TISSUE: CLASS 9: CBSE

 

Title: Cellular Organization in Living Organisms

1. Introduction
• All living organisms consist of cells as their fundamental structural and functional units.
• Cellular organization varies between unicellular and multicellular organisms.
2. Unicellular Organisms
• In unicellular organisms, a single cell performs all essential functions.
• Example: Amoeba carries out movement, food intake, gaseous exchange, and excretion within a single cell.
3. Multicellular Organisms
• Multicellular organisms consist of millions of cells.
• Most of these cells are specialized to perform specific functions efficiently.
4. Division of Labour
• Multicellular organisms exhibit a division of labour among specialized cells.
• Different groups of cells are responsible for distinct functions.
5. Specialized Cells in Humans
• In humans, muscle cells contract and relax for movement, nerve cells transmit messages, and blood transports oxygen, nutrients, hormones, and waste materials.
6. Specialized Cells in Plants
• Plants have vascular tissues that conduct food and water throughout the plant.
• This specialization optimizes the efficiency of function.
7. Formation of Tissues
• Cells with similar structure and function group together to form tissues.
• A tissue is a cluster of cells organized for efficient performance.
• Examples include blood tissue, phloem tissue, and muscle tissue.

Title: Comparative Analysis of Plant and Animal Tissues

Introduction

• Plants and animals differ in their structural organization and functions.
• This comparison explores the distinctions between plant and animal tissues.

Structural Differences

1. Plants are Stationary; Animals Move
• Plants are fixed in one place and do not exhibit movement.
• Animals are mobile and actively move in search of food, mates, and shelter.
2. Supportive Tissues
• Plants require substantial supportive tissue to remain upright.
• Supportive plant tissues often consist of dead cells.
• Animals do not require extensive supportive tissues as they can move to maintain their position.
3. Living vs. Dead Cells
• Most of the tissues in animals are composed of living cells.
• In contrast, many plant tissues contain dead cells, especially in supportive structures.

Growth Patterns

1. Plant Growth
• Growth in plants is primarily localized to specific regions.
• Some plant tissues continue to divide throughout their life, but this growth is confined to certain areas.
• Plant tissues can be categorized as meristematic (dividing) and permanent (non-dividing) based on their growth capacity.
2. Animal Growth
• Cell growth in animals is more uniform throughout their bodies.
• Unlike plants, there is no clear demarcation between dividing and non-dividing regions in animals.

Specialization in Organ Structure

1. Complexity in Animals
• Complex animals exhibit highly specialized and localized structural organization of organs and organ systems.
• This specialization reflects their diverse feeding methods and active locomotion.
2. Comparatively Simpler Plants
• Even very complex plants have a less specialized organ structure than complex animals.
• This difference arises from the sedentary nature of plants and their mode of obtaining nutrients.

Adaptations for Lifestyle

1. Sedentary Existence in Plants
• Plants are adapted for a sedentary lifestyle, with structures like roots anchoring them in place and leaves for photosynthesis.
2. Active Locomotion in Animals
• Animals are adapted for active locomotion, with structures like limbs or fins for movement.

Conclusion

• The contrasting structural organization and functions of plant and animal tissues are influenced by their distinct modes of life and nutritional strategies. Understanding these differences is essential in studying the concept of tissues in greater detail.

 

Title: Meristematic Tissue in Plants

Introduction

• In plants, growth is limited to specific regions due to the presence of meristematic tissue.
• Meristematic tissue is classified into apical, lateral, and intercalary meristems, depending on their locations.
• New cells produced by meristems initially resemble meristematic cells but gradually differentiate into other types of tissues.

Types of Meristematic Tissues

1. Apical Meristem
• Located at the growing tips of stems and roots.
• Responsible for increasing the length of stems and roots.
2. Lateral Meristem (Cambium)
• Responsible for increasing the girth (thickness) of stems and roots.
• Promotes secondary growth.
3. Intercalary Meristem
• Found near the nodes in some plants.

Characteristics of Meristematic Cells

• Meristematic cells are highly active and play a crucial role in plant growth.
• They exhibit several distinctive characteristics:
• Dense cytoplasm.
• Thin cellulose cell walls.
• Prominent nuclei.
• Lack of vacuoles.

Discussion: Lack of Vacuoles in Meristematic Cells

• Vacuoles are membrane-bound organelles found in plant cells, often filled with water, enzymes, and other substances.
• Meristematic cells lack vacuoles for several reasons:
1. Space for Expansion: Vacuoles occupy a significant amount of space within a plant cell. In meristematic cells, where rapid cell division and growth occur, space is needed for the cytoplasm and organelles to expand as the cell enlarges.
2. Cell Wall Rigidity: The absence of vacuoles helps maintain the rigidity of the cell wall, which is essential for supporting the actively growing regions of the plant, such as the tips of stems and roots.
3. High Metabolic Activity: Meristematic cells are metabolically active and require a higher concentration of cytoplasmic materials to support rapid growth and differentiation. The absence of large vacuoles allows for more cytoplasmic space for these essential processes.
4. Differentiation: As meristematic cells differentiate into specialized cell types, they develop vacuoles, which serve various functions depending on the type of cell. Vacuoles can store water, nutrients, pigments, and waste products in mature plant cells.

In summary, the lack of vacuoles in meristematic cells is a structural adaptation that supports their high metabolic activity, rapid growth, and maintenance of cell wall integrity during the initial stages of plant development.

 

Permanent Tissue: Transition from Meristematic Cells

1. Cell Fate Determination
• Cells produced by meristematic tissue undergo a crucial transformation.
• They acquire specific roles and lose their ability to divide further.
2. Formation of Permanent Tissue
• The transition from meristematic cells to specialized, non-dividing cells results in the formation of permanent tissue.
3. Differentiation
• The process through which cells take on a permanent shape, size, and function is known as differentiation.
• Differentiation leads to the development of various types of permanent tissues in the plant.

In summary, the transition from actively dividing meristematic cells to non-dividing specialized cells marks the formation of permanent tissues, with each type of permanent tissue serving distinct functions within the plant.

 

Simple Permanent Tissues in Plants

1. Parenchyma Tissue

• Located a few cell layers beneath the epidermis.
• Composed of relatively unspecialized cells with thin cell walls.
• These cells are living and usually loosely arranged, creating large intercellular spaces.
• Functions primarily in storing food.
• In some cases, contains chlorophyll for photosynthesis, referred to as chlorenchyma.
• In aquatic plants, parenchyma contains large air cavities, known as aerenchyma, aiding in flotation.

2. Collenchyma Tissue

• Found in leaf stalks below the epidermis.
• Provides flexibility to plant parts such as tendrils and climbing stems.
• Offers mechanical support.
• Cells are living, elongated, and irregularly thickened at the corners.
• Intercellular spaces are minimal.

3. Sclerenchyma Tissue

• Imparts hardness and rigidity to plant structures.
• Commonly seen in the husk of a coconut.
• Composed of dead cells with thickened walls containing lignin.
• Walls may be so thick that there is no internal space within the cell.
• Found in stems, around vascular bundles, in leaf veins, and in the hard coverings of seeds and nuts.

