Living Tissues: Biology Chapter 1 - PDF

Living tissuos Biology Biology Living tissues 01 You have studied...

Living tissuos Biology Biology Living tissues 01 You have studied about tissues as one of the organisational levels of a multicellular organisms in grade 10. You will learn more about tissues in this chapter. 1.1 Plant tissues Let's do the activity given below to study about plant tissues. Activity 1.1 Materials required :- Thin peel of lower epidermis of betel leaf, thin section of a potato tuber, thin cross section of a stem of a plant like Balsam Method :- ² Prepare temporary slides using above plant materials. ² Observe them under microscope. ² Try to identify tissues formed by cells with the help of your teacher. Figure. 1.1 - View of different plant tissues under optical microscope You may have observed that plant tissues are of different forms. Animal tissues are also of different forms. It is observable that different cell types are present in living beings and similar cells are arranged together. A group of cells with a common origin that has been modified to perform a specific function in the body is known as a tissue. 1 For free distribution Biology Living tissuos Classification of plant tissues Let's do the following activity to study further about how tissues are oraganized in plant organs. Activity -- 1'2 Materials required :- Prop root of Banion/ Stilt root of Pandanus/ Stilt root of Rampe Method :- ²² Observe the external view of the growing tips of above roots ²² Use a hand lens to observe them Figure 1.2 - External view of a root We can identify the nature of growing root from the above observation. Growing part is soft and light coloured. Mature part is rough and dark coloured. This is because of the nature of tissues. Figure 1.3 shows the microscopic view of longitudinal section of such root. It is observed that region A-A' has cells with the ability of cell division. Region B-B' contain different cell types that are different in nature from cells in region A-A'. B B' Plant tissues can be categorised using different criteria. Plant tissues can be divided into two groups according to the ability of cell division. A A' ²² Meristematic tissues š ²² Permanent tissues Root cap Permanent tissues can be found in region B-B' Figure 1.3 - Microscopic view of and Meristematic tissues in region A-A' as longitudinal section of root apex shown in figure 1.3. For free distribution 2 Living tissuos Biology 1.1.1 Meristematic tissues The tissues with cells that divide actively by mitosis to produce new cells are called meristematic tissues. These cells are not differentiated. The growth of plants takes place due to activity of meristematic tissues. Features of meristematic tissues ²² This tissue consists of small sized living cells ²² No inter cellular spaces or intercellular spaces are not prominent ²² There is a distint nucleus in each cell ²² Absence of large central vacuole but small vacuoles may be present ²² Large number of mitochondria are present Meristematic tissues are present in specific locations of the plant. They are of three types. Apical meristems Apical Meristems Apical meristems are found in shoot apex, root apex and axillary buds. Plant increases its Intercalary meristems height due to the activity of this tissue. Intercalary meristems Intercalary meristems are found at nodes. The length of internode increases due to the activity of the above tissue. They are found in plants of Lateral Meristems grass family Lateral meristems A B Lateral meristems are present laterally in the Figure 1.4 - Locations of meristematic stem and roots of plant. They are found parallel tissues to the longitudinal axis of plant. The diameter of the plant increases due to the activity of this tissue. Cambium tissue found in dicots is a lateral meristematic tissue. 