Ch 7: Structure and Functions of Living Beings - Animals 🦁

 

Chapter 7: Structure and Functions of Living Beings - Animals 🦁

A Comprehensive Guide for PSTET Paper-2 (Science)

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Chapter Overview

| Section | Topic | PSTET Weightage | Page No. |
|:---:|:---|::---:|:---:|
| 7.1 | Cell to Organism: Tissues, Organs, Organ Systems | High | 2 |
| 7.2 | Animal Nutrition: Modes of Feeding, Digestive System | High | 7 |
| 7.3 | Animal Respiration: Different Modes (Lungs, Gills, Skin, Trachea) | High | 14 |
| 7.4 | Animal Circulation: Heart, Blood, Blood Vessels | High | 19 |
| 7.5 | Excretion in Animals | Medium | 24 |
| 7.6 | Movement and Locomotion in Animals (including Human Skeletal and Muscular System) | High | 28 |
| Practice Zone | MCQs & Pedagogical Questions | - | 35 |

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Learning Objectives 🎯

After studying this chapter, you will be able to:

• ✅ Explain the hierarchical organization of life from cells to organ systems

• ✅ Describe different modes of nutrition and the digestive systems in various animals

• ✅ Compare different respiratory organs and their mechanisms across animal groups

• ✅ Understand the circulatory system components—heart, blood, and blood vessels

• ✅ Explain various excretory systems and waste products in animals

• ✅ Describe the human skeletal and muscular systems and their role in movement

• ✅ Apply pedagogical strategies to teach animal biology effectively to upper primary students

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Pedagogical Link 🔗

For Teachers: This chapter directly aligns with:

• Class 7 Science NCERT Chapter 2: "Nutrition in Animals"

• Class 7 Science NCERT Chapter 10: "Respiration in Organisms"

• Class 7 Science NCERT Chapter 11: "Transportation in Animals and Plants"

• Class 8 Science NCERT Chapter 8: "Cell—Structure and Functions"

• Class 9 Science NCERT Chapter 5: "The Fundamental Unit of Life"

• Class 9 Science NCERT Chapter 6: "Tissues"

Teaching Tips:

• Use models and charts to show organ systems

• Conduct interactive activities like measuring heart rate before and after exercise

• Use animations and videos to show digestion, respiration, and circulation

• Create comparison tables for different animal groups

• Connect concepts to health and hygiene for relevance

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Section 7.1: Cell to Organism: Tissues, Organs, Organ Systems 🔬

Introduction

Life is organized in a hierarchical manner. From the smallest unit of life—the cell—to the complex functioning of a complete organism, there are several levels of organization . Understanding this hierarchy helps us appreciate how bodies function.

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7.1.1 Levels of Organization in Animals

Table 7.1: Levels of Biological Organization

Level	Definition	Examples
Cell	Basic structural and functional unit of life	Nerve cell (neuron), Muscle cell, Blood cell
Tissue	Group of similar cells performing a specific function	Muscle tissue, Nervous tissue, Epithelial tissue
Organ	Group of tissues working together to perform a specific function	Heart, Stomach, Lungs, Brain
Organ System	Group of organs working together to perform major functions	Digestive system, Respiratory system, Circulatory system
Organism	Complete living being composed of multiple organ systems	Human, Cow, Bird, Fish

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7.1.2 Detailed Explanation of Each Level

A. The Cell 🧫

Definition: The cell is the smallest unit of life capable of performing all life functions .

Discovery: Robert Hooke (1665) first observed cells in cork using a microscope .

Key Components of an Animal Cell:

Cell Part	Function
Cell Membrane	Outer covering; regulates entry and exit of substances
Cytoplasm	Jelly-like substance where cellular reactions occur
Nucleus	Control center; contains genetic material (DNA)
Mitochondria	Powerhouse of cell; produces energy (ATP)
Endoplasmic Reticulum	Transport and synthesis of proteins and lipids
Golgi Apparatus	Packaging and modification of proteins
Lysosomes	Digestion and waste removal (suicide bags of cell)
Ribosomes	Protein synthesis

📝 PSTET Note: Animal cells do NOT have cell wall or chloroplasts (unlike plant cells).

B. Tissues 🧵

Definition: A tissue is a group of similar cells that work together to perform a specific function .

Types of Animal Tissues:

Tissue Type	Function	Location in Body
Epithelial Tissue	Covering and lining; protection; secretion	Skin, lining of organs, blood vessels
Muscular Tissue	Movement and locomotion	Muscles (skeletal, smooth, cardiac)
Connective Tissue	Support, connection, protection, transport	Bone, cartilage, blood, tendons, ligaments
Nervous Tissue	Receiving stimuli and transmitting signals	Brain, spinal cord, nerves

Detailed Classification:

1. Epithelial Tissue:

Type	Description	Location
Simple Squamous	Single layer of flat cells	Lung alveoli, blood vessel lining
Simple Cuboidal	Single layer of cube-shaped cells	Kidney tubules, glands
Simple Columnar	Single layer of tall cells	Stomach, intestine lining
Ciliated Columnar	Columnar cells with cilia	Respiratory tract
Stratified Squamous	Multiple layers of flat cells	Skin, mouth lining

