Life Processes · Class 10 Science: 88 flashcards

Nutrition, respiration, transportation (transport of materials) and excretion — the maintenance functions that run continuously in every living organism.

Maintenance processes (repair, replacement, keeping cellular order) run continuously and need energy — nutrition supplies that energy and the raw materials for growth and repair.

Viruses show no molecular movement or life processes on their own — only after infecting a host cell do they multiply. Since visible molecular movement is a mark of life, their status is borderline.

Making one's own food from simple inorganic materials (CO₂ and water) using sunlight and chlorophyll — done by green plants and some bacteria.

6CO₂ + 6H₂O --sunlight, chlorophyll--> C₆H₁₂O₆ + 6O₂. The carbohydrate is stored as starch.

(1) Absorption of light energy by chlorophyll; (2) splitting of water into hydrogen and oxygen using that energy; (3) reduction of CO₂ to carbohydrate.

They open stomata at NIGHT, take in CO₂ and store it as an intermediate; by day, with stomata shut, they use the stored CO₂ plus sunlight to make carbohydrate.

Tiny pores on leaf surfaces for gas exchange (CO₂ in, O₂ out) and transpiration. A pair of guard cells around each pore opens it by swelling with water and closes it by shrinking.

Open stomata lose large amounts of water by transpiration. Closing them when photosynthesis doesn't need CO₂ saves that water.

As inorganic nitrates and nitrites from the soil, or as organic compounds prepared from atmospheric nitrogen by bacteria — used to build proteins.

Breaking down food material OUTSIDE the body with secreted enzymes and then absorbing it — the mode of fungi such as bread mould, yeast and mushrooms.

Cuscuta (amarbel) on plants; ticks, lice, leeches and tapeworms on animals — all feed on a living host without killing it.

Pseudopodia extend around the food particle and enclose it in a food vacuole; enzymes digest it there; nutrients diffuse into the cytoplasm and undigested material is expelled.

Paramoecium has a definite shape and takes food in only at a specific spot — cilia (tiny hairs) covering the cell sweep the food to that spot.

It wets the food for easy swallowing, and its enzyme salivary amylase begins digestion by breaking starch into simple sugar.

Rhythmic contraction and relaxation of the muscles lining the alimentary canal, which pushes food along — it operates from the oesophagus all the way through the gut.

HCl makes the medium acidic and kills germs; pepsin digests proteins (works in acid); mucus protects the stomach's inner lining from the acid.

(1) It makes the acidic food from the stomach alkaline for pancreatic enzymes; (2) it emulsifies fats — breaks them into tiny droplets for faster enzyme action. Bile contains NO digestive enzymes.

Trypsin digests proteins; lipase digests emulsified fats; pancreatic amylase digests starch.

Starch → glucose; proteins → amino acids; fats → fatty acids + glycerol — all absorbed through the villi of the small intestine.

Finger-like projections lining the small intestine that enormously increase the absorbing surface; each is rich in blood vessels that carry absorbed food to the whole body.

Mouth bacteria acting on trapped sugars produce acids that soften enamel and dentine; the bacterial film (plaque) keeps saliva from neutralising the acid. Brushing after eating removes plaque and prevents cavities.

Breathing is the physical process of moving air into and out of the lungs. Respiration is the chemical process inside cells that breaks down food to release energy. Breathing supplies the oxygen respiration uses.

Glucose (6-carbon) is split into pyruvate (3-carbon) in the CYTOPLASM — the common first step of every respiration pathway in every organism.

With oxygen, pyruvate is completely broken into CO₂ and water in the MITOCHONDRIA, releasing the maximum amount of energy — the usual pathway in most organisms.

Fermentation: pyruvate → ethanol + CO₂, with only a little energy released. It happens in the cytoplasm and is the basis of bread-making and brewing.

It is converted to lactic acid (3-carbon) with little energy release. Lactic acid accumulation in muscles causes cramps after sudden vigorous exercise.

Both improve blood circulation to the muscle. The increased oxygen supply completes the breakdown of the accumulated lactic acid into CO₂ and water, relieving the cramp.

The energy currency of the cell — the molecule in which energy released during respiration is stored, and which is spent to power all cellular activities like muscle contraction, protein synthesis and nerve impulses.

Nostrils (filtered by hairs and mucus) → throat → trachea → bronchi (one per lung) → bronchioles → alveoli, the balloon-like sacs where gas exchange occurs.

Rings of cartilage in its wall keep the air passage permanently open, whatever the internal pressure.

