Life Processes

Living Characteristics

What Makes Something Alive?

• Identifying Life:
  • We see a dog running, a cow chewing cud, or a man shouting – we know they are alive.
  • Even when they are asleep, we recognize they are alive because they breathe.
• Plants:
  • Plants are alive even if they don’t move visibly.
  • Green leaves indicate life, but even non-green plants grow, showing they are alive.
• Movement and Life:
  • Movement, like growth, often indicates life.
  • Some movements, like breathing or molecular movements, are not always visible.

Invisible Movements

• Molecular Movements:
  • Tiny movements at the molecular level are crucial for life.
  • These movements are invisible but necessary for maintaining life.
• Viruses:
  • Viruses don’t show molecular movement until they infect a cell, causing debate about their status as living beings.

Maintenance Processes in Living Organisms

• Organized Structures:
  • Living organisms have organized structures (tissues, cells, smaller components).
  • The environment can disrupt this order, so organisms must constantly repair and maintain themselves.
• Molecule Movement:
  • Continuous movement of molecules is essential for maintaining life.

Let’s explore these maintenance processes further!

Life Processes

What Are Life Processes?

• Continuous Maintenance:
  • Maintenance functions continue even when we’re sitting or sleeping.
  • These ongoing maintenance activities are called life processes.
• Energy for Maintenance:
  • Energy is needed to prevent damage and breakdown.
  • This energy comes from food, which we take in from outside our bodies.

Nutrition

• Food and Growth:
  • Food provides energy and raw materials needed for growth.
  • Most food sources are carbon-based, as life on Earth depends on carbon molecules.
• Variety in Nutrition:
  • Different organisms use various nutritional processes to utilize these food sources.

Respiration

• Chemical Reactions:
  • Food is broken down through a series of chemical reactions, many involving oxygen.
  • Respiration is the process of taking in oxygen to help break down food for energy.

Single-Celled vs. Multi-Celled Organisms

• Single-Celled Organisms:
  • Do not need special organs for food intake or gas exchange.
  • Entire surface is in contact with the environment.
• Multi-Celled Organisms:
  • Cells aren’t all in direct contact with the environment.
  • Specialized tissues and organs are needed for various functions like nutrition and gas exchange.

Transportation System

• Need for Transport:
  • In multi-celled organisms, food and oxygen are taken up at specific locations.
  • A transportation system is needed to distribute them throughout the body.

Excretion

• Waste Removal:
  • Chemical reactions create by-products that can be harmful.
  • Waste needs to be removed from the body through a process called excretion.
• Specialized Tissues:
  • Multi-cellular organisms have specialized tissues for excretion.
  • The transportation system also helps carry waste to excretory tissues.

Let’s dive into each of these essential life processes one by one!

Nutrition

Why Do We Need Nutrition?

• Energy Usage:
  • Walking, riding a bicycle, and even resting require energy.
  • Energy and materials from food are essential for growth, development, and synthesizing proteins.
• Sources of Food:
  • All organisms need energy and materials but get them in different ways.
  • Some use simple inorganic sources (carbon dioxide and water), while others use complex substances.

Autotrophs vs. Heterotrophs

• Autotrophs:
  • Green plants and some bacteria.
  • Use photosynthesis to make their food from carbon dioxide and water.
• Heterotrophs:
  • Animals and fungi.
  • Depend on autotrophs for food, breaking down complex substances with enzymes.

Autotrophic Nutrition

• Photosynthesis:
  • Process by which autotrophs convert carbon dioxide and water into carbohydrates using sunlight and chlorophyll.
  • Carbohydrates provide energy for the plant, and excess is stored as starch.
• Photosynthesis Formula:
  • 6CO2+12H2O⟶Chlorophyll & SunlightC6H12O6(Glucose)+6O2+6H2O6CO2+12H2O⟶Chlorophyll & SunlightC6H12O6(Glucose)+6O2+6H2O

Steps of Photosynthesis

1. Light Absorption:
   • Chlorophyll absorbs light energy.
2. Energy Conversion and Water Splitting:
   • Light energy is converted to chemical energy.
   • Water molecules split into hydrogen and oxygen.
3. Carbon Dioxide Reduction:
   • Carbon dioxide is converted to carbohydrates.

