Life Processes Topic Hub

Life Processes — Class 10 Notes

CBSE 2027 — dates, rules and official papers →
Biology · Ch 5Class 10 · CBSE 2026–27High weightage

Life Processes

What the board actually asks: label-and-explain diagrams (the human digestive system, heart, nephron and respiratory system), the four life processes traced stage-by-stage, comparison tables (xylem vs phloem, aerobic vs anaerobic, arteries vs veins), and "why is it necessary" reasoning - one of the highest-weight Biology chapters.

NCERT VERBATIM sourced, word-for-wordAUTHORED LazyTopper teaching scaffolding
The Big Idea AUTHORED

Four processes keep a living body from falling apart - nutrition, respiration, transportation, excretion.

Every living body must take in food and energy, break it down to power its cells, move materials to where they are needed, and clear out the waste. In Class 10 these four life processes are examined mostly through labelled diagrams and stage-by-stage explanations, so most marks reward the exact NCERT terms and correctly drawn, correctly labelled structures.

Formulae
Photosynthesis (standard equation)
Glucose breakdown
Glucose (6C) to Pyruvate (3C) in cytoplasm; then aerobic to + energy, or anaerobic - yeast to ethanol + , muscle to lactic acid
ATP
ATP is the energy currency of the cell; breaking its terminal phosphate bond releases about 30.5 kJ/mol
Heart chambers
4 chambers - left/right atrium + left/right ventricle. Fish 2-chambered, amphibians/many reptiles 3-chambered, birds & mammals 4-chambered
Blood pressure
Systolic about 120 mm Hg, diastolic about 80 mm Hg (measured with a sphygmomanometer)
Alveolar surface
Spread out, the alveolar surface would cover about - maximising gas exchange
Kidney filtrate
About 180 L of initial filtrate a day, but only 1-2 L excreted - the rest is re-absorbed
Definitions the board rewards NCERT VERBATIM

State these in NCERT’s exact words

Life processes
NCERT verbatim — memorise this exact wording· Ch 5,
“The processes which together perform this maintenance job are life processes.”
What it means: The basic functions - nutrition, respiration, transportation, excretion - that every living body runs continuously to stay organised and alive.
Nutrition
NCERT verbatim — memorise this exact wording· Ch 5,
“So there must be a process to transfer a source of energy from outside the body of the organism, which we call food, to the inside, a process we commonly call nutrition.”
What it means: Taking in food from outside to supply the body with energy and raw materials.
Autotrophic nutrition (photosynthesis)
NCERT verbatim — memorise this exact wording· Ch 5,
“Carbon and energy requirements of the autotrophic organism are fulfilled by photosynthesis. It is the process by which autotrophs take in substances from the outside and convert them into stored forms of energy.”
What it means: Green plants and some bacteria make their own food from CO2 and water using sunlight and chlorophyll.
Respiration
NCERT verbatim — memorise this exact wording· Ch 5,
“The process of acquiring oxygen from outside the body, and to use it in the process of break-down of food sources for cellular needs, is what we call respiration.”
What it means: Breaking down glucose (usually with oxygen) inside cells to release energy for life activities.
Transportation
NCERT verbatim — memorise this exact wording· Ch 5,
“This situation creates a need for a transportation system for carrying food and oxygen from one place to another in the body.”
What it means: The system (blood in animals, vascular tissue in plants) that moves food, oxygen and wastes between the parts that supply them and the parts that need them.
Excretion
NCERT verbatim — memorise this exact wording· Ch 5,
“The biological process involved in the removal of these harmful metabolic wastes from the body is called excretion.”
What it means: Getting rid of the poisonous nitrogenous wastes (like urea) that the body's chemical reactions produce.
Key terms — NCERT verbatim (state word-for-word)
Stomata
...stomata ... which are tiny pores present on the surface of the leaves. (Ch 5, )
Aerobic respiration
Since this process takes place in the presence of air (oxygen), it is called aerobic respiration. (Ch 5, )
Anaerobic respiration
Since this process takes place in the absence of air (oxygen), it is called anaerobic respiration. (Ch 5, )
Alveoli
balloon-like structures which are called alveoli (singular - alveolus). The alveoli provide a surface where the exchange of gases can take place. (Ch 5, )
Haemoglobin
In human beings, the respiratory pigment is haemoglobin which has a very high affinity for oxygen. (Ch 5, )
Xylem
One, the xylem moves water and minerals obtained from the soil. (Ch 5, )
Phloem
The other, phloem transports products of photosynthesis from the leaves where they are synthesised to other parts of the plant. (Ch 5, )
Nephrons
Each kidney has large numbers of these filtration units called nephrons packed close together. (Ch 5, )
Must-know concepts AUTHORED FRAMING

