The Last-Minute Master Cheat Sheet

This is the revision section — designed for the night before (or morning of) the Board exam. Don't read this until you've worked through sections 1-10 first.

How to use this section:

  • Read it ONCE the night before the exam.
  • Read it AGAIN on the morning of the exam.
  • Don't try to memorise new material here — only refresh what you already know.

Chapter at a Glance

Life Processes is the chapter about what makes living things alive. It covers six fundamental processes:

  1. Nutrition — how organisms get food and energy.
  2. Respiration — how they release energy (ATP) from food.
  3. Transportation — how they move materials around (blood in animals, xylem/phloem in plants).
  4. Excretion — how they remove wastes.
  5. Control and coordination — how they respond to stimuli (covered in next chapter).
  6. Reproduction — how they make new individuals (covered later).

This chapter covers processes 1-4 in detail.

Why life processes need specialised systems

  • Unicellular organisms (Amoeba, Paramecium) — diffusion through the cell membrane is enough.
  • Multicellular organisms (humans, plants) — diffusion alone is too slow over long distances. Hence they evolved specialised systems (digestive, respiratory, circulatory, excretory).

The big picture flow

Food (carbs, proteins, fats)
     ↓ (NUTRITION — eaten and digested)
Glucose + amino acids + fats absorbed into blood
     ↓ (TRANSPORTATION — carried by blood)
Delivered to every cell of the body
     ↓ (RESPIRATION — broken down with O₂)
ATP (energy currency) + CO₂ + H₂O
     ↓ (EXCRETION — wastes removed)
Urea, CO₂, excess water, salts → out of the body

Let's now revisit each topic compactly.

Section 1-2: Nutrition Summary

Autotrophic vs Heterotrophic

Autotrophic Heterotrophic
Source of food Self-made from CO₂, H₂O From other organisms
Energy Sunlight (or chemicals) From food
Pigment needed Chlorophyll None
Examples Plants, cyanobacteria Animals, fungi, most bacteria

The master equation of photosynthesis (MEMORISE!)

6CO2+6H2O→Sunlight, ChlorophyllC6H12O6+6O26CO_2 + 6H_2O \xrightarrow{\text{Sunlight, Chlorophyll}} C_6H_{12}O_6 + 6O_2

Reactants: 6 CO₂ + 6 H₂O. Products: glucose (C₆H₁₂O₆) + 6 O₂. Catalyst (over arrow): chlorophyll + sunlight.

Site and stages

  • Site: Chloroplast (in palisade mesophyll of leaves).
  • Stages:
  • Light reactions — in thylakoid membranes (splits water, releases O₂, makes ATP/NADPH).
  • Dark reactions (Calvin cycle) — in stroma (uses ATP/NADPH to fix CO₂ into glucose).

Three raw materials

  1. Light (from sun).
  2. Water (from soil via xylem).
  3. Carbon dioxide (from atmosphere via stomata).

Stomata and guard cells

  • Stomata = pores on leaf surface (mainly lower epidermis).
  • Bordered by two guard cells (kidney-shaped, with chloroplasts).
  • Open when guard cells are turgid (water inside).
  • Closed when guard cells are flaccid (water outside).
  • Control regulated by K⁺ pumping (active transport).

Three heterotrophic types

Type Description Example
Holozoic Eats whole food → digests inside body Humans, Amoeba
Saprophytic Lives on dead matter, secretes digestive enzymes onto food Rhizopus, Mucor
Parasitic Lives on/in another living host Cuscuta, tapeworm

Five steps of holozoic nutrition

  1. Ingestion — taking food in.
  2. Digestion — breaking down food.
  3. Absorption — taking digested food into the body.
  4. Assimilation — using absorbed food.
  5. Egestion — expelling undigested food.

Nutrition in Amoeba (single cell does ALL 5 steps!)

  • Ingestion: pseudopodia engulf food → food vacuole (phagocytosis).
  • Digestion: enzymes in cytoplasm enter the vacuole (intracellular).
  • Absorption: simple molecules diffuse into cytoplasm.
  • Assimilation: used for energy/growth.
  • Egestion: food vacuole ruptures at cell membrane.