4. Epidermis

• The outermost layer of cells covering the entire plant surface.
• Typically consists of a single layer of cells.
• Epidermal cells on aerial plant parts often secrete a waxy layer on their outer surface.
• This waxy layer aids in protection against water loss, mechanical injury, and fungal invasion.
• Epidermal cells form a continuous layer without intercellular spaces.
• Most epidermal cells have relatively flat shapes, with outer and side walls thicker than the inner wall.
• Small openings called stomata are present in the epidermis, enclosed by two kidney-shaped guard cells, allowing gas exchange and transpiration.

5. Root Epidermis

• Epidermal cells of roots bear long, hair-like structures that increase the absorptive surface area for water absorption.

6. Specialized Epidermis in Desert Plants

• Some desert plants have a thick waxy cutin coating on the outer surface of the epidermis, providing waterproofing.

7. Cork Tissue

• Developed in older plant tissues as a secondary meristem located in the cortex.
• Forms layers of compactly arranged dead cells without intercellular spaces.
• Contains suberin in cell walls, making it impervious to gases and water.

In summary, plants have various types of simple permanent tissues, each with specific functions and structural characteristics, contributing to their growth, support, protection, and adaptability to different environments.

 

Simple Permanent Tissues in Plants: Structure and Function

1. Parenchyma Tissue

• Structure: Located just beneath the epidermis, parenchyma tissue consists of cells with thin cell walls. These cells are relatively unspecialized, living, and loosely arranged, creating ample intercellular spaces.
• Function: Parenchyma primarily serves as a storage tissue for food and nutrients. In some cases, it contains chlorophyll and carries out photosynthesis, referred to as chlorenchyma. In aquatic plants, parenchyma forms aerenchyma, which contains large air cavities, aiding in flotation.

2. Collenchyma Tissue

• Structure: Collenchyma tissue is typically found in leaf stalks below the epidermis. Its cells are elongated and have irregularly thickened corners. The cells are living, and intercellular spaces are minimal.
• Function: Collenchyma provides flexibility to plant parts, allowing them to bend without breaking. It also offers mechanical support to the plant.

3. Sclerenchyma Tissue

• Structure: Sclerenchyma tissue imparts hardness and rigidity to plant structures. Its cells are dead and have thick walls containing lignin. In some cases, these walls are so thick that there is no internal space within the cell.
• Function: Sclerenchyma tissue provides strength to plant parts, such as stems, vascular bundles, leaf veins, and the hard coverings of seeds and nuts.

4. Epidermis

• Structure: The epidermis is the outermost layer of cells that covers the entire plant surface. It usually consists of a single layer of cells. Epidermal cells on aerial plant parts often secrete a waxy layer on their outer surface. These cells form a continuous layer without intercellular spaces, and their outer and side walls are thicker than the inner wall.
• Function: The epidermis serves a protective role, safeguarding plant parts against water loss, mechanical injury, and fungal invasion. Small openings called stomata are present in the epidermis, allowing for gas exchange and transpiration.

5. Root Epidermis

• Structure: The epidermal cells of roots bear long, hair-like structures, increasing the surface area for water absorption.
• Function: Root epidermis plays a crucial role in the absorption of water and minerals from the soil.

6. Specialized Epidermis in Desert Plants

• Structure: Some desert plants have an epidermis with a thick waxy cutin coating on its outer surface.
• Function: This specialized epidermis provides waterproofing, helping the plant conserve water in arid environments.

7. Cork Tissue

• Structure: Cork tissue develops in older plant tissues as a secondary meristem located in the cortex. It comprises layers of compactly arranged dead cells without intercellular spaces and contains suberin in cell walls.
• Function: Cork tissue makes plant parts impervious to gases and water, serving as a protective layer in woody stems and roots.

In summary, plants have several types of simple permanent tissues, each with distinct structures and functions. These tissues contribute to the plant's growth, support, protection, and adaptation to various environmental conditions.

 

Complex Permanent Tissues in Plants: Xylem and Phloem

1. Introduction

• Complex permanent tissues are composed of more than one type of cell that work together to perform a common function.
• Xylem and phloem are examples of complex tissues, and they constitute vascular bundles.
• Vascular tissue, a characteristic of complex plants, enables their survival in terrestrial environments.

2. Xylem Tissue

• Composition: Xylem consists of several cell types, including tracheids, vessels, xylem parenchyma, and xylem fibers.
• Structural Characteristics:
• Tracheids and vessels have thick walls, and many become dead cells when mature.
• Tracheids and vessels are tubular structures, allowing them to transport water and minerals vertically.
• Xylem parenchyma stores food.
• Xylem fibers primarily provide support.

3. Phloem Tissue

• Composition: Phloem is composed of five types of cells: sieve cells, sieve tubes, companion cells, phloem fibers, and phloem parenchyma.
• Structural Characteristics:
• Sieve tubes are tubular cells with perforated walls.
• Phloem transports food, primarily from leaves to other plant parts.
• Except for phloem fibers, other phloem cells are living cells.

In summary, complex permanent tissues like xylem and phloem are composed of multiple cell types that collaborate to perform essential functions in plants. Xylem is responsible for water and mineral transport, while phloem transports food materials throughout the plant. The coordination of various cell types within these complex tissues is a vital aspect of plant physiology, enabling their adaptation to terrestrial environments.

 

 

1. Name types of simple tissues.

2. Where is apical meristem found?

3. Which tissue makes up the husk of coconut?

4. What are the constituents of phloem?

1. Types of Simple Tissues:
• Parenchyma
• Collenchyma
• Sclerenchyma
• Epidermis
2. Apical Meristem Location:
• Apical meristem is typically found at the growing tips of stems and roots. It is responsible for increasing the length of the stem and the root.
3. Tissue in the Husk of Coconut:
• The husk of a coconut is primarily made up of sclerenchymatous tissue. Sclerenchyma tissue provides hardness and stiffness to plant structures and is characterized by its thick-walled, lignified cells.
4. Constituents of Phloem:
• Phloem is composed of several cell types, including:
• Sieve tubes: Tubular cells with perforated walls, responsible for transporting food materials.
• Sieve cells: Specialized cells that function in food transport.
• Companion cells: Adjacent cells that support sieve tube function.
• Phloem fibers: Fibrous cells that provide structural support.
• Phloem parenchyma: Cells responsible for storing food and providing metabolic support to other phloem elements.

These answers provide an overview of the types of simple tissues, the location of apical meristem, the tissue in the coconut husk, and the constituents of phloem tissue in plants.

