Maharashtra Board Class 11 Biology Chapter 10 Animal Tissue Solutions

1. Choose Correct Option

Question (A)The study of structure and arrangement of tissue is called as -.
(a) anatomy
(b) histology
(c) microbiology
(d) morphology
Answer: (b) histology
In simple words: Histology is the specific branch of biology focused on studying the microscopic structure of tissues. It helps us understand how tissues are organized and function in an organism.

🎯 Exam Tip: Remember histology specifically refers to tissue study, differentiating it from anatomy (gross structure) and morphology (overall form).

Question (B)- is a gland which is both exocrine and endocrine.
(a) Sebaceous
(b) Mammary
(c) Pancreas
(d) Pituitary
Answer: (c) Pancreas
In simple words: The pancreas is a unique gland because it produces both digestive enzymes (exocrine function) and hormones like insulin (endocrine function). This dual role makes it a heterocrine gland.

🎯 Exam Tip: Glands with both exocrine (duct-based) and endocrine (ductless) functions are called heterocrine or mixed glands; the pancreas is a prime example.

Question (C)- cell junction is mediated by integrin.
(a) Gap
(b) Hemidesmosomes
(c) Desmosomes
(d) Adherens
Answer: (b) Hemidesmosomes
In simple words: Hemidesmosomes are cell junctions that anchor cells to the underlying basement membrane, and their strong adhesion is facilitated by integrin proteins. This provides stability and structural integrity to tissues.

🎯 Exam Tip: Integrins are key transmembrane proteins involved in cell-matrix adhesion, specifically mediating the connection in hemidesmosomes.

Question (D)The protein found in cartilage is -.
(a) ossein
(b) haemoglobin
(c) chondrin
(d) renin
Answer: (c) chondrin
In simple words: Chondrin is the characteristic protein component of the matrix of cartilage, providing its flexible yet supportive structure. Ossein, on the other hand, is the protein found in bone.

🎯 Exam Tip: Differentiate between ossein (bone matrix protein) and chondrin (cartilage matrix protein) to avoid common confusion in exams.

Question (E)Find the odd one out.
(a) Thyroid gland
(b) Pituitary gland
(c) Adrenal gland
(d) Salivary gland
Answer: (d) Salivary gland
In simple words: The salivary gland is an exocrine gland, secreting its products through ducts, whereas the thyroid, pituitary, and adrenal glands are all endocrine glands, secreting hormones directly into the bloodstream.

🎯 Exam Tip: Recognizing the difference between endocrine (ductless, hormone-secreting) and exocrine (ducts, non-hormone secreting) glands is crucial for classification questions.

2. Answer The Following Questions

Question (A)Identify and name the type of tissues in the following:
1. Inner lining of the intestine
2. Heart wall
3. Skin
4. Nerve cord
5. Inner lining of the buccal cavity
Answer:
1. Epithelial tissue (Columnar epithelium)
2. Cardiac muscles (Muscular tissue)
3. Epithelial tissue (Stratified epithelium)
4. Nervous tissue
5. Epithelial tissue (Ciliated epithelium)
In simple words: Different body parts are lined by specific types of tissues designed for their functions, such as columnar epithelium for absorption in the intestine, cardiac muscles for heart contractions, and nervous tissue for transmitting signals in the nerve cord. These tissues are specialized to perform unique roles.

🎯 Exam Tip: For tissue identification, focus on the primary function and structural arrangement of cells in each location.

Question (B)Why do animals in cold regions have a layer of fat below their skin?
Answer:
1. In adipose tissues, fats are stored in the form of droplets.
2. The adipose tissue acts as good insulator and helps retain heat in the body. This helps in survival of animals in the colder regions. Hence, animals in cold regions have a layer of fat below their skin.
In simple words: Animals in cold regions have a layer of fat under their skin because fat acts as an excellent insulator. This fatty layer traps body heat, preventing its loss to the cold environment, which is vital for their survival.

🎯 Exam Tip: Highlight the insulating property of adipose tissue and its role in thermoregulation for animals in cold climates.