2. Connective Tissue:

Type	Description	Location
Areolar Tissue	Loose connective tissue with fibers	Between organs, under skin
Adipose Tissue	Fat-storing tissue	Under skin, around organs
Bone	Hard, mineralized tissue	Skeleton
Cartilage	Flexible, semi-rigid tissue	Nose, ears, joints
Blood	Fluid connective tissue	Blood vessels
Lymph	Fluid in lymphatic system	Lymph vessels

3. Muscular Tissue:

Type	Structure	Control	Location
Skeletal Muscle	Striated, multinucleated	Voluntary	Attached to bones
Smooth Muscle	Non-striated, spindle-shaped	Involuntary	Internal organs (stomach, intestines)
Cardiac Muscle	Striated, branched, uninucleated	Involuntary	Heart

4. Nervous Tissue:

• Neurons: Structural and functional units

• Neuroglia: Supporting cells

Structure of a Neuron:

Part	Function
Cell Body (Cyton)	Contains nucleus and organelles
Dendrites	Receive impulses from other neurons
Axon	Conducts impulses away from cell body
Myelin Sheath	Insulates axon; speeds up impulse transmission
Synapse	Junction between two neurons

C. Organs

Definition: An organ is a structure composed of two or more tissues working together to perform a specific function.

Examples:

• Heart: Contains muscular tissue (for pumping), nervous tissue (for impulse conduction), connective tissue (for structure), and epithelial tissue (for lining)

• Stomach: Contains muscular tissue (for churning), epithelial tissue (for secretion), and connective tissue (for support)

D. Organ Systems

Definition: An organ system is a group of organs that work together to perform major functions.

Major Organ Systems in Humans:

System	Major Organs	Function
Digestive System	Mouth, esophagus, stomach, intestines, liver, pancreas	Breakdown of food; absorption of nutrients
Respiratory System	Nose, trachea, lungs, diaphragm	Gas exchange (O₂ intake, CO₂ removal)
Circulatory System	Heart, blood vessels, blood	Transport of nutrients, gases, wastes
Excretory System	Kidneys, ureters, bladder, urethra	Removal of metabolic wastes
Nervous System	Brain, spinal cord, nerves	Control and coordination
Skeletal System	Bones, cartilage, ligaments	Support, protection, movement
Muscular System	Skeletal, smooth, cardiac muscles	Movement
Reproductive System	Testes, ovaries, uterus, etc.	Reproduction
Endocrine System	Glands (pituitary, thyroid, etc.)	Hormone secretion
Integumentary System	Skin, hair, nails	Protection, temperature regulation

E. Organism

Definition: A complete living being composed of multiple organ systems working in coordination.

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7.1.3 Comparison: Animal Cells vs. Plant Cells

Feature	Animal Cell	Plant Cell
Cell Wall	Absent	Present (cellulose)
Chloroplasts	Absent	Present
Vacuoles	Small, temporary	Large, central vacuole
Shape	Irregular	Fixed, rectangular
Centrioles	Present	Absent (except lower plants)
Storage	Glycogen	Starch

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7.1.4 Pedagogical Implications

Teaching Strategy	Description	PSTET Focus
Microscope Activity	Observe cheek cells under microscope	Hands-on learning
Model Making	Create 3D cell models using clay/paper	Visual-spatial learning
Organ System Chart	Create charts showing different systems	Organization skills
Comparison Tables	Compare animal and plant cells	Analytical thinking

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Section 7.2: Animal Nutrition: Modes of Feeding, Digestive System 🍽️

Introduction

Nutrition is the process by which organisms obtain food and utilize it for growth, metabolism, and repair . Animals are heterotrophs—they cannot make their own food and depend on other organisms .

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7.2.1 Modes of Feeding in Animals

Mode	Description	Examples
Herbivores	Feed on plants	Cow, Deer, Elephant, Rabbit
Carnivores	Feed on other animals	Lion, Tiger, Snake, Eagle
Omnivores	Feed on both plants and animals	Human, Bear, Crow, Cockroach
Scavengers	Feed on dead animals	Vulture, Jackal, Hyena
Parasites	Live on or inside host and derive nutrition	Tapeworm, Leech, Lice, Mosquito
Filter Feeders	Strain food particles from water	Whale, Sponges, Oysters
Saprophytes	Feed on dead and decaying matter (fungi, some bacteria)	Mushroom (technically not animals)

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7.2.2 Steps of Nutrition in Animals

Step	Process	Description
1. Ingestion	Taking food into the body	Mouth parts capture and intake food
2. Digestion	Breaking down food into absorbable form	Mechanical (chewing) and Chemical (enzymes)
3. Absorption	Taking digested nutrients into blood	Through intestinal walls
4. Assimilation	Using absorbed nutrients for body functions	Cells use nutrients for energy, growth
5. Egestion	Removal of undigested food	Elimination of feces

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7.2.3 Digestive System in Different Animals

A. Digestive System in Humans

The Human Digestive Tract (Alimentary Canal):