Animal Tissues and Their Functions

1. Muscle Cells for Movement
• Muscle cells are specialized cells responsible for the movement of various body parts.
• Contraction and relaxation of muscle cells result in bodily movements, such as those observed during breathing.
2. Oxygen Transport via Blood
• Oxygen taken in during breathing is absorbed in the lungs and then transported to all body cells through the bloodstream.
• Cells require oxygen for various metabolic processes, as indicated by the function of mitochondria.
3. Blood's Circulatory Functions
• Blood acts as a carrier, flowing throughout the body and facilitating the transportation of various substances.
• It carries oxygen and nutrients to all cells, ensuring their proper functioning.
• Blood also collects waste products from different body parts and transports them to the liver and kidneys for disposal.
4. Types of Animal Tissues
• Based on the functions they perform, animal tissues can be categorized into different types:
• Epithelial Tissue: Tissue responsible for lining body surfaces and forming protective barriers.
• Connective Tissue: Tissue that connects and supports various body structures, including blood.
• Muscular Tissue: Tissue involved in movement and contraction, as seen in muscles.
• Nervous Tissue: Tissue responsible for transmitting nerve impulses and enabling communication within the nervous system.
5. Blood as Connective Tissue
• Blood is a type of connective tissue that plays a crucial role in transporting oxygen, nutrients, and waste products throughout the body.
• It acts as a vital connector, ensuring the proper functioning of various body cells and organs.

In summary, the human body contains different types of tissues, each with its specific functions. Muscle cells enable movement, blood transports essential substances, and there are various types of animal tissues, including epithelial, connective, muscular, and nervous tissues, each contributing to the body's overall functionality.

 

Epithelial Tissue in Animals

1. Introduction
• Epithelial tissues serve as the covering or protective tissues in the animal body.
• These tissues are found covering most organs and cavities within the body.
• Epithelium forms a barrier that separates various body systems.
2. Locations of Epithelial Tissues
• Epithelial tissue is found in various parts of the body, including:
• Skin
• Lining of the mouth
• Lining of blood vessels
• Lung alveoli
• Kidney tubules
3. Characteristics of Epithelial Tissue
• Cells in epithelial tissue are tightly packed, forming a continuous sheet.
• They have minimal cementing material between them and very few intercellular spaces.
• Epithelium plays a crucial role in regulating the exchange of materials between the body and the external environment and between different body parts.
• An extracellular fibrous basement membrane separates epithelium from the underlying tissue.
4. Types of Epithelial Tissues
• Different types of epithelia exhibit varying structures based on their unique functions:
• Simple Squamous Epithelium: Found in blood vessels and lung alveoli, it is extremely thin and flat, facilitating the transport of substances.
• Stratified Squamous Epithelium: Forms the skin and the lining of the mouth, arranged in multiple layers to provide protection.
• Ciliated Columnar Epithelium: Present in the respiratory tract, it has cilia on the cell surfaces that help move mucus to clear the airways.
• Columnar Epithelium: Found in the inner lining of the intestine, facilitating absorption and secretion.
• Cuboidal Epithelium: Lines kidney tubules and salivary gland ducts, providing mechanical support.
• Glandular Epithelium: Some epithelial tissues fold inward, forming multicellular glands specialized for secretion.

In summary, epithelial tissue serves as the body's protective covering and is found in various structures. The type and structure of epithelial tissue correlate with its function, which can include protection, absorption, secretion, and transportation of substances.

Connective Tissue in Animals

1. Introduction to Connective Tissue
• Connective tissue, like blood, earns its name because it connects various body parts.
• These tissues have loosely spaced cells embedded in an intercellular matrix with varying characteristics.
2. Blood as Connective Tissue
• Function of Blood: Blood has a fluid matrix called plasma that contains red blood corpuscles (RBCs), white blood corpuscles (WBCs), platelets, proteins, salts, and hormones.
• Role in Transport: Blood flows throughout the body, transporting gases, digested food, hormones, and waste materials to different body parts.
3. Bone as Connective Tissue
• Function of Bone: Bone serves as the body's framework, supporting and anchoring muscles and organs.
• Structural Characteristics: Bone is strong, nonflexible tissue with cells embedded in a hard matrix composed of calcium and phosphorus compounds.
4. Ligaments and Tendons
• Ligaments: These connective tissues are highly elastic and possess considerable strength. Ligaments contain minimal matrix and connect bones to bones.
• Tendons: Tendons are fibrous tissues with great strength but limited flexibility. They connect muscles to bones.
5. Cartilage as Connective Tissue
• Structural Characteristics: Cartilage contains widely spaced cells and a solid matrix composed of proteins and sugars.
• Function: Cartilage smoothes bone surfaces at joints and is present in the nose, ear, trachea, and larynx. It offers flexibility compared to bones.
6. Areolar Connective Tissue
• Locations: Areolar connective tissue is found between the skin and muscles, around blood vessels and nerves, in the bone marrow, and inside organs.
• Functions: It fills spaces inside organs, supports internal organs, and assists in tissue repair.
7. Adipose Tissue
• Location: Fat-storing adipose tissue is found beneath the skin and between internal organs.
• Cell Characteristics: Adipose tissue cells are filled with fat globules.
• Functions: This tissue stores fats and acts as an insulator.

In summary, connective tissue in animals serves various functions, including support, connection, transport, and insulation. Different types of connective tissues have unique structural characteristics that match their specific functions within the body.

 

Muscular Tissue in Animals

1. Introduction to Muscular Tissue
• Muscular tissue is composed of elongated cells known as muscle fibers.
• Its primary function is to facilitate movement in the body.
• Muscles contain contractile proteins that contract and relax, causing movement.
2. Voluntary Muscles (Skeletal Muscles)
• Characteristics: These muscles can be consciously controlled by the will.
• Function: Voluntary muscles, also known as skeletal muscles, are mostly attached to bones and are responsible for body movement.
• Microscopic Appearance: When viewed under a microscope with appropriate staining, they exhibit alternate light and dark bands or striations, hence referred to as striated muscles.
• Cell Characteristics: Skeletal muscle cells are long, cylindrical, unbranched, and multinucleate, meaning they have many nuclei.
3. Involuntary Muscles (Smooth Muscles)
• Characteristics: Involuntary muscles control movements that we cannot consciously initiate or stop.
• Functions: Smooth muscles are responsible for involuntary movements, such as the movement of food in the alimentary canal and the contraction and relaxation of blood vessels.
• Locations: They are found in various parts of the body, including the iris of the eye, ureters, and bronchi of the lungs.
• Microscopic Appearance: These muscles appear unstriated under a microscope.
• Cell Characteristics: Smooth muscle cells are long, spindle-shaped, and uninucleate, with a single nucleus.
4. Cardiac Muscles (Heart Muscles)
• Characteristics: Cardiac muscles exhibit rhythmic contraction and relaxation throughout life.
• Function: These involuntary muscles are found in the heart and are responsible for pumping blood.
• Cell Characteristics: Cardiac muscle cells are cylindrical, branched, and uninucleate.

In summary, muscular tissue in animals is diverse and includes voluntary (skeletal) muscles, involuntary (smooth) muscles, and cardiac muscles. Each type of muscle has distinct characteristics and functions, contributing to various aspects of movement and physiological processes in the body.

