Life Processes – Chapter 5 (Class X Science)

A comprehensive set of question-and-answer flashcards covering key concepts, definitions and processes from Chapter 5 “Life Processes,” including nutrition, digestion, respiration, transport, and excretion in plants and animals.

What are life processes?

The essential maintenance functions—nutrition, respiration, transport and excretion—that keep an organism alive even at rest.

Why is visible movement alone insufficient to decide if something is alive?

Some living organisms show no visible movement (e.g., dormant plants, sleeping animals), while molecular movements inside cells continue and are essential for life.

Why do living organisms need continuous molecular movement?

To repair, maintain and organise their complex structures, preventing breakdown caused by environmental effects.

Why is diffusion alone inadequate for oxygen supply in large multicellular organisms?

Because many cells are far from the exterior; diffusion would be too slow to meet their oxygen demands.

Define nutrition.

The process of obtaining energy and materials (food) from outside the body and transferring them inside for growth, maintenance and energy release.

Differentiate autotrophic and heterotrophic nutrition.

Autotrophs make organic food from CO₂ and H₂O using sunlight (photosynthesis); heterotrophs obtain ready-made complex food from other organisms and break it down with enzymes.

What raw materials do green plants require for photosynthesis?

Carbon dioxide, water, sunlight and chlorophyll.

State the overall equation of photosynthesis in words.

Carbon dioxide + Water → (sunlight/chlorophyll) → Carbohydrates + Oxygen

List the three main events of photosynthesis.

1) Light absorption by chlorophyll; 2) Conversion of light energy to chemical energy and splitting of water into H₂ and O₂; 3) Reduction of CO₂ to carbohydrates.

What are stomata and their function?

Tiny pores on leaf surfaces that regulate gas exchange (CO₂/O₂) and water loss through guard-cell-controlled opening and closing.

How do guard cells open a stomatal pore?

They absorb water, swell and curve, creating an opening; shrinking closes the pore.

Why do desert plants absorb CO₂ at night?

To minimise water loss; they form intermediates at night which are processed in daylight (CAM pathway).

Name the storage forms of excess carbohydrates in plants and humans.

Plants store as starch; humans store as glycogen.

Give two examples of organisms with extracellular digestion.

Bread mould (Rhizopus) and mushrooms (fungi).

What is parasitic nutrition? Give two examples.

Obtaining food from a living host without killing it; examples: cuscuta, leech, lice, tapeworm.

Describe food intake in Amoeba.

Uses pseudopodia to engulf food into a food vacuole where enzymes digest it; undigested residues are expelled.

Which enzyme in saliva starts starch digestion and into what product?

Salivary amylase converts starch to simple sugars (maltose).

Define peristalsis.

Rhythmic contraction of alimentary canal muscles that pushes food along the digestive tract.

List the three secretions of gastric glands and their roles.

Hydrochloric acid (acidic pH for pepsin & kills microbes), pepsin (protein digestion), mucus (protects stomach lining).

Why do herbivores have longer small intestines than carnivores?

To allow more time and surface area to digest cellulose-rich plant matter.

State two functions of bile.

1) Alkalises acidic chyme; 2) Emulsifies fats into small globules for efficient enzyme action.

Which pancreatic enzymes digest proteins and fats?

Trypsin digests proteins; lipase digests emulsified fats.

What structures in the small intestine increase surface area for absorption?

Villi (finger-like projections) richly supplied with blood vessels.

What is dental plaque and its consequence?

Sticky mass of bacteria and food particles on teeth; produces acids causing dental caries (tooth decay).

Define respiration.

The biochemical process of releasing energy from food (glucose) within cells, producing ATP.

Where in the cell does glycolysis occur and what is its product?

In the cytoplasm; glucose (6C) is split into two molecules of pyruvate (3C).

Write two end products of anaerobic respiration in yeast.

Ethanol and carbon dioxide.

What causes muscle cramps during strenuous exercise?

Accumulation of lactic acid produced by anaerobic breakdown of pyruvate in oxygen-deficient muscles.

Why is ATP called the energy currency of the cell?

It stores and transfers small, usable packets of energy (≈30.5 kJ/mol) for cellular reactions.

How do fish obtain oxygen?