• Desert Plants:
  • Take in carbon dioxide at night and store it as an intermediate to use during the day.

Chlorophyll and Photosynthesis

• Chloroplasts:
  • Green dots in leaf cells contain chlorophyll.
  • Chlorophyll is essential for photosynthesis.

Let’s explore an activity to see the importance of chlorophyll in photosynthesis!

Autotrophic Nutrition

How Plants Obtain Carbon Dioxide:

• Stomata:
  • Tiny pores on leaf surfaces.
  • Allow gas exchange (CO2 in, O2 out) for photosynthesis.
  • Guard cells control the opening and closing of stomata.
  • Stomata close to prevent water loss when CO2 is not needed.

Demonstrating the Need for Sunlight:

• Concept:
  • Only the plant exposed to sunlight will show starch presence, proving sunlight is essential for photosynthesis.

Other Raw Materials for Plants:

• Water and Minerals:
  • Water is taken up by roots from the soil.
  • Minerals like nitrogen, phosphorus, iron, and magnesium are essential for plant growth.
  • Nitrogen is used in protein synthesis, absorbed as nitrates, nitrites, or organic compounds from bacteria.

Heterotrophic Nutrition

Adaptation and Food Types:

• Adaptation:
  • Organisms are adapted to their environments and food availability.
  • Nutrition varies based on food type and how it is obtained (e.g., grass vs. deer).
• Different Strategies:
  • Some break down food outside the body (e.g., fungi like bread moulds, yeast, mushrooms).
  • Others take in whole food and break it down internally (e.g., animals).
• Parasitic Nutrition:
  • Some organisms derive nutrition from plants or animals without killing them.
  • Examples: cuscuta (amar-bel), ticks, lice, leeches, tape-worms.

How Organisms Obtain Their Nutrition

• Single-Celled Organisms:
  • Food intake occurs across the entire surface.
  • Example: Amoeba uses temporary finger-like extensions (pseudopodia) to engulf food, forming a food vacuole where digestion occurs.
• Paramoecium:
  • Has a definite shape and takes in food at a specific spot.
  • Cilia move food to this spot.

Nutrition in Human Beings

• Alimentary Canal:
  • A long tube from mouth to anus, with specialized regions for different functions.
  • Each part of the tube has a specific role in the digestion process.

Digestion Process

• Food Processing:
  • Food is crushed by teeth and mixed with saliva.
  • Saliva is not just water but contains enzymes like salivary amylase.
  • Salivary amylase breaks down starch into simple sugars.
• Role of Saliva:
  • Saliva wets food, making it easier to swallow.
  • Enzymes in saliva start breaking down complex molecules.
• Food Movement:
  • Muscles in the digestive canal push food forward through peristaltic movements.
  • Food moves from the mouth to the stomach via the oesophagus (food-pipe).

Digestion in the Stomach to Small Intestine:

• Stomach Function:
  • The stomach expands to hold food.
  • Muscular walls mix food with digestive juices.
• Gastric Juices:
  • Gastric glands in the stomach wall release:
    • Hydrochloric acid (HCl)
    • Pepsin (protein-digesting enzyme)
    • Mucus
• Roles of Gastric Juices:
  • HCl creates an acidic environment for pepsin to work.
  • Mucus protects the stomach lining from acid.
• Acidity:
  • Excessive acid can cause discomfort known as “acidity.”
• Sphincter Muscle:
  • Regulates food exit from the stomach to the small intestine in small amounts.

Digestion in the Small Intestine:

• Small Intestine:
  • Longest part of the alimentary canal, coiled to fit compactly.
  • Length varies by diet (longer in herbivores for digesting cellulose, shorter in carnivores for easier meat digestion).

• Complete Digestion Site:
  • Carbohydrates, proteins, and fats are fully digested here.
• Secretions:
  • Liver:
    • Produces bile juice which neutralizes stomach acid and breaks down fats into smaller globules (emulsification).
  • Pancreas:
    • Secretes pancreatic juice containing enzymes like trypsin (for proteins) and lipase (for fats).
  • Intestinal Juice:
    • Secreted by glands in the small intestine walls, containing enzymes that convert proteins to amino acids, complex carbohydrates to glucose, and fats to fatty acids and glycerol.