…and where they’re tested

Autotrophic vs heterotrophic nutrition
Autotrophs (green plants, some bacteria) build their own food from inorganic CO2 and water; heterotrophs (animals, fungi) take in the complex food made by others and break it down with enzymes.
3-mark: differentiate autotrophic and heterotrophic nutrition with examples.
Photosynthesis
In the leaf, chlorophyll in chloroplasts absorbs light; the three events are absorption of light energy, conversion to chemical energy plus splitting of water, and reduction of CO2 to carbohydrate. Raw materials: CO2 (through stomata), water (from roots) and sunlight.
NCERT Fig 5.1Cross-section of a leaf
Shows the leaf shape (midrib, lamina, vein with xylem/phloem bundle) and the cellular section (upper/lower epidermis, waxy cuticle, chloroplast, air spaces, guard cell) - the site of photosynthesis and gas exchange.
necessary conditions and by-products of autotrophic nutrition; role of stomata and guard cells.
Human digestive system
A long alimentary canal (mouth to oesophagus to stomach to small intestine to large intestine to anus) with region-specific enzymes; the small intestine is the site of complete digestion and its villi maximise absorption.
NCERT Fig 5.6Human alimentary canal
The full canal - mouth (buccal cavity), tongue, oesophagus, stomach, liver, gall bladder, bile duct, pancreas, small intestine, large intestine (colon), appendix, anus.
5-mark: label the human alimentary canal and name the enzymes and their functions; role of saliva / HCl / bile.
Respiration - aerobic vs anaerobic
Glucose (6 carbon) first splits to pyruvate (3 carbon) in the cytoplasm; then either aerobic (in mitochondria, giving CO2 + water and more energy) or anaerobic (yeast gives ethanol + CO2; muscle gives lactic acid, causing cramps).
differences between aerobic and anaerobic respiration with organisms; site of pyruvate breakdown.
Human circulatory system and double circulation
The four-chambered heart keeps oxygenated and de-oxygenated blood separate; blood (plasma plus cells) is pumped through arteries, capillaries and veins and passes through the heart twice per cycle.
NCERT Fig 5.10Schematic sectional view of the human heart
Four chambers with the vessels labelled - aorta, vena cava (upper/lower), pulmonary arteries and veins, left/right atrium, left/right ventricle, and the dividing septum. Pale-blue = de-oxygenated, peach = oxygenated.
5-mark: describe double circulation and why it is necessary; why oxygenated and de-oxygenated blood are separated in birds and mammals.
Transport in plants - xylem and phloem
Xylem carries water and minerals upward from the roots (root pressure plus transpiration pull); phloem translocates soluble food from the leaves in both directions, using energy from ATP.
differences between transport in xylem and phloem; how water and how food are transported in plants.
Excretion in humans - the nephron
Kidneys filter nitrogenous wastes (urea, uric acid); each nephron performs filtration in the Bowman's capsule then selective re-absorption along the tubule; urine passes through ureters to the bladder and out via the urethra.
NCERT Fig 5.14Structure of a nephron
The filtration unit - branch of renal artery/vein, glomerulus, Bowman's capsule, the tubular part, surrounding capillaries and the collecting duct.
5-mark: structure and functioning of the nephron; how the amount of urine is regulated; compare alveoli and nephron.
Worked examples — real solved problems NCERT VERBATIM

Solved exactly as the source does them

Every problem is a real sourced item, quoted verbatim with its page; the step-by-step decoding and mark-logic are LazyTopper-authored coaching.

Example Fig. 5.5 walkthrough,
“Trace how an Amoeba ingests and digests its food. [authored prompt]”
Ingestion.Amoeba takes in food using temporary finger-like extensions (pseudopodia) of the cell surface, which fuse over the food particle to form a food-vacuole.
1 mark
Digestion.Inside the food-vacuole, complex substances are broken down into simpler ones.
1 mark
Absorption.The simpler substances then diffuse into the cytoplasm.
Egestion.The remaining undigested material is moved to the surface of the cell and thrown out.
1 mark
Mark-scheme logic (authored): CBSE 3-mark - 1 mark each for pseudopodia/food-vacuole (ingestion), intracellular digestion, and egestion of undigested matter. Absorption (diffusion into the cytoplasm) is part of the process but is not a separately-credited step in the 3-mark scheme.
Example Fig. 5.6 walkthrough,
“Trace how food is digested as it passes mouth to stomach to small intestine. [authored prompt]”
Example Fig. 5.9 walkthrough,
“Explain how gases are exchanged in the human lungs during breathing. [authored prompt]”
Example Figs. 5.10-5.11 walkthrough,
“Trace the path of blood through the four chambers of the human heart. [authored prompt]”
Example Fig. 5.12 walkthrough,
“Explain how water rises from the roots to the top of a tall plant. [authored prompt]”
Example Figs. 5.13-5.14 walkthrough,
“Describe how urine is formed in the nephron. [authored prompt]”
Problem-solving strategies AUTHORED
Diagram question?Draw it large, label with straight ruled lines, and use exact NCERT terms - write "oesophagus" not "food pipe", "alveoli" not "air sacs".
"Differences between" asked?Answer in a two-column table (xylem vs phloem, aerobic vs anaerobic, arteries vs veins) - one clear point per row scores faster than a paragraph.
Enzyme / organ question?Pair every organ with its secretion and function - saliva to amylase to starch, stomach to pepsin + HCl to protein, pancreas to trypsin/lipase - examiners award the enzyme name AND its substrate separately.
"Why is it necessary?" add-on?Board answers want the reason, not just the process - e.g. double circulation is needed to stop oxygenated and de-oxygenated blood mixing, giving an efficient O2 supply for high energy needs.
Common mistakes that cost marks