They pass water through their mouths, over gill surfaces where dissolved O₂ diffuses into blood; faster breathing compensates for low O₂ solubility in water.

State two protective features of the human respiratory tract.

Nasal hairs (filter dust) and mucus lining (traps particles, moistens air).

What structure prevents collapse of the trachea?

C-shaped rings of cartilage.

Explain gas exchange in alveoli.

Thin-walled, highly vascular alveoli allow O₂ to diffuse into blood and CO₂ to diffuse out to air due to concentration gradients.

Why is haemoglobin essential in humans?

It binds O₂ with high affinity, transporting it efficiently; without it diffusion alone would be too slow.

How is most CO₂ transported in blood?

As bicarbonate ions dissolved in plasma.

Define double circulation.

Blood passes through the heart twice during one complete body circuit—pulmonary circulation (heart–lungs) and systemic circulation (heart–body).

Name the four chambers of the human heart.

Right atrium, right ventricle, left atrium, left ventricle.

Why are ventricular walls thicker than atrial walls?

They pump blood out of the heart with greater force to lungs/body, requiring more muscle.

What prevents back-flow of blood in the heart and veins?

Valves (atrioventricular and semilunar in heart; unidirectional valves in veins).

Distinguish arteries and veins (one key difference).

Arteries carry blood away from the heart under high pressure with thick elastic walls; veins return blood under low pressure and have valves.

Define systolic and diastolic blood pressure values.

Systolic: pressure during ventricular contraction (~120 mm Hg); Diastolic: pressure during ventricular relaxation (~80 mm Hg).

What is lymph and its two functions?

Colourless tissue fluid derived from plasma; returns excess fluid to blood and transports absorbed fats from intestine.

Role of platelets in circulation.

Initiate blood clotting to seal leaks and maintain pressure.

Name the two main conducting tissues in plants and their cargo.

Xylem transports water & minerals upward; phloem translocates sugars, amino acids etc., bidirectionally.

Explain transpiration pull.

Evaporation of water from leaves creates negative pressure that pulls water upward through xylem columns.

What is root pressure?

Osmotic pressure in root xylem caused by active ion uptake, pushing water upward—effective mainly at night.

Define translocation in plants.

Active transport of photosynthates (e.g., sucrose) through phloem from source (leaves/storage) to sink (growing or storage tissues).

Why is xylem transport considered physical while phloem transport is energy-dependent?

Xylem relies on passive forces (root pressure, cohesion-tension); phloem loading/unloading uses ATP to create osmotic pressure differences.

Define excretion.

Biological process of removing metabolic wastes (e.g., urea, CO₂) from an organism’s body.

List the main parts of the human excretory system.

Kidneys, ureters, urinary bladder, urethra.

What is a nephron?

The functional filtration unit of the kidney, consisting of Bowman’s capsule with glomerulus and a long tubular system.

Function of Bowman’s capsule and glomerulus.

Filtration: blood pressure forces water, urea, salts, glucose etc., into the capsule forming filtrate.

How is urine concentration regulated?

Selective reabsorption of water and solutes along nephron tubules based on body’s hydration and waste levels, controlled hormonally (e.g., ADH).

What volume of filtrate is produced daily and how much urine is excreted?

About 180 L filtrate; only 1–2 L urine after reabsorption.

Describe hemodialysis.

Patient’s blood passes through semi-permeable tubing in dialysing fluid; wastes diffuse out, cleaned blood returns—acting as artificial kidney without reabsorption.

Give two excretory strategies in plants.

Storing wastes in vacuoles, resins or leaves that later shed; excreting substances into surrounding soil; losing excess water by transpiration.

Why must oxygenated and deoxygenated blood remain separate in birds and mammals?

To supply high levels of O₂ needed for their high metabolic rate and constant body temperature regulation.

State two conditions required for autotrophic nutrition.

Presence of chlorophyll and availability of sunlight (plus CO₂ and H₂O).

What is the consequence of low haemoglobin levels?

Reduced oxygen-carrying capacity leading to fatigue, breathlessness, anaemia.

How are alveoli and nephrons structurally similar for their functions?

Both have extensive thin-walled capillary networks and large surface areas enabling efficient exchange (gases in alveoli, wastes/water in nephrons).