Absorption:

• Villi:
  • Finger-like projections in the small intestine increase surface area for absorption.
  • Richly supplied with blood vessels that transport absorbed nutrients to body cells for energy, tissue building, and repair.

Large Intestine:

• Unabsorbed Food:
  • Moves to the large intestine where more water is absorbed.
  • Remaining material is excreted via the anus, regulated by the anal sphincter.

Respiration

Activities to Understand Respiration

How Respiration Works

• Purpose: To provide energy for life processes.
• Process in Cells:
  • Glucose Breakdown:
    • Glucose (6-carbon) breaks into pyruvate (3-carbon) in the cytoplasm.
    • Anaerobic Respiration: In yeast, pyruvate converts to ethanol and carbon dioxide without oxygen.
    • Aerobic Respiration: In mitochondria, pyruvate breaks down into carbon dioxide and water with oxygen.
    • Energy Release: Aerobic respiration releases more energy than anaerobic.
• Muscle Cells:
  • In low oxygen, pyruvate converts to lactic acid, causing cramps.

Aerobic Respiration in Plants and Animals

• Plants:
  • Gas Exchange: Takes place through stomata and intercellular spaces.
  • Daytime: CO₂ from respiration is used in photosynthesis; oxygen is released.
  • Nighttime: No photosynthesis, so CO₂ is released.
  • Mechanism: Diffusion allows gases to move in and out of cells based on environmental conditions.
• Animals:
  • Different Organs: Various organs for oxygen intake and CO₂ removal.
  • Terrestrial Animals: Breathe oxygen from the atmosphere.
  • Aquatic Animals: Use dissolved oxygen in water.
  • Mechanism in Fish:

Adaptations for Respiration

• Surface Area: Organs have structures to increase the surface area for better oxygen absorption.
• Delicate Surface: Exchange surfaces are fine and delicate, placed inside the body for protection.
• Passages for Air: There are passages to carry air to and from these exchange surfaces.
• Air Movement: Mechanism to move air in and out of these areas to facilitate gas exchange.

Aerobic Respiration and Oxygen

• Aerobic Respiration: Needs oxygen.
• Plants: Use stomata for gas exchange.
  • Daytime: CO2 from respiration used for photosynthesis, oxygen is released.
  • Nighttime: CO2 elimination is the main activity.

Respiration in Animals

• Terrestrial Animals: Breathe oxygen from the air.
• Aquatic Animals: Use dissolved oxygen in water.

Breathing Rates

• Aquatic Organisms: Breathe faster due to low dissolved oxygen in water.
• Fishes: Take in water through their mouths, force it past gills, and take up oxygen.

Human Respiration

• Nose: Air enters through nostrils, filtered by hairs and mucus.
• Throat: Air passes through, protected by rings of cartilage.
• Lungs: Air passages divide into smaller tubes ending in alveoli.
  • Alveoli: Balloon-like structures for gas exchange.
  • Breathing in: Ribs lift, diaphragm flattens, chest cavity enlarges, air is sucked in.

Gas Exchange

• Oxygen: Taken up by blood in alveolar vessels.
• Carbon Dioxide: Brought by blood to alveoli, released.

Respiratory Pigments

• Large Animals: Use respiratory pigments for oxygen transport.
  • Human Pigment: Haemoglobin in red blood cells.
  • Carbon Dioxide Transport: More soluble in water, transported in dissolved form in blood.

Harmful Effects of Smoking

• Smoking and Health: Smoking is very bad for health.
  • Lung Cancer: A common cause of death worldwide.
  • Cilia: Small hair-like structures in the respiratory tract.
    • Function: Remove germs, dust, and harmful particles from inhaled air.
    • Effect of Smoking: Destroys cilia, allowing harmful substances into lungs, causing infections, cough, and lung cancer.

Interesting Facts About Lungs

• Alveolar Surface: If spread out, it covers about 80 m².
  • Efficiency: Large surface area makes gas exchange very efficient.
• Haemoglobin’s Role: Without haemoglobin, it would take 3 years for oxygen to travel from lungs to toes by diffusion.

