Chapter 6: Life Processes

Introduction:

Life processes are the basic functions carried out by living organisms to sustain life. These processes ensure growth, development, reproduction, and the ability to respond to stimuli in the environment. Life processes include nutrition, respiration, transportation, excretion, and reproduction, among others. Each of these processes plays a vital role in maintaining homeostasis and ensuring the survival of the organism. This chapter focuses on understanding how different organisms perform these life processes. Studying these processes helps us appreciate the complexity of life and how organisms, despite their diversity, share common biological functions that keep them alive.

Key Points of the Chapter:

1. Life Processes: The essential biological processes required for the maintenance of life, including nutrition, respiration, transportation, and excretion.
2. Autotrophic Nutrition: Process by which organisms prepare their own food using sunlight, carbon dioxide, and water (e.g., plants through photosynthesis).
3. Heterotrophic Nutrition: Nutrition mode where organisms obtain food from other organisms (e.g., humans, animals, fungi).
4. Photosynthesis: The process in plants where sunlight is used to convert carbon dioxide and water into glucose and oxygen.
5. Stomata: Pores on the leaf surface that regulate gas exchange and transpiration.
6. Chloroplast: The cell organelle responsible for photosynthesis in plants.
7. Saprophytic Nutrition: A type of heterotrophic nutrition where organisms feed on dead and decaying matter (e.g., fungi).
8. Respiration: The process of breaking down glucose to release energy in the form of ATP (Adenosine Triphosphate).
9. Aerobic Respiration: Respiration process that occurs in the presence of oxygen, producing carbon dioxide, water, and energy.
10. Anaerobic Respiration: Respiration in the absence of oxygen, producing less energy along with by-products like alcohol or lactic acid.
11. Respiratory System in Humans: Consists of organs like the nose, trachea, lungs, and diaphragm, responsible for gaseous exchange.
12. Transportation in Plants: Movement of water, minerals, and nutrients through xylem and phloem tissues.
13. Transpiration: The process of water loss from the aerial parts of the plant, mainly through stomata.
14. Human Circulatory System: Composed of the heart, blood vessels, and blood. The heart pumps blood, which transports oxygen, nutrients, and waste materials.
15. Double Circulation: Blood circulates twice through the heart in humans, once for oxygenation and once for delivering oxygen to the body.
16. Excretion in Humans: The process of removing metabolic wastes, primarily through the kidneys in the form of urine.
17. Excretory System: Includes organs like kidneys, ureters, bladder, and urethra, which help in the elimination of waste products.
18. Excretion in Plants: Removal of waste products via stomata, lenticels, and root exudation.
19. Dialysis: A medical process to remove waste products and excess fluid from the blood in case of kidney failure.
20. Homeostasis: The ability of organisms to maintain a stable internal environment despite external changes.

1. What Are Life Processes?

Life processes are the fundamental processes that are essential for the maintenance and continuation of life. These include nutrition, respiration, transportation, and excretion. Each of these processes is interconnected and necessary for survival. Organisms need energy to perform activities, and this energy comes from food. Respiration provides this energy by breaking down food, transportation moves nutrients and waste products, and excretion eliminates harmful substances.

Example: In daily life, just as a car needs fuel to run, the human body needs food to provide energy for various activities, from moving to thinking.

2. Nutrition

Nutrition is the process by which organisms obtain food and use it for energy, growth, and maintenance. It is classified into two types:

• Autotrophic Nutrition: Found in green plants and some bacteria, autotrophs prepare their own food through the process of photosynthesis. They use sunlight, carbon dioxide, and water to produce glucose.
• Heterotrophic Nutrition: Organisms like animals, fungi, and some bacteria rely on other organisms for food. They are unable to prepare their own food and depend on plants or other animals for nutrition.

Table: Differences Between Autotrophic and Heterotrophic Nutrition

3. Photosynthesis

Photosynthesis is a process by which green plants synthesize food using sunlight, carbon dioxide, and water. The chlorophyll pigment in the chloroplasts of plant cells captures sunlight, which drives the conversion of carbon dioxide and water into glucose and oxygen. This process is crucial not only for plants but also for other organisms as it provides food and oxygen for life on Earth.

