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Structural Organisation in Animals – CBSE NCERT Study Resources

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11th

11th - Biology

Structural Organisation in Animals

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Overview of the Chapter

This chapter, "Structural Organisation in Animals," introduces students to the basic structural and functional organization in animals, focusing on tissues, organs, and organ systems. It covers the four primary types of animal tissues—epithelial, connective, muscular, and neural—along with their structure and functions. The chapter also explores the anatomy and morphology of earthworms, cockroaches, and frogs as representative examples of different animal groups.

Animal Tissue: A group of cells with similar structure and function, working together to perform a specific role in the body.

Animal Tissues

Epithelial Tissue

Epithelial tissue forms the covering or lining of body surfaces. It is classified into simple (single-layered) and compound (multi-layered) epithelium. Functions include protection, secretion, absorption, and sensory reception.

Connective Tissue

Connective tissue supports and binds other tissues. It includes loose connective tissue (areolar, adipose), dense connective tissue (tendons, ligaments), and specialized types like cartilage, bone, and blood.

Matrix: The non-living, intercellular substance in connective tissue that provides support and structure.

Muscular Tissue

Muscular tissue is responsible for movement. It is categorized into three types: skeletal (voluntary), smooth (involuntary), and cardiac (found in the heart).

Neural Tissue

Neural tissue consists of neurons and neuroglia, which transmit nerve impulses and support neural functions, respectively.

Earthworm (Pheretima)

Earthworms exhibit metameric segmentation. Their body is divided into segments called metameres. Key features include a closed circulatory system, nephridia for excretion, and a hermaphroditic reproductive system.

Cockroach (Periplaneta americana)

Cockroaches belong to the phylum Arthropoda. They have an open circulatory system, Malpighian tubules for excretion, and a well-developed digestive and nervous system. Their body is divided into head, thorax, and abdomen.

Exoskeleton: A rigid external covering made of chitin that provides support and protection in arthropods.

Frog (Rana tigrina)

Frogs are amphibians with a moist, glandular skin. They have a three-chambered heart, respire through lungs and skin, and exhibit sexual dimorphism. Their life cycle includes metamorphosis from tadpole to adult.

All Question Types with Solutions – CBSE Exam Pattern

Explore a complete set of CBSE-style questions with detailed solutions, categorized by marks and question types. Ideal for exam preparation, revision and practice.

Very Short Answer (1 Mark) – with Solutions (CBSE Pattern)

These are 1-mark questions requiring direct, concise answers. Ideal for quick recall and concept clarity.

Question 1:
Define epithelial tissue.
Answer:
Definition: Tissue covering body surfaces, lining cavities, and forming glands.
Question 2:
Name the protein present in striated muscles.
Answer:

Actin and myosin.

Question 3:
What is the function of neuroglial cells?
Answer:

Support and protect neurons.

Question 4:
Identify the type of epithelium in alveoli.
Answer:

Simple squamous epithelium.

Question 5:
Give one example of fluid connective tissue.
Answer:

Blood.

Question 6:
What is the role of tendons?
Answer:

Connect muscles to bones.

Question 7:
Name the cartilage present in the ear pinna.
Answer:

Elastic cartilage.

Question 8:
Which cells produce adipose tissue?
Answer:

Adipocytes.

Question 9:
What is the structural unit of compact bone?
Answer:

Osteon (Haversian system).

Question 10:
Define neuron.
Answer:
Definition: Functional unit of the nervous system.
Question 11:
Name the connective tissue storing fats.
Answer:

Adipose tissue.

Question 12:
What is the function of ciliated epithelium?
Answer:

Moves mucus or particles.

Question 13:
Identify the muscle type found in the heart.
Answer:

Cardiac muscle.

Question 14:
Give one example of areolar tissue.
Answer:

Under the skin.

Question 15:
Name the epithelial tissue that forms the lining of blood vessels.
Answer:

The lining of blood vessels is made of simple squamous epithelium.
It allows smooth blood flow and diffusion of substances.

Question 16:
What is the function of areolar connective tissue?
Answer:

Areolar connective tissue provides support, elasticity, and fills spaces between organs.
It also helps in repair and defense by housing macrophages.

Question 17:
Identify the type of muscle found in the wall of the heart.
Answer:

The heart wall contains cardiac muscle tissue.
It is striated, involuntary, and has intercalated discs for synchronized contractions.

Question 18:
What is the role of neuroglial cells in nervous tissue?
Answer:

Neuroglial cells support, protect, and nourish neurons.
They maintain homeostasis and form myelin sheaths for faster signal transmission.

Question 19:
Name the protein present in cartilage that provides flexibility.
Answer:

Cartilage contains chondrin (a protein matrix) that gives it flexibility and resilience.

Question 20:
Which type of epithelium is found in the lining of the stomach?
Answer:

The stomach lining has simple columnar epithelium.
It secretes mucus and enzymes for digestion and protection from acid.

Question 21:
What is the function of tendons?
Answer:

Tendons connect muscles to bones, enabling movement.
They are made of dense regular connective tissue for high tensile strength.

Question 22:
Define stratified epithelium with an example.
Answer:

Stratified epithelium has multiple layers for protection.
Example: Stratified squamous epithelium in the skin (epidermis).

Question 23:
Why are osteocytes important in bone tissue?
Answer:

Osteocytes maintain bone matrix and regulate calcium balance.
They communicate via canaliculi for nutrient exchange.

Question 24:
Name the fluid connective tissue in humans.
Answer:

Blood and lymph are fluid connective tissues.
They transport nutrients, gases, and waste products.

Question 25:
What is the structural unit of compact bone?
Answer:

The osteon (Haversian system) is the structural unit of compact bone.
It contains concentric lamellae around a central canal.