Nervous Tissue in Animals

1. Introduction to Nervous Tissue
• Nervous tissue is highly specialized for responding to stimuli and rapidly transmitting signals within the body.
• It constitutes the brain, spinal cord, and nerves.
2. Nerve Cells (Neurons)
• Cell Structure: Neurons, the cells of nervous tissue, consist of a cell body with a nucleus and cytoplasm. They possess long, thin, hair-like structures.
• Axon and Dendrites: Neurons typically have a single long process called the axon and many short, branched processes called dendrites.
• Length: Individual neurons can be quite long, with some reaching up to a meter in length.
• Nerves: Nerve fibers, which are bundles of many nerve cells, are held together by connective tissue, forming nerves.
3. Nerve Impulses
• Definition: The signal that travels along a nerve fiber is known as a nerve impulse.
• Function: Nerve impulses play a crucial role in muscle movement, allowing us to control our muscles voluntarily.
• Fundamental Role: The combination of nervous tissue and muscle tissue is fundamental for most animals, enabling rapid responses to stimuli.

In summary, nervous tissue is specialized for responding to stimuli and transmitting signals quickly within the body. Nervous tissue includes neurons, which have a cell body, axon, and dendrites. Nerve impulses are vital for muscle movement and are central to the ability of animals to respond rapidly to various stimuli.

 

1. Tissue Responsible for Movement in Our Body:
• The tissue responsible for movement in our body is muscular tissue.
2. Appearance of a Neuron:
• A neuron typically consists of:
• A cell body with a nucleus and cytoplasm
• A long, thin process called an axon
• Many short, branched processes called dendrites
3. Features of Cardiac Muscles:
• Cardiac muscles exhibit the following features:
• Rhythmic contraction and relaxation.
• Cylindrical and branched cells.
• Uninucleate (having a single nucleus).
4. Functions of Areolar Tissue (areolar tissue):
• Areolar connective tissue serves several functions, including:
• Filling spaces inside organs.
• Supporting internal organs.
• Assisting in tissue repair.
• Connecting skin to muscles, blood vessels, and nerves.
• Providing flexibility and cushioning.

___________________________________________________________________________

 

1. Definition of "Tissue":
• Tissue is a group or collection of similar cells that perform a specific function within an organism.
2. Types of Elements in Xylem Tissue:
• The xylem tissue consists of four types of elements:
• Tracheids
• Vessels
• Xylem parenchyma
• Xylem fibers
3. Difference Between Simple Tissues and Complex Tissues in Plants:
• Simple tissues are composed of a single type of cell that performs a similar function, whereas complex tissues consist of multiple types of cells that work together to perform specialized functions.
4. Differences Between Parenchyma, Collenchyma, and Sclerenchyma Based on Cell Wall:
• Parenchyma: Thin cell walls, living cells with large intercellular spaces.
• Collenchyma: Unevenly thickened cell walls, living cells with limited intercellular spaces.
• Sclerenchyma: Thick and lignified cell walls, often dead cells with no intercellular spaces.
5. Functions of Stomata:
• Stomata are specialized pores found in the epidermis of leaves and stems in plants.
• Their functions include:
• Regulating gas exchange (carbon dioxide uptake and oxygen release) for photosynthesis and respiration.
• Controlling water vapor and transpiration.
• Facilitating the exchange of water and minerals with the surrounding environment.
6. Diagrammatic Representation of Muscle Fibres:
• Unfortunately, I cannot draw diagrams. However, you can easily find diagrams of the three types of muscle fibers (skeletal, smooth, and cardiac) by searching online or referring to biology textbooks.
7. Specific Function of Cardiac Muscle:
• The specific function of cardiac muscle is to contract rhythmically and involuntarily to pump blood throughout the circulatory system, ensuring the circulation of oxygen and nutrients to various body tissues.
8. Differences Between Striated, Unstriated, and Cardiac Muscles:
• Striated Muscles (Skeletal Muscles): Cylindrical, multinucleate, voluntary, and striated appearance under a microscope. Attached to bones for body movement.
• Unstriated Muscles (Smooth Muscles): Spindle-shaped, uninucleate, involuntary, and non-striated appearance. Found in various organs for involuntary movements.
• Cardiac Muscles: Branched, uninucleate, involuntary, and striated appearance. Present in the heart for continuous pumping of blood.
9. Labelled Diagram of a Neuron:
• I cannot create diagrams, but you can easily find labelled neuron diagrams in biology textbooks or online resources.
10. Naming the Following: (a) Tissue that forms the inner lining of our mouth: Epithelial tissue (b) Tissue that connects muscle to bone in humans: Tendon (c) Tissue that transports food in plants: Phloem tissue (d) Tissue that stores fat in our body: Adipose tissue (e) Connective tissue with a fluid matrix: Blood (or blood tissue) (f) Tissue present in the brain: Nervous tissue
11. Types of Tissues in the Given Examples:
• Skin: Epithelial tissue
• Bark of Tree: Cork (Protective tissue)
• Bone: Connective tissue (Osseous tissue)
• Lining of Kidney Tubule: Epithelial tissue
• Vascular Bundle: Contains xylem and phloem tissues

 

Top of Form

 

 

CONTROL AND COORDINATION: FULL CHAPTER

1. Introduction to the Concept of Movement in Living Organisms:
• In the previous chapter, we explored the life processes related to the maintenance functions in living organisms.
• One common notion is that we associate movement with life; if something is moving, we tend to consider it alive.
2. Types of Movements in Living Organisms:
• Some movements in organisms are a result of growth, like in plants. For example, when a seed germinates and grows, we observe the seedling pushing through the soil.
• However, not all movements are linked to growth. Animals and certain plants exhibit movements that are independent of their growth. Examples include a cat running, children on swings, or buffaloes chewing cud.
3. The Association of Movement with Life:
• We tend to associate visible movements with life because we perceive them as responses to changes in the organism's environment.
• These movements are often seen as efforts by living organisms to adapt to changes in their surroundings for their benefit.
4. Movement as a Response to Environmental Changes:
• For instance, a running cat might be responding to the presence of a mouse.
• Living organisms use environmental changes to their advantage through movement. Plants grow towards sunlight, children seek pleasure in swinging, and buffaloes chew cud to aid digestion of tough food.
5. Controlled and Purposeful Movements:
• It's crucial to note that the movements in response to the environment are not random; they are carefully controlled.
• Different environmental changes trigger specific movements. For instance, we whisper when talking to friends in class rather than shouting, showing that the appropriate movement depends on the situation.
6. The Role of Recognition and Coordination:
• To achieve such controlled movements, living organisms must possess systems for recognizing various events in their environment.
• Recognition of environmental events is followed by the execution of the correct, coordinated movement in response.
7. Specialized Tissues for Control and Coordination:
• To facilitate this recognition and coordination, multicellular organisms employ specialized tissues.
• These specialized tissues play a vital role in providing control and coordination activities within the organism, aligning with the general principles of body organization in multicellular beings.

Role of Nervous System in Animals:

1. In animals, control and coordination are facilitated by nervous and muscular tissues.
2. These tissues play a vital role in responding to urgent and potentially dangerous situations, such as touching a hot object.

Detection of Environmental Information: 3. To detect changes in the environment, specialized nerve cells with receptor tips are employed.