3 For free distribution Biology Living tissuos 1.1.2 Permanent tissues Do the following activity to identify different types of tissues of plant stem. Activity -- 1'3 Materials required :- Pumpkin / Tridex plant stem, A glass slide, A microscope Method :- ²² Observe the cross section of above plant stem using a microscope ²² Identify the different tissue types present in them Figure 1.5 - Microscopic view of cross section of dicot stem A specialized tissue that lost its ability to divide and perform a particular function is known as a permenant tissue. According to the nature of the permanent tissues, it can be grouped into two. ²² Simple Permanent tissues - One type of cells collected together ²² Complex Permanent tissues - Different types of cells collected together ²² Simple permanent tissues The tissue is composed of similar cells. According to the shape of cell and the nature of cell wall, three types of simple permanent tissues as parenchyma, sclerenchyma, and collenchyma can be identified in plants (Figure 1.6). Parenchyma Collenchyma Sclerenchyma Figure 1.6 - Simple permanent tissue types For free distribution 4 Living tissuos Biology yy Parenchyma The tissue that forms the soft parts of the plant body is the parenchyma tissue. This is the most abundant tissue found in the plant. Features of Parenchyma tissue Cell wall ²² Parenchyma tissue consists of living Inter cellular spaces cells. Nucleus ²² Cells are isodiametric (spherical) with a large central vacuole. ²² Nucleus is present peripherally in the cytoplasm Cross section of longitudinal section of ²² The cell wall is thin and made up of parenchyma parenchyma cellulose. Figure 1.7 - Parenchyma tissues ²² Inter cellular spaces are present. Locations of parenchyma tissues ²² Cortex and pith of plant stem ² Pith and cortex of roots ²² Fleshy parts of fruits ² Seeds (endosperm) ²² Leaves (mesophylls) Functions of parenchyma ² Photosynthesis - Palisade and spongy mesophylls in plant leaves contain chlorophyll within chloroplasts. Photosynthesis takes place within these chloroplasts. ² Food storage - Food is stored in some parenchyma tissues and they are called as storage tissues. E.g. : Potato tuber, Carrot and Sweet potato roots, Papaw and Banana fruits. ² Storage of water - Specially xerophytic plants store water in parenchyma tissue E.g. : Aloe leaves, Bryophyllum leaves, Cactus cladode ² Providing support - Herbaceous plants like Balsam absorb water into vacuoles of the parenchyma cells. Thereby cells become turgid and provide mechanical support to the plant. 5 For free distribution Biology Living tissuos yy Collenchyma Collenchyma tissue provides mechanical strength and support to the plant body. They are modified parenchyma cells. Nucleus Cell wall Cytoplasm Cross section of a collenchyma tissue Longitudinal section of a collenchyma tissue Figure 1.8 - Collenchyma tissue Features of collenchyma tissue ²² Collenchyma tissue consists of living cells ²² Cells possess a cytoplasm, nucleus and central vacuole ²² Generally cells are elongated and polygonal in cross section ²² The corners of the cell walls are thickened. ²² Intercellular spaces may present or may not present Locations of collenchyma The collenchyma forms a cylindrical tissue inner to the epidermis of herbaceous stems. They are found in the veins of dicot leaves. Functions of collenchyma 1' Support - Collenchyma provides mechanical support to dicot plant stem, before the formation of wood. (Provides mechanical support to herbs) This tissue provides support to the plant leaves by the collenchyma in veins. 2' Photosynthesis - Chloroplasts are found in the collenchyma of immature dicot stems. Photosynthesis is carried out by those cells. For free distribution 6 Living tissuos Biology yy Sclerenchyma Cross section of fibers Longitudinal section of sclereid sclerenchyma tissue Figure 1.9 - Sclerenchyma tissue Sclerenchyma tissue helps in providing mechanical strength and support to the plant body. This tissue has two types of cells as sclereids and sclerenchyma fibres. Features of sclerenchyma tissue ²² Sclerenchyma tissue consists of dead cells ²² Lignin is deposited on the cellulose cell wall ²² Cells are tightly packed. Therefore, no intercellular spaces ²² Cell wall is evenly thickened and forms a central lumen Locations of sclerenchyma tissue Fibres present in xylem are called as xylem fibres and in phloem as phloem fibres. Other than above, coconut fibres, agave fibres and cotton wool are made up of fibres (sclerenchyma) Selereids are found in endocarp of cocount, camphor and mango fruits, the pericarp of guava fruit and in pear fruit and seed coat of coffee and dates. Functions of sclerenchyma ²² Provide support to the plant body 7 For free distribution Biology Living tissuos yy Complex permanent tissues Different types of cells together form a complex permanent tissue. Two complex permanent tissues as xylem and phloem can be identified in plants (Figure 1.10). phloem Xylem and phloem are found in vascular systems of root, stem and leaves of the plant. Xylem Figure. 