Question 26:
Differentiate between exocrine and endocrine glands.
Answer:
  • Exocrine glands secrete products (e.g., sweat, saliva) via ducts.
  • Endocrine glands release hormones directly into the bloodstream.
Question 27:
Name the type of epithelium found in the lining of blood vessels.
Answer:

The lining of blood vessels is made of simple squamous epithelium. This epithelium allows easy diffusion of substances due to its thin, flat cells.

Question 28:
What is the function of areolar tissue?
Answer:

Areolar tissue acts as a supporting framework for organs, fills spaces between tissues, and helps in repair and defense by containing fibroblasts and macrophages.

Question 29:
Identify the protein present in striated muscles that gives them a striped appearance.
Answer:

The striped appearance of striated muscles is due to actin and myosin proteins arranged in alternating dark and light bands.

Question 30:
Which type of connective tissue stores fat in the body?
Answer:

Adipose tissue is the fat-storing connective tissue. It acts as an insulator and energy reserve.

Very Short Answer (2 Marks) – with Solutions (CBSE Pattern)

These 2-mark questions test key concepts in a brief format. Answers are expected to be accurate and slightly descriptive.

Question 1:
Name the four types of tissues found in animals.
Answer:

The four types of tissues found in animals are:
Epithelial tissue, Connective tissue, Muscular tissue, and Nervous tissue.

Question 2:
Differentiate between simple epithelium and compound epithelium.
Answer:

Simple epithelium consists of a single layer of cells, found in areas of absorption and filtration (e.g., lining of blood vessels).
Compound epithelium has multiple layers, providing protection (e.g., skin).

Question 3:
What are the two main types of skeletal muscle fibers?
Answer:

The two main types of skeletal muscle fibers are:
Red fibers (slow-twitch, high endurance)
White fibers (fast-twitch, rapid contraction).

Question 4:
Explain the role of neuroglial cells in the nervous system.
Answer:

Neuroglial cells provide support, insulation, and nutrients to neurons. They also help in maintaining the blood-brain barrier and repairing damaged neurons.

Question 5:
Name the three types of cartilage and give one location for each.
Answer:

The three types of cartilage are:
Hyaline cartilage (trachea)
Fibrocartilage (intervertebral discs)
Elastic cartilage (ear pinna).

Question 6:
What is the function of stratified squamous epithelium?
Answer:

Stratified squamous epithelium provides protection against mechanical and chemical stress. It is found in the skin, mouth, and esophagus.

Question 7:
Define neuron and list its three main parts.
Answer:

A neuron is the structural and functional unit of the nervous system. Its three main parts are:
Cell body, Dendrites, and Axon.

Question 8:
What is the significance of intercalated discs in cardiac muscles?
Answer:

Intercalated discs facilitate synchronized contraction of cardiac muscles by allowing rapid electrical impulse transmission between cells.

Question 9:
Name the protein present in white fibers of skeletal muscles.
Answer:

The protein present in white fibers is myosin, which enables rapid contraction.

Question 10:
How does adipose tissue help in thermoregulation?
Answer:

Adipose tissue acts as an insulator, reducing heat loss and maintaining body temperature. It also stores energy as fat.

Short Answer (3 Marks) – with Solutions (CBSE Pattern)

These 3-mark questions require brief explanations and help assess understanding and application of concepts.

Question 1:
Explain the structure and function of squamous epithelium with an example.
Answer:

The squamous epithelium is a single layer of flat, scale-like cells with irregular boundaries. It forms a delicate lining for surfaces involved in diffusion, filtration, or secretion.

Function: It allows easy passage of substances due to its thinness, making it ideal for gas exchange (e.g., alveoli of lungs) or filtration (e.g., Bowman’s capsule in kidneys).

Example: The lining of blood vessels (endothelium) and the air sacs of lungs (alveoli) are made of squamous epithelium.

Question 2:
Differentiate between smooth muscle and skeletal muscle based on structure and location.
Answer:

Smooth Muscle:

  • Structure: Spindle-shaped, uninucleate cells with no striations.
  • Location: Found in walls of hollow organs like the stomach, intestines, and blood vessels.

Skeletal Muscle:
  • Structure: Long, cylindrical, multinucleate cells with prominent striations.
  • Location: Attached to bones for voluntary movements.

Question 3:
Describe the role of neuroglial cells in the nervous system.
Answer:

Neuroglial cells are non-neuronal cells that provide support and protection to neurons.

Functions:

  • Provide structural support to neurons.
  • Supply nutrients and oxygen.
  • Insulate neurons (myelin sheath formation by oligodendrocytes and Schwann cells).
  • Defend against pathogens (microglia act as immune cells).

They maintain homeostasis and ensure efficient nerve impulse transmission.

Question 4:
What are compound epithelia? Give one example and its function.
Answer:

Compound epithelia consist of multiple layers of cells, providing protection against mechanical and chemical stress.

Example: Stratified squamous epithelium (found in skin, esophagus).

Function: It protects underlying tissues from abrasion, dehydration, and pathogens. The outer layer (keratinized in skin) adds extra toughness.

Question 5:
Explain the significance of earthworm's chloragogen cells.
Answer:

Chloragogen cells in earthworms are yellowish cells surrounding the intestine and blood vessels.

Functions:

  • Store glycogen and fats for energy.
  • Detoxify harmful nitrogenous wastes (similar to liver function in vertebrates).
  • Help in excretion by converting ammonia into urea.

They play a vital role in metabolism and immunity.

Question 6:
How does the cockroach's malpighian tubules aid in excretion?
Answer:

Malpighian tubules are thin, filamentous structures in cockroaches that remove waste from the hemolymph.

Process:
1. Tubules absorb nitrogenous wastes (mainly uric acid) and salts.
2. Wastes are released into the hindgut.
3. Water and useful ions are reabsorbed, leaving dry uric acid for excretion.