Dangers of Tobacco

• Tobacco Use: Harmful in all forms (cigars, cigarettes, bidis, hookah, gutkha).
  • Affects: Tongue, lungs, heart, and liver.
  • Smokeless Tobacco: Major risk for heart attacks, strokes, lung diseases, and cancers.
  • Oral Cancer in India: High incidence due to chewing tobacco (gutkha).

Stay Healthy: Say NO to tobacco and its products!

Transportation

Transportation in Human Beings

Blood and Its Functions

• Transport Functions: Blood carries food, oxygen, and waste materials.
  • Components:
    • Plasma: Fluid medium transporting food, CO2, and wastes.
    • Red Blood Cells: Carry oxygen.
    • Other Substances: Salts and more.
• Pumping Organ: Heart pumps blood throughout the body.
• Network of Tubes: Blood vessels reach all tissues.
• Repair System: Ensures the network can be fixed if damaged.

Our Pump – The Heart

• Heart Structure: Muscular organ, size of a fist.
• Function: Keeps oxygen-rich and carbon dioxide-rich blood separate.
  • Left Side: Handles oxygenated blood.
    • Left Atrium: Receives oxygen-rich blood from lungs.
    • Left Ventricle: Pumps oxygen-rich blood to the body.
  • Right Side: Handles deoxygenated blood.
    • Right Atrium: Receives deoxygenated blood from the body.
    • Right Ventricle: Pumps deoxygenated blood to the lungs.
• Ventricles: Have thicker walls because they pump blood to the whole body.
• Valves: Prevent backflow of blood.

Double Circulation

• High Efficiency: Separation allows efficient oxygen supply, important for birds and mammals.
• Other Animals:
  • Amphibians/Reptiles: Three-chambered hearts, mix oxygenated and deoxygenated blood.
  • Fishes: Two-chambered hearts, blood passes through the heart once per cycle.

The Tubes – Blood Vessels

• Arteries: Carry blood away from the heart, thick and elastic walls.
• Veins: Bring blood back to the heart, thinner walls with valves.
• Capillaries: Smallest vessels, walls one-cell thick, where material exchange happens.
• Flow: Arteries → Capillaries → Veins.

Maintenance by Platelets

• Function: Help in blood clotting to prevent leaks and maintain pressure.
• When Injured: Platelets form clots to minimize blood loss and maintain efficiency.

Lymph

• What is Lymph? A fluid involved in transportation.
  • Formation: Plasma, proteins, and blood cells escape into tissues to form lymph.
  • Properties: Similar to plasma but colorless and with less protein.
• Function:
  • Transports: Digested fats from intestines.
  • Drains: Excess fluid from tissues back into the blood.
• Flow: Lymph → Lymphatic Capillaries → Lymph Vessels → Larger Veins.

More to Know: Blood Pressure

• Blood Pressure: The force exerted by blood against the walls of blood vessels.
  • Higher in Arteries: Blood pressure is greater in arteries than in veins.
• Types of Blood Pressure:
  • Systolic Pressure: Pressure during heart’s contraction (ventricular systole).
    • Normal Value: 120 mm of Hg.
  • Diastolic Pressure: Pressure during heart’s relaxation (ventricular diastole).
    • Normal Value: 80 mm of Hg.
• Measuring Blood Pressure: Done with a device called a sphygmomanometer.
• High Blood Pressure (Hypertension):
  • Cause: Constriction of arterioles, leading to increased resistance to blood flow.
  • Risks: Can cause artery rupture and internal bleeding.

Transportation in Plants

Plant Needs and Transport Systems

• Energy and Raw Materials:
  • Plants take in CO2 and perform photosynthesis in leaves.
  • Roots absorb nutrients like nitrogen, phosphorus, and minerals from the soil.
• Need for Transport:
  • Simple diffusion isn’t enough for large plants.
  • Plants have transport systems to move materials efficiently.

Types of Transport Systems

1. Xylem:
   • Function: Transports water and minerals from roots to leaves.
   • Structure: Made of vessels and tracheids forming a continuous channel.
2. Phloem:
   • Function: Transports products of photosynthesis (like sugars) from leaves to other parts.
   • Structure: Composed of sieve tubes and companion cells.

