Life Processes · Class 10 Science: quick revision, 60 bites

The Life Processes

What sleeping bodies still do

All four run 24/7 — maintenance never sleeps, and maintenance costs energy.

Takeaway. Life = non-stop maintenance, powered by nutrition.

Autotroph vs Heterotroph

Cook or customer?

Takeaway. Cooks (autotrophs) feed the customers (heterotrophs).

Photosynthesis

The equation feeding the planet

The carbohydrate is stored as **starch** — the plant's pantry.

Takeaway. Air + water + light = food + the oxygen we breathe.

The Three Events of Photosynthesis

Three moves, one meal

They need not run back-to-back: desert plants collect CO₂ at NIGHT and finish the sugar-making by day.

Takeaway. Absorb → Split → Reduce (ASR).

Stomata and Guard Cells

Doors with a water bill

Leaf pores called **stomata** let CO₂ in and O₂ out. Twin **guard cells** swell to open the pore and shrink to close it. Since every open pore also LOSES water, plants shut stomata whenever CO₂ isn't needed.

Takeaway. Gas exchange has a water cost — guard cells manage the budget.

Raw Materials Checklist

More than just CO₂ and water

Takeaway. Air feeds the leaf; soil feeds the root.

Heterotroph Styles

Three ways to freeload

Takeaway. Outside-digester, host-drinker, whole-swallower.

Amoeba's Meal

Dinner without a mouth

Takeaway. Amoeba hugs its food and digests it in a bubble.

Mouth and Oesophagus

Digestion begins on the tongue

Teeth crush; saliva wets; **salivary amylase** starts starch → sugar (chew rice long enough and it turns sweet). Swallowed food travels the oesophagus by **peristalsis** — rhythmic muscle waves that squeeze it along the entire canal.

Takeaway. Chew, sweeten, squeeze along.

The Stomach's Three Tools

An acid bath with a shield

The sphincter muscle releases the churned food into the intestine in small doses.

Takeaway. Acid sets the stage, pepsin acts, mucus protects the theatre.

Small Intestine — the Main Stage

Where digestion actually finishes

Takeaway. Three juices finish the job; villi collect the winnings.

Villi — Why Fingers, Not Flat Walls

The surface-area trick again

Millions of finger-like **villi** fold the intestine's lining into a giant absorbing surface. Each villus carries a dense net of blood vessels that ferry glucose and amino acids to every cell of the body. Nature's rule: where exchange happens, surface area explodes.

Takeaway. Villi = maximum absorption in minimum length.

Dental Caries

The dentist's chemistry lesson

Mouth bacteria feast on trapped sugar and release **acids** that soften enamel, then dentine. The bacteria-food film — **plaque** — blocks saliva from neutralising the acid. Untreated, the cavity reaches the pulp and its nerves: pain. Brushing after meals evicts the plaque.

Takeaway. Sugar + bacteria + time = acid attack on teeth.

Board Favourites

The bankers of this topic

Takeaway. Five staples cover most marks here.

Memory Pack

Whole topic in three lines

Takeaway. Three codes, the whole topic.

Breathing ≠ Respiration

The pump and the factory

Takeaway. Breathing delivers the oxygen; respiration spends it.

Glucose → Pyruvate

Everyone starts here

The universal first step: the 6-carbon glucose splits into two 3-carbon **pyruvate** molecules — in the **cytoplasm**, in every organism, oxygen or not. Only pyruvate's fate differs afterwards.

Takeaway. 6C → 3C in the cytoplasm — the shared opening move.

Aerobic Respiration

The high-energy route

This finish runs in the **mitochondria** — the reason they're called the cell's powerhouses.

Takeaway. Oxygen + mitochondria = maximum energy payout.

Fermentation in Yeast

Why bread has holes

Without oxygen, yeast turns pyruvate into ethanol and CO₂ — the gas puffs up dough; the process brews alcohol.

Takeaway. Yeast's oxygen-free plan B feeds bakeries and breweries.

Lactic Acid and Cramps

The sprinting penalty

During sudden vigorous exercise, muscles outrun their oxygen supply. Pyruvate then becomes **LACTIC ACID**, and its build-up brings **cramps**. Massage or a hot bath boosts circulation — arriving oxygen finishes the lactic acid off to CO₂ and water.