This conserves water, making it an adaptation for terrestrial life.

Question 7:
Explain the role of epithelial tissue in animals with two examples.
Answer:

Epithelial tissue forms the protective covering of the body and internal organs. It plays a crucial role in protection, absorption, secretion, and sensation.

  • Example 1: Simple squamous epithelium in the alveoli of lungs facilitates gas exchange.
  • Example 2: Stratified squamous epithelium in the skin protects against mechanical injury and pathogens.
Question 8:
Differentiate between smooth muscle and skeletal muscle based on structure and function.
Answer:

Smooth Muscle:
Structure: Spindle-shaped, uninucleate, no striations.
Function: Involuntary movements (e.g., digestion, blood vessel constriction).

Skeletal Muscle:
Structure: Cylindrical, multinucleate, striated.
Function: Voluntary movements (e.g., walking, lifting).

Question 9:
Describe the structure and function of neuron with a labeled diagram.
Answer:

Structure:
1. Cell body (soma): Contains nucleus and cytoplasm.
2. Dendrites: Receive signals.
3. Axon: Transmits signals.
4. Myelin sheath: Insulates axon for faster signal transmission.

Function: Neurons transmit electrical and chemical signals for communication in the nervous system.

Diagram: (Draw a neuron with labels for cell body, dendrites, axon, and myelin sheath.)

Question 10:
What are the functions of connective tissue? Give two examples with their roles.
Answer:

Connective tissue provides support, binding, and protection to organs.

  • Example 1: Bone (rigid connective tissue) supports the body and protects vital organs.
  • Example 2: Blood (fluid connective tissue) transports nutrients, gases, and waste.
Question 11:
Explain the term compound epithelium and its significance.
Answer:

Compound epithelium consists of multiple layers of cells, providing mechanical protection against wear and tear.

Significance:
1. Found in skin, mouth, and esophagus.
2. Prevents water loss and pathogen entry.
3. Cells at the base divide to replace damaged surface cells.

Question 12:
How does cartilage differ from bone in terms of structure and flexibility?
Answer:

Cartilage:
Structure: Semi-rigid, contains chondrocytes in lacunae, matrix rich in chondroitin.
Flexibility: Highly flexible (e.g., ear pinna, trachea).

Bone:
Structure: Rigid, contains osteocytes in lacunae, matrix rich in calcium salts.
Flexibility: Non-flexible, provides structural support.

Long Answer (5 Marks) – with Solutions (CBSE Pattern)

These 5-mark questions are descriptive and require detailed, structured answers with proper explanation and examples.

Question 1:
Explain the structural hierarchy in animal tissues with reference to epithelial and connective tissues. How do these tissues contribute to organ function?
Answer:
Theoretical Framework

We studied that animal tissues follow a structural hierarchy: cells → tissues → organs → systems. Epithelial tissues form protective linings, while connective tissues provide support.

Evidence Analysis
  • Example 1: Simple squamous epithelium in alveoli aids gas exchange.
  • Example 2: Bone (connective tissue) supports and protects organs.
Critical Evaluation

NCERT highlights that epithelial tissues lack blood vessels, relying on diffusion. Connective tissues have abundant extracellular matrix.

Future Implications

Understanding tissue organization helps in regenerative medicine and organ transplantation research.

Question 2:
Compare skeletal, smooth, and cardiac muscles based on structure, location, and function. Provide two examples for each.
Answer:
Theoretical Framework

Muscle tissues are classified as skeletal (voluntary), smooth (involuntary), and cardiac (heart-specific).

Evidence Analysis
  • Skeletal: Attached to bones (e.g., biceps), striated.
  • Smooth: Walls of organs (e.g., intestine), non-striated.
  • Cardiac: Heart wall, branched fibers.
Critical Evaluation

Our textbook shows cardiac muscles have intercalated discs for synchronized contractions, unlike others.

Future Implications

Research on muscle types aids in treating myopathies and heart diseases.

Question 3:
Describe the morphology and anatomy of an earthworm. How does its segmentation enhance survival?
Answer:
Theoretical Framework

Earthworms exhibit metameric segmentation and a tube-within-tube anatomy.

Evidence Analysis
  • Example 1: Setae in each segment aid locomotion.
  • Example 2: Chloragogen cells detoxify blood.
Critical Evaluation

NCERT states segmentation allows redundancy; damage to one segment doesn’t affect others.

Future Implications

Studying earthworms aids soil fertility research and waste management.

Question 4:
Analyze the adaptive features of cockroach for its nocturnal lifestyle. Include sensory and locomotor adaptations.
Answer:
Theoretical Framework

Cockroaches have compound eyes, antennae, and tegmina for nocturnal survival.

Evidence Analysis
  • Example 1: Antennae detect air currents and chemicals.
  • Example 2: Hind wings enable quick flight from predators.
Critical Evaluation

Our textbook shows their exoskeleton reduces water loss, crucial for urban habitats.

Future Implications

Understanding adaptations can inspire bio-mimetic robots for dark environments.

Question 5:
Explain the digestive system of a frog with emphasis on enzymatic action and absorption. How does it differ from humans?
Answer:
Theoretical Framework

Frogs have a short alimentary canal with trypsin and lipase secretion in the duodenum.

Evidence Analysis
  • Example 1: Liver secretes bile for fat emulsification.
  • Example 2: Villi in humans increase surface area, absent in frogs.
Critical Evaluation

NCERT highlights frogs lack salivary amylase, unlike humans.

Future Implications

Comparative studies help understand evolutionary dietary adaptations.

Question 6:
Explain the structural and functional organization of epithelial tissues with two examples.
Answer:
Theoretical Framework

Epithelial tissues are tightly packed layers of cells covering body surfaces or lining cavities. They are classified as simple (single layer) or stratified (multiple layers), based on structure.

