PART-1 : LIFE PROCESSES

🧬  What Are Life Processes?

Class Level: 9–10 | NEP Aligned | Core Concepts: Biology

🌱 Chapter 5.1 :  Definition of Life Processes

Life processes are the vital functions or maintenance activities carried out by all living organisms to sustain life. Even when an organism is at rest, these processes continue internally to keep the body functional and healthy.

⚙️ Why Are Life Processes Important?

• They maintain internal stability (homeostasis).

• They help organisms grow, reproduce, repair damage, and adapt to changing conditions.

• Without life processes, cells would break down, and life would cease.

🔋 Energy Requirement

• All life processes need energy to operate.

• This energy comes from food, which contains carbon-based molecules.

• The food must be transferred into the body (nutrition), broken down (respiration), and distributed (transportation).

🍽️ Nutrition

• It is the process of acquiring energy and raw materials from the environment.

• Organisms use various modes of nutrition depending on complexity (e.g., autotrophic in plants, heterotrophic in animals).

• Food provides carbon-based molecules necessary for building body structures and generating energy.

💨 Respiration

• After food is taken in, it must be broken down into usable energy.

• Respiration is the chemical process where glucose (or similar molecules) is broken down using oxygen, releasing energy (ATP).

• These are typically oxidation-reduction (redox) reactions.

🚛 Transport System

• In single-celled organisms: nutrients, gases, and wastes are exchanged directly with the environment by diffusion.

• In multi-cellular organisms: specialised tissues (like blood in humans) are needed to transport substances (e.g., oxygen, nutrients, waste).

• Diffusion is too slow for large, complex bodies.

🚮 Excretion

• Excretion is the process of removing waste by-products of chemical reactions.

• These wastes (like carbon dioxide, urea, etc.) can be harmful if not removed.

• Specialised excretory tissues or organs (like kidneys in humans) are responsible for this function.

🧠 Conclusion

Life processes are interlinked and collectively maintain the internal environment of organisms. As complexity increases, organisms evolve specialised systems to handle basic life activities efficiently.

📝 Worksheet: Higher Order Thinking Skills (HOTS) on Life Processes

Skills Covered: Analysis | Application | Conceptual Reasoning | Evaluation
Total Marks: 25 | Class Level: 9–10 | Time: 40 min

✍️ SECTION A: Conceptual Reasoning (2 Marks Each)

1. Why is food considered a source of both energy and raw materials for organisms?

2. Explain why energy is needed even during sleep or inactivity.

3. Why can diffusion meet the needs of unicellular organisms but not multicellular ones?

4. What role do oxidation-reduction reactions play in the generation of energy in living organisms?

5. How does specialisation of tissues help in efficient functioning in multicellular organisms?

🔍 SECTION B: Compare and Contrast (3 Marks Each)

6. Compare nutrition and respiration in terms of purpose, location, and outcome in the body.

7. Contrast the process of transportation in unicellular organisms and in humans.

🧠 SECTION C: Application and Critical Thinking (4 Marks Each)

8. A scientist finds a new large multicellular organism that lacks a transport system. Predict and explain what limitations this organism might face in its environment.

9. If excretion is blocked in an organism, what might be the short-term and long-term consequences?

💡 SECTION D: Extension Challenge (4 Marks)

10. Propose a simple design for an artificial "life process machine" that performs nutrition, respiration, and excretion. How would each part function?

🌱 Chapter 5.2 – Nutrition

📘 Topic: Life Processes – Nutrition in Organisms

✅ What is Nutrition?

Nutrition is the process by which organisms obtain and use food to produce energy, grow, and maintain body functions.
Even when we are resting, our body uses energy to maintain internal order—this energy and raw material come from food.

🔄 Why Do Organisms Need Nutrition?

Organisms need nutrition for:

• Energy (for movement, repair, and basic life functions)

• Growth and development

• Maintenance of body structure

• Synthesis of proteins and enzymes

🌿 How Do Organisms Get Their Food?

All organisms need food, but how they obtain it differs:

🌞 1. Autotrophic Nutrition (Self-feeding)

Definition: Organisms that make their own food from inorganic substances like carbon dioxide and water using sunlight as energy.
Examples: Green plants, blue-green algae, some bacteria (like cyanobacteria).

🔬 Photosynthesis – The Autotrophic Process

Photosynthesis is the process by which green plants prepare food (glucose) using:

• Sunlight

• Chlorophyll (found in chloroplasts)

• Carbon dioxide (from air)

• Water (from soil)

Equation:

$$\text{Carbon dioxide} + \text{Water} \xrightarrow{\text{Sunlight + Chlorophyll}} \text{Glucose} + \text{Oxygen}$$ $$6CO_2 + 6H_2O \xrightarrow{\text{Light}} C_6H_{12}O_6 + 6O_2$$

🧪 Steps in Photosynthesis:

1. Absorption of light energy by chlorophyll.

2. Conversion of light energy into chemical energy and splitting of water into hydrogen and oxygen.

3. Reduction of carbon dioxide into carbohydrates (glucose).

💡 Note: These steps may occur separately. For example, desert plants take up CO₂ at night and use it during the day.

🧫 Where does Photosynthesis occur?

• Takes place in the chloroplasts (contain chlorophyll) present in green parts of the plant (mainly leaves).

• Stomata (tiny pores on leaves) allow gas exchange—CO₂ in, O₂ out.

⚙️ Role of Guard Cells in Stomatal Movement:

• Open pore: Guard cells swell with water.

• Close pore: Guard cells lose water and shrink.

• Helps control water loss and CO₂ uptake.

💧 Raw Materials Required for Photosynthesis:

• Carbon dioxide from air (via stomata).

• Water from soil (via roots).

• Minerals from soil like:

  • Nitrogen (for proteins) – taken as nitrates/nitrites or from organic compounds via nitrogen-fixing bacteria

  • Phosphorus, Magnesium, Iron – for enzyme and pigment production

🧪 Example Experiments (as referred in textbook):

1. Chlorophyll is essential for photosynthesis (e.g., variegated leaf test).

2. Sunlight is essential – use a leaf partially covered with black paper and observe starch formation.

🍄 2. Heterotrophic Nutrition

Definition: Organisms that cannot make their own food and depend on other organisms for nutrition.
Examples: Animals, fungi, most bacteria.

• They break down complex food into simpler molecules using enzymes (biological catalysts).

• They depend directly or indirectly on autotrophs for survival.

🧠 Summary Chart

Nutrition Type	Organisms Involved	Food Source	Example
Autotrophic	Green plants, algae	CO₂, water, sunlight	Mango tree, Chlorella
Heterotrophic	Animals, fungi	Other organisms	Human, Mushroom

🔁 Connection with Human Nutrition

• Plants store excess glucose as starch.

• Humans store extra glucose as glycogen in muscles and liver.

✍️ Conclusion

Nutrition is essential for the survival of all living beings. Autotrophs prepare food using sunlight and provide the base of the food chain, while heterotrophs depend on them directly or indirectly. Understanding photosynthesis helps us appreciate how life is sustained on Earth.

📘 Chapter 5.2.2 & 5.2.3: Heterotrophic Nutrition & How Organisms Obtain Their Nutrition

Subject: Biology | Level: Grade 10 (NEP/CBSE)

🌱 What is Heterotrophic Nutrition?

Heterotrophic nutrition is the mode of nutrition in which organisms cannot prepare their own food and depend on other organisms (plants or animals) for survival.

🔄 Unlike autotrophs (which make food using sunlight), heterotrophs must either:

• Consume other living organisms

• Feed on dead/decaying organic matter

• Absorb nutrients from a host organism

🍽️ Types of Heterotrophic Nutrition

Type	Description	Examples
Holozoic	Ingestion of solid food and internal digestion	Human, lion, cow, Amoeba
Saprophytic	Secretes enzymes outside the body to break down food and then absorb it	Fungi (mushroom, bread mould)
Parasitic	Obtains nutrients from a living host without killing it	Cuscuta, lice, leeches, tapeworm

🧠 Adaptation in Nutrition

Different organisms are adapted to their environment and food source:

• A cow (herbivore) eats grass (stationary), has flat teeth and a long digestive tract to digest cellulose.

• A lion (carnivore) hunts prey (mobile), has sharp teeth and a short gut adapted for protein digestion.

• A parasite like Cuscuta grows on host plants and absorbs nutrients from them without killing them.

🧫 How Do Organisms Obtain Their Nutrition?

The method of food intake and digestion varies depending on:

• Body structure

• Complexity of the organism

• Type of food

🦠 Unicellular Organisms (like Amoeba & Paramoecium)

🔬 Amoeba (Holozoic Nutrition)

• Uses pseudopodia (false feet) to surround and engulf food particles.

• Forms a food vacuole where enzymes digest the food.

• Simple substances diffuse into the cytoplasm, and undigested materials are expelled out.

🔬 Paramoecium

• Has a fixed shape.

• Uses cilia (tiny hair-like structures) to sweep food to a specific spot on the cell surface.

• Food enters through the oral groove and is digested inside a food vacuole.

➡️ Both organisms carry out intracellular digestion (digestion occurs inside the cell).

🧍‍♂️ Multicellular Organisms

As complexity increases:

• Specialised organs are developed (mouth, stomach, intestine, etc.)

• Different tissues perform different functions (ingestion, digestion, absorption, assimilation, and egestion).

➡️ For example, in humans:

• Mouth: ingestion and mechanical breakdown

• Stomach: protein digestion

• Small intestine: digestion and absorption

• Large intestine: water absorption and waste formation

🔄 Summary Chart

Organism Type	Food Intake Method	Digestion Type	Example
Amoeba	Pseudopodia engulf food	Intracellular	Amoeba
Paramoecium	Cilia move food to oral groove	Intracellular	Paramoecium
Mushroom (Fungi)	External enzyme secretion	Extracellular	Bread mould, yeast
Tapeworm, Leech	Absorbs food from host	Depends on host	Parasitic organisms
Humans, animals	Ingestion & internal digestion	Extracellular	Human, cow, lion

🧠 Key Takeaways:

• Heterotrophs depend on autotrophs directly or indirectly.

• The body design, food source, and environment determine how organisms obtain and digest food.

• Unicellular organisms use simple methods like diffusion and vacuole formation, while multicellular organisms need specialised systems for digestion and absorption.

🧠  5.2.4: Nutrition in Human Beings

🔹 What is the Human Digestive System?

The human digestive system consists of a long, coiled tube called the alimentary canal that runs from the mouth to the anus, along with digestive glands that release enzymes to aid in digestion.
Each part of the canal is specialised to perform a specific function during the process of nutrition.

🔹 Key Steps in Human Nutrition:

1. Ingestion (Mouth)

• Teeth grind and crush food into smaller particles to ensure smooth passage.

• Salivary glands secrete saliva, which contains the enzyme salivary amylase (also called ptyalin) that begins the breakdown of starch into sugar.

• The tongue mixes food and helps in swallowing.

• Food is moistened to ease passage through the alimentary canal.

2. Swallowing & Peristalsis

• Food travels through the oesophagus (food pipe).

• A wave-like muscular motion called peristalsis pushes the food downward in a regulated manner throughout the canal.

🔹 Stomach – Mechanical & Chemical Digestion

• Food enters the stomach, a muscular, expandable organ.

• Gastric glands in the stomach lining secrete:

  • Hydrochloric acid (HCl) – creates an acidic medium and kills bacteria.

  • Pepsin – a protein-digesting enzyme activated in the acidic medium.

  • Mucus – protects the inner lining from acid attack.

• Acid imbalance can lead to acidity, a common digestive discomfort.

🔹 Small Intestine – Complete Digestion & Absorption

• The longest part of the digestive tract; tightly coiled to fit in limited space.

• Food moves here in small amounts due to the action of a sphincter muscle between the stomach and intestine.

Role of Digestive Secretions:

• Liver produces bile, stored in the gallbladder and released into the intestine:

  • Neutralises the acidic food from the stomach.

  • Emulsifies fats into smaller globules (like soap on grease) to aid enzyme action.

• Pancreas secretes pancreatic juice, containing:

  • Trypsin (digests proteins),

  • Lipase (digests emulsified fats),

  • Other enzymes for carbohydrate digestion.

• Intestinal glands secrete enzymes that:

  • Convert proteins → amino acids,

  • Carbohydrates → glucose,

  • Fats → fatty acids + glycerol

🔹 Absorption of Nutrients

• The inner lining of the small intestine has finger-like projections called villi:

  • Increase surface area for maximum absorption,

  • Contain blood vessels to transport nutrients to all body cells.

• Cells use these nutrients for:

  • Energy production,

  • Tissue repair,

  • Growth and maintenance.

🔹 Large Intestine – Water Absorption & Egestion

• Absorbs excess water from the undigested food.

• Remaining waste is formed into semi-solid feces.

• Elimination of waste occurs via the anus, controlled by the anal sphincter.

🧪 Important Terms

Term	Description
Salivary Amylase	Enzyme that breaks down starch into sugar in the mouth.
Peristalsis	Rhythmic contraction of muscles to move food forward.
Pepsin	Enzyme that digests proteins in the stomach.
Bile Salts	Help emulsify fats for efficient digestion.
Villi	Finger-like structures in the small intestine that absorb digested food.

🔍 Insights & Higher Order Links:

• The co-ordination between enzymes, muscles, secretions, and pH levels shows a highly regulated biological system.

• Digestive system function reflects the adaptation of anatomy to diet (herbivores vs carnivores).

• A failure in any one part (like lack of bile, pancreatic damage, or loss of villi) can disrupt entire nutrient absorption, leading to malnutrition or illness.