Organ	Structure	Function
Mouth	Teeth, tongue, salivary glands	• Teeth: Mechanical breakdown (chewing) • Saliva: Contains amylase (starch digestion) • Tongue: Mixes food, taste perception
Pharynx	Common passage for food and air	Swallowing (food enters esophagus)
Esophagus	Muscular tube	Peristalsis pushes food to stomach
Stomach	J-shaped muscular organ	• Gastric glands secrete HCl (kills bacteria), pepsin (protein digestion) • Churning mixes food to form chyme
Small Intestine	Long coiled tube (about 6 m)	• Receives bile (from liver) and pancreatic juice • Complete digestion of carbs, proteins, fats • Absorption through villi
Large Intestine	Wider but shorter (1.5 m)	• Absorption of water and minerals • Formation of solid waste (feces)
Rectum	Last part of large intestine	Stores feces temporarily
Anus	Opening at end	Egestion of feces

Accessory Organs:

Organ	Secretion	Function
Salivary Glands	Saliva	Moistens food; starch digestion
Liver	Bile (stored in gall bladder)	Emulsifies fats (no enzymes)
Pancreas	Pancreatic juice	Contains enzymes for all food types

Digestive Enzymes and Their Actions:

Enzyme	Source	Substrate	Product
Salivary Amylase	Salivary glands	Starch	Maltose
Pepsin	Stomach (gastric glands)	Proteins	Peptides
Trypsin	Pancreas	Proteins	Peptides
Lipase	Pancreas	Fats	Fatty acids + Glycerol
Maltase	Small intestine	Maltose	Glucose
Peptidases	Small intestine	Peptides	Amino acids

Adaptations for Absorption—Villi:

Feature	Function
Finger-like projections in small intestine	Increase surface area for absorption
Rich blood supply	Transport absorbed nutrients
Thin walls (one cell thick)	Easy diffusion of nutrients

B. Digestive System in Ruminants (e.g., Cow) 🐄

Ruminants are herbivores with a specialized stomach for digesting cellulose.

Stomach Compartment	Description	Function
Rumen	Largest compartment	Contains bacteria that digest cellulose; food stored as cud
Reticulum	Honeycomb-like structure	Cud returned to mouth for chewing (rumination)
Omasum	Many folds	Absorbs water from food
Abomasum	True stomach	Secretes digestive enzymes (similar to human stomach)

Process:

1. Grass is swallowed quickly and stored in rumen

2. Later, cud is brought back to mouth for thorough chewing

3. Swallowed again; passes through reticulum → omasum → abomasum

C. Digestive System in Amoeba 🦠

Amoeba is a single-celled organism with a simple digestive process:

Step	Process
Ingestion	Engulfs food using pseudopodia (false feet)—process called phagocytosis
Digestion	Food vacuole forms; enzymes break down food
Absorption	Digested nutrients diffuse into cytoplasm
Egestion	Undigested waste expelled through cell membrane

D. Digestive System in Hydra 🌊

Hydra has a simple body plan with a single opening (mouth/anus):

Feature	Description
Tentacles	Capture prey (small aquatic animals)
Nematocysts	Stinging cells to paralyze prey
Gastrovascular Cavity	Single cavity for digestion; food enters and waste exits through same opening
Digestion	Both intracellular (within cells) and extracellular (in cavity)

E. Digestive System in Earthworm

Feature	Function
Mouth	Ingests soil containing organic matter
Pharynx	Sucks food
Crop	Temporary storage
Gizzard	Muscular organ that grinds food (mechanical digestion)
Intestine	Chemical digestion and absorption

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7.2.4 Teeth in Humans (Dentition)

Type of Teeth	Number	Function
Incisors	8	Cutting and biting food
Canines	4	Tearing food (especially meat)
Premolars	8	Crushing and grinding
Molars	12	Grinding food thoroughly

Dental Formula: 2-1-2-3 (Upper jaw) / 2-1-2-3 (Lower jaw) = 32 teeth in adults

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7.2.5 Pedagogical Implications

Teaching Strategy	Description	PSTET Focus
Model Making	Create digestive system model using clay	Hands-on learning
Role Play	Students role-play as different organs	Engaging multiple intelligences
Food Diary	Students record and analyze their own food intake	Real-life connection
Demonstration	Show starch digestion using iodine test on bread with saliva	Scientific method

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Section 7.3: Animal Respiration: Different Modes (Lungs, Gills, Skin, Trachea) 🌬️

Introduction

Respiration is the process by which organisms take in oxygen and release energy from food, with carbon dioxide as a waste product . Different animals have evolved different organs for respiration depending on their habitat and complexity .

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7.3.1 Types of Respiration

Type	Description	Occurrence
Aerobic Respiration	Requires oxygen; produces more energy (38 ATP per glucose)	Most animals, plants
Anaerobic Respiration	Without oxygen; produces less energy (2 ATP per glucose)	Some bacteria, yeast (fermentation)

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7.3.2 Respiratory Organs in Different Animals

Table 7.2: Respiratory Organs in Animals

Respiratory Organ	Description	Animals
Lungs	Spongy, air-filled organs for gaseous exchange	Humans, mammals, birds, reptiles, amphibians (adults)
Gills	Feathery structures rich in blood vessels; extract O₂ from water	Fish, tadpoles, crabs, prawns, mollusks
Skin	Moist, thin surface for gas exchange	Earthworms, frogs (partly), leeches
Tracheal System	Network of tubes (tracheae) delivering air directly to cells	Insects (cockroach, grasshopper, butterfly)
Diffusion	Simple exchange through body surface	Amoeba, Paramecium, Hydra (small organisms)

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7.3.3 Detailed Study of Each Respiratory Organ