Evidence Analysis
  • Simple squamous epithelium (e.g., alveoli) facilitates gas exchange due to thinness.
  • Stratified squamous epithelium (e.g., skin) provides protection against abrasion.
Critical Evaluation

Our textbook shows that epithelial cells exhibit polarity, with apical and basal surfaces, enabling selective absorption/secretion.

Future Implications

Understanding epithelial organization helps in studying diseases like carcinomas, where cell adhesion is disrupted.

Question 7:
Compare skeletal, cardiac, and smooth muscles based on structure, location, and function.
Answer:
Theoretical Framework

Muscle tissues are specialized for contraction. Skeletal muscles are voluntary, cardiac muscles are involuntary and striated, while smooth muscles are non-striated.

Evidence Analysis
  • Skeletal muscles (e.g., biceps) attach to bones for movement.
  • Cardiac muscles (e.g., heart wall) pump blood rhythmically.
  • Smooth muscles (e.g., intestine) control slow, involuntary movements.
Critical Evaluation

We studied that cardiac muscles have intercalated discs for synchronized contractions, unlike skeletal muscles.

Future Implications

Research on muscle types aids in treating myopathies and cardiovascular diseases.

Question 8:
Describe the morphology and anatomy of earthworms, highlighting adaptations for burrowing.
Answer:
Theoretical Framework

Earthworms (Pheretima) exhibit metameric segmentation and a hydrostatic skeleton, aiding in locomotion.

Evidence Analysis
  • Setae provide grip during burrowing.
  • Clitellum secretes cocoons for reproduction.
Critical Evaluation

Our textbook shows that their digestive system (crop, gizzard) adapts to soil digestion, enhancing nutrient absorption.

Future Implications

Studying earthworm anatomy helps in vermiculture and soil fertility management.

Question 9:
Analyze the role of connective tissues in providing mechanical support and immunity.
Answer:
Theoretical Framework

Connective tissues (CT) consist of cells, fibers, and ground substance, offering structural and defensive functions.

Evidence Analysis
  • Bone (rigid CT) supports body weight.
  • Blood (fluid CT) transports immune cells like leukocytes.
Critical Evaluation

We studied that collagen fibers in tendons resist tension, while lymphoid organs house lymphocytes for immunity.

Future Implications

CT research aids in regenerative medicine and autoimmune disease treatments.

Question 10:
Explain how neural tissue coordinates body functions through neurons and neuroglia.
Answer:
Theoretical Framework

Neural tissue comprises neurons (impulse transmission) and neuroglia (support cells). Neurons have dendrites, axons, and synapses.

Evidence Analysis
  • Motor neurons (e.g., spinal cord) relay signals to muscles.
  • Neuroglia (e.g., oligodendrocytes) insulate axons with myelin.
Critical Evaluation

Our textbook shows that action potentials propagate due to ion gradients, enabling rapid communication.

Future Implications

Understanding neural tissue helps in treating neurodegenerative disorders like Alzheimer's.

Question 11:
Describe the structure and functions of epithelial tissue with suitable examples. How does it differ from connective tissue?
Answer:

Epithelial tissue is a protective tissue that covers the body's surface, lines cavities, and forms glands. It is characterized by tightly packed cells with little extracellular matrix.

Structure:

  • Cells are closely packed with minimal intercellular spaces.
  • Avascular (no blood vessels) but innervated (has nerve supply).
  • Basement membrane separates it from underlying connective tissue.
Functions:
  • Protection (e.g., skin epidermis).
  • Absorption (e.g., intestinal lining).
  • Secretion (e.g., glandular epithelium).
  • Sensory reception (e.g., taste buds).
Examples: Squamous (skin), cuboidal (kidney tubules), columnar (stomach lining).

Difference from connective tissue:
  • Epithelial tissue has tightly packed cells, while connective tissue has scattered cells in a matrix.
  • Epithelial tissue is avascular, whereas connective tissue is vascular (except cartilage).
  • Epithelial tissue lacks fibers, but connective tissue has collagen, elastic, or reticular fibers.

Question 12:
Explain the structure and functions of neural tissue. How does it facilitate communication in the body?
Answer:

Neural tissue is specialized for transmitting electrical impulses and coordinating body activities. It consists of neurons and neuroglia (supporting cells).

Structure of a neuron:

  • Cell body (soma): Contains nucleus and organelles.
  • Dendrites: Receive signals from other neurons.
  • Axon: Transmits signals away from the cell body.
  • Myelin sheath: Insulates the axon (formed by Schwann cells in PNS).
Functions:
  • Rapid communication via electrical impulses (action potentials).
  • Integration of sensory input and motor output.
  • Maintenance of homeostasis through reflexes.
Communication process:
1. Dendrites receive signals.
2. Cell body integrates inputs.
3. Axon transmits the impulse to the next neuron or effector organ.
4. Synapses (junctions between neurons) use neurotransmitters for signal transmission.

Example: When touching a hot object, sensory neurons send signals to the spinal cord, and motor neurons trigger muscle contraction to withdraw the hand.

Question 13:
Compare and contrast striated, non-striated, and cardiac muscles based on their structure, location, and functions.
Answer:

Comparison of muscle types:

1. Striated (Skeletal) Muscle:

  • Structure: Long, cylindrical fibers with striations (alternating light and dark bands). Multinucleated.
  • Location: Attached to bones via tendons.
  • Function: Voluntary movement (e.g., walking, lifting).
2. Non-striated (Smooth) Muscle:
  • Structure: Spindle-shaped cells with no striations. Single nucleus.
  • Location: Walls of hollow organs (e.g., stomach, blood vessels).
  • Function: Involuntary movements (e.g., peristalsis, blood flow regulation).
3. Cardiac Muscle:
  • Structure: Branched fibers with striations and intercalated discs. Single nucleus.
  • Location: Heart wall.
  • Function: Involuntary, rhythmic contractions to pump blood.
Key differences:
  • Control: Striated is voluntary; others are involuntary.
  • Striations: Absent in smooth muscle.
  • Nuclei: Skeletal is multinucleated; others are uninucleated.