Question (C)What enables the ear pinna to be folded and twisted while the nose tip can't be twisted?
Answer:
1. The ear pinna (outer ear) is made up of a thin plate of elastic cartilage and is connected to the surrounding.
2. The nose tip is made up of elastic cartilage. However, several bones and cartilage make up the bony- cartilaginous framework of the nose.
Hence, even though the tip of the nose is made up of elastic cartilage, it cannot be twisted like the ear pinna due to presence of bony-cartilaginous framework.
In simple words: The ear pinna is highly flexible due to its primary composition of elastic cartilage with minimal rigid support, allowing it to bend and twist easily. In contrast, while the nose tip also contains elastic cartilage, it is embedded within a more extensive and rigid bony-cartilaginous framework, limiting its overall flexibility.

🎯 Exam Tip: The key difference lies in the *extent* of flexible cartilage versus rigid bone/cartilage framework in each structure.

Question (D)Sharad touched a hot plate by mistake and took away his hand quickly. Can you recognize the tissue and its type responsible for it?
Answer:
1. Nervous and muscular tissues are responsible for this action
2. Nervous tissue recognizes the stimuli whereas muscular tissue allows responding to the stimuli.
In simple words: When Sharad touched the hot plate, his nervous tissue quickly detected the heat stimulus and sent signals to his brain. In response, his muscular tissue then rapidly contracted, causing his hand to pull away. This is a reflex action involving both tissues.

🎯 Exam Tip: Emphasize the coordinated action: nervous tissue for sensing and transmitting, muscular tissue for movement/response.

Question (E)Priya got injured in an accident and hurt her long bone and later on she was also diagnosed with anaemia. What could be the probable reason?
Answer:
1. The centre of long bones (diaphysis) contains bone marrow, which is a site of production of blood cells (red blood cells).
2. Any severe injury to the bone marrow can affect rate of haematopoiesis (formation of blood cells).
3. A low count of erythrocytes (red blood cells) is characterised as anaemia. Hence, an injury to Priya's long bone might have resulted in anaemia.
In simple words: An injury to a long bone can damage the bone marrow located inside, which is responsible for producing red blood cells. If red blood cell production is impaired, it can lead to a deficiency of these cells, resulting in anaemia.

🎯 Exam Tip: Connect long bone injury directly to bone marrow damage and its critical role in red blood cell production (haematopoiesis) to explain anaemia.

Question (F)Supriya stepped out into the bright street from a cinema theatre. In response, her eye pupil shrunk. Identify the muscle responsible for the same.
Answer:
Smooth muscles (Involuntary muscles) are responsible for shrinking of eye pupil.
In simple words: The smooth muscles (involuntary muscles) within the iris of the eye are responsible for the constriction of the pupil when exposed to bright light. This reflex action helps regulate the amount of light entering the eye.

🎯 Exam Tip: Remember that pupil constriction (miosis) and dilation (mydriasis) are controlled by involuntary smooth muscles in the iris.

3. Answer The Following Questions

Question (A)What is cell junction? Describe different types of cell junctions.
Answer:
1. Cell junctions: The epithelial cells are connected to each other laterally as well as to the basement membrane by junctional complexes called cell junctions.
2. The different types of cell junctions are as follows:
a. Gap Junctions (GJs): These are intercellular connections that allow the passage of ions and small molecules between cells as well as exchange of chemical messages between cells.
b. Adherens Junctions (AJs): They are involved in various signalling pathways and transcriptional regulations.
c. Desmosomes (Ds): They provide mechanical strength to epithelial tissue, cardiac muscles and meninges.
d. Hemidesmosomes (HDs): They allow the cells to strongly adhere to the underlying basement membrane. These junctions help maintain tissue homeostasis by signalling.
e. Tight junctions (TJs): These junctions maintain cell polarity, prevent lateral diffusion of proteins and ions.
In simple words: Cell junctions are specialized structures that connect cells to each other or to the extracellular matrix, facilitating communication, adhesion, and structural integrity. They come in various types like gap junctions for communication, tight junctions for sealing, and desmosomes/adherens junctions for strong adhesion.

🎯 Exam Tip: For cell junctions, focus on the primary function of each type: communication (gap), sealing (tight), cell-to-cell adhesion (adherens, desmosomes), and cell-to-matrix adhesion (hemidesmosomes).

