist in blood clotting with a 7 to 10-day lifespan.
Lymph is a clear, colorless interstitial fluid lacking RBCs and platelets, functioning to drain excess interstitial fluid and transport lymphocytes.
Human blood groups follow the ABO system based on surface antigens: Group AB has both A and B antigens (no antibodies) and is the universal receiver; Group O lacks antigens and is the universal donor.
Blood pressure is measured in mmHg using a sphygmomanometer; standard healthy adult blood pressure is roughly 120/80 mmHg (systolic/diastolic).

Blood Group	Antigen on RBC	Antibody in Plasma	Donation Compatibility
A	A	Anti-B	Donates to A, AB
B	B	Anti-A	Donates to B, AB
AB	A and B	None	Universal Receiver
O	None	Anti-A and Anti-B	Universal Donor

Plant Physiology and Reproduction

Plant physiology encompasses vital plant life functions including transpiration, photosynthesis, respiration, and nutrient uptake.
Transpiration is the loss of excess water as water vapor from aerial plant organs, primarily occurring through microscopic leaf pores called stomata.
Guard cells regulate the opening and closing of stomata; transpiration facilitates the upward movement of water via xylem vessels and creates a cooling effect.
Sexual reproduction in angiosperms involves flower organs: the stamen (male part comprising anther and filament) and the pistil/carpel (female part comprising stigma, style, and ovary).
Pollination is the transfer of pollen grains from the anther to the sticky stigma by wind, water, insects, or birds.
After fertilization, the fertilized ovule develops into a seed, while the surrounding ovary ripens to form the fruit.
Asexual reproduction occurs without gamete fusion: natural vegetative propagation utilizes roots (sweet potato), stems (potato tubers, ginger), or leaves; artificial methods include cutting, layering, grafting, and tissue culture.

Plant and Animal Taxonomy

The plant kingdom is broadly classified into non-flowering, seedless Cryptogams and seed-bearing Phanerogams.
Thallophytes possess an undifferentiated body lacking true roots, stems, or leaves (e.g., Spirogyra algae, fungi).
Must knowBryophytes lack specialized vascular tissues (xylem/phloem), absorb water via hair-like rhizoids, and are termed the amphibians of the plant kingdom (e.g., mosses, liverworts).
Pteridophytes are primitive vascular plants that reproduce via spores rather than seeds (e.g., ferns, Lycopodium).
Gymnosperms bear naked, exposed seeds without flowers or enclosing fruits (e.g., pine, cycas), whereas Angiosperms produce covered seeds enclosed inside fruits (e.g., mango, apple).
Invertebrates lack a vertebral column; Porifera are aquatic pore-bearers lacking true tissues (sponges), Cnidaria feature radial symmetry and stinging cells (Hydra, jellyfish), Platyhelminthes are flatworms (tapeworms), Nematoda are roundworms, and Arthropoda feature segmented bodies with jointed appendages (insects, crabs).

Human Digestive and Endocrine Systems

The liver is the largest internal gland of the human body; it secretes alkaline bile juice (stored in the gall bladder) that emulsifies dietary fats in the small intestine.
The pancreas is a heterocrine (mixed) gland operating as an exocrine gland (secreting pancreatic juice with amylase, lipase for fats, and trypsin for proteins) and an endocrine gland.
Endocrine islets of Langerhans in the pancreas secrete insulin (lowers blood sugar by driving glucose storage as glycogen) and glucagon (raises blood sugar).
The pituitary gland located in the brain functions as the master gland, secreting growth hormone and tropic hormones controlling other glands.
The pineal gland is the smallest endocrine gland, releasing melatonin in darkness to regulate the circadian sleep-wake cycle.
The thyroid gland in the neck requires dietary iodine to synthesize thyroxine, which controls basal metabolic rate; deficiency leads to goitre.
Parathyroid glands secrete parathyroid hormone to regulate serum calcium ion levels.
Adrenal glands secrete epinephrine (adrenaline), the emergency "fight or flight" hormone, and cortisol to manage physiological stress.

Digestive Juice	Enzymes Present	Primary Substrate	End Products
Saliva	Ptyalin (Salivary amylase)	Starch	Maltose
Gastric Juice	Pepsin, Rennin	Proteins, Casein	Peptones, Calcium paracaseinate
Pancreatic Juice	Trypsin, Lipase, Amylase	Proteins, Fats, Starch	Peptides, Fatty acids, Maltose

Respiration, Excretion, and Senses

Aerobic respiration requires oxygen and breaks down glucose into carbon dioxide, water, and large yields of energy; anaerobic respiration proceeds without oxygen, producing lactic acid or ethyl alcohol.
Must knowThe respiratory pigment hemoglobin transports around 97% of oxygen as oxyhemoglobin; around 7-10% of carbon dioxide travels dissolved in plasma, and the rest travels as bicarbonate ions.
Specialized respiratory organs across fauna: skin/cutaneous (earthworms, frogs), gills (fishes, tadpoles), book lungs (spiders, scorpions), and tracheal tubes (insects).
The human heart features four chambers: the right side receives deoxygenated blood via superior and inferior vena cava and pumps it to the lungs via the pulmonary artery.
The left side receives oxygenated blood from the lungs via pulmonary veins and pumps it systematically throughout the body via the aorta.
The structural and functional unit of the kidney is the microscopic nephron; urine formation proceeds through glomerular filtration, tubular reabsorption, and secretion.
Eye vision defects: Myopia (nearsightedness; image forms in front of the retina; corrected with concave lenses) and Hypermetropia (farsightedness; corrected with convex lenses).

Key terms

Cytology: The biological study of cell structure, reproduction, and pathology.
Omnis cellula e cellula: Rudolf Virchow's principle that all living cells originate solely from pre-existing cells.
Cristae: The inward folds of the inner mitochondrial membrane that expand the surface area for ATP production.
Erythropoiesis: The physiological process by which red blood cells are produced in the bone marrow.
Sphygmomanometer: A medical diagnostic device used to measure arterial blood pressure.
Stomata: Microscopic pores on leaf surfaces regulated by guard cells for gas exchange and transpiration.
Bryophytes: Non-vascular land plants known as the amphibians of the plant kingdom.
Islets of Langerhans: Endocrine cell clusters in the pancreas responsible for synthesizing insulin and glucagon.
Nephron: The microscopic structural and functional filtration unit of the mammalian kidney.
Myopia: Refractive visual defect where close objects are clear but distant objects appear blurred; corrected using concave lenses.

Quick revision

Read these the night before the exam.

Robert Hooke first identified cells in cork tissue in 1665.
Anton van Leeuwenhoek discovered the first living cells under a microscope in 1674.
Mitochondria generate cellular energy in the form of ATP molecules.
Plant cell walls are primarily composed of cellulose, whereas fungal walls contain chitin.
Erythrocytes (RBCs) have a normal lifespan of approximately 120 days.
The human blood group AB is the universal recipient, whereas O is the universal donor.
Normal resting human adult blood pressure measures approximately 120/80 mmHg.
In DNA, Adenine binds to Thymine and Guanine binds to Cytosine; in RNA, Uracil replaces Thymine.
The pancreas functions as a mixed gland secreting both digestive enzymes and metabolic hormones.
Myopia is visually corrected using diverging concave lenses.

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