Question 14:
Explain the structure and functions of epithelial tissue with suitable examples. How does its arrangement contribute to its specialized roles in animals?
Answer:

Epithelial tissue is a protective layer of closely packed cells that covers body surfaces, lines cavities, and forms glands. It is classified based on shape and layering:

  • Simple epithelium: Single layer (e.g., squamous in alveoli for diffusion, cuboidal in kidney tubules for absorption).
  • Stratified epithelium: Multiple layers (e.g., skin epidermis for abrasion resistance).
  • Pseudostratified epithelium: Appears layered but is single-layered (e.g., trachea with cilia to trap dust).

Functions include:
Protection (skin against pathogens),
Secretion (glandular epithelium like sweat glands),
Absorption (intestinal lining with microvilli).

Its tight cell arrangement ensures minimal leakage, while basement membrane anchors it to connective tissue. Specializations like cilia or microvilli enhance function.

Question 15:
Describe the morphology and anatomy of an earthworm. How do its adaptations make it efficient in soil enrichment?
Answer:

Morphology: Earthworms (Pheretima) have a cylindrical, segmented body (100-120 segments) with:
Dorsal pores (release coelomic fluid),
Clitellum (glandular band for cocoon formation),
Setae (bristles for locomotion).

Anatomy:
Digestive system: Pharynx, gizzard (grinds soil), intestine with typhlosole (absorbs nutrients).
Circulatory system: Closed with dorsal and ventral vessels.
Nervous system: Ganglia and ventral nerve cord.

Adaptations for soil enrichment:
1. Burrowing aerates soil, improving root growth.
2. Castings (excreted soil) are nutrient-rich.
3. Decomposition: Gut microbes break down organic matter, recycling nitrogen/phosphorus.

Question 16:
Describe the structure and functions of epithelial tissue with suitable diagrams. Highlight its role in animal body organization.
Answer:

Epithelial tissue is a protective layer of closely packed cells covering body surfaces, lining cavities, and forming glands. It is classified into simple (single layer) and compound (multiple layers) types.

Structure:
1. Simple squamous epithelium: Flat cells for diffusion (e.g., alveoli).
2. Simple cuboidal epithelium: Cube-shaped cells for secretion (e.g., kidney tubules).
3. Simple columnar epithelium: Tall cells with microvilli for absorption (e.g., intestine).
4. Ciliated epithelium: Hair-like projections to move mucus (e.g., respiratory tract).
5. Stratified epithelium: Multiple layers for protection (e.g., skin).

Functions:

  • Protection: Shields underlying tissues from injury/infection.
  • Absorption/Secretion: Facilitates nutrient uptake and glandular activity.
  • Sensory reception: Detects stimuli (e.g., taste buds).

Role in organization: Forms barriers, regulates exchange, and maintains homeostasis. Diagrams should show cell arrangements and labeling.

Question 17:
Compare striated, non-striated, and cardiac muscles based on structure, location, and function. Include a labeled diagram for clarity.
Answer:

Comparison of muscle types:

  • Striated (Skeletal) Muscle:
    Structure: Long, cylindrical fibers with striations and multiple nuclei.
    Location: Attached to bones.
    Function: Voluntary movements (e.g., walking).
  • Non-striated (Smooth) Muscle:
    Structure: Spindle-shaped, uninucleate cells without striations.
    Location: Walls of hollow organs (e.g., stomach).
    Function: Involuntary movements (e.g., peristalsis).
  • Cardiac Muscle:
    Structure: Branched, striated fibers with intercalated discs and single nucleus.
    Location: Heart.
    Function: Involuntary, rhythmic contractions.

Diagram: Illustrate fiber shapes, striations, and nuclei. Highlight intercalated discs in cardiac muscle.

Question 18:
Explain the structure and functions of epithelial tissue with suitable diagrams. Highlight its role in protection, absorption, and secretion in animals.
Answer:

Epithelial tissue is a protective covering or lining present on all external and internal surfaces of the body. It consists of closely packed cells with little extracellular matrix. The structure and functions are as follows:

  • Structure:
    1. Cells are tightly packed with minimal intercellular spaces.
    2. It is avascular (lacks blood vessels) but innervated (has nerve supply).
    3. It rests on a basement membrane for support and attachment.
    4. Classified into simple (single layer) and compound (multiple layers) epithelium.
  • Functions:
    1. Protection: Acts as a barrier against mechanical injury, pathogens, and dehydration (e.g., skin).
    2. Absorption: Facilitates nutrient uptake (e.g., intestinal lining).
    3. Secretion: Glandular epithelium produces enzymes, hormones, and mucus (e.g., goblet cells).

Value-added info: Epithelial cells regenerate rapidly, aiding in wound healing. Ciliated epithelium in the respiratory tract helps in mucus movement.

Question 19:
Describe the structure and functions of neural tissue. How does it facilitate coordination and control in animals? Include a labeled diagram of a neuron.
Answer:

Neural tissue is specialized for rapid communication via electrical and chemical signals. It consists of neurons and neuroglia (supporting cells).

  • Structure of a Neuron:
    1. Cell body (soma): Contains nucleus and organelles.
    2. Dendrites: Short, branched extensions receiving signals.
    3. Axon: Long fiber transmitting impulses away from the cell body.
    4. Myelin sheath: Insulating layer (formed by Schwann cells) speeding up signal transmission.
  • Functions:
    1. Coordination: Neurons transmit sensory input to the brain and motor output to muscles.
    2. Control: Regulates voluntary (e.g., movement) and involuntary (e.g., heartbeat) actions.
    3. Integration: Processes information in the brain and spinal cord.