Question (B)Describe in brief about areolar connective tissue with the help of suitable diagram.
Answer:
Areolar tissue is a loose connective tissue found under the skin, between muscles, bones, around organs, blood vessels and peritoneum. It is composed of fibres and cells.
The matrix of areolar tissues contains two types of fibres i.e. white fibres and yellow fibres.
a. White fibres: They are made up of collagen and give tensile strength to the tissue.
b. Yellow fibres: They are made up of elastin and are elastic in nature.
The four different types of cells present in this tissue are as follows:
a. Fibroblast: Large flat cells having branching processes. They produce fibres as well as polysaccharides that form the ground substance or matrix of the tissue.
b. Mast cells: Oval cells that secrete heparin and histamine.
c. Macrophages: Amoeboid, phagocytic cells.
d. Adipocytes (Fat cells): These cells store fat and have eccentric nucleus.
In simple words: Areolar connective tissue is a widespread, loose tissue that provides support, strength, and elasticity to various organs. It contains different cell types like fibroblasts, mast cells, macrophages, and adipocytes, embedded in a matrix of collagen and elastic fibers, found beneath the skin and around organs.

🎯 Exam Tip: When describing areolar tissue, remember to mention its widespread location, the types of fibers (collagen, elastin), and the diverse cell population (fibroblasts, mast cells, macrophages, adipocytes).

Question (C)Describe the structure of multipolar neuron.
Answer:
A neuron is the structural and functional unit of the nervous tissue. A neuron is made up of cyton or cell body and cytoplasmic extensions or processes.
1. Cyton:
The cyton or cell body contains granular cytoplasm called neuroplasm and a centrally placed nucleus. The neuroplasm contains mitochondria, Golgi apparatus, RER and Nissl's granules.
2. Cytoplasmic extensions or processes:
(a) Dendron: They are short, unbranched processes.
The fine branches of a dendron are called dendrites.
Dendrites carry an impulse towards the cyton.
(b) Axon: It is a single, elongated and cylindrical process.
1. The axon is bound by the axolemma.
2. The protoplasm or axoplasm contains large number of mitochondria and neurofibrils.
3. The axon is enclosed in a fatty sheath called the myelin sheath and the outer covering of the myelin sheath is the neurilemma. Both the myelin sheath and the neurilemma are parts of the Schwann cell.
4. The myelin sheath is absent at intervals along the axon at the Node of Ranvier.
5. The fine branching structure at the end of the axon (terminal arborization) is called telodendron.
In simple words: A multipolar neuron has a cell body (cyton) with a nucleus and organelles, multiple short, branched extensions called dendrites that receive signals, and a single, long extension called an axon that transmits signals away from the cell body. The axon is often covered by a myelin sheath for faster impulse conduction.

🎯 Exam Tip: Focus on the three main parts of a neuron-cyton, dendron (dendrites), and axon-and their respective functions in signal reception and transmission.

Question (D)How to differentiate the skeletal and the smooth muscles based on their nucleus?
Answer:
Skeletal muscles contain nucleus arranged at periphery. Striated or smooth muscles are with centrally placed single large oval nucleus therefore, skeletal and smooth muscle fibres can be identified.
In simple words: Skeletal muscle cells are typically multinucleated with nuclei located at the periphery, while smooth muscle cells are single-nucleated with a centrally placed, oval nucleus. This nuclear arrangement is a key distinguishing feature.

🎯 Exam Tip: Remember nuclear position and number as primary identifiers: peripheral multinucleated for skeletal, central uninucleated for smooth muscle.

Question 4.Complete the following table.
Answer:

🎯 Exam Tip: Focus on understanding the unique function of each listed cell/tissue type, as these are common identification points in exams.

Question 5.Match the following.

🎯 Exam Tip: Learn the specific covering or membrane associated with each tissue type; this helps in understanding their protective and structural organization.

Practical / Project:

Question 1.To study the different tissues with the help of permanent slides in your college laboratory.
Answer:
Students may observe permanent slides of different tissues like epithelial tissue, connective tissue, muscular tissue and nervous tissue slides in laboratory.
[Students are expected to perform this activity on their own.]
In simple words: This project involves observing prepared microscope slides of various animal tissues, such as epithelial, connective, muscular, and nervous tissues, to understand their distinct cellular structures and arrangements.

🎯 Exam Tip: For practical exams, be able to identify key tissue types under a microscope and describe their characteristic features.