A. Lungs (Pulmonary Respiration)

Human Respiratory System:

Part	Function
Nostrils	Air enters; lined with hairs to filter dust
Nasal Cavity	Warms and moistens air; mucus traps particles
Pharynx	Common passage for air and food
Larynx	Voice box; contains vocal cords
Trachea (Windpipe)	Tube with C-shaped cartilaginous rings; prevents collapse
Bronchi	Two branches from trachea (one to each lung)
Bronchioles	Smaller branches within lungs
Alveoli	Tiny air sacs; site of gas exchange; surrounded by blood capillaries

Mechanism of Breathing (Humans):

Process	Muscles Involved	Changes in Chest Cavity	Air Movement
Inhalation (Inspiration)	Diaphragm contracts and flattens; rib muscles contract	Chest cavity expands; pressure decreases	Air rushes IN
Exhalation (Expiration)	Diaphragm relaxes; rib muscles relax	Chest cavity contracts; pressure increases	Air moves OUT

Gas Exchange at Alveoli:

• Oxygen: Alveoli → blood (diffusion)

• Carbon Dioxide: Blood → alveoli (diffusion)

B. Gills (Branchial Respiration)

Structure: Gills are feathery, filamentous structures with rich blood supply.

Mechanism:

1. Water enters through mouth

2. Passes over gills

3. Oxygen dissolved in water diffuses into blood

4. Carbon dioxide diffuses out into water

5. Water exits through gill slits

Adaptations:

• Counter-current flow (water and blood flow in opposite directions)—maximizes O₂ extraction

C. Skin (Cutaneous Respiration)

Requirements for Skin Respiration:

• Skin must be thin and moist

• Rich blood supply near surface

Examples:

• Earthworm: Entire respiration through skin; secretes mucus to keep skin moist

• Frog: Respires through skin when underwater and through lungs on land

D. Tracheal System

Structure:

• Network of air tubes called tracheae

• Branch into smaller tracheoles

• Open to outside through spiracles (small openings on body segments)

Mechanism:

1. Air enters through spiracles

2. Travels through tracheae and tracheoles

3. Delivered directly to cells (no blood involvement in gas transport)

Example: Cockroach, Grasshopper, Housefly

E. Diffusion (Direct Exchange)

Simple Organisms:

• No specialized respiratory organs

• Gas exchange occurs directly through cell membrane

• Sufficient because organisms are small and have large surface area to volume ratio

Examples: Amoeba, Paramecium, Hydra

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7.3.4 Comparison: Respiration in Different Animals

Animal	Respiratory Organ	Habitat	Special Feature
Human	Lungs	Terrestrial	Diaphragm for breathing
Fish	Gills	Aquatic	Counter-current exchange
Earthworm	Skin	Terrestrial (soil)	Moist skin needed
Frog	Lungs + Skin	Terrestrial + Aquatic	Can respire through skin underwater
Cockroach	Tracheal system	Terrestrial	Spiracles on body segments
Whale/Dolphin	Lungs	Aquatic (marine mammals)	Must surface to breathe
Amoeba	Cell membrane	Aquatic	No specialized organs

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7.3.5 Breathing Rate in Different Animals

Animal	Breathing Rate (breaths/minute)
Human (adult)	15-18
Human (infant)	30-40
Dog	15-30
Cat	20-30
Elephant	4-6
Frog	15-20
Fish	30-60 (gill movements)

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7.3.6 Pedagogical Implications

Teaching Strategy	Description	PSTET Focus
Demonstration	Show lung model using bell jar and balloons	Visual learning
Experiment	Measure breathing rate before/after exercise	Hands-on learning
Comparison Charts	Compare respiratory organs across animals	Analytical thinking
Microscope Observation	Observe gills of fish under microscope	Scientific observation

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Section 7.4: Animal Circulation: Heart, Blood, Blood Vessels ❤️

Introduction

Circulatory system transports nutrients, oxygen, hormones, and waste products throughout the body . It consists of the heart, blood vessels, and blood .

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7.4.1 Components of Circulatory System

Component	Description	Function
Heart	Muscular pumping organ	Pumps blood throughout body
Blood Vessels	Network of tubes	Carry blood to and from heart
Blood	Fluid connective tissue	Transports substances

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7.4.2 Types of Circulatory Systems

Type	Description	Examples
Open Circulatory System	Blood flows freely in body cavities (sinuses); not enclosed in vessels	Insects, cockroach, crabs, snails
Closed Circulatory System	Blood flows through continuous network of vessels	Humans, vertebrates, earthworms

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7.4.3 Human Circulatory System

A. The Heart

Structure:

Feature	Description
Location	In thoracic cavity, between lungs, slightly tilted to left
Size	About fist-sized
Pericardium	Double-walled protective membrane with fluid to reduce friction
Chambers	4 chambers: 2 upper atria, 2 lower ventricles

Chambers of the Heart:

Chamber	Position	Receives Blood From	Pumps Blood To
Right Atrium	Upper right	Body (via vena cava)	Right ventricle
Right Ventricle	Lower right	Right atrium	Lungs (via pulmonary artery)
Left Atrium	Upper left	Lungs (via pulmonary veins)	Left ventricle
Left Ventricle	Lower left	Left atrium	Body (via aorta)

Valves of the Heart:

