Biology and Life Sciences
🟢 Lite — Quick Review (1h–1d)
Rapid summary for last-minute revision before your exam.
Cell — The Basic Unit of Life
All living organisms are made of cells. The cell theory (Schleiden, Schwann, 1839):
- All living organisms are composed of cells
- The cell is the basic unit of life
- All cells arise from pre-existing cells (Rudolf Virchow, 1855)
Types of Cells:
| Feature | Plant Cell | Animal Cell |
|---|---|---|
| Cell wall | ✅ Present (cellulose) | ❌ Absent |
| Chloroplast | ✅ Present | ❌ Absent |
| Vacuole | Large, central | Small, many |
| Centrioles | ❌ Absent (mostly) | ✅ Present |
| Shape | Rectangular, fixed | Irregular |
| Lysosomes | Rare | Abundant |
Cell Organelles & Their Functions:
- Nucleus: Contains DNA, controls cell activities; contains nucleolus (makes ribosomes)
- Mitochondria: “Powerhouse of cell” — produces ATP (adenosine triphosphate) via respiration
- Endoplasmic Reticulum (ER): Rough ER (ribosomes attached → protein synthesis); Smooth ER (lipid synthesis)
- Golgi Apparatus: Modifies, packages, and ships proteins (called “post office of cell”)
- Lysosomes: Contain digestive enzymes — digest worn-out organelles and foreign particles
- Chloroplast: Site of photosynthesis — contains chlorophyll (green pigment)
- Ribosomes: Site of protein synthesis (free in cytoplasm or attached to ER)
- Cell membrane: Selectively permeable — controls what enters/exits the cell (Fluid Mosaic Model)
⚡ UPTET tip: The mitochondria is called the “powerhouse” because it produces the most ATP through cellular respiration.
Photosynthesis
The process by which green plants make food using sunlight, carbon dioxide, and water:
$$6CO_2 + 6H_2O \xrightarrow{\text{sunlight/chlorophyll}} C_6H_{12}O_6 + 6O_2$$
Two Stages:
Light Reaction (Grana/thylakoid membrane):
- Chlorophyll absorbs light energy
- Water splits: $2H_2O \rightarrow 4H^+ + 4e^- + O_2$
- Photolysis of water produces O₂
- ATP and NADPH₂ produced
- Occurs only in presence of light
Dark Reaction / Calvin Cycle (Stroma):
- CO₂ is fixed into glucose using ATP and NADPH₂
- Doesn’t directly need light (but needs products of light reaction)
- Occurs in stroma of chloroplast
C3 and C4 Plants:
- C3 plants: Rice, wheat, barley — first product is 3-carbon compound (phosphoglyceric acid)
- C4 plants: Maize, sugarcane, sorghum — first product is 4-carbon compound (oxaloacetic acid); more efficient in hot climates
⚡ UPTET tip: “Photophosphorylation” = making ATP using light energy. Cyclic: only ATP produced. Non-cyclic: ATP + NADPH₂ both produced.
🟡 Standard — Regular Study (2d–2mo)
Standard content for students with a few days to months.