Question 2.Collect the information about the exercise to keep muscles healthy and strong.
Answer:
1. Muscles become stronger when we are physically active.
2. Physical activities like walking, jogging, lifting weights, playing tennis, climbing stairs, jumping, and dancing are good ways to exercise our muscles.
3. Apart from this, swimming and biking can also be considered as good workouts for muscles.
4. Different kinds of activities, work different muscles. Hence, it is essential to perform various types of physical activities.
5. Also, activities that increase our breath rate, help in exercising our heart muscle as well.
[Students are expected to collect more information on their own.]
In simple words: Regular physical activity, including aerobic exercises like walking and swimming, and strength training like weightlifting, is crucial for maintaining and improving muscle health, strength, and endurance across the body, including the heart.

🎯 Exam Tip: Understand the two main categories of exercise (aerobic and anaerobic/strength training) and how each contributes to muscular system health and performance.

Can You Recall? (Textbook Page No. 116)

What is tissue?
Answer:
A group of cells having the same origin, same structure and same function is called 'tissue'.
In simple words: A tissue is a collection of similar cells that work together to perform a specific function, sharing common origin and structure.

🎯 Exam Tip: A concise definition of "tissue" highlighting its cellular composition, shared origin, and unified function is important.

Do You Know? (Textbook Page No. 116)

Number of cells in human body.
Answer:
There are about 100 trillion of 200 different types of cells in the human body.
In simple words: The human body is incredibly complex, made up of approximately 100 trillion cells, belonging to about 200 distinct types, each specialized for different roles.

🎯 Exam Tip: While exact numbers vary, recognizing the vast scale and diversity of cells in the human body is key.

Can You Tell? (Textbook Page No. 119)

Explain basic structure of epithelial tissue and mention its types.
Answer:
The characteristics of epithelial tissues are as follows:
1. Epithelial tissue forms a covering on inner and outer surface of body and organs.
2. The cells of this tissue are compactly arranged with little intercellular matrix.
3. The cells rest on a non-cellular basement membrane.
4. The epithelial cells are polygonal, cuboidal or columnar in shape.
5. A single nucleus is present at the centre or at the base of the cell.
6. The tissue is avascular and has a good regeneration capacity.
7. The major function of the epithelial tissue is protection. It also helps in absorption, transport, filtration and secretion.
The different types of epithelial tissues are as follows:
1. Simple epithelium: Epithelial tissue made up of single layer of cells is known as simple epithelium. Simple epithelium is further classified into:
a. Squamous Epithelium
b. Cuboidal Epithelium
c. Columnar Epithelium
d. Ciliated Epithelium
e. Glandular Epithelium
f. Sensory epithelium
g- Germinal epithelium
2. Compound epithelium: Epithelium composed of several layers is called compound epithelium. Compound epithelium is further classified into:
a. Stratified epithelium
b. Transitional epithelium
In simple words: Epithelial tissue covers body surfaces and lines cavities, characterized by tightly packed cells on a basement membrane with little matrix, and is avascular with high regeneration. It's broadly classified into simple (single-layered, e.g., squamous, cuboidal, columnar) and compound (multi-layered, e.g., stratified, transitional) types, performing functions like protection, absorption, and secretion.

🎯 Exam Tip: When describing epithelial tissue, emphasize its covering/lining function, cellular arrangement, presence of a basement membrane, and its avascular nature and regenerative capacity. List the major types based on cell layers and shapes.

Epithelial tissue has good capacity of regeneration. Give reason.
Answer:
Epithelial tissue rests on a basement membrane which acts as a scaffolding on which epithelium can grow and regenerate after injuries.
In simple words: Epithelial tissue's high regeneration capacity comes from its cells resting on a basement membrane. This membrane acts as a stable foundation, providing structural support and signaling cues that allow new epithelial cells to rapidly grow and replace damaged ones after an injury.

🎯 Exam Tip: The basement membrane is key to epithelial regeneration, providing both structural support and guidance for cell growth and repair.

Can You Recall? (Textbook Page No. 116)

Where is squamous epithelium located?
Answer:
Location: It is present in blood vessels, alveoli, coelom, etc.
In simple words: Squamous epithelium is found in places where rapid diffusion or filtration is needed, such as the lining of blood vessels (endothelium), air sacs of lungs (alveoli), and body cavities (coelom).

🎯 Exam Tip: Associate simple squamous epithelium with locations requiring thin barriers for efficient diffusion and filtration.