Equation of Photosynthesis:
​6CO2​+6H2​O →sunlight, chlorophyll​→C6​H12​O6​+6O2​

Daily Life Example: Plants growing in sunlight exhibit vigorous growth due to efficient photosynthesis, while those deprived of light appear weak and yellowish.

4. Respiration

Respiration is the process by which organisms convert the glucose obtained from food into energy. This energy is stored in the form of ATP (Adenosine Triphosphate), which is used for various cellular activities.

There are two types of respiration:

• Aerobic Respiration: Occurs in the presence of oxygen and produces carbon dioxide, water, and a significant amount of energy.
• Anaerobic Respiration: Takes place in the absence of oxygen, producing less energy and by-products like lactic acid (in humans) or ethanol (in yeast).

Table: Comparison of Aerobic and Anaerobic Respiration

5. Transportation in Plants

Transportation in plants involves the movement of water, minerals, and food through specialized tissues called xylem and phloem.

• Xylem: Transports water and dissolved minerals from roots to other parts of the plant.
• Phloem: Transports food prepared in the leaves to all parts of the plant.

Daily Life Example: Just as water is supplied to each floor of a building through pipes, xylem and phloem serve as conduits for transporting essential nutrients in plants.

6. Human Circulatory System

The human circulatory system consists of the heart, blood, and blood vessels. The heart acts as a pump to circulate blood, which carries oxygen, nutrients, and waste products to and from different parts of the body.

Components:

• Heart: A muscular organ that pumps blood through rhythmic contractions.
• Blood Vessels: Arteries carry oxygen-rich blood away from the heart, veins bring deoxygenated blood back to the heart, and capillaries facilitate the exchange of gases and nutrients.
• Blood: Contains red blood cells (for oxygen transport), white blood cells (for immunity), platelets (for clotting), and plasma (for transporting nutrients and waste).

7. Excretion in Humans

Excretion is the process of eliminating waste products from the body. The primary organ involved in excretion is the kidney, which filters out waste products from the blood and excretes them in the form of urine. Other excretory organs include the skin (sweat) and lungs (carbon dioxide).

Daily Life Example: In everyday life, just as a house needs to dispose of garbage regularly to remain clean, our body needs to remove waste products to remain healthy.

8. Excretion in Plants

Excretion in plants is relatively simple compared to animals. Plants excrete waste products such as oxygen (a by-product of photosynthesis) through stomata and lenticels. They also excrete excess water through the process of transpiration. Additionally, some waste products are stored in dead tissues like bark or leaves, which are eventually shed.

Key Excretory Mechanisms in Plants:

• Gaseous Exchange: Oxygen is released during photosynthesis, and carbon dioxide is expelled during respiration.
• Water Loss: Excess water is excreted through transpiration and guttation.
• Storage in Dead Parts: Certain waste products like resins and gums accumulate in dead parts of the plant.

Table: Comparison Between Excretion in Plants and Animals

9. Transpiration

Transpiration is the process by which water evaporates from the aerial parts of a plant, primarily from the leaves through stomata. This process plays a crucial role in the movement of water and nutrients from the roots to other parts of the plant. It also helps regulate temperature in plants.

Daily Life Example: Just as sweating cools down the human body, transpiration helps regulate the temperature in plants. It also creates a suction force that pulls water from the roots to the leaves.

Table: Importance of Transpiration in Plants

10. Respiratory System in Humans

The human respiratory system consists of several organs working together to facilitate the exchange of gases—oxygen is taken in, and carbon dioxide is expelled.

Key Parts of the Respiratory System:

• Nose: Filters and moistens the air before it enters the lungs.
• Trachea: The windpipe that connects the nose and mouth to the lungs.
• Lungs: The primary organs of the respiratory system where gaseous exchange occurs in tiny sacs called alveoli.
• Diaphragm: A dome-shaped muscle that plays a crucial role in breathing by contracting and relaxing to allow air movement.

Daily Life Example: Just like an air conditioner filters and circulates air in a room, the human respiratory system filters and circulates oxygen into the bloodstream while expelling carbon dioxide.