Cell Division — Mitosis and Meiosis
Mitosis (Equational Division):
- One parent cell → two identical daughter cells
- Chromosome number: Maintained (2n → 2n)
- Purpose: Growth, repair, asexual reproduction
- Stages: Prophase → Metaphase → Anaphase → Telophase (PMAT)
- Prophase: Chromatin condenses → chromosomes visible; nuclear membrane dissolves
- Metaphase: Chromosomes line up at equator; spindle fibers attach to centromeres
- Anaphase: Sister chromatids separate → move to opposite poles
- Telophase: Nuclear membrane reforms; chromosomes become chromatin again
Meiosis (Reduction Division):
- One parent cell → four non-identical daughter cells (gametes)
- Chromosome number: Halved (2n → n)
- Purpose: Formation of gametes (sex cells), introduces genetic variation
- Two divisions: Meiosis I (reduction) + Meiosis II (equational)
- Meiosis I: Homologous chromosomes pair and separate (crossing over occurs — genetic recombination)
- Meiosis II: Sister chromatids separate (like mitosis)
| Feature | Mitosis | Meiosis |
|---|---|---|
| Divisions | One | Two |
| Daughter cells | 2 | 4 |
| Genetic variation | No | Yes (crossing over) |
| Chromosome number | Same as parent | Half of parent |
| Where | All somatic cells | Germ cells |
Human Body Systems
Digestive System:
- Parts: Mouth → Pharynx → Oesophagus → Stomach → Small intestine (duodenum, jejunum, ileum) → Large intestine (caecum, colon, rectum) → Anus
- Small intestine: Main site of absorption; has villi (finger-like projections) and microvilli
- Digestive enzymes:
- Salivary amylase (mouth): Breaks starch → maltose
- Pepsin (stomach): Proteins → peptides
- Trypsin (pancreas): Proteins → peptides
- Lipase (pancreas): Fats → fatty acids + glycerol
- Maltase, sucrase, lactase (intestine): Disaccharides → monosaccharides
Respiratory System:
- Nose → Pharynx → Larynx → Trachea → Bronchi → Bronchioles → Alveoli (gas exchange site)
- Breathing mechanism: Diaphragm contracts → volume increases → pressure decreases → air rushes in (inspiration)
- Tidal volume: Normal breath = ~500 mL; Vital capacity = ~4500 mL
Circulatory System:
- Heart: 4 chambers — RA, RV, LA, LV; mammals have double circulation (pulmonary + systemic)
- Blood vessels: Arteries (carry blood from heart, thick walls), Veins (carry to heart, valves), Capillaries (exchange sites)
- Blood components: Plasma (55%) + Blood cells (45%)
- Red blood cells: Carry O₂ (haemoglobin); no nucleus; live ~120 days
- White blood cells: Fight infection (neutrophils, lymphocytes, monocytes, eosinophils, basophils)
- Platelets: Blood clotting (thrombocytes); live 8-9 days
- Blood groups: ABO system (A, B, AB, O) and Rh factor (+ or −)
Excretory System:
- Kidneys (bean-shaped, retroperitoneal) → Ureters → Urinary bladder → Urethra
- Nephron = functional unit of kidney:
- Glomerular filtration (water + waste from blood)
- Tubular reabsorption (water, glucose, amino acids back into blood)
- Tubular secretion (extra waste products secreted into tubule)
- Urine composition: Water (95%), urea, creatinine, uric acid, salts
Nervous System:
- CNS: Brain (forebrain, midbrain, hindbrain) + Spinal cord
- PNS: Somatic (voluntary) + Autonomic (involuntary — sympathetic, parasympathetic)
- Reflex arc: Receptor → Sensory neuron → Relay neuron → Motor neuron → Effector (muscle/gland)
- Synapse: Junction between two neurons; uses neurotransmitters (acetylcholine, dopamine, serotonin)
🔴 Extended — Deep Study (3mo+)
Comprehensive coverage for students on a longer study timeline.