Can You Tell? (Textbook Page No. 119)

Write a note on glandular epithelium.
Answer:
Structure:
1. The cells of the glandular epithelium can be columnar, cuboidal or pyramidal in shape.
2. The nucleus of these cells is large and situated towards the base.
3. Secretory granules are present in the cell cytoplasm.
4. Glands consist of glandular epithelium. The glands may be either unicellular (goblet cells of intestine) or multicellular (salivary gland), depending on the number of cells.
5. Types: Depending on the mode of secretion, multicellular glands can be further classified as duct bearing glands (exocrine glands) ad ductless glands (endocrine glands).
a. Exocrine glands: These glands pour their secretions at a specific site. e.g. salivary gland, sweat gland, etc.
b. Endocrine glands: These glands release their secretions directly into the blood stream, e.g. thyroid gland, pituitary gland, etc.
6. Function: Glandular epithelium secretes mucus to trap the dust particles, lubricate the inner surface of respiratory and digestive tracts, secrete enzymes and hormones, etc.
Heterocrine glands
1. Heterocrine glands or composite glands have both exocrine and endocrine function.
2. Pancreas is called a heterocrine gland because it secretes the hormone insulin into blood which is an endocrine function and enzymes into digestive tract which is an exocrine function.
In simple words: Glandular epithelium is specialized for secretion, forming glands that can be unicellular or multicellular. These glands are classified as exocrine (secrete via ducts, like salivary glands), endocrine (secrete hormones directly into blood, like thyroid), or heterocrine (both functions, like the pancreas).

🎯 Exam Tip: When describing glandular epithelium, differentiate clearly between exocrine, endocrine, and heterocrine glands based on their mode of secretion and presence/absence of ducts.

Use Your Brain Power? (Textbook Page No. 118)

When do the transitional cells change their shape?
Answer:
Transitional cells change their shape depending on the degree of distention (stretch) needed. As the tissue stretches, the transitional cells start changing shape from round and globular to thin and flat.
In simple words: Transitional cells, found in organs like the bladder, change shape to accommodate stretching; they appear rounded when relaxed and flatten out when the organ is distended.

🎯 Exam Tip: The defining characteristic of transitional epithelium is its ability to change shape, allowing organs to expand and contract without damage.

Can You Tell? (Textbook Page No. 119)

How do cell junctions help in functioning of epithelial tissue?
Answer:
1. Cell junctions: The epithelial cells are connected to each other laterally as well as to the basement membrane by junctional complexes called cell junctions.
2. The different types of cell junctions are as follows:
a. Gap Junctions (GJs): These are intercellular connections that allow the passage of ions and small molecules between cells as well as exchange of chemical messages between cells.
b. Adherens Junctions (AJs): They are involved in various signalling pathways and transcriptional regulations.
c. Desmosomes (Ds): They provide mechanical strength to epithelial tissue, cardiac muscles and meninges.
d. Hemidesmosomes (HDs): They allow the cells to strongly adhere to the underlying basement membrane. These junctions help maintain tissue homeostasis by signalling.
e. Tight junctions (TJs): These junctions maintain cell polarity, prevent lateral diffusion of proteins and ions.
In simple words: Cell junctions are crucial for epithelial tissue function as they provide strong adhesion between cells and to the basement membrane, ensuring structural integrity. They also facilitate intercellular communication (gap junctions) and create barriers to control substance movement (tight junctions), maintaining tissue polarity and homeostasis.

🎯 Exam Tip: For epithelial cell junctions, emphasize their dual role in providing mechanical stability (adherens, desmosomes, hemidesmosomes) and regulating cell-to-cell communication and permeability (gap, tight junctions).

Can You Tell? (Textbook Page No. 122)

Give reason. As we grow old, cartilage becomes rigid.
Answer:
Calcified cartilage is a type of cartilage that becomes rigid due to deposition of salts in the matrix. This reduces the flexibility of joints in old age and cartilage becomes rigid.
In simple words: As people age, cartilage can become more rigid due to the accumulation of mineral salts within its matrix, a process called calcification. This hardening reduces its natural flexibility and can affect joint movement.

🎯 Exam Tip: The rigidity of cartilage in old age is primarily due to calcification, where mineral salts are deposited, reducing flexibility.