Application: Reflex arcs (e.g., knee-jerk reaction) showcase rapid neural responses without brain involvement.
Diagram note: A labeled neuron should show dendrites, cell body, axon, myelin sheath, and nodes of Ranvier.

Question 20:
Explain the structure and functions of epithelial tissue with suitable diagrams. Highlight its role in protection, absorption, and secretion.
Answer:

Epithelial tissue is a protective covering or lining present on external and internal body surfaces. It consists of tightly packed cells with minimal intercellular matrix.

Structure:
1. Cells are arranged in single or multiple layers (simple or stratified).
2. Avascular (no blood vessels).
3. Basement membrane provides support.
4. Classified by shape: squamous, cuboidal, or columnar.

Functions:

  • Protection: Skin epithelium prevents mechanical injury and pathogen entry.
  • Absorption: Intestinal epithelium absorbs nutrients via microvilli.
  • Secretion: Glandular epithelium (e.g., salivary glands) releases enzymes/mucus.

Value-add: Cilia in respiratory epithelium trap dust, showing specialization. Always draw labeled diagrams of squamous (flat) and columnar (elongated) types for full marks.

Question 21:
Compare striated, non-striated, and cardiac muscles based on structure, location, and control. Include one functional adaptation of each type.
Answer:

Comparison:

FeatureStriatedNon-striatedCardiac
StructureLong, cylindrical, multinucleatedSpindle-shaped, uninucleatedBranched, uninucleated
LocationAttached to bonesWalls of hollow organs (e.g., intestine)Heart
ControlVoluntaryInvoluntaryInvoluntary

Functional Adaptations:

  • Striated: High contractile force for locomotion (e.g., biceps).
  • Non-striated: Slow, sustained contractions for peristalsis.
  • Cardiac: Intercalated discs ensure rhythmic heartbeat.

Note: Striations in skeletal/cardiac muscles are due to actin-myosin arrangement. Diagrams must show these differences clearly.

Case-based Questions (4 Marks) – with Solutions (CBSE Pattern)

These 4-mark case-based questions assess analytical skills through real-life scenarios. Answers must be based on the case study provided.

Question 1:
In a lab study, epithelial tissues from the intestine and trachea were compared. Analyze the structural adaptations of these tissues for their functions.
Answer:
Case Deconstruction

We studied that intestinal epithelium is simple columnar with microvilli for absorption, while tracheal epithelium is pseudostratified ciliated for mucus movement.

Theoretical Application
  • Microvilli increase surface area (e.g., nutrient absorption in jejunum).
  • Cilia in trachea expel pathogens (e.g., dust particles trapped in mucus).
Critical Evaluation

Textbook data confirms cilia beat frequency (10-20 Hz) aligns with respiratory defense, whereas microvilli density correlates with digestive efficiency.

Question 2:
A student observed striated, non-striated, and cardiac muscles under a microscope. Differentiate them based on location and regulatory mechanisms.
Answer:
Case Deconstruction

Striated muscles are voluntary (e.g., biceps), while non-striated (e.g., intestine) and cardiac muscles are involuntary.

Theoretical Application
  • Cardiac muscles auto-rhythmically contract (e.g., pacemaker cells in SA node).
  • Non-striated muscles respond to neurotransmitters (e.g., adrenaline in blood vessels).
Critical Evaluation

Our textbook shows striations correlate with sarcomere organization, explaining faster contraction in skeletal muscles.

Question 3:
Compare the earthworm and cockroach circulatory systems. How does their open or closed nature impact metabolic rates?
Answer:
Case Deconstruction

Earthworms have closed circulation with capillaries, while cockroaches rely on hemolymph in open sinuses.

Theoretical Application
  • Closed systems enable higher pressure (e.g., aortic arches in earthworms).
  • Open systems limit oxygen delivery (e.g., tracheal reliance in cockroaches).
Critical Evaluation

Data shows earthworms sustain longer activity due to efficient nutrient transport, unlike cockroaches’ sporadic mobility.

Question 4:
During dissection, two types of neural tissues were identified: gray matter and white matter. Explain their roles in signal transmission with examples.
Answer:
Case Deconstruction

Gray matter contains neuron cell bodies (e.g., cerebral cortex), while white matter has myelinated axons (e.g., corpus callosum).

Theoretical Application
  • Gray matter processes information (e.g., memory in hippocampus).
  • White matter ensures rapid conduction (e.g., reflex arcs).
Critical Evaluation

Textbook diagrams confirm myelin sheath thickness directly affects impulse speed (120 m/s in white matter).

Question 5:
In a histology lab, students observed squamous epithelium and cuboidal epithelium under a microscope. Compare their structure and functions with examples.
Answer:
Case Deconstruction

We studied that squamous epithelium consists of flat, scale-like cells, while cuboidal epithelium has cube-shaped cells.

Theoretical Application
  • Squamous epithelium forms linings of blood vessels (endothelium) and alveoli for diffusion.
  • Cuboidal epithelium is found in kidney tubules and gland ducts for secretion and absorption.
Critical Evaluation

Our textbook shows squamous cells reduce friction, whereas cuboidal cells actively transport molecules, demonstrating functional adaptation.

Question 6:
A student dissected an earthworm and noted chloragogen cells surrounding the intestine. Explain their role and compare them with liver cells in humans.
Answer:
Case Deconstruction

Chloragogen cells in earthworms store glycogen and detoxify wastes, similar to human liver cells.