Section 4: Human Digestive System Summary

Path of food (memorise this order)

Mouth→Oesophagus→Stomach→Small intestine→Large intestine→Rectum→Anus\text{Mouth} \to \text{Oesophagus} \to \text{Stomach} \to \text{Small intestine} \to \text{Large intestine} \to \text{Rectum} \to \text{Anus}

Major digestive organs and what they secrete

Organ Secretion Enzyme Acts on
Mouth (salivary glands) Saliva Salivary amylase (ptyalin) Starch → maltose
Stomach Gastric juice HCl + Pepsin + Mucus Proteins → peptides; sterilises food
Small intestine Intestinal juice Trypsin, lipase, maltase, peptidases Completes all digestion
Pancreas Pancreatic juice Trypsin (protein), Lipase (fat), Amylase (starch) Major digestion
Liver Bile NO enzymes — only emulsifies fats Fat emulsification

Three roles of HCl in stomach

  1. Kills microbes.
  2. Activates pepsinogen → pepsin.
  3. Provides acidic pH (~2) for pepsin to work.

Mucus = stomach's protective shield

Without mucus, HCl would digest the stomach itself → peptic ulcers.

Villi — the absorption specialists

  • Finger-like projections in small intestine.
  • ~250 m² total surface area.
  • Each villus has: outer epithelium (with microvilli) + blood capillaries + central lacteal (lymph vessel).
  • Glucose, amino acids → into blood capillaries.
  • Fatty acids, glycerol → into lacteals (lymph).

Why is the small intestine so long (7 m)?

  • More time for digestion.
  • More surface area (with villi) for absorption.
  • Herbivores have even longer intestines than carnivores due to cellulose.

Large intestine

  • Absorbs water (and some salts).
  • Houses bacteria that produce vitamin K and vitamin B12.
  • Faeces are formed and stored in rectum until egestion.

Section 5: Respiration Summary

Cellular respiration — definition

The controlled breakdown of glucose to release ATP (energy currency of the cell).

Aerobic vs Anaerobic — comparison

Feature Aerobic Anaerobic
Oxygen needed YES NO
Site Mitochondria Cytoplasm
Glucose breakdown Complete Partial
Products CO₂ + H₂O Ethanol+CO₂ (yeast) OR Lactic acid (muscle)
ATP yield ~38 ~2

Equations to MEMORISE

Aerobic: C6H12O6+6O2→6CO2+6H2O+38 ATPC_6H_{12}O_6 + 6O_2 \to 6CO_2 + 6H_2O + 38\text{ ATP}

Anaerobic in yeast: C6H12O6→2C2H5OH+2CO2+2 ATPC_6H_{12}O_6 \to 2C_2H_5OH + 2CO_2 + 2\text{ ATP}

Anaerobic in muscle (under low O₂): C6H12O6→2C3H6O3+2 ATPC_6H_{12}O_6 \to 2C_3H_6O_3 + 2\text{ ATP}

(C₃H₆O₃ = lactic acid → causes muscle cramps)

Human respiratory system — path of air

Nostrils→Pharynx→Larynx→Trachea→Bronchi→Bronchioles→Alveoli\text{Nostrils} \to \text{Pharynx} \to \text{Larynx} \to \text{Trachea} \to \text{Bronchi} \to \text{Bronchioles} \to \text{Alveoli}

Mechanism of breathing (memorise!)

Phase Diaphragm Ribs Cavity volume Cavity pressure Air
Inhalation Contracts (DOWN) UP and OUT Increases Decreases IN
Exhalation Relaxes (UP) DOWN and IN Decreases Increases OUT

Driven by Boyle's Law: volume up = pressure down.

Gas exchange at alveoli

  • Alveoli have thin walls (1 cell thick) and rich blood supply.
  • Total surface area: ~80 m² (size of a small house!).
  • O₂ diffuses from alveoli → blood → binds to haemoglobin in RBCs.
  • CO₂ diffuses from blood → alveoli → exhaled out.