Can You Recall? (Textbook Page No. 116)

Enlist functions of bone.
Answer:
Bones support and protect different organs and help in movement.
In simple words: Bones serve multiple vital functions: they provide structural support for the body, protect delicate internal organs, and act as levers for muscle attachment, enabling movement.

🎯 Exam Tip: Key functions of bone include support, protection, and facilitating locomotion; also recall their role in mineral storage and blood cell production.

Can You Tell? (Textbook Page No. 122)

(i) Give reason. Bone is stronger than cartilage.
Answer:
a. Bone is rigid, non-pliable, dense connective tissue characterised by the hard matrix called ossein (made up of calcium salt hydroxyapatite). An outer tough membrane called periosteum encloses the matrix. The matrix is arranged in the form of concentric layers called lamellae. Bones are well vascularized and possess blood vessels and nerves that pierce through the periosteum,
b. Cartilage is a pliable supportive connective tissue. On comparison with bones, cartilage is thin, avascular and flexible. In cartilage, a sheath of collagenous fibres called perichondrium encloses the matrix.
Hence, a bone is stronger than a cartilage.
In simple words: Bone is stronger than cartilage primarily due to its hard, mineralized matrix containing calcium salts and ossein, making it rigid and dense. Cartilage, by contrast, has a pliable, unmineralized matrix, making it more flexible but less strong.

🎯 Exam Tip: The strength difference between bone and cartilage lies in their matrix composition: bone is mineralized (hydroxyapatite), while cartilage is flexible (chondrin and fibers) but not mineralized.

(ii) Explain histological structure of mammalian bone.
Answer:
a. The bone is characterised by hard matrix called ossein which is made up of mineral salt hydroxy apatite (\(Ca_{10} (PO_4)_6 (OH)_2\)).
b. An outer tough membrane called periosteum encloses the matrix.
c. Blood vessels and nerves pierce through the periosteum.
d. The matrix is arranged in the form of concentric layers called lamellae.
e. Each lamella contains fluid filled cavities called lacunae from which fine canals called canaliculi radiate.
f. The canaliculi of adjacent lamellae connect with each other as they traverse through the matrix.
g. Active bone cells called osteoblasts and inactive bone cells called osteocytes are present in the lacunae.
h. The mammalian bone shows the peculiar haversian system.
i. The haversian canal encloses an artery, vein and nerves.

ℹ️ चित्र व्याख्या (Diagram Explanation): यह चित्र एक हड्डी की विस्तृत संरचना को दर्शाता है, जिसमें केंद्रीय कैनाल, लैमेला, ओस्टियोसाइट, पेरिओस्टेम और विभिन्न रक्त वाहिकाएँ और तंत्रिकाएँ शामिल हैं। यह हड्डी के ऊतक में हावेर्सियन सिस्टम की व्यवस्था को स्पष्ट रूप से दिखाता है।
In simple words: Mammalian bone has a hard matrix of ossein and calcium hydroxyapatite, enclosed by a periosteum. Its structure features concentric lamellae, with osteocytes residing in lacunae connected by canaliculi. The characteristic Haversian system contains a central canal housing blood vessels and nerves, forming a highly organized and vascularized tissue.

🎯 Exam Tip: Focus on describing the Haversian system (osteon) including lamellae, lacunae, canaliculi, and the central Haversian canal as the core histological features of compact bone.

Can You Recall? (Textbook Page No. 122)

How can exercise improve your muscular system?
Answer:
1. Exercise can improve both muscular strength and stamina endurance.
2. Exercises are commonly grouped into two types depending on the effect they have on the body:
a. Aerobic exercises: such as cycling, walking, and running. They increase muscular endurance and cardiovascular health, etc.
b. Anaerobic exercises: such as weight training or sprinting, increase muscle strength, etc.
3. Anaerobic exercies: It comprises brief periods of physical exertion and high-intensity, strength-training activities.
Anaerobic exercise is a physical exercise intense enough to cause lactate to form. It is used by athletes to promote strength, speed and power; and by body builders to build muscle mass.
In simple words: Exercise strengthens the muscular system by increasing both muscle strength and endurance. Aerobic activities enhance stamina and cardiovascular health, while anaerobic exercises, like weight training, build muscle mass, speed, and power by intense, short bursts of activity.

🎯 Exam Tip: Differentiate clearly between aerobic (endurance, cardiovascular) and anaerobic (strength, power, mass) exercise types and their specific benefits for the muscular system.