Genetics — Inheritance and Variation
Mendel’s Laws:
- Law of Dominance: In a heterozygote, the dominant allele masks the recessive allele
- Law of Segregation: During gamete formation, paired factors (alleles) separate; each gamete gets one allele
- Law of Independent Assortment: Alleles of different genes segregate independently during gamete formation (only true for genes on different chromosomes)
Key Genetic Terms:
- Allele: Alternate form of a gene
- Genotype: Genetic makeup (e.g., TT, Tt, tt)
- Phenotype: Physical appearance (e.g., tall, short)
- Homozygous: Same alleles (TT or tt)
- Heterozygous: Different alleles (Tt)
- Dominant: Expressed in heterozygote (T)
- Recessive: Only expressed in homozygote (t)
Punnett Square Examples:
- Monohybrid cross: Tt × Tt → 3 Tall (TT, Tt, Tt) : 1 Short (tt) = 3:1 ratio
- Test cross: Tt × tt → 1 Tall (Tt) : 1 Short (tt) = 1:1 ratio
Sex Determination:
- Human: XX (female) / XY (male) — determined by father
- Male produces X and Y sperm (50:50); Female produces only X eggs
- Sex ratio at birth: ~105 males : 100 females
Human Genetic Disorders:
| Disorder | Type | Cause | Symptoms |
|---|---|---|---|
| Colour blindness | Sex-linked (X) | Recessive X^b | Can’t distinguish red/green |
| Haemophilia | Sex-linked (X) | Recessive X^h | Blood doesn’t clot |
| Down syndrome | Autosomal | Trisomy 21 (extra chromosome 21) | Mental retardation, flat face |
| Turner syndrome | Sex chromosomal | XO (45 chromosomes) | Female, short stature, infertility |
| Klinefelter syndrome | Sex chromosomal | XXY (47 chromosomes) | Male, tall, some female traits |
Nutrition and Health
Nutrients — Types and Sources:
| Nutrient | Function | Sources |
|---|---|---|
| Carbohydrates | Main energy source (4 kcal/g) | Rice, wheat, sugar |
| Proteins | Growth and repair (4 kcal/g) | Pulses, eggs, meat, milk |
| Fats | Energy storage (9 kcal/g) | Oil, ghee, butter, nuts |
| Vitamins | Regulate body processes | Fruits, vegetables (A,B,C,D,E,K) |
| Minerals | Body functions (Ca, Fe, K, Na) | Milk (Ca), spinach (Fe) |
| Water | Solvent, transport, temperature | 60-70% of body weight |
Vitamins — Key Facts for UPTET:
- Vitamin A (Retinol): Night vision, healthy skin — deficiency: night blindness, xerophthalmia — sources: carrots, papaya, fish liver oil
- Vitamin B1 (Thiamine): Energy metabolism — deficiency: Beriberi — sources: whole grains, nuts
- Vitamin C (Ascorbic acid): Collagen synthesis, immunity — deficiency: Scurvy (bleeding gums) — sources: citrus fruits, amla
- Vitamin D (Calciferol): Calcium absorption — deficiency: Rickets (bone deformities) — sources: sunlight, fish, milk
- Vitamin K: Blood clotting — deficiency: excessive bleeding — sources: green leafy vegetables
⚡ UPTET exam question: “Which vitamin is produced by our body when exposed to sunlight?” → Vitamin D (cholecalciferol synthesized in skin)
Diseases and Immunity
Common Human Diseases:
| Disease | Causative Agent | Vector/Transmission | Symptoms |
|---|---|---|---|
| Malaria | Plasmodium (protozoa) | Female Anopheles mosquito | Fever, chills, anaemia |
| Dengue | Dengue virus | Aedes aegypti mosquito | High fever, rash, joint pain |
| Typhoid | Salmonella typhi (bacteria) | Contaminated food/water | High fever, weakness |
| Tuberculosis | Mycobacterium tuberculosis | Air (coughing/sneezing) | Persistent cough, weight loss |
| AIDS | HIV (Retrovirus) | Blood, sexual contact, mother-child | Weakens immunity |
| Pneumonia | Bacteria/virus | Air | Lung infection, fever |
| cholera | Vibrio cholerae | Contaminated water | Severe diarrhoea |
Immunity:
- Innate (non-specific): Skin, mucous membranes, tears, stomach acid, phagocytes
- Acquired (specific):
- Humoral (B-cells): Produces antibodies against antigens
- Cell-mediated (T-cells): Directly destroys infected cells
- Active immunity: Body produces antibodies (slow, long-lasting) — either natural (infection) or artificial (vaccination)
- Passive immunity: Antibodies given directly (fast, short-lasting) — either natural (maternal antibodies in breast milk) or artificial (antivenom, gamma globulin)
⚡ UPTET tip: Vaccines work on the principle of acquired immunity — they contain weakened/inactivated pathogens that stimulate the immune system without causing disease. This is called “artificial active immunity.”
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Sources & verification
- Official UPTET syllabus & pattern: https://updeled.gov.in/
- Editorial methodology: research → draft → fact-verify → curate pipeline
- Reviewed by Pushkar Saini · last updated
- Found an error? Email pushkersaini@gmail.com with the page URL and a one-line description — corrections typically actioned within 48 hours.