Valve	Location	Function
Tricuspid Valve	Between right atrium and right ventricle	Prevents backflow of blood
Bicuspid/Mitral Valve	Between left atrium and left ventricle	Prevents backflow of blood
Pulmonary Valve	Between right ventricle and pulmonary artery	Prevents backflow
Aortic Valve	Between left ventricle and aorta	Prevents backflow

Heartbeat:

• Systole: Contraction of heart chambers

• Diastole: Relaxation of heart chambers

• Heart Rate: 72-75 beats per minute in adult humans

• Pulse: Wave of expansion in artery due to heartbeat

B. Blood Vessels

Type	Direction	Structure	Function
Arteries 🟥	Away from heart	Thick, muscular, elastic walls; no valves	Carry oxygenated blood (except pulmonary artery) under high pressure
Veins 🟦	Toward heart	Thin walls; have valves	Carry deoxygenated blood (except pulmonary vein) under low pressure
Capillaries	Connect arteries and veins	One cell thick walls	Exchange of gases, nutrients, wastes with tissues

C. Blood

Composition of Blood:

Component	Percentage	Function
Plasma	55%	Liquid matrix; transports nutrients, hormones, wastes
Red Blood Cells (RBCs)	45%	Contain hemoglobin; transport oxygen
White Blood Cells (WBCs)	<1%	Fight infection; immunity
Platelets	<1%	Blood clotting

Types of Blood Cells:

Cell Type	Characteristics	Function	Normal Count
RBC (Erythrocytes)	Biconcave, no nucleus, contain hemoglobin	O₂ transport	4.5-5.5 million/mm³
WBC (Leukocytes)	Have nucleus, colorless	Immunity	6,000-8,000/mm³
Platelets (Thrombocytes)	Tiny fragments	Clotting	1.5-4 lakh/mm³

Types of WBCs:

• Phagocytes: Engulf germs (Neutrophils, Monocytes)

• Lymphocytes: Produce antibodies

Blood Groups:

Blood Group	Antigens on RBC	Antibodies in Plasma	Can Donate To	Can Receive From
A	A	Anti-B	A, AB	A, O
B	B	Anti-A	B, AB	B, O
AB	A and B	None	AB	All groups (universal recipient)
O	None	Anti-A and Anti-B	All groups (universal donor)	O

Rh Factor:

• Rh-positive: Have Rh antigen (85% Indians)

• Rh-negative: No Rh antigen

D. Double Circulation

Humans have double circulation—blood passes through heart twice for one complete cycle:

Circuit	Pathway	Function
Pulmonary Circulation	Heart → Lungs → Heart	Oxygenation of blood
Systemic Circulation	Heart → Body → Heart	Supply O₂ to body tissues

Pathway of Blood Flow:

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Body (deoxygenated) → Vena Cava → Right Atrium → Right Ventricle → Pulmonary Artery → Lungs (oxygenation) → Pulmonary Vein → Left Atrium → Left Ventricle → Aorta → Body

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7.4.4 Circulation in Other Animals

Animal	Heart Type	Circulation Type
Fish	2-chambered (1 atrium, 1 ventricle)	Single circulation
Frog/Reptiles	3-chambered (2 atria, 1 ventricle)	Incomplete double circulation
Birds/Mammals	4-chambered (2 atria, 2 ventricles)	Complete double circulation
Earthworm	5 pairs of pseudo-hearts	Closed circulation
Cockroach	Tubular heart with chambers	Open circulation

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7.4.5 Pedagogical Implications

Teaching Strategy	Description	PSTET Focus
Model Making	Create heart model using clay	Hands-on learning
Pulse Measurement	Students measure their pulse before/after exercise	Experiential learning
Blood Grouping	Discuss blood group compatibility (theory)	Real-life application
Heart Dissection	Demonstrate using charts/videos (if actual dissection not possible)	Scientific observation

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Section 7.5: Excretion in Animals 🚽

Introduction

Excretion is the process of removing metabolic waste products from the body . If wastes accumulate, they become toxic and can damage cells .

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7.5.1 Excretory Products in Different Animals

Animal	Main Excretory Product	Reason
Humans, Mammals	Urea (ureotelic)	Moderately toxic; requires less water
Fish, Tadpoles	Ammonia (ammonotelic)	Highly toxic; requires plenty of water
Birds, Reptiles, Insects	Uric acid (uricotelic)	Least toxic; conserves water
Earthworm	Urea + Ammonia	Adaptable

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7.5.2 Human Excretory System

Organs of Excretion in Humans:

Organ	Waste Product
Kidneys	Urea, excess water, salts (urine)
Skin	Sweat (water, salts,少量 urea)
Lungs	Carbon dioxide, water vapor
Liver	Bile pigments (from broken RBCs)
Large Intestine	Undigested food (feces)

Human Excretory System Components:

Part	Function
Kidneys (2)	Filter blood; produce urine
Ureters (2)	Carry urine from kidneys to bladder
Urinary Bladder	Stores urine temporarily
Urethra	Carries urine out of body

Structure of Kidney:

Region	Description
Cortex	Outer region; contains nephrons
Medulla	Inner region; contains tubules and collecting ducts
Renal Pelvis	Funnel-shaped; collects urine

Nephron—Functional Unit of Kidney:

Part of Nephron	Function
Glomerulus	Cluster of blood capillaries; filtration
Bowman's Capsule	Cup-shaped structure; collects filtrate
Proximal Convoluted Tubule (PCT)	Reabsorption of glucose, amino acids, water
Loop of Henle	Reabsorption of water and salts
Distal Convoluted Tubule (DCT)	Further reabsorption; secretion of wastes
Collecting Duct	Collects urine from multiple nephrons

Urine Formation Process:

Step	Location	Process	Result
Glomerular Filtration	Glomerulus	Blood pressure forces water and small molecules into Bowman's capsule	Filtrate (contains glucose, amino acids, urea, salts, water)
Tubular Reabsorption	Tubules	Useful substances reabsorbed into blood	Glucose, amino acids,大部分 water returned
Tubular Secretion	Tubules	Additional wastes (H⁺, K⁺, drugs) added to filtrate	Urine formed

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7.5.3 Excretion in Other Animals

Animal	Excretory Organ	Excretory Product
Earthworm	Nephridia	Urea + Ammonia
Cockroach/Insects	Malpighian tubules	Uric acid
Fish	Kidneys	Ammonia
Birds	Kidneys	Uric acid
Amoeba	Contractile vacuole	Excess water, ammonia

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7.5.4 Pedagogical Implications

Teaching Strategy	Description	PSTET Focus
Model Making	Create kidney/nephron model	Hands-on learning
Comparison Chart	Compare excretory products across animals	Analytical thinking
Health Connection	Discuss kidney stones, dialysis	Real-life relevance

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Section 7.6: Movement and Locomotion in Animals (including Human Skeletal and Muscular System) 🦴

Introduction

Movement is a characteristic of living organisms. Locomotion refers to movement from one place to another, while movement includes both locomotion and movement of body parts .

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7.6.1 Types of Movement in Animals

Type	Description	Examples
Amoeboid Movement	Using pseudopodia (false feet)	Amoeba, White blood cells
Ciliary Movement	Using cilia (tiny hair-like structures)	Paramecium, Epithelial cells of respiratory tract
Flagellar Movement	Using flagella (whip-like structures)	Euglena, Sperm cells
Muscular Movement	Using muscles attached to skeleton	Humans, animals, birds

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7.6.2 Human Skeletal System

Functions of Skeletal System:

1. Support: Provides framework for body

2. Protection: Protects vital organs (brain protected by skull, lungs/heart by rib cage)

3. Movement: Bones act as levers for muscles

4. Blood Cell Production: Bone marrow produces RBCs, WBCs, platelets

5. Storage: Stores minerals (calcium, phosphorus)

Structure of Human Skeleton:

Division	Parts	Number of Bones
Axial Skeleton	Skull, vertebral column, rib cage, sternum	80
Appendicular Skeleton	Limbs, shoulder girdle, pelvic girdle	126
Total		206

Axial Skeleton:

Part	Description	Number of Bones
Skull	Cranium (8) + Facial bones (14)	22
Hyoid Bone	In neck; supports tongue	1
Vertebral Column	33 vertebrae: Cervical (7), Thoracic (12), Lumbar (5), Sacral (5 fused), Coccyx (4 fused)	33
Rib Cage	Ribs (12 pairs) + Sternum (breastbone)	24 + 1 = 25
Ear Ossicles	Malleus, Incus, Stapes (smallest bones)	6 (3 each ear)

Appendicular Skeleton:

Part	Description	Number of Bones
Shoulder Girdle	Clavicle (collarbone) + Scapula (shoulder blade)	4 (2 each)
Upper Limbs	Humerus (arm), Radius + Ulna (forearm), Carpals (wrist, 8), Metacarpals (palm, 5), Phalanges (fingers, 14)	30 × 2 = 60
Pelvic Girdle	Hip bones (2)	2
Lower Limbs	Femur (thigh), Patella (kneecap), Tibia + Fibula (leg), Tarsals (ankle, 7), Metatarsals (foot, 5), Phalanges (toes, 14)	30 × 2 = 60

Types of Joints:

Type	Movement	Examples
Fixed (Fibrous)	No movement	Skull bones (sutures)
Slightly Movable (Cartilaginous)	Limited movement	Vertebrae, pubic symphysis
Freely Movable (Synovial)	Free movement	Various types below

Types of Synovial Joints:

Joint Type	Movement	Examples
Ball and Socket	Movement in all directions	Shoulder, Hip
Hinge Joint	Movement in one plane (like door hinge)	Elbow, Knee, Fingers
Pivot Joint	Rotational movement	Neck (atlas-axis), Radio-ulnar joint
Gliding Joint	Sliding movement	Wrist, Ankle, Vertebrae
Saddle Joint	Two-way movement	Thumb (carpometacarpal)
Condyloid Joint	Movement in two planes but no rotation	Wrist (radiocarpal)

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7.6.3 Human Muscular System

Types of Muscles (Recap from Section 7.1):

Type	Location	Control	Structure
Skeletal Muscle	Attached to bones	Voluntary	Striated, multinucleated
Smooth Muscle	Internal organs (stomach, intestine)	Involuntary	Non-striated, spindle-shaped
Cardiac Muscle	Heart	Involuntary	Striated, branched, uninucleated

How Muscles Work:

• Muscles work in antagonistic pairs (one contracts, the other relaxes)