(1) Enormous combined surface area (~80 m²); (2) extremely thin, one-cell-thick walls; (3) a dense network of blood capillaries around each sac — all favouring rapid diffusion.

The ribs lift outward and the diaphragm flattens downward, increasing the chest volume; the pressure inside falls, and air rushes in through the nostrils to fill the lungs. Relaxation of these muscles reverses the changes and expels air.

The air that always remains in the lungs even after exhalation. It ensures continuous gas exchange — oxygen absorption and CO₂ release don't stop between breaths.

By haemoglobin — the red pigment in red blood cells that has a high affinity for oxygen. It picks up O₂ at the alveoli and releases it at the tissues.

CO₂ is much more soluble in water than oxygen, so it is transported mostly in DISSOLVED form in the blood plasma, back to the lungs for exhalation.

The amount of oxygen DISSOLVED in water is far lower than the oxygen in air. To gather enough, aquatic animals like fish must pass water over their gills at a much faster rate.

Water taken in through the mouth is forced over the gills, where dissolved oxygen diffuses into the blood; the water then exits through the gill slits.

By simple diffusion through stomata (and loosely packed cells) — each part of the plant handles its own gas exchange; there is no transport of gases from one organ to another.

Yes — respiration runs continuously. In daylight, photosynthesis is much faster and its O₂ release masks the respiratory CO₂; at night only respiration operates, so CO₂ release becomes evident.

Simple unicellular organisms like Amoeba — gases simply diffuse across the cell membrane; no specialised respiratory organ is needed at that size.

CO binds to haemoglobin far more strongly than oxygen does, so the blood loses its capacity to carry O₂ — a person suffocates internally without warning. Hence never burn fuel in unventilated rooms.

We absorb only part of the inhaled oxygen — exhaled air still contains roughly 16% O₂, enough to oxygenate another person's blood during resuscitation.

The mitochondrion — called the powerhouse of the cell because the energy-rich aerobic breakdown of pyruvate (and ATP charging) happens there.

Plasma — fluid that carries food, CO₂, wastes and salts; red blood cells — carry O₂ via haemoglobin; white blood cells — fight infection; platelets — plug wounds by triggering clotting.

Oxygen is poorly soluble in water, so a dedicated carrier — haemoglobin in RBCs — evolved. CO₂, much more soluble, does travel largely dissolved in plasma.

Arteries have thick elastic walls to withstand the high-pressure surge each heartbeat sends from the heart. Veins carry low-pressure return blood, so thinner walls suffice — but they need VALVES to stop backflow.

In the capillaries — vessels with walls only one cell thick, thin enough for oxygen, food, CO₂ and wastes to pass between blood and cells.

Right atrium and left atrium (upper, receiving chambers); right ventricle and left ventricle (lower, pumping chambers).

The left ventricle pumps blood through the aorta to the ENTIRE body — a far longer, higher-resistance circuit than the right ventricle's short push to the lungs — so it needs more muscle.

They are one-way doors: they let blood pass forward and slam shut against any backward flow, keeping circulation strictly one-directional.

Body → vena cava → right atrium → right ventricle → pulmonary artery → lungs, where CO₂ is released and O₂ absorbed.

Lungs → pulmonary vein → left atrium → left ventricle → aorta → arteries to all organs.

Blood passes through the heart twice in each full round — once to the lungs (pulmonary) and once to the body (systemic). It keeps oxygenated and deoxygenated blood separate, ensuring the highly efficient O₂ supply needed to maintain our constant body temperature.

The pulmonary artery carries deoxygenated blood (heart → lungs); the pulmonary vein carries oxygenated blood (lungs → heart) — the exceptions to the usual content pattern.

Two chambers. Blood is pumped to the gills for oxygenation and flows on to the body directly — passing the heart only ONCE per round (single circulation).

They are cold-blooded — body temperature follows the surroundings — so they don't burn energy for constant warmth and can afford some mixing of oxygenated and deoxygenated blood.

Lymph is plasma-like fluid that leaks from capillaries into tissue spaces; colourless, with less protein. Lymph vessels collect it and drain it back into blood. Functions: carries digested fats absorbed from the intestine and drains excess fluid from tissues.

They rush to the wound and trigger blood clotting — forming a plug that stops blood loss (which would drop the system's pressure) and blocks germ entry.

Systolic (~120 mm Hg) is arterial pressure during ventricular contraction; diastolic (~80 mm Hg) during ventricular relaxation. Measured with a sphygmomanometer.