4. These receptors are typically found in sense organs like the inner ear, nose, tongue, and others.
5. Different types of receptors, such as gustatory for taste and olfactory for smell, are responsible for detecting specific environmental cues.

Transmission of Information within Neurons: 6. Information acquired by these receptors triggers a chemical reaction that generates an electrical impulse at the dendritic tip of a nerve cell.

7. This electrical impulse then travels from the dendrite to the cell body and along the axon to its endpoint.
8. At the axon's endpoint, the electrical impulse initiates the release of certain chemicals.
9. These chemicals cross a synapse (a gap) and stimulate a similar electrical impulse in the dendrite of the next neuron.
10. This process represents the general scheme of how nervous impulses travel within the body.

Delivery of Impulses to Other Cells:

       11. A similar synapse allows the transmission of nervous impulses from neurons to other cells, such as muscle cells or glands.

Structure of Nervous Tissue:

      12. Nervous tissue is structured as an organized network of nerve cells, or neurons.

13. It is specialized for transmitting information via electrical impulses from one part of the body to another.

Impact of Blocked Nose on Taste:

       14. When your nose is blocked, there can be a difference in how sugar and food taste.

15. This variation occurs because the sense of taste is closely linked to the sense of smell.
16. The receptors responsible for detecting smell are located in the nasal passages.
17. When the nose is blocked, the ability to detect certain odor molecules is diminished, impacting the overall perception of flavor.
18. A similar situation may be experienced when you have a cold due to nasal congestion.

Reflex Actions in Response to Bright Light:

1. Common Understanding of Reflex Actions:
• Reflex actions are immediate responses to environmental stimuli that occur without conscious thought or control.
• Examples include quickly jumping out of the way of a bus, pulling one's hand away from a flame, or experiencing mouthwatering due to hunger.
2. Control and Coordination in Reflex Actions:
• Reflex actions involve responding to changes in the environment.
• Despite the lack of conscious thought or control, the body still exhibits purposeful actions in response to stimuli.
3. Response to a Dangerous Stimulus - Touching a Flame:
• Touching a flame is a dangerous situation for humans and animals alike.
4. Conscious Thinking vs. Reflexive Response:
• One way to respond to touching a flame would be to consciously think about the pain and the risk of getting burned before moving the hand away.
• However, thinking involves the transmission of nerve impulses, which can be a complex and time-consuming process.
5. Complex Nature of Thinking:
• Thinking is a complex activity that requires interactions among many nerve impulses from multiple neurons.
6. Thinking Tissue in the Brain:
• The thinking part of the brain, located in the forward end of the skull, receives signals from all parts of the body.
• It processes these signals before generating responses.
7. Need for Quick Response:
• In urgent situations like touching a hot object, relying solely on conscious thought may result in significant delay, potentially causing burns.
8. Role of Reflex Arcs:
• To address this issue, the body utilizes reflex arcs, which are efficient neural pathways for rapid responses to stimuli.
• Reflex arcs allow for a more direct connection between sensory input and motor output.
9. Location of Reflex Arc Connections:
• Reflex arc connections are typically made where sensory nerves first meet motor nerves.
• These connections are often formed within the spinal cord, where nerves from different parts of the body converge on their way to the brain.
10. The Efficiency of Reflex Arcs:
• Reflex arcs are evolutionarily advantageous because they provide swift responses, especially in situations where complex neural processing (thinking) is not necessary.
• Even in organisms with complex neural networks for thinking, reflex arcs remain efficient for quick reactions to immediate threats.
11. Sequence of Events in Reflex Actions:
• When a bright light is focused on your eyes, the following sequence of events occurs within a reflex arc:
• Sensory receptors in the eyes detect the intense light.
• Nerve impulses are generated and transmitted through sensory nerves.
• These impulses quickly reach the spinal cord, where a reflex arc is formed.
• In the spinal cord, a rapid response is generated without the need for conscious thought.
• Motor nerves carry the response signal to the muscles controlling the eye's reaction.
• The eye responds by contracting the iris or squinting, reducing the amount of light entering the eye and protecting it from potential harm.

Functions of the Human Brain and Spinal Cord:

1. Reflex Actions vs. Complex Functions:
• Reflex actions are not the only functions of the spinal cord. Humans possess complex thinking abilities.
• The spinal cord contains nerves that transmit information, while thinking involves more intricate mechanisms and neural connections, primarily located in the brain.
2. Central Nervous System (CNS):
• The central nervous system comprises the brain and spinal cord.
• It receives information from all parts of the body and integrates it.
3. Voluntary Actions and Muscle Control:
• Voluntary actions, like writing, talking, and moving objects, result from conscious decision-making.
• The brain sends messages to the muscles, facilitating voluntary actions.
• This communication between the central nervous system and muscles is the second way in which the nervous system functions.
4. Peripheral Nervous System (PNS):
• The peripheral nervous system includes cranial nerves arising from the brain and spinal nerves arising from the spinal cord.
• It facilitates communication between the central nervous system and other body parts.
5. Brain's Role in Thinking and Decision-Making:
• The brain enables thinking and taking actions based on that thinking.
• It consists of different regions responsible for various functions.
6. Three Major Parts of the Brain:
• The brain has three major regions: the fore-brain, mid-brain, and hind-brain.
7. Fore-Brain:
• The fore-brain is the primary thinking part of the brain.
• It contains regions specialized for receiving sensory impulses from various receptors.
• Separate areas within the fore-brain handle hearing, smell, sight, and other senses.
• Association areas in the fore-brain interpret sensory information by integrating it with data from other receptors and stored information.
• Decisions are made based on this interpretation and transmitted to motor areas that control voluntary muscle movement.
• Certain sensations, such as feeling full after eating, are associated with specific centers within the fore-brain.
8. Mid-Brain and Hind-Brain:
• The mid-brain and hind-brain control involuntary actions, which occur without conscious thought.
• These actions include heartbeat, digestion, and other functions.
• The medulla in the hind-brain governs various involuntary actions like blood pressure, salivation, and vomiting.
• The cerebellum, a part of the hind-brain, is responsible for precise voluntary actions, posture maintenance, and balance of the body.
9. Involuntary Muscle Movements:
• Between simple reflex actions and thought-out actions, there exists a category of muscle movements over which we have no conscious control.
• Examples include salivation, heartbeats, and digestion.
• The mid-brain and hind-brain regulate many of these involuntary actions.
10. Role of the Medulla:
• The medulla in the hind-brain is responsible for controlling various involuntary functions, ensuring their proper operation.
11. Cerebellum's Role:
• The cerebellum, located in the hind-brain, plays a crucial role in enabling precision in voluntary actions and maintaining body posture and balance.

Protection of Delicate Organs - Brain and Spinal Cord:

1. Brain Protection:
• The brain, a vital and delicate organ responsible for numerous bodily functions, requires careful protection.
• The body is designed with a specific safeguard: the brain is situated within a protective bony enclosure.
2. Bony Enclosure for the Brain:
• The brain is housed within a bony box, which provides a sturdy physical barrier.
• This bony box or cranial cavity shields the brain from external impacts and injuries.
3. Fluid-Filled Balloon Surrounding the Brain:
• Inside the protective cranial cavity, the brain is further safeguarded by a fluid-filled balloon-like structure.
• This cerebrospinal fluid-filled space provides additional shock absorption, preventing damage to the brain during sudden movements or impacts.
4. Spinal Cord Protection:
• Similar to the brain, the spinal cord, which is an extension of the central nervous system, requires protection.
• The vertebral column, commonly known as the backbone, serves as the protective structure for the spinal cord.
5. The Role of the Vertebral Column:
• Running your hand down the middle of your back, you can feel a hard and somewhat bumpy structure.
• This structure is the vertebral column, or backbone, consisting of a series of individual vertebrae.
6. Protection of the Spinal Cord:
• The vertebral column envelops and shields the spinal cord from external harm.
• It acts as a protective casing for the spinal cord, helping to prevent injury to this essential neural pathway.

How Nervous Tissue Causes Action:

1. Overview of Nervous Tissue Functions:
• Nervous tissue plays a crucial role in collecting information, transmitting it throughout the body, processing data, making decisions based on this information, and conveying decisions to muscles for action.
2. Role of Muscle Tissue in Action:
• When it comes to executing actions or movements, the final task is performed by muscle tissue.
3. Muscle Cell Movement:
• For muscle cells to move, they must change their shape, typically by shortening.
4. Mechanism of Muscle Cell Shape Change:
• Muscle cells achieve shape change through chemical processes within their cellular components.
5. Special Proteins in Muscle Cells:
• Muscle cells contain specific proteins that can alter both their shape and arrangement within the cell in response to electrical impulses from nerves.
6. Result of Protein Rearrangement:
• When these proteins rearrange in response to nerve impulses, the muscle cells assume a shorter form.
7. Different Types of Muscles:
• In previous discussions in Class IX, we learned about various types of muscles, including voluntary muscles and involuntary muscles.
8. Differences Between Voluntary and Involuntary Muscles:
• Voluntary muscles are under conscious control, meaning individuals can decide when to activate them, and they typically move in response to conscious commands.
• Involuntary muscles, on the other hand, function automatically without conscious effort or control.

 

 

Answer the questions.

1. What is the difference between a reflex action and walking?

2. What happens at the synapse between two neurons?

3. Which part of the brain maintains posture and equilibrium of the body?

4. How do we detect the smell of an agarbatti (incense stick)?

5. What is the role of the brain in reflex action?

 

1. Difference between a Reflex Action and Walking:
• Reflex Action:
• Reflex actions are involuntary and automatic responses to specific stimuli.
• They do not involve conscious thought and occur rapidly.
• Reflex actions are typically protective or defensive in nature, such as withdrawing a hand from a hot object.
• Walking:
• Walking is a voluntary action.
• It requires conscious control and coordination of muscles.
• Walking involves a series of voluntary muscle contractions and relaxation, coordinated by the brain, to move the body in a desired direction.
2. What Happens at the Synapse between Two Neurons:
• At the synapse between two neurons, the following events occur:
• When an electrical impulse (action potential) reaches the end of the axon of the presynaptic neuron, it triggers the release of chemical neurotransmitters.
• These neurotransmitters are released into the synaptic cleft, the tiny gap between the presynaptic neuron's axon terminal and the dendrite of the postsynaptic neuron.
• The neurotransmitters then bind to specific receptor sites on the membrane of the postsynaptic neuron.
• This binding leads to changes in the postsynaptic neuron's electrical charge, either depolarizing it (excitatory effect) or hyperpolarizing it (inhibitory effect).
• If the change in electrical charge is significant enough, it may generate an action potential in the postsynaptic neuron, continuing the transmission of the nerve impulse.
3. Part of the Brain that Maintains Posture and Equilibrium:
• The part of the brain responsible for maintaining posture and equilibrium (balance) of the body is the cerebellum, which is located in the hind-brain.
4. How We Detect the Smell of an Agarbatti (Incense Stick):
• When we detect the smell of an agarbatti or incense stick, it involves the olfactory system:
• Odor molecules from the incense stick are released into the air.
• These odor molecules enter our nasal passages during inhalation.
• Within the nasal passages, specialized olfactory receptors detect the presence of these molecules.
• These receptors send signals to the olfactory bulb in the brain.
• The brain processes these signals and interprets them as a particular smell, allowing us to perceive the aroma of the incense.
5. Role of the Brain in Reflex Action:
• The brain plays a role in reflex actions by:
• Receiving sensory information from the body, including signals from sensory receptors that detect stimuli.
• Processing this sensory information.
• Making decisions based on the sensory input, such as whether to initiate a reflex response or not.
• Sending signals to motor neurons and muscles to execute the reflex action.
• In some cases, the brain may also inhibit or modulate reflex responses based on higher cognitive functions, especially in situations where conscious thought and control are involved.

 

Coordination in Plants:

1. Absence of Nervous System and Muscles:
• Unlike animals, plants lack a nervous system and muscles for controlling and coordinating their activities.
2. Plant Responses to Stimuli:
• Plants are capable of responding to stimuli in their environment despite the absence of a nervous system.
• Their responses are a result of specialized mechanisms.
3. Example: 'Sensitive' or 'Touch-Me-Not' Plant (Mimosa family):
• When the leaves of a sensitive plant (chhui-mui) are touched, they exhibit rapid folding and drooping.
• This movement in the sensitive plant is quick and responsive to touch, and it does not involve growth.
4. Example: Seed Germination:
• During seed germination, the root grows downward into the soil, while the stem grows upward into the air.
• This directional movement of a seedling is a result of growth.
5. Two Types of Plant Movement:
• Plants display two distinct types of movement:
• Movement Dependent on Growth:
• Growth-related movement occurs when plant parts like roots and stems change their positions as they grow.
• Inhibited growth results in a lack of movement in these cases.
• Movement Independent of Growth:
• Some plant responses, such as the folding of sensitive plant leaves upon touch, are rapid and do not involve growth processes.
• These movements are immediate reactions to stimuli in the environment.

Immediate Plant Response to Stimuli (e.g., Touch):

1. Absence of Nervous and Muscle Tissues:
• Unlike animals, plants lack both nervous tissue and muscle tissue for sensing and responding to stimuli.
2. Detection of Touch:
• When a plant, like the sensitive plant, is touched, it needs to detect the touch without having specialized sensory organs.
3. Communication of Touch Information:
• Movement in response to touch occurs at a different location than the point of touch.
• To facilitate this movement, the plant must convey information about the touch event.
4. Absence of Specialized Information-Conducting Tissue:
• Unlike animals, plants do not possess specialized tissue for the conduction of information.
• Instead, they use electrical-chemical means to transmit information from one cell to another.
5. Role of Changing Cell Shape:
• In both animals and plants, some cells must change shape to enable movement.
• In plants, rather than specialized proteins like those in animal muscle cells, cell shape changes occur by altering the water content within the cells.
• This change in water content leads to swelling or shrinking of plant cells, resulting in changes in their shapes.
6. Immediate Response Mechanism in Plants:
• The immediate response to stimuli, such as touch, in plants involves:
• Detection of the stimulus by specialized cells.
• Transmission of information about the stimulus through electrical-chemical means, even in the absence of dedicated information-conducting tissue.
• Changing cell shapes through water content adjustments, which leads to rapid movement, as seen in the folding of sensitive plant leaves.

Plant Movements and Hormonal Coordination:

1. Variety in Plant Responses to Stimuli:
• Plants exhibit different responses to stimuli in their environment.
• These responses can be categorized into immediate movements and slow, directional growth movements.
2. Immediate Movements - Example: Sensitive Plant (Mimosa):
• In immediate responses, such as the folding of sensitive plant leaves upon touch, there is no growth involved.
• Touch detection and leaf movement are rapid but do not involve growth.
3. Directional Growth Movements:
• Some plant responses involve directional growth, where plant parts grow in a particular direction in response to external stimuli.
• These movements are relatively slow but contribute to the plant's ability to adapt to its environment.
4. Phototropic Movements:
• Environmental triggers like light or gravity influence the direction of plant growth.
• Phototropic movements can be either towards the stimulus (positive phototropism) or away from it (negative phototropism).
• Example: Shoots bending towards light (positive phototropism) while roots bending away from it (negative phototropism).
5. Geotropism - Response to Gravity:
• Roots typically exhibit positive geotropism (grow towards gravity), while shoots display negative geotropism (grow away from gravity).
• These growth responses help roots penetrate the soil and shoots grow upwards into the air.
6. Hydrotropism and Chemotropism:
• Hydrotropism refers to plant growth responses towards water.
• Chemotropism relates to growth influenced by chemicals.
• Examples and specific instances of these directional growth movements can be found in plant behavior.
7. Role of Plant Hormones:
• Hormones play a crucial role in coordinating plant growth, development, and responses to the environment.
• Different plant hormones regulate various aspects of plant physiology.
8. Auxin Hormone and Phototropic Growth:
• Auxin is a hormone synthesized at the shoot tip.
• When light comes from one side of the plant, auxin diffuses towards the shaded side.
• Higher auxin concentration on the shaded side stimulates cell elongation and growth on that side.
• This growth results in the plant appearing to bend towards the light source.
9. Other Plant Hormones:
• Gibberellins and auxins promote stem growth.
• Cytokinins encourage cell division, especially in fruits and seeds.
• Abscisic acid inhibits growth and can lead to effects like wilting of leaves.
10. Diversity in Plant Hormones:
• Plant hormones vary in their functions, promoting or inhibiting growth and responding to specific environmental cues.
11. Hormonal Coordination in Plants:
• Plant hormones are synthesized at one location and can diffuse to the areas where they are needed for specific actions.
• They help plants adapt to their surroundings by regulating growth, development, and responses to stimuli.

 

Answer the following questions

1. What are Plant Hormones?
• Plant hormones, also known as phytohormones, are chemical substances produced by plants in minuscule amounts that regulate various physiological processes within the plant. These hormones control growth, development, responses to stimuli, and coordination of plant activities.
2. Difference Between the Movement of Leaves of the Sensitive Plant and the Movement of a Shoot Towards Light:
• Movement of Leaves of the Sensitive Plant:
• The movement of leaves in the sensitive plant (like Mimosa) is an immediate response to touch or stimuli.
• It is rapid and does not involve growth; instead, it results from the rapid changes in the turgor pressure within cells, leading to leaf folding and drooping.
• Movement of Shoot Towards Light (Phototropic Movement):
• Shoots exhibit phototropic movement towards a light source.
• This movement is relatively slow compared to the immediate response of the sensitive plant.
• Phototropic movement involves growth towards the light source, where the plant's cells elongate on the shaded side, causing the shoot to bend towards the light.
3. Example of a Plant Hormone that Promotes Growth:
• Auxins are a class of plant hormones that promote the growth of plant tissues, especially in the context of cell elongation and expansion. They are responsible for phototropic and geotropic responses.
4. How Auxins Promote the Growth of a Tendril Around a Support:
• When a tendril of a plant like a pea plant comes in contact with a support, it detects the touch or support.
• Auxins, a plant hormone, accumulate on the side of the tendril away from the support.
• This uneven distribution of auxin leads to more rapid cell elongation on the side without support.
• As a result, the tendril bends and curls around the support structure, effectively allowing the plant to cling to it.
5. Experiment to Demonstrate Hydrotropism:
• Objective: To demonstrate hydrotropism, the directional growth response of plant roots towards a water source.
• Materials:
• Several small potted plants with well-established root systems
• Plastic containers
• Water
• Measuring tools
• Labels
• Light source
• Procedure:

1.                   Label the potted plants to keep track of their conditions.

2.                   Fill plastic containers with a uniform layer of soil.

3.                   Place one potted plant in each container and ensure that the roots are evenly buried in the soil.

4.                   Position the containers in an area with uniform light conditions.

5.                   Water the containers evenly so that the soil is moist but not saturated.

6.                   Observe and measure the initial direction of root growth (e.g., straight down).

7.                   Create a water source by placing a container filled with water at one side of the plants.

8.                   Ensure that the water source is at a distance from the plants, allowing the roots to respond to the moisture gradient.

9.                   Over several days, monitor the direction of root growth and record any changes.

10.               Compare the growth direction of roots towards the water source to demonstrate hydrotropism.

Questions for Experiment:

• What is the initial direction of root growth before introducing the water source?
• Do the roots exhibit a change in growth direction over time in response to the water source?
• Is there a noticeable difference in the growth pattern between plants exposed to the water source and those without it?

This experiment will illustrate how plant roots respond to moisture gradients and demonstrate hydrotropism, where roots grow in the direction of a water source.

Hormones in Animals and Their Functions:

1. Adrenaline in Response to Stress:
• Animals, including humans, use hormones like adrenaline to respond to stressful situations.
• When animals face danger, their bodies prepare for either fighting or fleeing.
• Adrenaline is secreted by the adrenal glands and released into the bloodstream.
• Adrenaline acts on target organs and tissues, including the heart, to facilitate immediate responses.
• Effects of adrenaline include increased heart rate, redirection of blood flow to muscles, and increased breathing rate.
2. Endocrine System:
• Adrenaline and other hormones are part of the endocrine system in animals.
• The endocrine system uses chemical signals (hormones) to coordinate various functions in the body.
3. Hormones vs. Plant Growth:
• Unlike plants that use hormones for directional growth responses, animal hormones serve different functions.
• Animals do not exhibit directional growth in response to hormones like plants.
4. Controlled Growth in Animals:
• Growth in animals is carefully regulated in specific regions of the body.
• Unlike plants that grow leaves in multiple locations, animals have controlled body designs even during growth.
5. Iodine and Thyroxin Hormone:
• Iodine is essential for the synthesis of thyroxin hormone, produced by the thyroid gland.
• Thyroxin regulates metabolism, including carbohydrate, protein, and fat metabolism.
• Iodine deficiency can lead to conditions like goitre, characterized by a swollen neck.
6. Growth Hormone and Dwarfism:
• The pituitary gland secretes growth hormone, which regulates growth and development.
• Growth hormone deficiency during childhood can result in dwarfism.
7. Puberty and Sex Hormones:
• During puberty, dramatic changes occur in appearance due to the secretion of sex hormones.
• Males produce testosterone, while females produce estrogen, leading to secondary sexual characteristics.
8. Insulin and Blood Sugar Regulation:
• Insulin is a hormone produced by the pancreas to regulate blood sugar levels.
• Insufficient insulin secretion can lead to diabetes, causing adverse effects on health.
• Feedback mechanisms regulate hormone secretion, ensuring the precise timing and quantity of hormones.
• For example, when blood sugar levels rise, the pancreas produces more insulin, and as levels fall, insulin secretion decreases.

 

1. How does chemical coordination take place in animals?
• Chemical coordination in animals occurs through the endocrine system, which involves the production and release of hormones.
• Hormones are chemical messengers secreted by various glands in the body.
• These hormones travel through the bloodstream and target specific organs or tissues, where they initiate specific responses or regulate physiological processes.
• The timing and amount of hormone secretion are regulated by feedback mechanisms to maintain homeostasis in the body.
2. Why is the use of iodised salt advisable?
• The use of iodised salt is advisable because iodine is essential for the production of thyroxin, a hormone produced by the thyroid gland.
• Thyroxin regulates various metabolic processes in the body, including carbohydrate, protein, and fat metabolism.
• Iodine deficiency can lead to thyroid-related disorders, such as goitre, characterized by a swollen neck.
• Iodised salt helps ensure an adequate intake of iodine, preventing these health issues.
3. How does our body respond when adrenaline is secreted into the blood?
• When adrenaline is secreted into the blood, the body undergoes various physiological responses to prepare for fight or flight in response to a stressful situation.
• These responses include:
• Increased heart rate: Adrenaline stimulates the heart to beat faster, providing more oxygen to muscles.
• Redistribution of blood flow: Blood is diverted from the digestive system and skin to skeletal muscles, enhancing physical readiness.
• Increased breathing rate: Adrenaline causes the diaphragm and rib muscles to contract, resulting in faster breathing.
• These combined effects make the body ready to respond quickly and effectively to a perceived threat.
4. Why are some patients of diabetes treated by giving injections of insulin?
• Some patients with diabetes are treated with insulin injections because their bodies do not produce or use insulin effectively.
• Insulin is a hormone produced by the pancreas that regulates blood sugar levels by facilitating the uptake of glucose into cells.
• In diabetes, either the pancreas does not produce enough insulin (Type 1 diabetes) or the body's cells do not respond properly to insulin (Type 2 diabetes).
• Insulin injections provide the necessary hormone to help cells absorb glucose, lowering blood sugar levels and preventing the harmful effects of high blood sugar, such as organ damage and complications.

 

1. Which of the following is a plant hormone?
• (d) Cytokinin.
2. The gap between two neurons is called a
• (b) Synapse.
3. The brain is responsible for
• (d) All of the above. (Thinking, regulating the heart beat, balancing the body)
4. What is the function of receptors in our body?
• Receptors in our body detect various stimuli or changes in the environment and convert them into electrical signals that can be interpreted by the nervous system. They play a crucial role in sensing external and internal changes and allow organisms to respond appropriately.
• When receptors do not work properly, it can lead to sensory deficiencies or incorrect responses to stimuli. For example, if the receptors for temperature sensation in the skin are damaged, a person may not be able to feel hot or cold objects, increasing the risk of burns or frostbite.
5. Draw the structure of a neuron and explain its function.
• I'm unable to draw diagrams, but I can describe the structure and function of a neuron.
• A neuron consists of:
• Cell body (soma): Contains the nucleus and other organelles.
• Dendrites: Branch-like extensions that receive incoming signals.
• Axon: A long, slender projection that conducts electrical impulses away from the cell body.
• Myelin sheath: A fatty insulating layer around the axon that speeds up signal transmission.
• Axon terminals: The ends of the axon that release neurotransmitters to transmit signals to other neurons or target cells.
• Neurons transmit electrical impulses (nerve impulses) from one part of the body to another. Dendrites receive signals, and if the signal is strong enough, it travels down the axon. At the axon terminals, neurotransmitters are released to transmit the signal to the next neuron or target cell.
6. How does phototropism occur in plants?
• Phototropism is the directional growth of plant parts in response to light.
• When light is detected by photoreceptors (like phototropins) in plant cells, it triggers the transport of the hormone auxin towards the shaded side of the plant.
• Higher auxin concentration on the shaded side stimulates cell elongation and growth, causing the plant to bend towards the light source.
7. Which signals will get disrupted in case of a spinal cord injury?
• In case of a spinal cord injury, the signals transmitted through the spinal cord would be disrupted. These signals include sensory information from the body to the brain and motor signals from the brain to muscles. As a result, there could be a loss of sensation, paralysis, or impaired muscle function below the level of the injury.
8. How does chemical coordination occur in plants?
• Chemical coordination in plants involves the use of plant hormones, also called phytohormones, to regulate growth, development, and responses to the environment.
• Plant hormones are synthesized at specific sites in the plant and are transported to target tissues or organs through the vascular system.
• These hormones, such as auxins, cytokinins, gibberellins, and abscisic acid, play roles in processes like phototropism, gravitropism, flowering, and stress responses.
9. What is the need for a system of control and coordination in an organism?
• A system of control and coordination is essential in organisms to:
• Respond to changes in the environment for survival.
• Regulate internal processes and maintain homeostasis.
• Coordinate various physiological functions and activities.
• Adapt to external and internal stimuli.
• Ensure efficient communication between cells, tissues, and organs.
10. How are involuntary actions and reflex actions different from each other?
• Involuntary actions are physiological responses or movements that occur without conscious control, such as heartbeat, digestion, and breathing.
• Reflex actions are rapid, involuntary responses to specific stimuli, typically involving a sensory receptor, sensory neuron, motor neuron, and an effector organ. Reflexes are protective and occur without conscious thought.
11. Compare and contrast nervous and hormonal mechanisms for control and coordination in animals.
• Nervous System:
• Involves electrical impulses transmitted through neurons.
• Rapid communication and immediate responses.
• Localized effects and specific target cells.
• Short-duration responses.
• Endocrine (Hormonal) System:
• Involves chemical signals (hormones) released into the bloodstream.
• Slower communication and gradual responses.
• Widespread effects, affecting many cells or organs.
• Longer-duration responses.
• Both systems work together to regulate various physiological processes in animals.
12. What is the difference between the manner in which movement takes place in a sensitive plant and the movement in our legs?
• Movement in a sensitive plant (like Mimosa pudica) is a rapid, reversible response to touch or mechanical stimuli. It involves the rapid folding and drooping of leaflets in response to touch, but this movement does not involve growth.
• Movement in our legs (muscle movement) is typically controlled and voluntary. It involves muscle contraction and skeletal movement, allowing us to walk, run, or perform various actions. This movement is conscious and controlled by the nervous system.