Theoretical Application
  • Both cells regulate metabolism: chloragogen cells convert ammonia to urea, while liver cells process nitrogenous wastes.
  • Liver cells additionally produce bile, absent in earthworms.
Critical Evaluation

Our textbook shows chloragogen cells lack specialized structures like hepatocytes, reflecting evolutionary complexity in vertebrates.

Question 7:
Analyze how the striated muscles in frogs differ from human skeletal muscles in terms of fatigue resistance. Support with two examples.
Answer:
Case Deconstruction

Frog striated muscles fatigue slower due to anaerobic glycolysis adaptations, unlike human muscles relying on aerobic respiration.

Theoretical Application
  • Frog leg muscles sustain prolonged jumping; human quadriceps tire faster during sprinting.
  • Frog muscles accumulate less lactate, delaying fatigue compared to human athletes.
Critical Evaluation

Our textbook shows this difference aligns with frogs' escape behavior versus humans' burst activities.

Question 8:
During cockroach dissection, a student identified malpighian tubules. Justify their excretory mechanism and contrast it with nephrons.
Answer:
Case Deconstruction

Malpighian tubules absorb nitrogenous wastes from hemolymph and discharge them into the hindgut.

Theoretical Application
  • Unlike nephrons, they lack filtration; wastes are directly secreted via active transport.
  • Both structures conserve water: tubules reabsorb ions, nephrons use loop of Henle.
Critical Evaluation

Our textbook shows tubules are more energy-efficient for insects, while nephrons support complex osmoregulation in mammals.

Question 9:
In a lab study, epithelial tissues from the intestine and trachea were compared. Case Deconstruction: Identify the type of epithelium in each and their adaptations. Theoretical Application: How do these adaptations aid their functions? Critical Evaluation: Why can’t tracheal epithelium be replaced by intestinal epithelium?
Answer:
Case Deconstruction:
  • Intestinal epithelium: Simple columnar with microvilli for absorption.
  • Tracheal epithelium: Pseudostratified ciliated columnar with goblet cells for mucus secretion.

Our textbook shows microvilli increase surface area, while cilia move mucus.

Theoretical Application:
  • Microvilli enhance nutrient absorption in the intestine.
  • Cilia in the trachea trap and remove pathogens.
Critical Evaluation:

Tracheal epithelium requires cilia for clearance, which intestinal epithelium lacks. Replacing it would impair respiratory defense.

Question 10:
A student observed striated, non-striated, and cardiac muscle fibers under a microscope. Case Deconstruction: List two structural differences between them. Theoretical Application: How does cardiac muscle’s structure support its function? Critical Evaluation: Why can’t non-striated muscles perform rapid contractions like striated ones?
Answer:
Case Deconstruction:
  • Striated: Multinucleated, voluntary.
  • Non-striated: Spindle-shaped, involuntary.
  • Cardiac: Branched, uninucleated.

We studied that striations enable rapid contractions.

Theoretical Application:

Cardiac muscle’s intercalated discs allow synchronized contractions for pumping blood.

Critical Evaluation:

Non-striated muscles lack sarcomeres, limiting speed. Their slow contractions suit visceral functions like peristalsis.

Question 11:
A frog’s vascular system and skin were analyzed for oxygen exchange. Case Deconstruction: Name the two respiratory surfaces in frogs. Theoretical Application: How does cutaneous respiration complement pulmonary respiration? Critical Evaluation: Why can’t mammals rely on cutaneous respiration like frogs?
Answer:
Case Deconstruction:
  • Skin (cutaneous): Thin, moist.
  • Lungs (pulmonary): Sac-like.

Our textbook shows frogs use both surfaces.

Theoretical Application:

Cutaneous respiration works underwater, while lungs aid terrestrial oxygen uptake.

Critical Evaluation:

Mammalian skin is thicker and keratinized, reducing permeability. Frogs’ moist skin and low metabolic rate enable cutaneous respiration.

Question 12:
Two neurons—myelinated and non-myelinated—were compared for signal transmission. Case Deconstruction: What is the role of the myelin sheath? Theoretical Application: How does saltatory conduction improve efficiency? Critical Evaluation: Why are non-myelinated neurons still essential?
Answer:
Case Deconstruction:

The myelin sheath insulates axons, speeding up impulses.

Theoretical Application:

Saltatory conduction jumps between nodes of Ranvier, reducing energy use.

Critical Evaluation:

Non-myelinated neurons are crucial in autonomic functions where slower, sustained signals are needed, like digestion.

Question 13:

A student observed a slide of smooth muscle tissue under a microscope and noted the following features: spindle-shaped cells, single nucleus, and absence of striations. Based on this, answer the following:

  • Identify the type of muscle tissue and its location in the human body.
  • Explain how the structure of this tissue relates to its function.
Answer:

The observed tissue is smooth muscle tissue, which is found in the walls of hollow organs such as the stomach, intestines, blood vessels, and urinary bladder.

The spindle-shaped cells with a single nucleus and no striations allow for slow, sustained, and involuntary contractions. This structure is ideal for functions like peristalsis (movement of food in the digestive tract) and regulation of blood flow in vessels. The absence of striations ensures smooth, rhythmic contractions without fatigue.

Question 14:

During a dissection, a group of students observed a cockroach's digestive system and noted the presence of a crop and gizzard. Answer the following:

  • Describe the role of the crop and gizzard in digestion.
  • Compare the digestive system of a cockroach with that of an earthworm.
Answer:

The crop in a cockroach acts as a storage chamber for food, while the gizzard has chitinous teeth that grind the food into smaller particles, aiding in mechanical digestion.

In comparison, an earthworm lacks a crop and gizzard but has a muscular pharynx for sucking in food and a gizzard for grinding. However, earthworms rely more on microbial digestion in their intestine, whereas cockroaches use enzymatic digestion in their midgut.