Where students lose easy marks

Writing "food pipe" instead of oesophagus, or "wind pipe / air sacs" instead of trachea / alveoli - CBSE demands the exact technical term.
Confusing xylem and phloem: xylem = water + minerals, roots upward (one-way); phloem = food, both directions. Reversing them loses the whole mark.
Mislabelling heart chambers - putting oxygenated blood on the right, or swapping atria and ventricles. Remember: LEFT side = oxygen-rich, and ventricles have thicker walls than atria.
Saying anaerobic respiration in muscles gives ethanol - in human muscle cells pyruvate becomes lactic acid (ethanol + CO2 is only in yeast/fermentation).
Describing filtration only and forgetting that in the nephron useful substances (glucose, amino acids, salts, water) are RE-ABSORBED.
Formulae
Photosynthesis (standard equation)
Glucose breakdown
Glucose (6C) to Pyruvate (3C) in cytoplasm; then aerobic to + energy, or anaerobic - yeast to ethanol + , muscle to lactic acid
ATP
ATP is the energy currency of the cell; breaking its terminal phosphate bond releases about 30.5 kJ/mol
Heart chambers
4 chambers - left/right atrium + left/right ventricle. Fish 2-chambered, amphibians/many reptiles 3-chambered, birds & mammals 4-chambered
Blood pressure
Systolic about 120 mm Hg, diastolic about 80 mm Hg (measured with a sphygmomanometer)
Alveolar surface
Spread out, the alveolar surface would cover about - maximising gas exchange
Kidney filtrate
About 180 L of initial filtrate a day, but only 1-2 L excreted - the rest is re-absorbed
Mindmap
      • Autotrophic - photosynthesis (CO2 + water + sunlight + chlorophyll)
      • Heterotrophic - animals & fungi; enzymes break down complex food
      • Human digestion - mouth to stomach to small intestine; villi absorb
      • Amoeba - pseudopodia + food-vacuole
      • Glucose to pyruvate (cytoplasm)
      • Aerobic (mitochondria) to CO2 + water + more energy
      • Anaerobic - yeast to ethanol + CO2; muscle to lactic acid
      • Energy stored as ATP
      • Human - 4-chambered heart, double circulation
      • Blood vessels - arteries, veins, capillaries
      • Plants - xylem (water, up) & phloem (food, both ways)
      • Transpiration pull + root pressure
      • Human - kidney, nephron (filtration + re-absorption)
      • Path - ureter to bladder to urethra
      • Plants - waste in vacuoles, resins/gums, falling leaves
      • Use NCERT terms - oesophagus, alveoli, not slang
      • Xylem vs phloem direction
      • Correct heart-chamber labels
      • Nephron = filtration + RE-ABSORPTION

The diagrams you must be able to draw and label - Life Processes is examined heavily through labelled figures. Learn each one in the exact NCERT form.

NCERT Fig 5.1Cross-section of a leaf
Shows the leaf shape (midrib, lamina, vein with xylem/phloem bundle) and the cellular section (upper/lower epidermis, waxy cuticle, chloroplast, air spaces, guard cell) - the site of photosynthesis and gas exchange.
NCERT Fig 5.5Nutrition in Amoeba
Stages (a)-(d): pseudopodia engulf the food particle into a food-vacuole, then intracellular digestion and egestion. Labels: nucleus, food particle, pseudopodia, food vacuole.
NCERT Fig 5.6Human alimentary canal
The full canal - mouth (buccal cavity), tongue, oesophagus, stomach, liver, gall bladder, bile duct, pancreas, small intestine, large intestine (colon), appendix, anus.
NCERT Fig 5.9Human respiratory system
Torso view with the alveoli inset - nasal passage, throat, bronchi, lungs, diaphragm, and the balloon-like alveoli where gas exchange occurs.
NCERT Fig 5.10Schematic sectional view of the human heart
Four chambers with the vessels labelled - aorta, vena cava (upper/lower), pulmonary arteries and veins, left/right atrium, left/right ventricle, and the dividing septum. Pale-blue = de-oxygenated, peach = oxygenated.
NCERT Fig 5.13Excretory system in human beings
The pair of kidneys with the vena cava and aorta, the ureters carrying urine to the urinary bladder, and the urethra.
NCERT Fig 5.14Structure of a nephron
The filtration unit - branch of renal artery/vein, glomerulus, Bowman's capsule, the tubular part, surrounding capillaries and the collecting duct.