1.10 - Complex permanent tissues Xylem tissue Vessels Vessels Pore š Xylem tube Vessels Tracheids Xylem Xylem Parenchyma parenchyma fibre Figure 1.11 - Xylem tissue This tissue is composed of four different types of cells. ²² Xylem vessel element ²² Tracheids ²² Fibres ²² Parenchyma cells Xylem vessel elements are cylindrical elongated cells. Xylem vessel element stack on top of the others and the cross walls are dissolved to form a continuous xylem vessel. This tubular structure helps in transportation of water in plants. Tracheids are elongated, spindle shaped cells. They also help in transportation For free distribution 8 Living tissuos Biology of water. Xylem fibers are narrower and shorter than tracheids. Xylem vessels, tracheids and xylem fibers become dead due to lignification of cell walls. They provide support to the xylem tissue. Xylem parenchyma are living cells with a thin cell wall. They involve in food storage. Functions of xylem ²² Transportation of water and minerals to the plant body which are absorbed by plant roots. ²² Providing of mechanical support to plant body. Pholem tissue Sieve plate Phloem parenchyma Companion cell Sieve tube Sieve tube element Parenchyma ccell Companion cell Sieve plate Sieve plate pores Sieve tube element Figure. 1.12 - Longitudinal section of the Figure. 1.13 - Cross section of the phloem tissue phloem tissue Phloem tissue is composed of four different types of cells. ²² Sieve tube elements ²² Companion cells ²² Phloem fibres ²² Phloem parenchyma The sieve tube elements fuse end to end and the cross walls are incompletely dissolved to form a sieve tube. The cross walls in these sieve tubes are called sieve plates. Sieve tubes transport food (mainly sucrose) throughout the plant, as a solution. Companion cells are elongated cells associated with sieve tube elements. The nucleus of the companion cell controls the activities of the sieve tube elements (sieve tube elements lack a nucleus) Seive tube elements, companion cells and phloem parenchyma are living cells whereas phloem fibres are dead and found scattered in phloem tissue. Functions of phloem tissue The food synthesized in the leaves are transported throughout the plant body by this tissue (Translocaton). 9 For free distribution Biology Living tissuos Assignment 1.1 Compare structural and functional characteristics of phloem and xylem. Include them in a table. 1.2 Animal tissues The animal body is also made up of different types of cells. Example :- The human body is made up of about 210 different types of cells. There are groups of cells with common origin to perform a specific function in the multicellular animal body. Main types of animal tissues are given below. ²² Epithelial tissue ²² Connective tissue ²² Muscle tissue ²² Nervous tissue Connective Nervous tissue tissue Bone tissue Cardiac muscle tissue Epithelial tissue Smooth muscle tissue Figure 1.14 - Different tissues in human body For free distribution 10 Living tissuos Biology 1.2.1 Epithelial tissue This is the tissue that lines up the free surfaces (internal and external) of the vertebrate body. Some of them are composed of single layer of cells and the others are with several cell layers. Features of epithelial tissues Tightly packed cells Nucleus basement membrane Figure 1.15 - epithelial tissue ²² The cells are placed on a basement membrane ²² The cells are tightly packed ²² A nerve supply is present within the tissue but there is no blood supply The epithelial tissue is classified according to the shape of the cell and the number of cell layers. Examples for several locations of epithelial tissues are given below. ²² Wall of blood capillaries ²² Thyroid gland ²² Lining of nasal cavity ²² Wall of urinary bladder ²² Skin (Epidermis) Functions of epithelial