• Example: Biceps and triceps in arm

  • Biceps contracts, triceps relaxes → arm bends

  • Triceps contracts, biceps relaxes → arm straightens

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7.6.4 Locomotion in Other Animals

Animal	Locomotory Organ	Type of Movement
Earthworm	Setae (bristles) + muscles	Peristaltic movement (circular and longitudinal muscles)
Snail	Muscular foot	Gliding movement with mucus
Cockroach	Three pairs of legs + wings	Walking, running, flying
Fish	Fins	Swimming
Bird	Wings	Flying
Snake	Body muscles + scales	Slithering (serpentine, rectilinear, concertina)
Frog	Hind legs (webbed feet)	Jumping, swimming

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7.6.5 Pedagogical Implications

Teaching Strategy	Description	PSTET Focus
Model Making	Create joint models	Hands-on learning
Body Movements Activity	Students identify joints and movements	Experiential learning
Skeleton Chart	Label bones on skeleton chart	Visual learning
Muscle Demonstration	Feel biceps/triceps during arm movement	Self-observation

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Chapter Summary: Key Points for Revision 📝

Quick Revision Table

Topic	Key Points	Common PSTET Questions
Cell to Organism	Cell → Tissue → Organ → System → Organism	Levels of organization
Animal Tissues	Epithelial, Connective, Muscular, Nervous	Types of tissues, functions
Human Digestion	Mouth (amylase), Stomach (pepsin, HCl), Small intestine (absorption via villi), Large intestine (water absorption)	Enzyme functions, digestive organs
Ruminant Digestion	4-chambered stomach (rumen, reticulum, omasum, abomasum)	Why cows chew cud?
Respiration	Lungs (humans), Gills (fish), Skin (earthworm), Trachea (insects)	Respiratory organs in different animals
Human Respiratory System	Nostrils → Pharynx → Larynx → Trachea → Bronchi → Bronchioles → Alveoli	Pathway of air
Circulation	4-chambered heart, arteries (away), veins (toward), capillaries	Blood flow pathway
Blood Components	RBC (O₂ transport), WBC (immunity), Platelets (clotting), Plasma	Functions of blood components
Excretion	Kidneys (urea), Skin (sweat), Lungs (CO₂)	Excretory organs
Skeletal System	206 bones, axial (80) + appendicular (126), types of joints	Bone count, joint types
Muscular System	Skeletal (voluntary), Smooth (involuntary), Cardiac (heart)	Muscle types and location

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Practice Zone: PSTET-Style Questions 🎯

Content-Based MCQs

Q1. Which of the following is NOT a type of animal tissue?
a) Epithelial tissue
b) Connective tissue
c) Vascular tissue
d) Muscular tissue

Q2. The enzyme pepsin acts on:
a) Carbohydrates
b) Fats
c) Proteins
d) Vitamins

Q3. Which organelle is known as the "powerhouse of the cell"?
a) Nucleus
b) Ribosome
c) Mitochondria
d) Golgi apparatus

Q4. In which part of the digestive system are villi found?
a) Stomach
b) Small intestine
c) Large intestine
d) Esophagus

Q5. Which animal respires through gills?
a) Earthworm
b) Cockroach
c) Fish
d) Frog

Q6. How many chambers does the human heart have?
a) 2
b) 3
c) 4
d) 5

Q7. Which blood vessel carries blood away from the heart?
a) Vein
b) Artery
c) Capillary
d) Venule

Q8. The main excretory product in humans is:
a) Ammonia
b) Urea
c) Uric acid
d) Carbon dioxide

Q9. Which type of joint is present in the shoulder?
a) Hinge joint
b) Pivot joint
c) Ball and socket joint
d) Gliding joint

Q10. Which muscle type is found in the heart?
a) Skeletal muscle
b) Smooth muscle
c) Cardiac muscle
d) Striated voluntary muscle

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Pedagogical MCQs

Q11. To teach the concept of cell to a Class 8 student, the most effective approach would be:
a) Give a long lecture
b) Show a diagram of cell and ask students to memorize labels
c) Have students observe cheek cells under a microscope
d) Read from textbook

Q12. A teacher wants to explain peristalsis. The best demonstration would be:
a) Draw diagram on board
b) Show a video of food moving through esophagus
c) Ask students to swallow water and feel the movement
d) Both b and c

Q13. While teaching about different types of teeth, a teacher should:
a) Only use textbook diagrams
b) Have students observe their own teeth in a mirror and identify types
c) Give a list to memorize
d) Show a video only

Q14. To explain the function of alveoli, the best analogy would be:
a) Like a balloon
b) Like a bunch of grapes surrounded by tiny blood vessels
c) Like a tunnel
d) Like a pump

Q15. A student asks, "Why is the left ventricle thicker than the right ventricle?" The teacher should explain that:
a) "That's how it is made"
b) Left ventricle pumps blood to entire body (more force), right ventricle pumps only to lungs (less force)
c) "I don't know"
d) Ignore the question

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Answer Key with Explanations