11. Double Circulation in Humans

In humans, blood circulates through the heart twice in one complete cycle: once for oxygenation and once for distribution throughout the body. This system is called double circulation.

1. Pulmonary Circulation: Blood is pumped from the heart to the lungs for oxygenation and back to the heart.
2. Systemic Circulation: Oxygen-rich blood is pumped from the heart to the rest of the body and returns deoxygenated blood back to the heart.

Table: Pulmonary vs. Systemic Circulation

12. Heart: Structure and Function

The heart is a muscular organ that pumps blood throughout the body. It consists of four chambers: two atria and two ventricles.

• Right Atrium: Receives deoxygenated blood from the body.
• Right Ventricle: Pumps deoxygenated blood to the lungs.
• Left Atrium: Receives oxygenated blood from the lungs.
• Left Ventricle: Pumps oxygenated blood to the rest of the body.

The heart operates through rhythmic contractions, regulated by electrical signals, ensuring continuous blood flow.

13. Human Excretory System

The human excretory system consists of organs that filter waste products from the blood and expel them from the body. The main excretory organs are the kidneys, which filter urea, water, and other wastes to form urine.

Components of the Excretory System:

• Kidneys: Filter blood and form urine.
• Ureters: Tubes that carry urine from the kidneys to the bladder.
• Bladder: Stores urine until it is expelled.
• Urethra: A tube that excretes urine out of the body.

Daily Life Example: Just like a water filter removes impurities from tap water, kidneys filter harmful substances from the blood.

14. Dialysis

Dialysis is a medical procedure used when the kidneys are unable to filter blood properly due to kidney failure. The process involves the use of a machine to remove waste products and excess fluids from the blood.

• Hemodialysis: The patient’s blood is circulated through a dialysis machine that filters out wastes.
• Peritoneal Dialysis: A dialysis solution is introduced into the patient’s abdominal cavity to absorb waste products, which are then drained out.

Daily Life Example: Similar to how a purifier cleans water, dialysis machines purify blood in patients with kidney failure.

15. Nutrition in Human Beings

In humans, nutrition is a complex process involving the ingestion, digestion, absorption, and assimilation of food. The human digestive system consists of several organs:

• Mouth: Where food is chewed and mixed with saliva to begin the digestion process.
• Stomach: Where food is broken down by stomach acids and enzymes.
• Small Intestine: Absorbs nutrients from the digested food into the bloodstream.
• Large Intestine: Absorbs water and forms waste for excretion.

Daily Life Example: Just as a kitchen processes raw ingredients into a meal, the human digestive system processes food into usable nutrients for the body.

16. Nutrition in Amoeba

Amoeba, a unicellular organism, uses a method called phagocytosis to capture food. The cell membrane surrounds the food particle, forming a food vacuole where digestion takes place.

Steps of Nutrition in Amoeba:

1. Ingestion: The amoeba engulfs food by extending pseudopodia.
2. Digestion: Enzymes are secreted into the food vacuole to break down the food.
3. Absorption: The nutrients are absorbed into the cytoplasm.
4. Assimilation: The nutrients are used for growth and energy.
5. Egestion: Waste materials are expelled from the cell.

Daily Life Example: Amoeba’s method of capturing food is akin to a vacuum cleaner sucking in dirt, where the food is “sucked” into the organism and processed internally.

17. Transportation in Humans

The transportation system in humans involves the circulatory system, which consists of the heart, blood, and blood vessels. Blood transports oxygen, nutrients, and waste products throughout the body.

• Arteries: Carry oxygen-rich blood away from the heart.
• Veins: Carry deoxygenated blood back to the heart.
• Capillaries: Thin blood vessels that allow the exchange of gases and nutrients between blood and tissues.

18. Human Digestive System

The human digestive system consists of the mouth, esophagus, stomach, intestines, and associated glands. The process of digestion involves the breakdown of complex food substances into simpler forms that can be absorbed by the body.

Stages of Digestion:

• Ingestion: Intake of food.
• Digestion: Mechanical and chemical breakdown of food.
• Absorption: Absorption of nutrients into the bloodstream.
• Assimilation: Utilization of absorbed nutrients.
• Egestion: Removal of undigested food.

Table: Components of the Human Digestive System

19. Respiration in Amoeba

Amoeba, being a unicellular organism, respires directly through its cell membrane via diffusion. Oxygen from the surrounding water diffuses into the cell, and carbon dioxide diffuses out. Since amoeba is small in size and has a large surface area relative to its volume, diffusion is sufficient to meet its respiratory needs.

Process of Respiration in Amoeba:

• Oxygen Intake: Oxygen diffuses through the cell membrane from the surrounding water.
• Carbon Dioxide Release: Carbon dioxide, a waste product of respiration, diffuses out of the amoeba into the water.

Daily Life Example: Similar to how air fresheners diffuse their fragrance into a room, gases diffuse in and out of amoeba through its membrane.

20. Importance of Transport in Plants

Transport in plants is vital for the distribution of water, minerals, and nutrients. Two major types of tissues are responsible for this:

• Xylem: Transports water and dissolved minerals from the roots to other parts of the plant.
• Phloem: Transports the products of photosynthesis (mainly sugars) from the leaves to other parts of the plant.

Daily Life Example: Just as a water supply system transports water to different parts of a city, the xylem distributes water throughout the plant, and the phloem distributes food.

Table: Xylem vs. Phloem

21. Photosynthesis and Its Importance

Photosynthesis is the process by which green plants synthesize their food using sunlight, carbon dioxide, and water. This process takes place in chloroplasts, which contain the pigment chlorophyll. Oxygen is released as a by-product during this process.

The Chemical Equation of Photosynthesis:

6CO2​+6H2​O→Sunlight​→C6​H12​O6​+6O2​

Importance of Photosynthesis:

• It is the primary source of energy for all life forms on Earth.
• It helps maintain the balance of oxygen and carbon dioxide in the atmosphere.
• It provides the energy required for plant growth and the formation of biomass.

Daily Life Example: Similar to how solar panels convert sunlight into electrical energy, plants convert sunlight into chemical energy through photosynthesis.

22. Assimilation in Humans

Assimilation is the process by which absorbed nutrients are incorporated into the body’s cells and tissues. After digestion and absorption, nutrients such as glucose, amino acids, and fatty acids are transported via the bloodstream to cells, where they are used for various functions like energy production, growth, and repair.

Daily Life Example: Similar to how raw materials are delivered to factories for production, absorbed nutrients are delivered to body cells for energy and growth.

23. Gaseous Exchange in Plants

Plants exchange gases through stomata present on the surface of leaves and lenticels on stems. During photosynthesis, plants take in carbon dioxide and release oxygen, while during respiration, they take in oxygen and release carbon dioxide.

• During Daylight: Photosynthesis occurs, and plants primarily release oxygen.
• During Night: Since photosynthesis does not occur, plants respire, taking in oxygen and releasing carbon dioxide.

Daily Life Example: Just as humans exhale carbon dioxide during respiration, plants also release carbon dioxide during respiration, especially at night.

24. Root Pressure and Transpiration Pull

Water is transported in plants through two primary mechanisms: root pressure and transpiration pull.

• Root Pressure: A force that pushes water upward from the roots into the xylem.
• Transpiration Pull: The evaporation of water from leaves creates a suction force that pulls water from the roots to the leaves.

These two forces ensure a continuous supply of water and minerals to the entire plant.

Daily Life Example: Similar to how a straw pulls liquid upward when you sip, transpiration creates a pulling force that draws water upward in plants.

25. Transpiration in Plants

Transpiration is the process by which water is lost from the aerial parts of plants, primarily through the stomata in the leaves. This process is crucial for several reasons:

• Cooling: Transpiration helps in cooling the plant, especially in hot environments.
• Water Movement: It creates a suction force (transpiration pull) that helps in the upward movement of water from roots to leaves.
• Mineral Transport: Along with water, dissolved minerals are transported from roots to other parts of the plant.

Factors Affecting Transpiration:

• Temperature: Higher temperatures increase the rate of transpiration.
• Humidity: High humidity reduces the rate of transpiration, as the air is already saturated with moisture.
• Wind: Windy conditions increase the rate of transpiration by removing the moist air near the stomata.
• Light: Stomata open in the presence of light, which increases transpiration during the day.

Daily Life Example: Similar to how humans sweat to cool down, plants lose water through transpiration to regulate their temperature and facilitate water and nutrient movement.

26. Excretion in Plants

Plants also carry out excretion, though not as actively as animals. Waste materials are produced during metabolic activities such as photosynthesis and respiration. The methods through which plants excrete their waste are:

• Oxygen and Carbon Dioxide: These are released as by-products of photosynthesis and respiration, respectively.
• Exudation: Excess water, along with other waste products, is lost through guttation or transpiration.
• Storage: Some waste materials like resins and gums are stored in dead cells or vacuoles.
• Leaf Fall: Plants accumulate waste products in leaves, which are later shed during leaf fall.

Daily Life Example: Just like how old or damaged organs in humans are surgically removed, plants get rid of their waste through natural shedding processes like leaf fall.

27. Artificial Respiration and its Importance

Artificial respiration is a procedure to assist or stimulate respiration when someone’s breathing has stopped or is insufficient. It is crucial in emergencies such as drowning, choking, or electric shock. One of the most common forms of artificial respiration is Cardiopulmonary Resuscitation (CPR), which involves chest compressions combined with mouth-to-mouth breathing.

Steps of CPR:

1. Check responsiveness: Make sure the person is unresponsive before starting CPR.
2. Chest Compressions: Perform 30 chest compressions at a rate of 100-120 per minute.
3. Rescue Breaths: Give 2 rescue breaths after every set of 30 compressions.

Daily Life Example: Similar to how car mechanics jumpstart a car when the battery fails, CPR acts as a “jumpstart” to restart the breathing process.

28. Transport in Animals

The transport system in animals involves the circulatory system, which is responsible for moving nutrients, gases, and waste products throughout the body. In higher animals like humans, the circulatory system consists of:

• Heart: Pumps blood throughout the body.
• Blood Vessels: Include arteries, veins, and capillaries that transport blood.
• Blood: The medium that carries oxygen, nutrients, and waste products.

Components of Blood:

• Red Blood Cells (RBCs): Carry oxygen.
• White Blood Cells (WBCs): Fight infections.
• Platelets: Help in blood clotting.
• Plasma: The liquid part that transports nutrients, hormones, and waste products.

Table: Blood Components and Their Functions

Daily Life Example: Just as a delivery system transports goods from factories to consumers, the circulatory system transports nutrients and oxygen to cells and removes waste.

29. Lymphatic System

In addition to the blood circulatory system, animals also have a lymphatic system, which is a network of vessels that helps in maintaining fluid balance and plays a role in the immune response.

Functions of the Lymphatic System:

• Collects excess fluid from tissues and returns it to the bloodstream.
• Absorbs fats from the digestive system and transports them to the blood.
• Helps in the immune response by transporting white blood cells to areas where they are needed.

Daily Life Example: Similar to how a drainage system collects and redirects excess water from roads, the lymphatic system collects and drains excess fluid from tissues.

30. Importance of Excretion in Animals

Excretion is the process by which animals remove harmful metabolic waste products. The excretory system in humans primarily involves the kidneys, which filter out waste from the blood in the form of urine.

Excretory Organs in Humans:

• Kidneys: Filter blood and remove waste.
• Ureters: Transport urine from kidneys to the bladder.
• Bladder: Stores urine.
• Urethra: Expels urine from the body.

Table: Key Excretory Organs and Their Functions

Daily Life Example: Similar to how a water filtration system removes impurities from water, kidneys filter waste products from the blood to maintain the body’s health.

31. Role of Kidneys in Human Excretion

The kidneys are the primary organs of excretion in humans. They are responsible for filtering waste products, toxins, and excess substances from the blood and converting them into urine, which is later excreted from the body. Each kidney contains millions of tiny filtering units called nephrons, which are the functional units of the kidney.

Functions of the Kidneys:

• Filtration: Blood enters the kidney through the renal artery, where the nephrons filter waste products and excess substances like salts, water, and urea.
• Reabsorption: As the filtrate passes through the nephron tubules, essential substances like glucose, certain salts, and water are reabsorbed into the bloodstream.
• Secretion: The remaining waste products, along with excess water, form urine, which is collected in the renal pelvis and passed to the bladder.

Daily Life Example: Similar to how a water purifier filters out impurities from water and returns clean water for drinking, kidneys purify the blood by removing waste and sending clean blood back to the body.

32. Formation of Urine

The process of urine formation in the kidneys occurs through three main steps: filtration, reabsorption, and secretion.

1. Glomerular Filtration: Blood enters the glomerulus, where blood pressure forces water, salts, glucose, and urea out of the blood and into the Bowman’s capsule. This is the initial filtrate.
2. Tubular Reabsorption: As the filtrate moves through the nephron’s tubules, essential substances like glucose, amino acids, and a significant portion of water are reabsorbed back into the blood through surrounding capillaries.
3. Tubular Secretion: Additional waste products like hydrogen ions, potassium, and ammonia are secreted into the tubule from the surrounding capillaries. These substances, along with the remaining filtrate, form urine.
4. Urine Collection: The final urine, containing waste products and excess water, is collected in the renal pelvis and sent to the bladder through the ureters.

Table: Stages of Urine Formation

Daily Life Example: Just like in a factory where different materials are filtered, sorted, and sent to their required destination, the kidneys filter blood, reabsorb what is needed, and send the waste out in the form of urine.

33. Dialysis

When kidneys are unable to function properly, a process called dialysis is used to filter the blood artificially. Dialysis is a life-saving procedure for patients with kidney failure or severe kidney damage.

Types of Dialysis:

• Hemodialysis: Blood is drawn from the body, passed through a dialysis machine where it is filtered, and then returned to the body. This process is usually done in a hospital or dialysis center.
• Peritoneal Dialysis: The lining of the abdomen (peritoneum) acts as a natural filter. A special fluid is introduced into the abdomen, which absorbs waste products from the blood. After some time, the fluid containing the waste is drained from the abdomen.

Daily Life Example: Dialysis functions much like an external filtering system, similar to how a water filtration machine purifies water when the natural filtration system is damaged or fails.

34. Excretion in Other Animals

Excretion processes vary among different animals depending on their habitat and the complexity of their body structures:

1. Amoeba: In unicellular organisms like amoeba, waste products are excreted directly through the cell membrane by diffusion.
2. Fish: Fish excrete ammonia directly into the surrounding water, which dilutes the toxic substance. This is known as ammonotelism.
3. Birds and Reptiles: These animals excrete uric acid in a semi-solid form, which helps conserve water. This form of excretion is called uricotelism.
4. Mammals: Mammals, including humans, excrete urea as their main nitrogenous waste product. This is known as ureotelism.

Table: Excretion Methods in Different Organisms

Daily Life Example: Just as different types of waste management systems are used for solid, liquid, and hazardous waste in cities, animals have evolved different excretory products and methods based on their habitat and survival needs.

35. The Role of the Skin in Excretion

In humans, the skin plays a minor but important role in excretion through the process of sweating. Sweat glands in the skin help remove excess water, salts, and small amounts of urea from the body. This process also helps in regulating body temperature.

• Sweat Composition: Sweat mainly consists of water, with small amounts of salts (like sodium chloride), urea, and other waste products.
• Cooling Effect: As sweat evaporates from the surface of the skin, it cools the body, preventing overheating.

Daily Life Example: Similar to how air conditioners release warm air to maintain the room’s temperature, sweating helps the body cool down by releasing heat and waste.

Final Conclusion

Chapter 6, “Life Processes,” in Class 10 Science, provides a deep understanding of the fundamental biological processes necessary for life. It covers a wide range of topics from nutrition, respiration, transportation, and excretion, emphasizing how organisms—both plants and animals—maintain their internal environment and function efficiently. By breaking down each life process, supported by examples, tables, and comparisons to daily life, these notes aim to offer a comprehensive and detailed resource for mastering the chapter, making it the best available for students seeking in-depth understanding.