tissue ²² Lining up of free surfaces and protection - Protects the internal organs from pressure, friction and microbes ²² Absorptive function - The epithelium of digestive tract absorbs digestive end products ²² Perception of stimuli - The epithelium of tongue and nose, detect taste and smell senses ²² Secretory function - Secretion of mucous by the lining epithelium of respiratory tract ²² Filtering - Epithelium of Bowman's capsule in nephrons, filters blood 11 For free distribution Biology Living tissuos 1.2.2 Connective tissue Connective tissue is composed of different types of cells and fibres. These cells and fibres are embedded in a large matrix. Most connective tissues possess nerve and blood supply. Connective tissue Bones Cartilage Blood under skin Figure 1.16 - Different Connective tissue present in human arm The connective tissues provide connection between tissues and organs and provide support too. E.g. :- Blood tissue, Bone tissue Blood tissue Blood is a special connective tissue The speciality is that the matrix (plasma) is not secreted by the blood cells. Blood tissue helps in maintaining proper connection between organs and tissue of the human body. Features of blood tissue ²² Blood is composed of a fluid matrix called plasma and cells ²² The matrix contains cells called red blood cells (erythrocytes) and white blood cells (leucocytes) and cellular fragments called platelets Figure 1.17 - Blood tissue ²² Fibres are not found always but during blood clotting they appear Functions of blood tissue ² Transportation of materials - Nutrients, respiratory gases, excretory materials and hormones are transported to the relevant organs ² Protection - White blood cells destroy foreign bodies (Microbes) by phagocytosis and by producing antibodies ² Maintenace of homeostasis For free distribution 12 Living tissuos Biology 1.2.3 Muscle tissue Muscle tissue is one of the main tissues that makes up the human body. Muscletis- sue is made up of muscle cells or muscle fibres. These muscle fibres possess con- traction and relaxation ability. Not like epithelium, the muscle tissue possesses a good blood supply. Therefore muscle tissue receives oxygen and nutrients at a high rate. Muscle tissue acts as one of the effectors in responding in coordination. Muscle tissue is of three types, ²² Smooth muscle tissue ²² Skeletal muscle tissue ²² Cardiac muscle tissue Assignment 1.2 Compare the characteristics of different muscle tissues. Smooth muscle tissue Smooth muscle tissue is made up of smooth muscle cells. This tissue is found in the walls of organs with cavities. Example :- Walls of digestive tract, uterus, blood vessels and bladder Features of smooth muscle cell ²² These cells are spindle shaped and present separately. The cells are unbranched ²² These cells have one nucleus at the centre. No striations ²² These cells do not become fatigue Plasma quickly. They are controlled membrane Nucleus involuntarily Figure 1.18 - smooth muscle cell 13 For free distribution Biology Living tissuos Skeletal muscle tissue Skeletal muscle tissue is made up of skeletal muscle fibres. These are mostly associated with skeletal system. The skeletal muscles help in locomotion and movements of chordates. Features of skeletal muscle fibres Skeletal muscular fibres ²² Skeletal muscle fibres are long, cylindrical, unbranched cells. ²² They are multinucleate cells with striations. The nuclei present peripherally, and many mitochondria are present in them. ²² These cells are voluntarily controlled and Nucleus Plasma membrane become fatigue easily. Figure 1.19 - Skeletal muscular tissue E.g. :- Bicep muscle, Tricep muscle, Muscles in leg, Facial muscles Cardiac muscle tissue Cardiac muscle tissue is made up of cardiac muscle cells. It is exclusively found in the vertebrate heart. Features of cardiac muscle fibres Intercalated disc ²² Cardiac muscle cells are uninucleate, striated and short cells ²² Intercalated discs are present among cells ²² They never become fatigue. They Nucleus contract rhythmically Plasma membrane Figure 1.20 - Cardiac muscle tissue ²² They are involuntarily controlled For free distribution 14 Living tissuos Biology 1.2.4 Nervous tissue Cell body Node of Ranvier