Persistently high blood pressure, often caused by constriction of arterioles increasing resistance. It can rupture vessels, causing internal bleeding and organ damage.

Root cells actively absorb mineral ions from soil using energy. The ions raise the solute concentration inside the root, so water follows in by osmosis — creating root pressure that pushes water into the xylem.

As water evaporates from leaf stomata, it tugs on the continuous water column in the xylem, pulling water upward from the roots — the main force lifting water in tall plants, requiring no energy from the plant, and effective in daylight when stomata are open.

(1) Temperature regulation — evaporation cools the plant; (2) it maintains the upward stream that distributes dissolved minerals from roots to every part.

The transport of food (mainly sucrose) by phloem from leaves to other parts. Sugar is loaded into sieve tubes using ATP energy; osmotic entry of water raises pressure, which pushes the sap toward regions of lower pressure — wherever food is needed, in any direction.

(1) Direction: xylem moves only upward; phloem moves both up and down. (2) Energy: xylem's flow rides physical forces (transpiration pull/root pressure) at no energy cost; phloem's loading spends ATP. (Also: xylem carries water/minerals through dead vessels; phloem carries food through living sieve tubes.)

Excretion is the removal of harmful metabolic wastes produced inside cells (urea, CO₂). Egestion is the passing out of undigested food that was never absorbed — it involves no metabolic waste.

In the liver, from the breakdown of excess amino acids (proteins cannot be stored). Blood then carries the urea to the kidneys for removal.

Two kidneys → two ureters → urinary bladder → urethra (K-U-B-U). The lungs (CO₂) and skin (sweat) assist excretion too.

The basic filtration unit of the kidney — a glomerulus (capillary cluster) cupped in Bowman's capsule, leading into a long tubule. Each kidney contains about a million of them.

A knot of capillaries inside Bowman's capsule where blood pressure filters water and small solutes (glucose, salts, amino acids, urea) out of the blood into the capsule.

Water, glucose, amino acids, salts and urea — everything small. Blood cells and large proteins remain in the blood.

As filtrate flows along the nephron's tubule, useful substances — glucose, amino acids, salts and most of the water — are absorbed back into the surrounding blood capillaries, leaving wastes behind.

The body's water balance: how much excess water there is, and how much dissolved waste needs to be excreted. More excess water → less reabsorption → more dilute urine, and vice versa.

Mainly water with dissolved urea (and some salts) — the un-reabsorbed remainder of the filtrate. An adult produces about 1-2 litres a day.

Urine stored in the muscular bladder stretches it; the stretch signals the nervous system, and release through the urethra is under voluntary nervous control.

Because the tubule reabsorbs all filtered glucose back into blood. Glucose in urine indicates abnormally high blood sugar — a sign of diabetes.

An artificial blood-cleaning procedure used when kidneys fail: blood flows through semi-permeable tubing immersed in dialysing fluid, and urea plus excess salts diffuse out; the cleaned blood is returned to the body.

The dialysing fluid is prepared with glucose and salts at the same concentration as normal blood — with no gradient, they don't diffuse out. Only urea and excess salts (absent from the fluid) leave.

(1) The kidney reabsorbs useful substances selectively; dialysis relies only on diffusion with a matched fluid — no reabsorption. (2) The kidney works continuously; dialysis requires repeated sessions every few days.

The lungs excrete carbon dioxide (a metabolic waste) during exhalation; the skin's sweat glands remove water and some salts.

By simple diffusion through stomata — oxygen (photosynthesis's by-product) during the day and carbon dioxide (from respiration) especially at night.

They deposit wastes in cell vacuoles and in ageing leaves that then FALL; convert some into resins and gums stored in old xylem; and secrete some into the surrounding soil.

Excess water — effectively a waste when in surplus — is removed as vapour through the stomata by transpiration.

Plants produce waste far more slowly than animals (lower metabolic rate), can store wastes harmlessly in vacuoles/old tissues, and can simply shed waste-loaded parts — so diffusion and storage suffice without dedicated organs.

In summer, much water leaves as sweat, so the tubules reabsorb more water and urine is concentrated and scanty. In winter, sweating is minimal, less water is reabsorbed, and urine volume rises.

Urea and other nitrogenous wastes accumulate in the blood to poisonous levels, disturbing the body's chemistry fatally — which is why dialysis or a kidney transplant becomes essential.

Each kidney's million nephrons give enormous spare capacity — one healthy kidney can filter enough blood and maintain normal waste removal and water balance on its own.