Why O₂ transport is special

  • O₂ doesn't dissolve well in water.
  • It binds to haemoglobin (Fe-containing pigment in RBCs).
  • Hb + 4O₂ → oxyhaemoglobin (in lungs).
  • Oxyhaemoglobin → Hb + 4O₂ (at tissues, releases O₂).

Section 6: Transportation in Humans Summary

Three components of the circulatory system

  1. Heart (the pump).
  2. Blood vessels (arteries, veins, capillaries).
  3. Blood (the fluid).

Plus the parallel lymphatic system.

The four-chambered heart

Chamber Function
Right atrium Receives deoxygenated blood from BODY
Right ventricle Pumps deoxygenated blood to LUNGS
Left atrium Receives oxygenated blood from LUNGS
Left ventricle Pumps oxygenated blood to BODY (thickest wall)

Atria RECEIVE; ventricles PUMP.

Four valves (one-way doors)

  • Tricuspid — right atrium ↔ right ventricle.
  • Bicuspid (mitral) — left atrium ↔ left ventricle.
  • Pulmonary semilunar — exit of right ventricle.
  • Aortic semilunar — exit of left ventricle.

Lub-dub sound = valves closing.

Double circulation

Pulmonary: Right ventricle → Pulmonary artery → Lungs → Pulmonary veins → Left atrium.

Systemic: Left ventricle → Aorta → Body tissues → Vena cavae → Right atrium.

Blood passes through heart TWICE per cycle — hence DOUBLE circulation.

Why double circulation?

  • Keeps oxygenated and deoxygenated blood SEPARATE.
  • Essential for warm-blooded animals with high energy needs.
  • Fish have single circulation (only 2 chambers) — adequate for cold-blooded animals.

Blood vessels comparison

Feature Artery Vein Capillary
Direction AWAY from heart TOWARDS heart Connects
Wall Thick, muscular Thinner 1 cell thick
Valves NO YES NO
Pressure High Low Very low
Blood (usual) Oxygenated Deoxygenated Mixed

Exception: Pulmonary artery has DEOXYGENATED blood; pulmonary vein has OXYGENATED.

Blood components (4)

Component % Function
Plasma ~55% Liquid medium
RBCs ~45% Carry O₂ via haemoglobin
WBCs <1% Immune defence
Platelets <1% Blood clotting

Adult body has ~5 L of blood.

Lymph

  • Source: leaked tissue fluid from blood capillaries.
  • Composition: less protein, more lymphocytes, fats from intestine.
  • Functions: return fluid to blood, transport fats, defence at lymph nodes.

Section 7: Transportation in Plants Summary

Xylem vs Phloem — the comparison table

Feature Xylem Phloem
Carries Water + minerals Food (sucrose)
Direction UPWARD only BOTH ways (source → sink)
Cells Mostly DEAD Mostly LIVING
Walls Lignified Cellulose
Driving force Transpiration pull Pressure flow (Münch's)
ATP needed NO (passive) YES (active)
Speed ~15 m/h ~1 m/h

Xylem cell types (4)

  1. Tracheids — dead.
  2. Vessels (trachea) — dead, hollow tubes.
  3. Xylem fibres — dead, support.
  4. Xylem parenchyma — LIVING, storage.

Phloem cell types (4)

  1. Sieve tubes — living, no nucleus, with sieve plates.
  2. Companion cells — living, with nucleus.
  3. Phloem fibres — dead, support.
  4. Phloem parenchyma — living, storage.

How water rises in tall plants (3 forces)

  1. Osmosis at root hairs (water IN from soil).
  2. Root pressure (small push from below; shown by GUTTATION).
  3. Transpiration pull — the BIG force (suction created by stomatal water loss).

Cohesion-Tension Theory

Water column held together by:

  • Cohesion (water-water attraction via H-bonds).
  • Adhesion (water-xylem wall attraction).

Four functions of transpiration

  1. Drives upward water transport.
  2. Drives mineral transport (in same flow).
  3. Cools the leaf (evaporative cooling).
  4. Maintains turgor (cell shape).

Why 'necessary evil'? — Loses water (evil) but is essential for the 4 functions (necessary).