Q.No.	Answer	Explanation
1	c) Vascular tissue	Vascular tissue is found in plants (xylem, phloem); animal tissues are epithelial, connective, muscular, nervous
2	c) Proteins	Pepsin is a protein-digesting enzyme in stomach
3	c) Mitochondria	Mitochondria produce ATP through cellular respiration
4	b) Small intestine	Villi increase surface area for absorption in small intestine
5	c) Fish	Fish respire through gills (extract O₂ from water)
6	c) 4	Human heart has 2 atria and 2 ventricles
7	b) Artery	Arteries carry blood away from heart; veins carry blood toward heart
8	b) Urea	Humans are ureotelic—excrete urea as main nitrogenous waste
9	c) Ball and socket joint	Shoulder and hip have ball and socket joints allowing movement in all directions
10	c) Cardiac muscle	Cardiac muscle is specialized, involuntary, and found only in heart
11	c) Microscope observation	Hands-on observation is most effective for cell structure
12	d) Both b and c	Video shows process; swallowing helps students feel peristalsis
13	b) Observe in mirror	Self-observation makes learning concrete and memorable
14	b) Grapes surrounded by blood vessels	Best visual analogy for structure-function relationship
15	b) Left ventricle pumps to body	Correct scientific explanation based on function

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Pedagogical Reflection for Teachers 🤔

Think-Pair-Share Activity:

1. Think: How would you explain the difference between breathing and respiration to your students?

2. Pair: Discuss with a colleague how you would set up a "Body Systems Learning Corner" in your classroom with models and charts.

3. Share: Design a 15-minute activity to teach the path of food through the digestive system using a role-play where students act as different organs.

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NCERT Textbook Linkages 📚

Class	Chapter	Topic
Class 7	Chapter 2	Nutrition in Animals
Class 7	Chapter 10	Respiration in Organisms
Class 7	Chapter 11	Transportation in Animals and Plants
Class 8	Chapter 8	Cell—Structure and Functions
Class 9	Chapter 5	The Fundamental Unit of Life
Class 9	Chapter 6	Tissues
Class 10	Chapter 5	Life Processes

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Chapter End Notes

Key Terminology Glossary

Term	Definition
Cell	Basic structural and functional unit of life
Tissue	Group of similar cells performing specific function
Organ	Group of tissues working together
Organ System	Group of organs working together
Ingestion	Taking food into the body
Digestion	Breaking down food into absorbable form
Absorption	Taking digested nutrients into blood
Assimilation	Using absorbed nutrients for body functions
Egestion	Removal of undigested food
Respiration	Process of releasing energy from food using oxygen
Inhalation	Taking air into lungs
Exhalation	Expelling air from lungs
Circulation	Transport of substances through blood
Systole	Contraction of heart chambers
Diastole	Relaxation of heart chambers
Excretion	Removal of metabolic wastes
Nephron	Functional unit of kidney
Locomotion	Movement from one place to another
Joint	Place where two bones meet

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Quick Tips for PSTET Aspirants ⚡

✅ Memorize with Mnemonics:

• Tissue Types: "Every Cool Monkey Needs" = Epithelial, Connective, Muscular, Nervous

• Digestive Enzymes: "Amylase (mouth), Pepsin (stomach), Trypsin (pancreas), Lipase (pancreas)" = A P T L

• Heart Chambers: "Rice Pudding Lemon Soda" = Right atrium, Right ventricle, Left atrium, Left ventricle

• Blood Flow: "Very Angry Cats" = Veins (toward heart), Arteries (away from heart), Capillaries (connect)

• Excretory Products: "All Unicorns Urinate" = Ammonia (fish), Urea (humans), Uric acid (birds)

• Joint Types: "Ball, Hinge, Pivot, Gliding, Saddle" = BHPGS

✅ Common Exam Traps:

• Pepsin digests proteins, not carbohydrates

• Bile emulsifies fats but contains NO enzymes

• RBCs have no nucleus (in humans)

• Pulmonary artery carries deoxygenated blood (exception to "arteries carry oxygenated blood")

• Pulmonary vein carries oxygenated blood (exception to "veins carry deoxygenated blood")

• Left ventricle is thickest chamber (pumps to whole body)

• Urea is main excretory product in humans, not ammonia or uric acid

• Cardiac muscle is involuntary but striated (unique)

• Smooth muscle is non-striated and involuntary

✅ Important Facts:

• 206 bones in adult human skeleton (300 at birth, some fuse later)

• Smallest bone: Stapes in ear (0.25-0.33 cm)

• Longest bone: Femur (thigh bone)

• Hardest substance in body: Tooth enamel

• Largest organ: Skin

• Heart beats about 100,000 times per day

• Blood volume: 5-6 liters in adults

• Nephrons: About 1 million per kidney

• Alveoli: About 300-500 million in lungs (surface area ~70-100 m²)

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Answers to "Check Your Understanding"

[To be filled by student]

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📝 Note for Self-Study: After completing this chapter, ensure you can:

• Explain the levels of organization from cell to organism

• Name all four animal tissues with their functions and locations

• Trace the path of food through human digestive system

• List enzymes and their actions in digestion

• Explain ruminant digestion process

• Describe respiratory organs in different animals

• Trace blood flow through heart and body

• List components of blood and their functions

• Explain urine formation in nephron

• Name all major bones and their locations

• Identify types of joints with examples

• Differentiate between skeletal, smooth, and cardiac muscles

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End of Chapter 7

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Next Chapter: Chapter 8 - Biological Classification and Evolution (Basic Concepts)
Topics Covered: Need for Classification, Classification of Plants and Animals

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