Transport of Water

• Process:
  • Root cells absorb ions from the soil, creating a concentration difference.
  • Water moves into roots to balance this difference, creating upward pressure.
  • Transpiration Pull: Evaporation from leaves creates suction, pulling water upwards.
  • Transpiration: Loss of water vapor from leaves, helps in water movement and temperature regulation.

Transport of Food and Other Substances

• Translocation:
  • Movement of soluble products of photosynthesis (sugars) from leaves to other parts.
  • Phloem Function: Also transports amino acids and other substances to storage organs and growing tissues.
  • Mechanism: Uses energy from ATP to transfer materials into phloem, creating pressure that moves the substances to areas of lower pressure.
  • Example: In spring, stored sugars are moved to growing buds.

Plants efficiently move water, minerals, and food through xylem and phloem, ensuring they get all necessary nutrients and energy to grow and thrive.

Excretion

What is Excretion?

• Definition: Removal of harmful metabolic wastes from the body.
• Different Strategies:
  • Unicellular organisms: Simple diffusion.
  • Multicellular organisms: Specialized organs.

Excretion in Human Beings

Human Excretory System Components:

• Kidneys: Located in the abdomen, filter blood to produce urine.
• Ureters: Tubes that carry urine from kidneys to the bladder.
• Urinary Bladder: Stores urine.
• Urethra: Releases urine from the body.

How is Urine Produced?

• Purpose: Remove waste products from blood, like urea and uric acid.
• Filtration Unit:
  • Nephrons in kidneys filter blood.
  • Blood capillaries form a cluster in Bowman’s capsule to collect filtrate.
  • Essential substances like glucose, amino acids, salts, and water are reabsorbed.
• Storage and Release: Urine flows from kidneys to bladder through ureters and is expelled through the urethra when necessary.

Interesting Fact: Artificial Kidney (Hemodialysis)

• Function: Used when kidneys fail, removes nitrogenous wastes.
• Mechanism: Blood passes through tubes in dialysing fluid, wastes diffuse out, and clean blood is returned to the body.

Think it Over: Organ Donation

• Act of Generosity: Donating organs to save or improve someone’s life.
• Common Transplants: Include corneas, kidneys, heart, liver, lungs, etc.
• Living and Deceased Donors: Some organs can be donated while alive; most donations occur after death.

Excretion in Plants

Plant Excretory Strategies:

• Photosynthesis Byproduct: Oxygen is a waste product.
• Transpiration: Removes excess water.
• Storage of Wastes:
  • In vacuoles within cells.
  • In leaves that eventually fall off.
  • As resins and gums in old xylem.
• Soil Excretion: Some wastes are excreted into the soil.

Plants and animals have unique ways of managing waste, ensuring their bodies function efficiently and remain healthy.

Chapter Summary:

• Movement of various types indicates life.
• Maintenance of life requires processes like nutrition, respiration, transport, and excretion.
• Autotrophic nutrition:
  • Intake of simple inorganic materials from the environment.
  • Uses an external energy source like the Sun to make complex high-energy organic material.
• Heterotrophic nutrition:
  • Intake of complex material prepared by other organisms.
• In human beings:
  • Food is broken down in the alimentary canal.
  • Digested food is absorbed in the small intestine and sent to all cells.
• Respiration:
  • Organic compounds like glucose are broken down to provide energy in the form of ATP.
  • ATP provides energy for other reactions in the cell.
• Types of Respiration:
  • Aerobic respiration: Produces more energy.
  • Anaerobic respiration: Produces less energy.
• Circulatory System:
  • Transports oxygen, carbon dioxide, food, and excretory products.
  • Consists of the heart, blood, and blood vessels.
• In highly differentiated plants:
  • Transport of water, minerals, food, and other materials is done by vascular tissue.
  • Vascular tissue consists of xylem and phloem.
• Excretory System in Human Beings:
  • Soluble nitrogen compounds are removed by nephrons in the kidneys.
• Excretion in Plants:
  • Waste material may be stored in cell vacuoles, as gum and resin, removed in falling leaves, or excreted into the soil.