Translocation (food transport in phloem)

  • Source-sink concept.
  • Source: where food is made/released (leaves, storage organs in spring).
  • Sink: where food is needed/stored (roots, fruits, growing buds).
  • Pressure-flow hypothesis (Münch): sucrose loaded at source → high pressure; unloaded at sink → low pressure; sap flows source → sink.
  • Requires ATP.

Guttation vs Transpiration

Guttation Transpiration
What's lost Liquid water Water vapour
From where Hydathodes Stomata
When Early morning Daytime
Driver Root pressure Transpiration pull

Girdling experiment

Remove bark (= remove phloem) → xylem still works → leaves stay green briefly → but roots starve → tree dies.

Proves: phloem carries food; phloem is in outer layers.

Section 8: Excretion Summary

Main waste in humans

Urea — formed in liver from amino acid breakdown; removed by kidneys via urine.

Four excretory organs in humans

  1. Kidneys (main) — urea, water, salts.
  2. Lungs — CO₂, water vapour.
  3. Skin — sweat (water, salts, small urea).
  4. Liver — bile pigments.

Different organisms, different N-wastes

Organism Waste Why
Fish Ammonia Has unlimited water
Mammals (humans) Urea Limited water
Birds, reptiles, insects Uric acid Need to save water (flight, desert)

Path of urine in humans (memorise!)

Kidney→Ureter→Urinary bladder→Urethra→Out\text{Kidney} \to \text{Ureter} \to \text{Urinary bladder} \to \text{Urethra} \to \text{Out}

Kidney structure

  • Cortex (outer, pale) — nephrons start.
  • Medulla (inner, dark) — long tubules.
  • Pelvis (centre, funnel) — collects urine.
  • Each kidney has ~1 million nephrons.

Nephron parts (in order)

Glomerulus (in Bowman's capsule)
    ↓
PCT (Proximal Convoluted Tubule)
    ↓
Loop of Henle (descending + ascending)
    ↓
DCT (Distal Convoluted Tubule)
    ↓
Collecting Duct

Memory tip: G-B-P-L-D-C.

Three steps of urine formation

Step Site Direction Substance
1. Ultrafiltration Glomerulus → Bowman's capsule Blood → tubule Water, urea, small molecules
2. Selective reabsorption PCT, Loop, DCT Tubule → blood Glucose (100%), amino acids (100%), water (~99%), salts
3. Tubular secretion DCT Blood → tubule H⁺, K⁺, drugs

Volume: 180 L filtered → 1.5 L urine (>99% water reabsorbed).

Glucose in urine = diabetes

  • In healthy person: 100% glucose reabsorbed in PCT. None in urine.
  • In diabetes: blood glucose > renal threshold (~180 mg/dL) → carriers overwhelmed → glucose spills into urine (glycosuria).

Dialysis (artificial kidney)

  • Used when kidneys fail.
  • Blood passes through dialyser containing tubes of semi-permeable membrane.
  • Surrounded by dialysing fluid (similar to plasma but NO urea).
  • Wastes diffuse OUT of blood into the fluid.
  • Filtered blood returned to patient.
  • Sessions: 3 × week, 4-5 hours each.
  • Permanent solution: kidney transplant.

Plant excretion (5 methods)

  1. Gaseous wastes through stomata + lenticels.
  2. Excess water via transpiration.
  3. Storage in vacuoles (calcium oxalate, tannins).
  4. Shedding old leaves, bark, flowers.
  5. Secretion of gum, resin, latex, alkaloids.

Master Comparison Tables (memorise these!)

Autotrophic vs Heterotrophic Nutrition

Autotrophic Heterotrophic
Food Self-made From others
Pigment Chlorophyll None
Examples Plants Animals, fungi

Aerobic vs Anaerobic Respiration

Aerobic Anaerobic
Oxygen YES NO
Site Mitochondria Cytoplasm
Products CO₂ + H₂O Ethanol/Lactic acid
ATP ~38 ~2

Artery vs Vein

Artery Vein
Direction Away from heart Toward heart
Wall Thick Thin
Valves NO YES
Pressure High Low

Xylem vs Phloem

Xylem Phloem
Carries Water + minerals Food (sucrose)
Direction UP only BOTH ways
Cells Mostly dead Mostly living
ATP NO YES

Single vs Double Circulation

Single Double
Heart chambers 2 (fish) 4 (mammals, birds)
Through heart per cycle Once Twice
Blood mixing Yes No
Found in Fish Mammals, birds

Transpiration vs Guttation

Transpiration Guttation
What Water vapour Liquid water
Through Stomata Hydathodes
Driver Sun + low humidity Root pressure

Photosynthesis vs Respiration (opposites!)