Takeaway. Cramps = lactic acid; oxygen is the cleanup crew.

ATP — Energy Currency

The cell's wallet

Takeaway. Respiration charges ATP; life spends it.

The Air Route

Follow one breath

Takeaway. Nose to alveoli: filter, pipe, branch, exchange.

Alveoli — the Exchange Floor

A badminton court in your chest

Takeaway. Maximum surface + minimum wall = perfect diffusion.

How We Inhale

The chest's bellows trick

Takeaway. We don't suck air — we make room and let it fall in.

How the Gases Travel

The two couriers

**Oxygen** rides the pigment **haemoglobin** in red blood cells — its high O₂ affinity makes it the dedicated carrier. **CO₂** is far more soluble in water, so most of it commutes **dissolved in the plasma** back to the lungs.

Takeaway. O₂ takes the haemoglobin taxi; CO₂ swims in plasma.

Fish and Their Gills

Why the aquarium bubbles

Fish gulp water through the mouth and force it over **gills**, which strip the DISSOLVED oxygen. Water carries much less O₂ than air — so fish breathe noticeably **faster** than land animals, and aquaria need aerators.

Takeaway. Less O₂ in water → faster breathing under it.

Respiration in Plants

The plant's quiet breathing

Plants respire **24/7** by simple diffusion through stomata — each root, stem and leaf serving itself. At night, with photosynthesis off, CO₂ release is what you'd measure; by day, photosynthesis's oxygen output masks it entirely.

Takeaway. Plants always respire — daylight just hides it.

Carbon Monoxide Danger

The silent killer in closed rooms

Takeaway. CO hijacks haemoglobin — never burn fuel unventilated.

Board Favourites

The bankers of this topic

Takeaway. Five staples carry this topic's marks.

Memory Pack

Whole topic in three lines

Takeaway. Three lines, the whole engine room.

What Blood Is Made Of

Four workers in one red river

Takeaway. One river, four specialised services.

Artery vs Vein vs Capillary

Pressure pipes vs return lanes

Takeaway. A = Away; V = Valves; capillaries do the actual trading.

The Heart's Architecture

Two floors, four rooms

Two **atria** upstairs receive blood; two **ventricles** downstairs pump it out — through one-way **valves**. Ventricle walls are thicker than atria's, and the **left ventricle** is the mightiest: it drives blood to the whole body.

Takeaway. Receive upstairs, pump downstairs, thickest wall pumps farthest.

The Blood's Route

Follow one drop around

Takeaway. Right side = lung trip; left side = body trip.

Double Circulation

Twice through the pump

Each full round crosses the heart TWICE — once lung-bound, once body-bound. The payoff: **oxygenated and deoxygenated blood never mix**, giving the rich constant O₂ supply that warm-blooded bodies burn for temperature control.

Takeaway. Two passes, zero mixing, maximum efficiency.

2, 3 and 4 Chambers

Hearts across the animal kingdom

Takeaway. More separation for hotter metabolisms.

Platelets and Clotting

The emergency plumbers

A leak anywhere would drain the pressurised system and invite germs. **Platelet cells** swarm the injury and trigger a **clot** — a plug that seals the breach within minutes. That's why small cuts stop bleeding by themselves.

Takeaway. Platelets plug leaks before pressure (or sterility) is lost.

Lymph

Blood's quiet understudy

It also carries absorbed FATS from the intestine and drains excess tissue fluid.

Takeaway. Leaked plasma gets a second pipeline home.

Blood Pressure

120 over 80, explained

**Systolic** (~120 mm Hg) is the push during ventricle contraction; **diastolic** (~80 mm Hg) the baseline during relaxation. Measured by **sphygmomanometer**. Persistent hypertension — often from narrowed arteries — can rupture vessels and damage organs.

Takeaway. Contraction/relaxation pressures; high numbers hurt pipes.

Xylem and Transpiration Pull

A fountain with no pump

Roots take in mineral ions, water follows by osmosis (**root pressure**) — but the real elevator is **TRANSPIRATION PULL**: evaporation from leaf stomata tugs an unbroken water column up the xylem, tens of metres if needed, at zero energy cost. One-way traffic: upward only.

Takeaway. Evaporation above pulls; roots below push a little.