Axon Myelin sheath Dendrites Nucleus Figure 1.21- Stucture of a typical neuron It is an important tissue found in chordates body. The stuctural unit of nervous tissue is nerve cell or neuron. Neurons are specialised to transmit impulses. Features of neuron ²² Neuron is composed of two parts. They are cell body and nerve fibres ²² Nucleus, mitochondria, golgi body and endoplasmic reticulum are found in the cell body ²² Axon arises from the cell body as a single process. The axon transmits impulses away from the cell body. ²² Dendrons branch out to form dendrites. Dendrites receive stimuli and transmit impulses to the cell body Most of the axons in chordates are myelinated. Myelin sheath is not continuous and the interrupted places are known as nodes of Ranvier. The myelin sheath increases the speed of transmission. Functions of neurons The function of the neuron is to receive the information from the receptors (eye, ear, nose tongue, skin) or another neuron and to transmit them to the effector (muscles) or to another neuron. According to the function of the neuron, they can be divided into three types as follows, ²² Sensory neuron ²² Inter neuron ²² Motor neuron 15 For free distribution Biology Living tissuos Sensony neuron Motor neuron Inter neuron Figure 1.22 - Types of neurons wledge Extra kno Sensory neuron They transmit impulses from sensory organs to the central nervous system. The cell body of the sensory neuron is present at the centre of the nerve fibes. The cell bodies are present inside ganglion. The dendrites are present at the sensory organs. Ganglion is a stucture formed by the collection of cell bodies. Motor neuron The function of the motor neuron is to transmit impulses from central nervous system to effector (muscles). A motor neuron possesses a star shaped cell body with many fibres. One of them is the axon and it is long. Sometimes it is greater than 1m in length. The other fibres and cell body are found within the central nervous system. Inter neuron The whole neuron is present within the central nervous system. The axons are short. Many dendrites are present. The inter neuron connects the sensory neuron with motor neuron. For free distribution 16 Living tissuos Biology Summary Summary 17 For free distribution Biology Living tissuos Exercise ^1& Underline the correct answer I. Out of the cells and tissues given below which type is of dead cells? 1. Fibres 2. Parenchyma 3. Collenchyma 4. Sieve tube element II. Which is the complex tissue out of the following? 1. Parenchyma 2. Xylem 3.Sclerenchyma 4.Collenchyma III. Features mentioned below could be observed in a plant tissue under a microscope. Identify the tissue. ²² Isodiametric cells ²² Large vacuoles ²² Living cells 1. Sclerenchyma 2. Collenchyma 3. Xylem 4. Parenchyma iv. A characteristic of skeletal muscle fibre is, 1. Spindle shaped 2. Possesses cross striations 3. Uninucleate 4. Never becomes fatigue v. When a student observes an animal tissue under the microscope, he observed the cells present on a basement membrane. The tissue is, 1. Epithelial tissue 2. Posseses connective tissue 3. Muscular tissue 4. Nervous tissue vi' Which is correct about cardiac muscle fibres? 1. Non striated 2. Posseses intercalated discs 3. Multinucleate 4. Long, cylindrical cells ^2& State two differences between meristematic and permanent tissues. (3) Name the tissues given below For free distribution 18 Living tissuos Biology (4) State two structural differences between a cardiac muscle fibre and a skeletal muscle fibre. ^5'& Name the animal tissues given below in diagrams. Technical terms Meristematic tissues úNdcl mgl ¤›°øǯ® Apical meristems w.%ia: úNdcl Ea]¨ ¤›°øǯ® Lateral meristems md¾Yaúl úNdcl Cøh¨ ¦S¢u ¤›°øǯ® Intercalary meristems wka;ria: úNdcl £UP¨ ¤›°øǯ® Parenchyma tissue uDÿia;r mglh ¦øhU P»Âøǯ® Collenchyma tissue ia:Q,fldaKdia;r mgl JmkU P»Âøǯ® Sclerenchyma tissue oDVia;r mglh ÁÀ»¸SU P»Âøǯ® Xylem tissue ffY,u mglh PõÌ Phloem tissue maf,dahu mglh E›¯® Fibres ;ka;= |õºPÒ Sclereids Wm, ÁÀ¾¸UPÒ Animal tissues i;a;aj mgl »[Qøǯ® Epithelial tissues wmsÉPo mgl »[Qøǯ® Muscle tissues fmaYs mgl uø\°øǯ® Connective tissues iïnkaOl mgl öuõk¨¤øǯ® Nervous tissues iakdhq mgl |µ®¤øǯ® 19 For free distribution