Both organisms have adaptations suited to their diets: cockroaches are omnivorous, while earthworms feed on decaying organic matter.

Question 15:

During a dissection class, students observed the earthworm's internal structure and noticed chloragogen cells surrounding the intestine. The teacher asked them to explain the role of these cells and their significance in the earthworm's physiology. Write a detailed answer.

Answer:

Chloragogen cells are specialized cells found in earthworms that play multiple roles in their physiology:

  • They function similarly to the liver in vertebrates by storing glycogen and fat, helping in energy regulation.
  • They assist in excretion by converting nitrogenous waste into less toxic compounds like urea and ammonia.
  • These cells also contribute to immunity by engulfing foreign particles.

Their presence around the intestine ensures efficient nutrient absorption and waste management, making them vital for the earthworm's survival.

Question 16:

A student observed a cockroach's digestive system under a microscope and noticed the presence of gastric caecae. The teacher asked the student to explain their function and how they aid in digestion. Provide a detailed response.

Answer:

The gastric caecae in cockroaches are finger-like projections located at the junction of the foregut and midgut. Their functions include:

  • Secreting digestive enzymes that break down complex food particles into simpler forms.
  • Increasing the surface area for absorption of nutrients.
  • Housing symbiotic bacteria that assist in digesting cellulose, which the cockroach cannot digest on its own.

This adaptation ensures efficient digestion and nutrient absorption, supporting the cockroach's survival in diverse environments.

Question 17:

A student observed a slide of smooth muscle tissue under a microscope and noted the following features: spindle-shaped cells, uninucleate, and no striations. Based on these observations, answer the following:

  • Identify the type of muscle tissue and its location in the human body.
  • Explain how the structure of this tissue relates to its function.
Answer:

The observed tissue is smooth muscle tissue, which is found in the walls of hollow organs such as the stomach, intestines, blood vessels, and urinary bladder.

The spindle-shaped cells with a single nucleus and absence of striations allow this tissue to contract slowly and rhythmically, enabling involuntary movements like peristalsis in the digestive tract. The lack of striations ensures sustained contractions without fatigue, which is essential for functions like maintaining blood pressure and pushing food through the digestive system.

Question 18:

During a dissection, a group of students identified an organ covered by a thin, protective layer. Upon further examination, they found it was composed of cuboidal epithelium. Answer the following:

  • Name the organ and the function of cuboidal epithelium in it.
  • Compare cuboidal epithelium with squamous epithelium in terms of structure and function.
Answer:

The organ is likely the kidney, where cuboidal epithelium lines the tubules and ducts. Its primary function is secretion and absorption, crucial for urine formation and maintaining electrolyte balance.

Comparison:
Cuboidal epithelium consists of cube-shaped cells with a central nucleus, specialized for secretion and absorption.
Squamous epithelium has flat, scale-like cells, ideal for diffusion and filtration, as seen in the alveoli of lungs or blood vessels.

While cuboidal epithelium is active in metabolic processes, squamous epithelium provides a smooth surface for passive transport.

Question 19:

A student observed a slide of cockroach under a microscope and noticed a chitinous exoskeleton with distinct segments. Based on this observation, answer the following:

  • Why is the exoskeleton of a cockroach referred to as chitinous?
  • How does the segmented body of a cockroach contribute to its movement?
Answer:

The exoskeleton of a cockroach is called chitinous because it is primarily composed of chitin, a tough polysaccharide that provides rigidity and protection.

The segmented body of a cockroach allows for flexible movement due to the presence of jointed appendages and muscle attachments at each segment. This segmentation enables coordinated locomotion, such as walking and climbing.

Question 20:

While dissecting an earthworm, a student observed the presence of setae and a closed circulatory system. Answer the following:

  • What is the function of setae in an earthworm?
  • How does a closed circulatory system benefit the earthworm?
Answer:

Setae are tiny bristle-like structures that help the earthworm grip the soil during movement, preventing slipping.

A closed circulatory system ensures efficient transport of nutrients and oxygen through blood vessels, maintaining higher metabolic activity. This system also allows for better regulation of blood flow, which is crucial for burrowing and survival in soil.

Question 21:
A student observed a slide of earthworm under a microscope and noticed a segmented body with a distinct clitellum. Based on this observation, answer the following:
a) Identify the role of clitellum in earthworms.
b) Explain how the segmented body aids in locomotion.
Answer:

a) The clitellum is a thickened glandular and non-segmented part of the earthworm's body, visible from the 14th to 16th segments. Its primary role is to secrete a cocoon for egg fertilization and protection during reproduction.

b) The segmented body (metamerism) aids in locomotion through the following steps:

1. Each segment has muscles (circular and longitudinal) and setae (bristles) for grip.
2. Contraction of circular muscles elongates the body, while longitudinal muscles shorten it.
3. Hydrostatic skeleton (fluid-filled coelom) provides support and flexibility.
4. Coordinated movement of segments creates peristaltic waves, enabling efficient burrowing.

Question 22:
A cockroach's dissected digestive system shows the following parts: foregut, midgut, and hindgut. Explain the function of each part and how they collectively contribute to digestion.
Answer:

The cockroach's digestive system is divided into three regions:

Foregut (stomodaeum):
1. Includes the mouth, pharynx, esophagus, and crop.
2. Mechanical digestion occurs here with the help of mandibles and salivary enzymes.

Midgut (mesenteron):
1. Contains gastric caecae that secrete digestive enzymes.
2. Chemical digestion (breakdown of proteins, carbs, and fats) happens here.

Hindgut (proctodaeum):
1. Includes the ileum, colon, and rectum.
2. Absorbs water and salts and forms fecal pellets.

Collectively, these parts ensure efficient nutrient absorption and waste elimination.

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