Photosynthesis Respiration
Site Chloroplast Mitochondria
Uses CO₂ + H₂O O₂ + glucose
Produces Glucose + O₂ CO₂ + H₂O + ATP
Energy Absorbs (stores) Releases
Time Day (needs light) 24×7
In Green plants only All cells

NCERT-Canonical Phrases (use these in Board answers!)

These exact phrases are what CBSE markers reward. Reproduce them verbatim wherever possible.

General

  • "The biological process involved in the removal of harmful metabolic wastes from the body is called excretion."
  • "All organisms need an inward transport of food and outward transport of wastes."

Photosynthesis

  • "The process by which autotrophs take in substances from the outside and convert them into stored forms of energy is photosynthesis."
  • "Carbon dioxide and water are converted into carbohydrates in the presence of sunlight and chlorophyll."

Stomata

  • "Massive amounts of gaseous exchange takes place in the leaves through tiny pores called stomata."
  • "Opening and closing of the pore is a function of the guard cells."

Digestion

  • "The walls of the stomach secrete hydrochloric acid that creates an acidic medium that facilitates the action of the enzyme pepsin."
  • "Bile from the liver emulsifies the fats."

Respiration

  • "Cellular respiration releases energy to make ATP, the energy currency of the cell."
  • "During aerobic respiration, glucose is broken down completely to CO₂ and H₂O."

Circulation

  • "The pumping of blood is done by the heart."
  • "Mammals and birds have four-chambered hearts with complete separation of left and right sides."
  • "This separation allows for double circulation, with no mixing of oxygenated and deoxygenated blood."

Plant Transport

  • "In plants, the transport system carries energy stores from leaves and raw materials from roots."
  • "Loss of water in the form of vapour from the aerial parts of the plant is known as transpiration."
  • "The transport of soluble products of photosynthesis is called translocation, and it occurs in the part of the vascular tissue known as phloem."

Excretion

  • "The basic filtration unit of the kidney is the nephron."
  • "In case of kidney failure, an artificial kidney can be used."

Top Diagrams You MUST Practise

Board exam will almost certainly ask one of these (especially the 5-mark questions). Practise drawing each:

Must-know diagrams (in order of frequency)

  1. Human heart (4-chambered, with valves and major vessels labelled).
  2. Nephron (with all 6 parts: Bowman's capsule, glomerulus, PCT, Loop of Henle, DCT, collecting duct).
  3. Human digestive system (full layout with mouth → anus).
  4. Human respiratory system (full layout: nostrils → alveoli).
  5. Leaf cross-section (showing stomata, mesophyll, vascular bundles).
  6. Stomata with guard cells (open and closed).
  7. Double circulation pathway (loop diagram).

Drawing tips

  • Use a pencil first, then darken with pen.
  • Make diagrams at least 5 cm × 5 cm (small diagrams = fewer marks).
  • Use arrows with leader lines for labels.
  • Label EVERY major part — labels count for marks.
  • Use block letters for labels.
  • Use colored pencils for blood vessels (red = oxygenated, blue = deoxygenated) if allowed.

What examiners notice

  • Neatness: even an imperfect diagram earns marks if labels are clear.
  • Labelling: half the diagram marks come from labels alone.
  • Title above diagram: tiny detail but earns a 0.5 mark sometimes.

If you can draw and label all 7 diagrams above, you've covered 80% of the diagram-based Board questions.

Last 24 Hours — Revision Strategy

Night before the exam

8 PM:

  • Skim through the section 11 cheat sheet (this one).
  • Focus on tables and equations.
  • Re-read the NCERT-canonical phrases (section 11.9).

