Class 10 Science: Life Processes

Introduction

All living organisms perform certain basic functions to maintain and sustain life. These essential activities are known as life processes.

Life processes are the basic biological activities that are necessary for an organism to survive, grow, develop, repair damage, and reproduce.

Examples of life processes include:

• Nutrition

• Respiration

• Transportation

• Excretion

These processes provide energy and maintain the proper functioning of the body.

What Are Life Processes?

Life processes are the activities performed by living organisms to maintain life.

Unlike non-living things, living organisms need continuous energy to carry out various functions. This energy is obtained from food and utilized through different life processes.

Characteristics of Living Organisms

• Growth

• Movement

• Reproduction

• Respiration

• Nutrition

• Excretion

• Response to stimuli

1. Nutrition

Nutrition is the process by which organisms obtain food and utilize it for energy, growth, repair, and maintenance.

Modes of Nutrition

There are two main modes of nutrition:

A. Autotrophic Nutrition

Organisms prepare their own food from simple inorganic substances.

Examples:

• Green plants

• Algae

Plants synthesize food by the process of photosynthesis.

6CO_2 + 6H_2O \xrightarrow{\text{Sunlight, Chlorophyll}} C_6H_{12}O_6 + 6O_2

Requirements for Photosynthesis

• Sunlight

• Chlorophyll

• Carbon dioxide

• Water

B. Heterotrophic Nutrition

Organisms depend on other organisms for food.

Types of heterotrophic nutrition:

• Holozoic nutrition (humans, animals)

• Saprophytic nutrition (fungi)

• Parasitic nutrition (Cuscuta, tapeworm)

Human Digestive System

The digestive system breaks down complex food into simpler forms.

Main Organs of the Digestive System

• Mouth

• Oesophagus

• Stomach

• Small intestine

• Large intestine

• Rectum

• Anus

Steps of Nutrition in Humans

1. Ingestion

2. Digestion

3. Absorption

4. Assimilation

5. Egestion

Role of Digestive Juices

• Saliva contains salivary amylase.

• Gastric juice contains hydrochloric acid and pepsin.

• Bile juice helps in fat digestion.

• Pancreatic juice digests carbohydrates, proteins, and fats.

2. Respiration

Respiration is the process of breaking down food to release energy.

The energy released is stored in the form of ATP (Adenosine Triphosphate).

Types of Respiration

A. Aerobic Respiration

• Occurs in the presence of oxygen.

• Produces a large amount of energy.

C_6H_{12}O_6 + 6O_2 \rightarrow 6CO_2 + 6H_2O + \text{Energy (ATP)}

B. Anaerobic Respiration

• Occurs in the absence of oxygen.

• Produces less energy.

Examples:

• Yeast fermentation

• Human muscle cells during vigorous exercise

Human Respiratory System

Main organs include:

• Nostrils

• Nasal cavity

• Pharynx

• Larynx

• Trachea

• Bronchi

• Lungs

• Alveoli

Mechanism of Breathing

Inhalation

• Ribs move upward and outward.

• Diaphragm contracts and flattens.

• Chest cavity expands.

Exhalation

• Ribs move downward and inward.

• Diaphragm relaxes.

• Chest cavity decreases.

Gas Exchange

Gas exchange takes place in the alveoli.

• Oxygen diffuses into the blood.

• Carbon dioxide diffuses out of the blood.

3. Transportation

Transportation is the movement of substances such as food, water, gases, hormones, and waste products within the body.

Transportation in Human Beings

The circulatory system consists of:

• Heart

• Blood

• Blood vessels

Human Heart

The human heart has four chambers:

• Right atrium

• Right ventricle

• Left atrium

• Left ventricle

Blood Vessels

Arteries

• Carry blood away from the heart.

• Thick and elastic walls.

Veins

• Carry blood toward the heart.

• Contain valves.

Capillaries

• Thin-walled vessels for exchange of materials.

Components of Blood

• Plasma

• Red blood cells (RBCs)

• White blood cells (WBCs)

• Platelets

Double Circulation

Blood passes through the heart twice during one complete cycle.

Pulmonary Circulation

Heart → Lungs → Heart

Systemic Circulation

Heart → Body → Heart

Transportation in Plants

Plants transport water, minerals, and food through vascular tissues.

Xylem

Functions:

• Conducts water and minerals from roots to leaves.

Phloem

Functions:

• Transports prepared food from leaves to other parts of the plant.

Transpiration

Transpiration is the loss of water in the form of water vapour through stomata.

Importance of Transpiration

• Creates suction force.

• Helps in water transport.

• Regulates temperature.

4. Excretion

Excretion is the removal of metabolic waste products from the body.

Human Excretory System

Main organs include:

• Kidneys

• Ureters

• Urinary bladder

• Urethra

Structure of Kidney

The functional unit of the kidney is the nephron.

Functions of Nephron

• Filtration of blood

• Reabsorption of useful substances

• Secretion of wastes

• Formation of urine

Formation of Urine

The process occurs in three steps:

1. Ultrafiltration

2. Selective reabsorption

3. Tubular secretion

Waste Products Excreted by Humans

• Urea

• Excess salts

• Excess water

• Uric acid

Excretion in Plants

Plants remove wastes through:

• Stomata

• Lenticels

• Shedding of leaves

• Storage in vacuoles

• Exudation of gums and resins

Importance of Life Processes

Life processes are essential because they:

• Provide energy for survival.

• Maintain internal balance (homeostasis).

• Help in growth and repair.

• Remove harmful wastes.

• Ensure proper functioning of organs.

• Support reproduction and continuity of life.

Key Differences

Nutrition vs Respiration

NutritionRespirationObtaining foodReleasing energy from foodInvolves digestionInvolves oxidation of food

Arteries vs Veins

ArteriesVeinsCarry blood away from heartCarry blood toward heartThick wallsThin wallsNo valvesValves present

Xylem vs Phloem

XylemPhloemTransports water and mineralsTransports foodMovement is upward onlyMovement is bidirectional

Important Terms

• ATP: Energy currency of the cell

• Chlorophyll: Green pigment involved in photosynthesis

• Alveoli: Air sacs in lungs

• Nephron: Functional unit of kidney

• Stomata: Pores present on leaves

• Hemoglobin: Oxygen-carrying pigment in blood

Conclusion

Life processes are the basic functions that keep organisms alive. Nutrition provides energy-rich food, respiration releases energy, transportation distributes materials throughout the body, and excretion removes harmful wastes.

Understanding these processes helps us learn how living organisms function and maintain life efficiently.