Phloem and Translocation

The sugar courier pays in ATP

**Sucrose is loaded into phloem sieve tubes using ATP**; osmosis then drives water in, and the pressure pushes the sap toward wherever demand calls — growing tips, fruits, roots. Living tissue, energy-spending, and **bidirectional** — spring reverses winter's downward flow.

Takeaway. Loaded with energy, driven by osmotic pressure, both directions.

Xylem vs Phloem

The two pipelines, side by side

Takeaway. Free one-way water lift vs paid two-way food delivery.

Root Pressure at Dawn

Dew that isn't dew

Takeaway. Night's root pressure literally squeezes water out of leaf tips.

Board Favourites

The bankers of this topic

Takeaway. Five staples dominate this topic's papers.

Memory Pack

Whole topic in three lines

Takeaway. Three codes, the whole transport network.

Excretion vs Egestion

Trash made inside vs trash passed through

Egestion, by contrast, expels undigested food that was never absorbed. Faeces ≠ excretion.

Takeaway. Excretion = cell-made waste out; egestion = food that never got in.

Urea's Journey

Made in one organ, removed by another

Excess amino acids can't be stored — the **LIVER** converts their nitrogen into **UREA**, which rides the blood until the **KIDNEYS** filter it out. Manufacturer: liver. Disposal: kidneys.

Takeaway. Liver makes urea; kidneys remove it.

K-U-B-U

The exit route

Takeaway. Kidney → Ureter → Bladder → Urethra.

The Nephron

A million filters per kidney

Each kidney holds ~**one million nephrons** — each a capillary knot (**glomerulus**) cupped in **Bowman's capsule**, draining into a long **tubule**. The nephron is where blood is cleaned and urine born.

Takeaway. Nephron = glomerulus + capsule + tubule, a million strong.

Step 1 — Filtration

The crude sieve

Blood pressure in the glomerulus squeezes the SMALL molecules — water, glucose, amino acids, salts, **and urea** — out into Bowman's capsule. Blood cells and proteins are too big and stay behind. Nothing selective yet: the good goes out with the bad.

Takeaway. Pressure filters everything small — valuables included.

Step 2 — Selective Reabsorption

The smart recovery

As filtrate travels the tubule, the body reclaims its valuables into the wrapping capillaries: **glucose, amino acids, salts and MOST of the water**. How much water returns depends on the body's surplus and the waste to be dissolved. Urea is left to leave.

Takeaway. The tubule buys back the good stuff; urea stays condemned.

The Kidney's Arithmetic

180 litres in, 1.5 litres out

Nephrons filter roughly **180 L** of fluid from blood daily — then reabsorb about 99% of it. Final urine: **1-2 L** of water carrying the day's urea. That reclaim ratio is why dehydration turns urine scanty and dark.

Takeaway. Massive filtration, near-total recovery, small yellow remainder.

Bladder and Release

The nerve-controlled tank

Urine collects in the muscular **bladder**, whose stretching sends the 'full' signal. Release through the urethra is under **nervous — and learned voluntary — control**. That's also why anxiety and pressure on the abdomen influence the urge.

Takeaway. Storage is automatic; release is a decision.

Dialysis

A kidney outside the body

In kidney failure, blood is looped through **semi-permeable tubing** bathed in **dialysing fluid**: urea and excess salts diffuse out, and the cleaned blood returns. The fluid is pre-matched to normal blood levels of glucose and salts, so nothing useful is lost.

Takeaway. Diffusion does the cleaning; the fluid recipe protects the good.

Dialysis vs Real Kidney

Machine vs organ

Takeaway. Dialysis substitutes, never fully replaces.

Lungs and Skin as Excretors

The other exits

Excretion isn't the kidneys' monopoly: the **lungs** expel the metabolic waste **CO₂** with every breath, and **sweat** carries away water and some salts — cooling the body as a bonus.

Takeaway. CO₂ exits by lung; salts hitch a ride on sweat.

How Plants Excrete

No kidneys, no problem

Takeaway. Diffuse, transpire, store, shed — the plant playbook.

Urine as a Health Mirror

What your urine report reads

Takeaway. Urine contents report blood's story — that's why labs test it.

Board Favourites

The bankers of this topic

Takeaway. Five staples own this topic's mark-sheet.

Memory Pack

Whole topic in three lines

Takeaway. Three codes, the whole waste department.