9 PM:

  • Practise drawing the 7 must-know diagrams from memory.
  • Don't worry about perfection — just labels.

10 PM:

  • Stop studying.
  • Light dinner. Avoid heavy food / caffeine.
  • Sleep early (at least 7-8 hours).

Morning of the exam

Wake up early, refresh:

  • Review tables one more time (autotrophic vs heterotrophic; aerobic vs anaerobic; xylem vs phloem; artery vs vein).
  • Re-write the photosynthesis and respiration equations.
  • Don't try to learn new material!

1 hour before exam:

  • Eat a light breakfast (no over-eating).
  • Stay calm. Trust your preparation.
  • Avoid last-minute panic study.

In the exam hall

First 5 minutes:

  • Read ALL questions carefully.
  • Identify the 5-mark questions; allocate ~8 minutes each.
  • Identify the 1-2 mark questions; do them first to gain confidence.

Strategy:

  • Easy first — answer the questions you know best first.
  • Diagrams first, then explain — for diagram questions, draw the diagram first then write the explanation around it.
  • Use tables for comparisons — examiners love clear tables.
  • Use NCERT phrases — they win marks.
  • Underline keywords — helps the examiner find them.
  • End every answer with a conclusion sentence — "Hence, the answer is…"

Time budget (80-mark Science paper, 3 hours = 180 min):

  • 1-mark questions: 1.5 min each.
  • 2-mark questions: 3 min each.
  • 3-mark questions: 5 min each.
  • 5-mark questions: 8 min each.
  • Last 20 min: Review your answers, add forgotten labels.

Common Board exam pitfalls (AVOID these!)

  • Skipping diagrams to 'save time' — costs you 2-3 marks per missed diagram.
  • Writing paragraphs for comparisons instead of tables — tables get more marks.
  • Missing keywords like 'ultrafiltration', 'emulsifies', 'translocation', 'transpiration pull'.
  • Forgetting to label all parts on a diagram.
  • Ignoring the question's mark allotment — write more for 5-mark, less for 1-mark.
  • Last-minute panic re-studying in the exam hall.

Mental approach

This chapter is HEAVY but RICH. You've covered it thoroughly through 11 sections. Trust your preparation. Stay calm. Write clearly.

Good luck — you've got this!

One-Line Summary of the Whole Chapter

Every living organism — from a single Amoeba to a 100-metre tall Eucalyptus to a 70 kg human — performs six fundamental life processes: nutrition (getting food: autotrophic in plants via photosynthesis, heterotrophic in animals via digestion), respiration (releasing energy as ATP: aerobic in mitochondria, anaerobic when O₂ is low), transportation (moving materials: blood + 4-chambered heart with double circulation in mammals, xylem + phloem in plants), excretion (removing wastes: kidneys with 1 million nephrons via 3 steps of urine formation in humans, storage and shedding in plants), control and coordination (responding to environment), and reproduction (continuing the species). These processes work together as a single, integrated whole — making life possible at every scale.

The Big Connections

Notice how everything in this chapter is connected:

  • Nutrition brings food in → broken down by digestion → glucose absorbed → transported by blood → used in respiration to make ATP → wastes (CO₂, urea) removed by excretion.

  • Plants do all this in reverse for CO₂: Photosynthesis absorbs CO₂ + water → makes glucose + O₂ → glucose is transported by phloem → respiration uses the glucose → CO₂ is excreted.

Living things are one big chemistry circuit — taking in inputs, processing them, and outputting energy and wastes. Life is metabolism in motion.

Your Journey Through Chapter 5

You've now completed all 11 sections of Life Processes — one of the heaviest chapters in Class 10 Science. You've learned:

  • The six life processes that define life.
  • How plants make their own food, and how animals get it from others.
  • How food is digested in your own body, and how it provides energy.
  • How blood circulates through your four-chambered heart, doubly.
  • How water rises 100 metres in tall trees without any pump.
  • How your kidneys filter 180 litres of blood every day to give you 1.5 L of urine.
  • How plants get rid of waste without a kidney.

That's biology at its most elegant.

All the best for your Board exam — you're ready!