3 competency questions from the CBSE board pattern, with the full step-marked solution for each — the marks are shown per step, as the official scheme awards them.

1 markSection A

Oxygen saturation levels refer to the extent haemoglobin is bound to oxygen. As altitude increases, the atmospheric pressure decreases. Which of the following graphs correctly represents the oxygen saturation levels as altitude increases?

Four graphs P, Q, R and S of oxygen saturation against altitude
  1. (A) P
  2. (B) Q
  3. (C) R
  4. (D) S
Step-marked solution
  1. [1 mark] At higher altitude, atmospheric pressure (and pO2) is lower ⟹ less O2 binds to haemoglobin ⟹ O2 saturation decreases as altitude increases. Graph Q shows a decreasing trend matching this physiology.
1 markSection A

Patient X was suffering from a pancreatic condition due to which the pancreas was not functioning adequately. Which of the following is a doctor likely to suggest to such an individual?

  1. (A) including a large amount of protein in the diet
  2. (B) eating a diet with low-fat content
  3. (C) eating only carbohydrates
  4. (D) including only liquid foods
Step-marked solution
  1. [1 mark] Pancreas secretes lipase (digests fats) along with amylase, trypsin. If pancreas malfunctions, fat digestion is impaired ⟹ low-fat diet recommended.
2 marksSection B

A plant X was enclosed in a glass jar with some lizards. A similar plant Y was enclosed in another glass jar but without lizards. Both jars are kept under the same light conditions for a few hours. Which plant is likely to photosynthesize more and why?

Step-marked solution
  1. [1 mark] Lizards respire and release CO2 inside the jar, increasing CO2 concentration around plant X.
  2. [1 mark] Higher CO2 availability + adequate light ⟹ higher rate of photosynthesis in X compared to Y (which has limited CO2 in the closed jar).
Practise Life Processes competency questions

Official NCERT chapter PDF (jesc105) — ncert.nic.in

Sources: NCERT 2026-27 (tap to view)
Source ledger PROVENANCE

Source edition: NCERT Reprint 2026-27, Class 10 Science, Ch 5. One row per sourced item — every verbatim, example and NCERT figure traces to its page.

ItemTypeSource
Life processesverbatimNCERT 2026-27 Ch5
NutritionverbatimNCERT 2026-27 Ch5
Autotrophic nutrition (photosynthesis)verbatimNCERT 2026-27 Ch5
RespirationverbatimNCERT 2026-27 Ch5
TransportationverbatimNCERT 2026-27 Ch5
ExcretionverbatimNCERT 2026-27 Ch5
StomataverbatimNCERT 2026-27 Ch5
Aerobic respirationverbatimNCERT 2026-27 Ch5
Anaerobic respirationverbatimNCERT 2026-27 Ch5
AlveoliverbatimNCERT 2026-27 Ch5
HaemoglobinverbatimNCERT 2026-27 Ch5
XylemverbatimNCERT 2026-27 Ch5
PhloemverbatimNCERT 2026-27 Ch5
NephronsverbatimNCERT 2026-27 Ch5
Nutrition in AmoebaexampleNCERT 2026-27 Ch5 Fig 5.5
Digestion in the human alimentary canalexampleNCERT 2026-27 Ch5 Fig 5.6 -86
Exchange of gases in the alveoliexampleNCERT 2026-27 Ch5 Fig 5.9 -90
Double circulation through the human heartexampleNCERT 2026-27 Ch5 Figs 5.10-5.11
Transport of water in plants (transpiration pull)exampleNCERT 2026-27 Ch5 Fig 5.12 -95
Urine formation in the nephronexampleNCERT 2026-27 Ch5 Figs 5.13-5.14 -97
NCERT Fig 5.1figureNCERT 2026-27 Ch5 5.1
NCERT Fig 5.5figureNCERT 2026-27 Ch5 5.5
NCERT Fig 5.6figureNCERT 2026-27 Ch5 5.6
NCERT Fig 5.9figureNCERT 2026-27 Ch5 5.9
NCERT Fig 5.10figureNCERT 2026-27 Ch5 5.10
NCERT Fig 5.13figureNCERT 2026-27 Ch5 5.13
NCERT Fig 5.14figureNCERT 2026-27 Ch5 5.14

Life Processes · spec-rendered note · NCERT Reprint 2026-27, Class 10 Science, Ch 5

Practise writing answers the way examiners mark them → Guide