Can You Recall? (Textbook Page No. 122)

How many skeletal muscles are present in human body?
Answer:
There are over 650 named skeletal muscles in the human body.
In simple words: The human body contains more than 650 individually named skeletal muscles, all working together to facilitate movement and maintain posture.

🎯 Exam Tip: Knowing the approximate number of skeletal muscles (over 650) helps appreciate the complexity of the muscular system.

Can You Tell? (Textbook Page No. 125)

Differentiate between medullated and non-medullated fibre.
Answer:

🎯 Exam Tip: The presence or absence of the myelin sheath is the primary distinguishing factor, directly impacting impulse conduction speed and the mechanism (saltatory vs. continuous).

Internet Is My Friend. (Textbook Page No. 125)

Question. Learn about transmission of impulse from one neuron to another.
Answer:
1. A nerve impulse is transmitted from one neuron to another through junctions called synapses.
2. A synapse is formed by the membranes of a pre-synaptic neuron and a post-synaptic neuron, which may or may not be separated by a gap called synaptic cleft.
3. There are two types of synapses, namely, electrical synapses and chemical synapses.
4. Electrical synapses: The membranes of pre- and post-synaptic neurons are in very close proximity.
Thus, electrical current can flow directly from one neuron into the other across these synapses.
Impulse transmission across an electrical synapse is faster.
5. Chemical synapse: The membranes of the pre- and post-synaptic neurons are separated by a fluid- filled space called synaptic cleft.
6. Chemicals called neurotransmitters are involved in the transmission of impulses at these synapses.
7. The axon terminals contain vesicles filled with these neurotransmitters.
8. When an impulse arrives at the axon terminal, it stimulates the movement of the synaptic vesicles towards the membrane where they fuse with the plasma membrane and release their neurotransmitters into the synaptic cleft.
9. The released neurotransmitters bind to their specific receptors, present on the post-synaptic membrane.
10. This binding opens ion channels and allows the entry of ions which can generate a new potential in the post-synaptic neuron.
[Students are expected to refer the given information and collect more information from the internet.]
[Note: Students can scan the adjacent QR code to get conceptual clarity with the aid of a relevant video ]
In simple words: Nerve impulses transmit from one neuron to another at synapses. This can be through direct electrical flow or via chemical neurotransmitters released into a synaptic cleft, binding to receptors on the next neuron to generate a new impulse.

🎯 Exam Tip: Understanding the types of synapses (electrical vs. chemical) and the steps of neurotransmitter release is crucial for explaining nerve impulse transmission accurately.

Observe And Discuss (Textbook Page No. 125)

Question. Explain the structure of nerve.
ℹ️ चित्र व्याख्या (Diagram Explanation): यह चित्र एक तंत्रिका की आंतरिक संरचना और उसके सुरक्षात्मक आवरणों को दर्शाता है। इसमें व्यक्तिगत एक्सॉन को एंडोन्यूरियम, फ़ैसिकल को पेरिन्यूरियम और संपूर्ण तंत्रिका को एपिन्यूरियम से घिरा हुआ दिखाया गया है। रक्त वाहिकाएं तंत्रिका को पोषण प्रदान करती हुई भी प्रदर्शित हैं।
Answer:
1. Each spinal nerve consists of many axons and contains layers of protective connective tissue coverings.
2. Axons are enclosed in a fatty sheath called myelin sheath.
3. Individual axons within a nerve are wrapped in an an endoneurium (innermost layer).
4. Groups of axons with their endoneurium are arranged in bundles called fascicles.
5. Each fascicle is wrapped in perineurium (middle layer).
6. The outermost covering over the entire nerve is the epineurium. The epineurium extends between fascicles.
7. Many blood vessels nourish the nerve and are present within the perineurium and epineurium.
[Source: Tortora. G, Derrickson. B. Principles of Anatomy and Physiology. 11th Edition.]
In simple words: A nerve is composed of multiple axons, each with a myelin sheath and surrounded by connective tissue layers – endoneurium, perineurium, and epineurium – which organize them into fascicles and the complete nerve, supported by blood vessels.

🎯 Exam Tip: Clearly identifying and describing the specific connective tissue layers (endoneurium, perineurium, epineurium) and their roles in nerve organization is key for full marks.

11th Std Biology Questions And Answers: