Chapter-6 Tissues

Explanation:

(b) Sclerenchyma is the tissue that has dead cells. The dead cells provide structural support and strength to the plant. The other options, namely Parenchyma, Collenchyma, and Epithelial tissue, do not have dead cells. Parenchyma and Collenchyma have living cells, while Epithelial tissue is composed of tightly packed, closely connected cells.

Explanation:

(c) Apical and intercalary meristems are permanent tissues is an incorrect sentence. Apical and intercalary meristems are examples of primary meristems, which are responsible for the growth in length of plants, but they are not permanent tissues. They differentiate into other tissues as the plant grows. The correct statement would be that apical and intercalary meristems are examples of primary meristems, which are responsible for the growth in length of plants. The other options are correct statements. Intercellular gaps can be found in parenchymatous tissues, whereas collenchymatous tissues have irregularly thickened corners and early meristematic tissues lack vacuoles.

Explanation:

(b) Lateral meristem is responsible for the increase in girth or thickness of the stem. The lateral meristem is also known as the cambium, and it is located in the secondary growth region of the stem. New cells that develop into secondary xylem (wood) and secondary phloem are produced by the cambium. Secondary growth is the process that causes the girth or thickness of the stem to increase. The other options, namely apical meristem, intercalary meristem, and vertical meristem, are not responsible for an increase in girth or thickness of the stem. The apical meristem is responsible for the growth in length of the stem, while the intercalary meristem is responsible for the growth in length of the internodes or the regions between nodes. The term "vertical meristem" is not commonly used in plant anatomy. 

Explanation:

(a) Tracheids do not have perforated cell walls. Tracheids are elongated cells with tapered ends and thick secondary walls that provide support and conduct water in plants. However, they do not have perforations or sieve plates in their cell walls, unlike vessels and sieve tubes. Companion cells and sieve tubes are part of the phloem tissue, and they have perforated cell walls with sieve plates. Vessels are part of the xylem tissue, and they also have perforated cell walls with perforation plates.

Explanation:

(b) The intestine's colomnar epithelium is in charge of absorbing the components of digested food. A single layer of tall, elongated cells with a brush border of microvilli on their apical side makes up the columnar epithelium. The microvilli aid in the digestion and absorption of nutrients and enhance the surface area for absorption.. The other options, namely stratified squamous epithelium, spindle fibers, and cuboidal epithelium, are not responsible for absorbing digested food materials in the intestine. Stratified squamous epithelium is found in the skin and lining of the oral cavity, esophagus, and vagina. Spindle fibers are responsible for the movement of chromosomes during cell division. Cuboidal epithelium is found in the kidney tubules and other glands and functions in secretion and absorption.

Explanation:

(c) Ligament break may be the possible reason for the dislocation of two long bones of the hand. Ligaments are tough, fibrous connective tissues that attach bones to bones and provide stability to the joints. Injuries to the ligaments can result in joint dislocation or instability. The other options, namely tendon break, break of skeletal muscle, and areolar tissue break, are less likely to cause the dislocation of two long bones of the hand. Tendons attach muscles to bones, and a tendon break may cause muscle weakness or joint immobility. Break of skeletal muscle may cause muscle injury but may not lead to joint dislocation. Areolar tissue is a loose connective tissue that provides support and flexibility to organs, but it is not directly involved in joint movement or stability.

Explanation:

(d) During work and running, skeletal muscles contract and pull the tendon to move the bones. Tendons, which are strong, fibrous connective fibres that connect skeletal muscles to bones, transfer the force produced by the muscle to the bone, creating movement. Tendons pull on the bones as the skeletal muscles contract, causing movement. Involuntary smooth muscles are not directly engaged in moving the bones; instead, they are found in internal organs like the blood vessels and digestive tract. Ligaments, on the other hand, connect bones to one another and give joints stability, but they are not directly engaged in the contraction or movement of muscles.

Explanation:

(b) (ii) and (iii) act involuntarily. Smooth muscles and cardiac muscles are both types of involuntary muscles, which means that they are not under conscious control. Smooth muscles are found in the walls of internal organs, such as the digestive tract and blood vessels, and they function involuntarily to control the movement of substances through these organs. Cardiac muscles are found in the walls of the heart and function involuntarily to contract and pump blood throughout the body. Striated muscles and skeletal muscles, on the other hand, are voluntary muscles that are under conscious control, and their contractions are initiated by conscious effort or reflexes.

Explanation:

(c) Meristematic tissues in plants are localised and dividing cells. Meristematic tissues are responsible for the growth and development of the plant body. They are present in localized regions of the plant such as the apical meristem (located at the tips of shoots and roots) and the lateral meristem (located along the sides of stems and roots). These tissues consist of actively dividing cells that are responsible for generating new cells and increasing the length or girth of the plant. Meristematic tissues are not permanent and eventually differentiate into specialized cells that perform specific functions in the plant body.

Explanation:

(c) Conduction of water is not a function of the epidermis. The epidermis is the outermost layer of cells covering the surface of plants and performs several functions such as protection from adverse conditions, regulation of water loss through transpiration, absorption of minerals, and gaseous exchange. The cells of the epidermis are flattened and form a continuous layer that covers the entire plant body. The outer walls of these cells are often thickened and covered with a waxy layer, known as the cuticle, which helps to prevent water loss through transpiration. The epidermis also contains specialized cells such as stomata, which are responsible for gaseous exchange and transpiration. However, the epidermis does not have specialized structures for conduction of water, which is the function of specialized tissues such as xylem and phloem.

Explanation:

(c) "Tendons are non-fibrous tissue and fragile" is an incorrect sentence. Tendons are actually made up of dense regular connective tissue, which is composed of strong, fibrous collagen fibers that are arranged in parallel to provide strength and flexibility. Tendons connect muscles to bones and are responsible for transmitting the force generated by the muscle to the bone, allowing movement to occur. While tendons can be injured or torn, they are not typically considered fragile due to their strong and flexible nature.

Explanation:

(c) The kidney does not contain cartilage. A form of connective tissue called cartilage gives the body's numerous organs support and flexibility. It can be found throughout the body, including in the joints, larynx, nose, and ears. Yet, the kidney does not contain it. Nephrons, unique cells in the kidney that filter waste from the blood and produce urine, make up the majority of the kidney tissue. The renal capsule, a layer of connective tissue that surrounds the nephrons and aids in supporting and protecting the kidney, is not cartilage.

Explanation:

(b)Adipose tissue serves as the body's storage location for fat. Adipocytes, which are cells specifically designed to store fat, are found in adipose tissue, a special kind of connective tissue. The body has adipose tissue in a number of places, including bone marrow, the area under the skin, and the area surrounding internal organs. It helps to regulate body temperature and acts as insulation for the body, acting as a reservoir of stored energy that may be used when necessary.

Explanation:

(b) Bone matrix is rich in calcium and phosphorus. Bone is a type of connective tissue that is composed of cells, fibers, and a matrix of mineralized material. The mineralized material in bone matrix is made up primarily of calcium and phosphorus, which combine to form hydroxyapatite crystals. These crystals give bone its hardness and strength, making it an important component of the skeletal system. Other minerals, such as magnesium and fluoride, may also be present in smaller amounts in bone matrix.

Explanation:

(c) Contractile proteins are found in muscles. Muscles are specialized tissues that are responsible for producing movement in the body. They contain two types of contractile proteins, actin and myosin, which work together to produce contractions. When the muscle is stimulated, calcium ions are released, which bind to the actin and allow the myosin to pull on the actin filaments. This causes the muscle to contract, generating force and producing movement. Contractile proteins are not found in bones, blood, or cartilage. 

Explanation:

(b) Voluntary muscles are found in limbs. Voluntary muscles, also known as skeletal muscles, are muscles that are under conscious control. They are responsible for movements of the limbs and other parts of the body, such as the neck and trunk. The alimentary canal, iris of the eye, and bronchi of the lungs are all examples of muscles that are involuntary, meaning they are not under conscious control. The alimentary canal has smooth muscles, the iris of the eye has smooth muscles and the bronchi of the lungs have smooth muscles and some involuntary striated muscles.

Explanation:

Nervous tissue is not found in tendons. Nervous tissue is specialized tissue that forms the nervous system, which is responsible for communication and coordination between different parts of the body. It is found in the brain, spinal cord, and nerves. Tendons, on the other hand, are made up of dense regular connective tissue, and their main function is to attach muscles to bones. They do not contain nervous tissue.

Explanation:

(c) tendons.

Nerve cells, also known as neurons, are specialized cells that transmit nerve impulses throughout the body. They consist of a cell body, dendrites, an axon, and nerve endings (also called terminal branches or axon terminals).

Dendrites are the branching extensions of a neuron that receive signals from other neurons or sensory receptors. The axon is a long, slender extension that carries signals away from the cell body and towards the nerve endings. Nerve endings are specialized structures at the end of the axon that allow for communication with other cells, such as muscle cells or other neurons.

Tendons, on the other hand, are tough connective tissues that attach muscle to bone and help to transmit forces generated by muscle contraction. They are not present in nerve cells.

Explanation:

 Areolar tissue.

Areolar tissue, also known as loose connective tissue, is a type of connective tissue that fills the spaces between organs and tissues, and provides support and cushioning. It is found in various parts of the body, including beneath the skin, around blood vessels and organs, and between muscles.

Areolar tissue contains various types of cells, such as fibroblasts, macrophages, and mast cells, as well as collagen and elastin fibers. It plays an important role in the repair of tissues by providing a framework for the growth of new cells and blood vessels, and by helping to bring in immune cells to fight infection.

Tendons are not involved in tissue repair or filling up space inside an organ, but rather attach muscle to bone and transmit forces generated by muscle contraction. Adipose tissue, also known as fat, stores energy and insulates the body. Cartilage is a type of connective tissue that provides support and cushioning to joints, but does not fill up space inside an organ.

Explanation:

Cardiac muscle is a specialized type of muscle tissue found only in the heart. It functions continuously throughout life to pump blood to the rest of the body, and is able to do so without fatigue due to its unique characteristics.

Unlike skeletal muscle, which can become fatigued and requires periods of rest, cardiac muscle is able to maintain a steady and continuous contraction without tiring. This is due in part to its rich supply of mitochondria, which provide energy for the muscle cells, as well as its ability to utilize a variety of energy sources, including glucose, fatty acids, and ketones.

Smooth muscle, which is present in the walls of blood arteries and organs, is in charge of uncontrollable movements like peristalsis. The skeletal muscle that controls voluntary motion might get tired after a while of activity. Skeletal muscle is also referred to as voluntary muscle and is controlled by the mind.

Explanation:

(d) Chondrocytes.

Chondrocytes are the cells that are found in the cartilaginous tissue of the body. Cartilage is a type of connective tissue that is found in many areas of the body, including the joints, ears, nose, and trachea. It provides support and cushioning to the bones and helps to reduce friction between them.

Chondrocytes are responsible for the production and maintenance of the extracellular matrix of the cartilage, which is composed of collagen, proteoglycans, and other proteins. They are also responsible for the growth and repair of the cartilage tissue.

Mast cells and basophils are both types of immune cells that are involved in allergic reactions and inflammation. Osteocytes are the cells that are found in bone tissue and are responsible for the maintenance and remodeling of the bone.

Explanation:

(d) Sieve tubes.

Sugars and other organic nutrients are transported throughout the plant through sieve tubes, which are the phloem's live conducting elements. The sieve tube components, however, lose the majority of their organelles during differentiating, including their nuclei, vacuoles, and cytoplasm, and end up being essentially hollow and non-living. The companion cell, which gives the sieve tube elements energy and support, is the living part of the sieve tube element.

The phloem tissue is made up of companion cells, phloem fibres, and phloem parenchyma, all of which are living organisms. Sieve tube components are intimately paired with companion cells, which support their metabolic operations. Phloem fibres are elongated cells that give the plant structural support. Living cells called phloem parenchyma cells carry out a variety of tasks, including storage, metabolism and support.

Explanation:

(a) Companion cells.

Companion cells are specialized parenchyma cells that are closely associated with sieve tube elements in the phloem tissue of vascular plants. They play a crucial role in regulating the activity of the sieve tube elements and providing them with metabolic support. Companion cells do not lose their nucleus at maturity and continue to function as living cells throughout the life of the plant.

Red blood cells, also known as erythrocytes, are specialized cells in the blood that transport oxygen from the lungs to the body's tissues. They lose their nucleus during maturation in order to make room for more hemoglobin, the protein that binds to oxygen. This lack of a nucleus also gives red blood cells their characteristic biconcave shape.

Vessels are the conducting elements of the xylem tissue in plants, responsible for the transport of water and minerals from the roots to the rest of the plant. They are composed of dead cells called vessel elements that lose their nucleus and other organelles during differentiation, forming a long tube for water to flow through.

Sieve tube cells are the conducting elements of the phloem tissue in plants, responsible for the transport of sugars and other organic nutrients throughout the plant. They also lose their nucleus and most of their organelles during differentiation, becoming essentially hollow and non-living.

Explanation:

(a) Cuticle.

The cuticle is a waxy, waterproof layer that covers the epidermis of the leaves and stems of plants. It plays an important role in reducing the rate of water loss through transpiration, particularly in plants that live in dry environments such as deserts.

The cuticle acts as a barrier, preventing water from evaporating from the surface of the plant. It also helps to protect the plant from damage due to UV radiation and pathogens. In desert plants, the cuticle is often thicker than in plants that live in more humid environments, helping to further reduce water loss.

Stomata are the small pores on the surface of leaves and stems that are responsible for gas exchange and transpiration. While stomata can help to regulate the rate of water loss in plants by opening and closing in response to environmental cues, they do not themselves reduce water loss.

Lignin is a complex organic polymer that provides structural support to plant cell walls. It does not play a direct role in reducing water loss.

Suberin is a waxy substance that is found in the cell walls of some plant tissues, particularly in roots and stems. It helps to prevent water from entering or leaving the plant, but does not reduce the rate of water loss through transpiration..

Explanation:

(d) Xylem vessels.

Xylem is the specialized tissue in plants that is responsible for the transport of water and minerals from the roots to the rest of the plant. It is composed of several types of cells, including tracheids, vessel elements, fibers, and xylem parenchyma.

The xylem vessels are the elongated, tube-like structures that form the main conduit for water transport in the xylem tissue. They are composed of dead cells that have lost their end walls, forming an uninterrupted column for water to flow through.

In the branches of a tree, the xylem vessels help to conduct water sideways from the trunk to the leaves and other parts of the branch. Xylem parenchyma cells, which are living cells that support the functions of the xylem tissue, may also play a role in the sideways conduction of water.

Collenchyma is a type of supportive tissue in plants that provides flexible support to growing parts of the plant. Parenchyma cells are thin-walled, living cells that perform a variety of functions such as photosynthesis, storage, and support, but do not play a significant role in water transport.

Explanation:

(b) Apical meristem.

The apical meristem is a type of meristematic tissue found at the tips of roots and shoots in plants. It is responsible for the primary growth of the plant, including elongation of the stem and root, and the production of new leaves and branches.

In sugarcane plants, the apical meristem is located at the tip of the stem, and is responsible for the growth and elongation of the stem. If the tip of the sugarcane plant is removed, the apical meristem is also removed, but the plant can still continue to grow due to the presence of dormant lateral buds along the stem.

These lateral buds can become activated and start to grow in response to environmental cues or hormonal signals, resulting in the production of new shoots and branches. However, the rate of growth may be slower compared to a plant with an intact apical meristem.

Explanation:

(c) Remain at the same position.

When a nail is inserted into a tree, it penetrates the bark and outer layers of the tree's trunk, but does not reach the central core of the trunk where the xylem and phloem are located. The xylem and phloem are responsible for the transport of water, nutrients, and sugars throughout the tree, and are located deep within the trunk.

Over a period of three years, the growth of the tree may cause the bark and outer layers of the trunk to expand, which could potentially cause the nail to become partially covered or surrounded by new growth. However, the nail itself will not move up, down, or sideways in the trunk as it is inserted firmly and deeply enough to remain in place.

Explanation:

(a) Relatively unspecified and thin-walled.

Parenchyma cells are a type of simple, unspecialized plant cell that are found in various organs of the plant body, including leaves, stems, roots, and fruits. They have thin cell walls and are relatively unspecialized, meaning that they can perform a wide range of functions such as photosynthesis, storage, and support.

Parenchyma cells are typically round or oval in shape, and have a large central vacuole that occupies most of the cell volume. The cell wall is thin and flexible, which allows the cell to expand and contract as needed.

While some specialized forms of parenchyma cells exist, such as the collenchyma and sclerenchyma, the majority of parenchyma cells are relatively unspecialized and thin-walled.

Explanation:

(a) Collenchyma.

Collenchyma cells are a type of simple, elongated plant cell that provide mechanical support to growing organs of the plant such as stems, leaves and petioles. They are characterized by their thick, flexible cell walls which allow the cells to stretch and elongate, providing flexibility to the plant.

Collenchyma cells are typically found in the corners of stems and leaves, and may be arranged in strands or cylinders. Their cell walls are thickened with cellulose and pectin, which provides the cell with the strength and flexibility needed to support growing organs.

While other types of plant cells, such as sclerenchyma cells, also provide mechanical support to plants, collenchyma cells are specifically adapted to provide flexibility due to their flexible and elastic cell walls.

Explanation:

(c) Suberin.

Cork cells are specialized cells that form the outer bark of trees and woody plants. These cells are dead at maturity and are impervious to water and gases due to the presence of suberin, a waxy, hydrophobic substance that is deposited in the cell walls.

Suberin is a complex polymer that is found in the cell walls of cork cells, and it helps to make these cells impermeable to water and gases. This allows the cork cells to protect the underlying tissues of the plant from damage and infection, and helps to prevent water loss through the outer layers of the plant.

While other substances such as lipids and lignin also contribute to the impermeability of cork cells, suberin is the primary substance responsible for making these cells impervious to water and gases. 

Explanation:

(b) Conducting tissue.

The terrestrial environment is characterized by a scarcity of water, which makes it difficult for plants to absorb and transport the water and nutrients they need to survive. However, the presence of specialized conducting tissues in plants, such as xylem and phloem, has made it possible for plants to survive in this environment.

Water and minerals are moved from the roots to the leaves and other parts of the plant by a form of conducting tissue called xylem. Contrarily, phloem is in charge of moving sugars and other organic molecules from the leaves to the remainder of the plant.

Together, these two varieties of conducting tissue aid in ensuring that plants can carry the water, nutrients, and other materials necessary for their survival and development on land. While meristematic and parenchymatous tissues also contribute significantly to plant growth and development, it is the specialised conducting tissue that has allowed plants to flourish in the terrestrial environment.

Explanation:

(c) Epithelial tissues have intercellular spaces between them is the wrong statement.

Epithelial tissues are composed of closely packed cells with little or no intercellular space between them. These tissues cover the body surfaces, line body cavities and hollow organs, and form glands. The cells in epithelial tissues are tightly connected to each other by various types of intercellular junctions, such as tight junctions, desmosomes, and gap junctions, which help to provide structural support and regulate the movement of molecules across the tissue.

Explanation:

(c) Tracheids.

Gymnosperms are a group of plants that includes conifers, cycads, and ginkgos, among others. They are characterized by the presence of a specialized water-conducting tissue called tracheids in their xylem. Tracheids are elongated, tube-like cells with thick walls that are reinforced by a substance called lignin. They function to transport water and minerals from the roots to the rest of the plant, and are able to withstand the negative pressure generated by transpiration. While some gymnosperms, such as conifers, may also have vessels, they are not as common or widespread as tracheids..

Explanation:

Animals that live in colder regions, such as polar bears, seals, and penguins, and fishes that live in cold water, such as Arctic cod and Antarctic krill, have thicker layers of subcutaneous fat as a means of insulation and to maintain their body temperature.

Subcutaneous fat is a layer of fat located beneath the skin that serves as a natural insulator. It is made up of adipose tissue, which consists of cells called adipocytes that are specialized in storing energy in the form of fat. In colder environments, the thick layer of subcutaneous fat helps to reduce heat loss from the body and keep the animal warm.

In fishes, the thick layer of subcutaneous fat also helps to reduce heat loss, as cold water can rapidly conduct heat away from the body. This is especially important for fish that live in deep waters or at high latitudes, where the water temperature can drop below freezing.

In addition to insulation, the thick layer of subcutaneous fat also provides buoyancy for aquatic animals, such as whales and seals, helping them to float and swim more efficiently in water.

Overall, the thick layer of subcutaneous fat is an adaptation that helps animals and fishes survive in colder environments, by providing insulation, buoyancy, and energy storage.

Explanation:

(a) Fluid connective tissue – (v) Blood

(b) Filling of space inside the organs – (iv) Areolar tissue

(c) Striated muscle – (iii) Skeletal muscle

(d) Adipose tissue – (i) Subcutaneous layer

(e) Surface of joints – (ii) Cartilage

(f) Stratified squamous epithelium – (vi) Skin

Explanation:

(A) – (B)

(a) Parenchyma – (i) Thin-walled, packing cells

(b) Photosynthesis – (ii) Carbon fixation

(c) Aerenchyma – (iv) Buoyancy

(d) Collenchyma – (iii) Localized thickenings

(e) Permanent tissue – (v) Sclerenchyma

Explanation:

When a potted plant is covered with a glass jar, the transpiration process of the plant continues as usual. Transpiration is the process by which water is lost from the leaves of the plant in the form of water vapour. When the water vapour molecules come in contact with the cooler surface of the glass jar, they lose their energy and condense into liquid droplets on the surface of the glass jar. This is similar to how dew forms on the grass in the early morning.

Therefore, the appearance of water vapours on the wall of the glass jar is a result of the plant's transpiration process and the difference in temperature between the plant and the glass

surface.

Explanation:

The different components of xylem are:

Tracheids: These are elongated, tube-like cells with tapered ends and lignified walls that provide mechanical support.

Vessels: These are large, tubular cells with perforated end walls called perforations, that allow water to move freely from one vessel to another.

Xylem fibers: These are long, slender cells with thick walls that provide mechanical support and protection.

Xylem parenchyma: These are living cells that store food and help in the lateral conduction of water.

A living component of xylem is the xylem parenchyma, which is a type of simple tissue that is made up of living cells with thin cell walls. These cells play a supportive role by storing food and nutrients and are involved in the lateral conduction of water and mineral ions. The diagram below shows the different components of xylem and their arrangement.

Explanation:

Explanation:

(a) True. Epithelial tissue covers and protects the surfaces and organs of the body.

(b) True. The lining of these structures is made up of epithelial tissue that performs specific functions related to their location and type.

(c) False. Epithelial cells have very little intercellular space as they are closely packed together to form a barrier.

(d) True. Epithelial layers can be selectively permeable to regulate the movement of materials between different compartments of the body.

(e) False. The regulation of material exchanges between the body and its environment, such as the removal of waste products and the absorption of nutrients, is greatly influenced by epithelial layers.

Explanation:

Voluntary muscles are the muscles that are under conscious control, and their contraction is usually initiated by the somatic nervous system. They are mainly involved in body movement, and their contraction is slow and prolonged. Skeletal muscles are an example of voluntary muscles.

On the other hand, involuntary muscles are the muscles that work without our conscious control and are controlled by the autonomic nervous system. These muscles are found in internal organs, and their contraction is quick and short-lived. Smooth muscles and cardiac muscles are examples of involuntary muscles.

An example of a voluntary muscle is the biceps muscle in the arm, while an example of an involuntary muscle is the cardiac muscle present in the heart.

Explanation:

(a) Jumping of frog - Voluntary (V) muscles

(b) Pumping of the heart - Involuntary (IV) muscles

(c) Writing with hand - Voluntary (V) muscles

(d) Movement of chocolate in your intestine - Involuntary (IV) muscles

Explanation:

(a) Lining of blood vessels is made up of endothelial cells, which are a type of epithelial tissue.

(b) Lining of small intestine is made up of columnar epithelial tissue.

(c) Lining of kidney tubules is made up of cuboidal epithelial tissue.

(d) Epithelial cells with cilia are found in the respiratory tract, such as in the trachea and bronchi.

Explanation:

Water hyacinth floats on the surface of water due to the presence of its spongy, air-filled, and bulbous petioles (leaf stalks). These petioles have large air spaces, which provide buoyancy to the plant and enable it to float on the water surface. Additionally, the leaves of water hyacinth are waxy, and they repel water, preventing the plant from sinking. The roots of water hyacinth are also adapted to live in water, as they are long, thin, and flexible, enabling them to absorb nutrients and anchor the plant to the bottom of the water body.

Explanation:

The cell wall is the structure that protects the plant body against the invasion of parasites. The cell wall acts as a physical barrier to prevent the entry of pathogens and parasites, and also contains various defense mechanisms such as lignin, suberin, and phytoalexins, which help to prevent the growth and spread of parasites and pathogens. Additionally, the waxy cuticle on the surface of leaves and stems also provides a barrier against pathogens and parasites.

Explanation:

(a) Cork cells possess suberin on their walls that makes it impervious to gases and water.

(b) Sieve tubes have tubular cells with perforated walls and are living in nature.

(c) Bone possesses a hard matrix composed of collagen and calcium phosphate.

Explanation:

The outermost layer of cells covering the plant's aerial components, such as the leaves, stem, and roots, is called the epidermis. It accomplishes a number of crucial tasks, including:

1. Protection: The epidermis guards the underlying tissues against bruising, excessive water loss, and disease and insect invasion.

2. Control of gas exchange: The stomata, which are little pores found in the epidermis, control the flow of gases like oxygen and carbon dioxide between the plant and the atmosphere.

3.Nutrient and water uptake: The epidermis of roots has specialised cells known as root hairs that improve the surface area for uptake of nutrients and water from the soil.

4.Secretion: To defend the plant from diseases, herbivores, and water loss, the epidermis may secrete waxy or mucilaginous compounds.Therefore, the epidermis plays a vital role in the survival and growth of plants.

Explanation:

a. Xylem and Phloem

b. Stomata

c. Suberin

d. Sclenchyma

e. Collenchyma

f. Xylem;Phloem

g. Water and minerals

h. Food, leaf

Explanation:

Sclerenchyma and parenchyma are two types of plant tissues with distinct characteristics and functions.

Sclerenchyma tissue:

1.Sclerenchyma cells are usually dead at maturity.

2.They have thick, lignified secondary cell walls.

3.Sclerenchyma cells provide mechanical support and protection to the plant.

4.They are found in stems, leaves, fruits, and seeds.

5.Two types of sclerenchyma cells are fibers and sclereids.

Parenchyma tissue:

1.Parenchyma cells are living cells with thin primary cell walls.

2.They have large central vacuoles and a variety of functions including storage, photosynthesis, and secretion.

3,Parenchyma cells are found in all parts of the plant including the stem, roots, leaves, and flowers.

4.They can divide and differentiate to form other types of cells and tissues.

5.Parenchyma cells are unspecialized and adaptable to different functions.

Epithelial tissues are one of the four major types of animal tissues. They cover and line various surfaces and cavities of the body. The structure and function of different types of epithelial tissues are as follows:

1.Simple Squamous Epithelium:

Structure: This type of epithelium consists of a single layer of flat, thin cells. The cells have a centrally located nucleus and are tightly packed together. They are thin enough to allow for rapid diffusion of gases and other small molecules.

Function: Simple squamous epithelium lines the alveoli of the lungs and the walls of blood vessels. It allows for the exchange of gases (oxygen and carbon dioxide) and other small molecules.

2.Stratified Squamous Epithelium:

Structure: This type of epithelium consists of multiple layers of cells. The outermost layer consists of flat, thin cells while the innermost layer consists of columnar cells. The cells in the outermost layer are dead and are constantly shed and replaced.

Function: Stratified squamous epithelium forms the outermost layer of skin, lining of the oral cavity, esophagus, vagina, and anal canal. It provides protection against abrasion, friction, and invasion by foreign organisms.

3.Simple Cuboidal Epithelium:

Structure: The cube-shaped cells that make up this form of epithelium are arranged in a single layer. The nucleus of the cells is in the middle, and they are closely clustered.

Function: Simple cuboidal epithelium lines the kidney tubules, glandular ducts, and the surface of the ovaries. It participates in material absorption, secretion, and transportation.

4.Simple Columnar Epithelium:

Structure: The cells in this form of epithelium are arranged in a single layer and have a columnar shape. The nucleus of the cells is in the middle, and they are closely clustered. Microvilli and cilia are present in some of the cells.

Simple columnar epithelium lines the small intestine, large intestine, and stomach. It participates in the transport, secretion, and absorption of materials. In addition to facilitating the passage of materials over the surface, the presence of microvilli and cilia enhances the surface area available for absorption and secretion.5.Pseudostratified Columnar Epithelium:

Structure: This type of epithelium appears stratified but consists of a single layer of column-shaped cells. The cells have nuclei located at different levels, which gives the appearance of stratification. Some of the cells possess cilia.

Function: Pseudostratified columnar epithelium lines the trachea and bronchi. It is involved in the movement of mucus and trapped particles out of the respiratory tract.

6.Transitional Epithelium:

Structure: This type of epithelium consists of multiple layers of cells. The cells at the surface are dome-shaped while the cells in the lower layers are cuboidal or columnar. The cells have the ability to stretch and expand.

Function: Transitional epithelium lines the bladder, ureters, and parts of the urethra. It allows for the expansion of these organs as they fill with urine.

Explanation:

the several muscle groups that can be found in the human body:

1. Skeletal Muscle: These muscles are joined to bones and control how the body moves. They appear striated and are controlled voluntarily.

Smooth muscle is a type of muscle that lines the insides of internal organs such the blood vessels, intestines, and stomach. They don't look to be striated and are being controlled against their will.

3. Cardiac Muscle: This muscle can only be found in the heart and it pumps blood all over the body. It has a striated appearance and is being controlled unconsciously.

These muscles each have a distinct structure that enables them to carry out their individual tasks within the body.

Explanation:

Because these cells are continually dividing and producing new cell components like cell wall, cell membrane, and organelles, they lack vacuoles but have a conspicuous nucleus and thick cytoplasm. The cells differentiate into specialised cells as they get older and form vacuoles..

(b) Intercellular spaces are absent in sclerenchymatous tissues because these tissues provide mechanical support to the plant and are composed of dead cells with thick cell walls. The thick walls of these cells leave no intercellular spaces between them.

(c) We get a crunchy and granular feeling when we chew a pear fruit because it contains sclereids or stone cells, which are specialized parenchyma cells with heavily thickened cell walls. These cells give the fruit a gritty texture.

(d) Branches of a tree move and bend freely in high wind velocity due to the presence of a flexible tissue called collenchyma. Collenchyma cells are elongated and

have thickened cell walls, providing both support and flexibility to the plant.

€The coconut tree's husk is made of a hard, fibrous tissue called sclerenchyma, which makes it challenging to remove. The lignin and cellulose that are strongly incorporated into the cell walls of sclerenchyma cells provide them strength and resistance to mechanical stress.

Explanation:

Cork is a type of protective tissue that forms the outermost layer of many plant stems, roots, and bark. The following are the characteristics of cork:

1.Dead cells: Cork cells are dead at maturity, and they lack protoplasm.

2.Waxy substance: The cell walls of cork cells contain a waxy substance called suberin, which makes them impervious to water, gases, and some chemicals.

3.Small intercellular spaces: Cork cells are compactly arranged with small intercellular spaces.

4.Presence of lenticels: Cork cells have small pores called lenticels that allow gas exchange between the plant and the environment.

Cork cells are formed by the cork cambium, which is a type of lateral meristem. The cork cambium produces cork cells on the outer side, which replace the epidermis in older stems, roots, and bark. The cork cambium also produces secondary cortex cells on the inner side, which replace the primary cortex.

The role of cork is to protect the plant from external factors such as water loss, mechanical injury, and pathogens. Cork also provides thermal insulation and helps regulate gas exchange between the plant and the environment through its lenticels. Cork is used commercially for making bottle stoppers, flooring, insulation, and other products.

Xylem and phloem are called complex tissues because they are composed of more than one type of cell. Both xylem and phloem are vascular tissues found in plants that are responsible for the transportation of water, minerals, and organic nutrients throughout the plant body.

The main differences between xylem and phloem are as follows:

1.Composition: Phloem is made up of four different cell types: companion cells, fibres, parenchyma cells, and sieve tube elements, whereas xylem is made up of four different cell types: tracheids, vessel elements, fibres, and parenchyma cells.

2.Function: Xylem primarily transports water and minerals from roots to the aerial parts of the plant, while phloem primarily transports organic nutrients (sugars) from leaves to the other parts of the plant.

3.Direction of flow: Xylem transports water and minerals upwards, from roots to leaves, while phloem transports organic nutrients in both upward and downward directions, from leaves to roots and from roots to leaves.

4.Cell wall: The cell walls of xylem cells are thickened with lignin, which provides mechanical support and makes the cells impermeable to water, while the cell walls of phloem cells are thin and permeable.

5.Cell structure: The cells of xylem are dead at maturity and lack protoplasts, while the cells of phloem are living and retain their protoplasts.

Explanation:

(a) Difference between meristematic and permanent tissues in plants:

Meristematic Tissues Permanent Tissues

These tissues are undifferentiated and immature | 1. These tissues are fully differentiated and mature

They have the ability to divide and differentiate into other tissues | 2. They have lost the ability to divide and differentiate into other tissues

Cells are small, with thin cellulose walls, large nuclei, dense cytoplasm, and little or no vacuole | 3. Cells are larger, with thick cellulose walls, small nuclei, and prominent vacuoles

Found at the apices of roots and shoots, cambium, and other locations in the plant body where growth is taking place | 4. Found throughout the plant body, with specialized functions such as support, storage, and conduction

Primary meristem gives rise to primary tissues while secondary meristem gives rise to secondary tissues | 5. Simple and complex tissues are the two types of permanent tissues

(b)

Unspecialized cells become specialised cells with particular tasks through the process of differentiation. Cells undergo morphological and functional changes during differentiation in order to perform a specific role.Two examples of simple permanent tissues in plants are:

Parenchyma tissue: Composed of thin-walled cells with large vacuoles and prominent nuclei. It is involved in the storage of nutrients, photosynthesis, and secretion.

Collenchyma tissue: Composed of elongated cells with unevenly thickened cell walls. It provides mechanical support to the plant organs.

Two examples of complex permanent tissues in plants are:

Xylem tissue: Composed of four types of cells: tracheids, vessels, xylem fibers, and xylem parenchyma. It conducts water and minerals from roots to aerial parts of the plant.

Phloem tissue: Composed of four types of cells: sieve elements, companion cells, phloem fibers