Thinking Process

Different kinds of stains are used to colour the plant tissues to facilitate the histological studies. Safrinin and fastgreen are few of them.

Answer

(a) The xylem is coloured red with safrinin and phloem green with fast green, whereas other colours are not given by safranin and fast green.

Thinking Process

The cells get specialised to perform special functions in different plant organs.

Answer

(b) Meristem It is a group of actively dividing cells which is responsible for the life long growth occurring in the plants.

Parenchyma It is a permanent tissue and widely distributed in plant body. It is mainly involved in photosynthesis in chlorophyll containing cells and also store food materials.

Collenchyma The cells of collenchyma tissue have thickening at corners of cells and this provide mechanical strength to herbaceous green stems.

Sclerenchyma This tissue is dead at maturity, have thickening along all sides of walls. Sclereids and fibre are this types of tissue.

Epidermal tissue The epidermal tissue system forms the otuer most covering of the whole plant body and comprises epidermal cells, stomata and the epidermal appendages the trichomes and hairs.

Answer

(a) Cuticle It is a waxy layer present all over the plant body except root.

Bulliform Cells These are empty colourless cells when the bulliform cells in the leaves absorbed water and becomes turgid the leaf surface is exposed. When they are flaccid due to water stress, they make the leaves, curl inwards to minimise water loss.

Stomata These are minute apertures in the epidermis, meant for gas exchange. Each aperture is bounded by two kidney shaped cells, called guard calls. Guard cells control closing and opening of stomata.

Epidermis It is generally uniseriate, i.e., composed of single layer of epidermal cells. In some cases epidermis may be multilayered, e.g., Ficus, Nerium.

Answer

(c) Epidermis is usually a single layered structure, present on the entire body surface of the plant and this makes epidermal tissue system. It consists of epidermis, cuticle, stomata unicellular hairs and multicellular trichomes.

Whereas, parenchyma is a kind of tissue present in all organs of the plant, e.g., roots, stems, leaves, flowers, fruits and seeds.

Xylem and phloem are the complex tissue found in all vascular plants.

Thinking Process

Cell walls of the plant tissue some times get deposited with chemicals like lignin, suberin and harden to give mechanical strength to tissues and plant parts.

Answer

(c) Collenchyma This tissue provide mechanical support mainly to herbaceous young growing stem. The cells have angular thickening at the corners. Whereas, xylem is conductive complex tissue, transports water and mineral.

Sclerenchyma is dead at maturity, present in hard areas of the plant. Epidermis is usually a single layered structure present on the entire body surface of the plant.

Answer

(c) Epidermis It is usually a single layered structure, present all over the body surface of the plant. In case of root, it is called epiblema instead of epidermis.

Whereas stele is collective term for vascular tissues in case of vascular plants (pteridophyte gymnosperms and angiosperms).

Endodermis and Pericycle are the part of root or stem encircling vascular strands.

Answer

(d) Dicot Stem

Vascular bundles are said to be open when cambium is present in between the xylem and phloem. Conjoint means the xylem and phloem are united and are present on the same radius.

Answer

(c) Interfascicular cambium and cork cambium are formed due to cell dedifferentiation.

Differentiation The process which leads to maturation of cells is called differentiation. During differentiation, a few or major changes happen in protoplasm and cell walls of the cells.

Dedifferentiation A differentiated cell can regain its capacity for cell division under certain conditions. This phenomenon is called dedifferentiation. Formation of interfascicular cambium and cork cambium from fully differentiated parenchyma cells is an example of dedifferentiation.

Redifferentiation A dedifferentiated plant cell once again loses its capacity to divide and becomes mature. This phenomenon is called redifferentiation.

Answer

(b) Cortical Cells In the dicot stem the cortical cells gets differentiated to give rise to another meristematic tissue which is called cork cambium or phellogen. On the outer side it forms phellem (cork) and in the inner region it forms secondary cortical cells (phelloderm).

Answer

(a) Root and shoot tip of an actively growing plant has high meristematic activity. The cells in this region are highly active and keep dividing. So, the cells do not get differentiated to epidermal tissue, so epidermis is absent in root and shoot tips.

Answer

(c) Apical Meristem It is always present at the growing apices. Plants having 4 branches and 26 leaves will have 5 growing apices (4 growing apex of the branches + one growing apex of the main plant axis).

Answer

(c) Pine it is a gymnosperm. The plants belonging to this group do not have vessels instead, they have trachieds. Whereas teak, mango and palm are angiospermic trees. Angiospermic xylem contains vessels, tracheids, parenchyma and fibres.

Answer

(a) Collenchyma It is a group of specialised cells meant for mechanical support. It has the thickening at the corners of the cells which is mainly because of the deposition of pectin and hemicellulose.

Thinking Process

Leaves have mainly photosynthetic tissues so, the cells are adapted to carry out photosynthesis.

Answer

(c) primary phloem

The primary phloem is formed in apical meristems of the roots and shoots. The primary phloem may consist of protophloem or metaphloem. The sieve tubes of protophloem are torn and are destroyed as the plant grows since it cannot stretch with elongating tissues. The other types of cells in the phloem get converted into fibers.

Answer

(a) Periderm Patato is a underground stem. The outer epidermal layer of the stem is known as periderm. So when we remove skin of potato, we are actually removing the periderm.

Answer

(d) Trochodendron The species of this genus have a very unique feature of the angiosperms, i.e., it lack vessel elements in its wood, but has prominent sieve tube cells.

Answer

The correct option is (C) Protoderm

Anticlinal and periclinal division:In anticlinal cell division, cells divide perpendicular to the surface of the plant body. In periclinal cell division, cells divide parallel to the surface of the plant body.

Protoderm: Cells of the protoderm divide by the anticlinal division.

Fusiform initial cells, root cap and phellogen: Fusiform initial cells, cells of root cap and phellogen tissue divides by periclinal cell division.

Final answer: Option c. Protoderm.

Answer

(a) Primary xylem is present in the centre of the root. As secondary growth occurs in the root the primary phloem is pushed outside whereas, primary xylem remains inside of the root.

Thinking Process

Glucose is the first product of photosynthesis. It is highly reactive molecule. It gets converted into a disaccharide-sucrose which has 2 glucose molecule joined by $\boldsymbol{\alpha}-7$ - 4 glycosidic linkage. This is a ready form of sugar for transportation.

Answer

The food gets stored in specialised parenchymatous cells present either in roots and stems or in their modifications in the form of a polysaccharide called starch.

Thinking Process

Xylem is a complex permanent tissue which develops from primary meristematic tissue. It functions for the transportation of water and minerals in the plant.

Answer

It protoxylem lies next to phloem the condition of the xylem arrangement is called as exarch. It is found roots.

Thinking Process

Phloem is complex conductive tissue responsible for conduction of food material to all parts of the plant. It has four kinds of cells-sieve tube/cell, phloem parenchyma, phloem fibre and companion cells.

Answer

The main function of phloem parenchyma is to store food and other substances like resins, latex and mucilage. They also help in transport of food.

Thinking Process

Plant continuously lose water from its body surface, specially leaves through the process of transpiration. To prevent this loss, different plants have devised different mechanisms to prevent this loss of water.

Answer

Cuticle It is a waxy coating covering the entire plant body surface. It is absent in roots, it prevents the loss of water through the surface of the plant body.

Answer

Bulliform cells check the water loss. Bulliform or motor cells are modified epidermal cells present in monocots or grasses. Under stressed conditions, they help in shutting down stomata and thus reduce water loss through transpiration.

Thinking Process

Plant tissues exhibit special characteristics in root, stem and leaves. Just by looking at them, it can be confirmed whether tissue is from which part of the plant.

Answer

(a) Radial Vascular Bundle The xylem and phloem are present on the separate radii of the root. This arrangement of vascular bundle is known as radial vascular bundle.

(b) Polyarch Xylem When many strands of xylem are present, it is referred to as polyarch condition-a characteristic feature of monocot root.

(c) Well Developed Pith Dicot stem and monocot roots have well developed pith formed of parenchymatous cell with intercellular spaces..

Thinking Process

Plant loses water continuously by the process of transpiration. It is called the ’necessary Evil’. The plants have developed certain structures and mechanism to combat this problem.

Answer

Bulliform cells are bubble shaped cells present in grasses. Loss of turgor pressure in these cells causes leaf to curl during water stress, thus reduce transpiration.

Thinking Process

Cambium is a meristematic tissue. It is found in dicot plants and is responsible for secondary growth of stem and roots.

Answer

Interfascicular and intrafascicular cambia together form a ring of cambium called cambial ring. It is formed due to the meristematic activity of cambium.

The cambium which is found between the xylem and phloem is called fasicular or intrafasicular cambium and the newly formed cambium between the two vascular bundle is known as interfasicular cambium. Both type of cambium combine to form the cambial ring.

Answer

Phellogen is a meristematic tissue, while phelloderm is a permanent tissue. Phellogen (cork cambium) develops from the cortical cells, sometimes from pericycle cells. These cells actively divide and forms phellem on outerside and phelloderm (cortex cells)innerside on so phelloderm takes its origin from phellogen.

Formation of phellogen and phelloderm

Answer

Phellem or cork is the outer most layer, followed by phellogen (cork cambium) which in turn is followed by phelloderm (secondary cortex).

Thinking Process

Bark is a dead tissue of the plant stem, usually present on dicotyledonous trees.

Answer

Debark means the removal of bark, i.e., all tissue exterior to the vascular cambium, including secondary phloem. Bark refers to a number of tissue types, viz., periderm (phellogen, phellem and phelloderm) and secondary phloem.

Answer

Root is the organ which shows the features given in the question. Vascular bundles are present on separate radii thus called radial arrangement. Protoxylem is towards periphery of root thus making exarch condition.

Thinking Process

Wood is secondary xylem. It is formed as a result of secondary growth in gymnosperms and dicotyledonous angiosperms.

Answer

Distinguish between softwood and hardwood is as

Thinking Process

The peach or pear is a pome fruit. The fleshy thalamus is the edible part of the fruit.

Answer

The pulpy part of fruit of peach and pear, the stone cells are present, which are an sclerenchymatous cells and which are dead in nature. Their function is to give mechanical support to the soft tissue.

Answer

The commerical cork is obtained from the cork tissue of Quercus suber, which yields bottle cork. Cork is formed by cork cambium or phellogen cell. Cork cambium cells divide periclinally, cutting cells towards the inside and outside. The cells cut off twowards the outside become suberised and dead.

These are compactly packed in radial rows without intercellullar spaces and form cork of phellem. Cork is impervious to water due to suberin and provides protection to the underlying tissues.

Answer

(a) Coir It is a natural fibre obtained from husk of coconut. It is the fibrous mesoderm of the coconut fruit Cocos nucifera.

(b) Hemp The fibre is obtained from the stems of Cannabis sativa. It is the bast fibre (soft or stem fibre) obtained from secondary phloem.

(c) Cotton The fibre is the epidermal growth of cotton (Gossypium hirsutum) seed. It is elongated structure made up of cellulose.

(d) Jute It is a natural bast fibre obtained from Corchorus capsularis and made up of cellulose and lignin.

Thinking Process

Vascular tissue is a complex tissue made up of more than one type of cells. In gymnosperms, it is in primitive form and is advanced in angiosperms.

Answer

Difference between gymnosperm and angiosperm is as follows

Thinking Process

The epidermal tissue system forms the outer most covering of the whole plant body and comprises of one cell thick layer of epidermal tissue.

Answer

Modification of Epidermal Cells

The epidermal tissue has the following modifications

(i) Root hair

Structure	Function
Unicellular hairs are the extensions of epidermal cell of roots in the root hair zone.	It increases the surface area for absorption of water and minerals.

(ii) Epidermal Appendages

Structure	Function
These are called trichomes and are epidermal cell modifications. There may be unicellular or multicellular.	Some performs for stinging produces and some glandular secretions.
Appendages of epidermis of leaves A- Stellate hair of a Alyssum
B- Glandular hair of Pelargonium
C- Short glandular hair of Lavandula
D- Floccose hair of Ma/va
E- Glandular hair of Solanum
F- Urtivating hair of Verbascum

Thinking Process

Lawn grass is a runner stem modification of the family-Poaceae. It grows beautifully on the surface of the soil, thus covering entire soil surface, so, it is grown for landscaping in gardens.

Answer

The meristematic tissue is responsible for the rapid growth of such mowed lawn grass. When the apex of grass is cut frequently, it leads to the growth of the lateral branches, that makes it more bushy.

Thinking Process

Water is a need of every living being (all unicellular or multicellular organisms). So water is called ‘Elixir of life’.

Answer

Plants use water for several metabolic process as photosynthesis, transpiration and respiration. Plants die when watered in excess, because excess water removes the air trapped between the soil particles.

So, plant roots do not get $\mathrm{O}_{2}$ for respiration. Once root cells die, water and mineral absorption is stopped and this leads to gradual death of a plant.

Thinking Process

A tree grows in the height as well as width. The growth of width of a tree is a characteristic growth pattern resulted due to the activity of lateral meristematic tissues in dicot plants.

Answer

Concentric Rings The concentric growth rings are called annual rings. These rings are formed due to the secondary growth. Secondary growth occurs in dicot trees due to the activity of cambium which is a meristematic tissue.

The rate of activity of cambium is more in spring so wood formed has larger wider xylem cells, whereas wood formed in winter has narrower and smaller xylem elements. This results in the formation of two rings called growth rings.

By counting these rings, age of the tree can be determined. This branch of science is known as dendrochronology or growth ring analysis.

Answer

It is anatomical abnormality. It is an abnormal type of secondary growth, where a regular vascular cambium or cork cambium is not formed in its normal position. In case of old tree trunks, anomalous secondary growth produces cortical and medullary vascular bundles.

Thus, the additional or accessory vascular bundles given appearance of several fused trunks.

Thinking Process

The gaseous exchange mainly $O_{2}$ and $CO_{2}$ is the need of all plants. This occurs by means

of several openings present in the plant body.

Answer

Difference between lenticels and stomata is as follows

Lenticels	Stomata
Lenticels are formed due to loosening of the epidermal and cortical tissues.	Stomata are specialised epidermal structure.
These are mostly found on the stem region. Lenticels does not have guard cells.	Mostly found on lower surface of leaves. Stoma has guard cells.
These openings are not regulated. They are used for removal of waste.	Opening and closing is regulated mechanism. They are involved in gaseous exchange, removal of extra water and waste.

Answer

Sieve tube

It is present in the phloem tissue. It’s function is the transportation of synthesised food through out the plant.

Interfascicular Cambium

It’s function is to bring about secondary growth in the dicot stem and root. It is a kind of secondary meristematic tissue present in between two vascular bundles.

Collenchyma

It’s function is to provide mechanical support to young growing herbaceous stem. It’s cells have angular thickening at corners.

Aerenchyma

It provides buyoncy to the hydrophytic plants. It is a specialised parenchyma having large air spaces.

Thinking Process

Stomatal apparatus is a special modification of epidermal tissue present over leaf area.

Answer

The epidermal cells surrounding the guard cells of stomata are called subsidiary cells. Differences between guard cells and epidermal calls are

Thinking Process

Peepal is a dicot plant so will show the characteristic feature of dorsiventral leaf whereas maize is monocotyledonous, so leaf will be of isobilateral type. Discuss the anatomical features of both leaves by comparing different tissues like epidermis, stomata, vascular bundles etc.

Answer

Difference between Ficus leaf and maize leaf is as follows

Character	Ficus leaf (Dicot Leaf)	Maize leaf (Monocot Leaf)
Type of leaf	Dorsiventral.	Isobilateral.
Stomata	Usually more on lower epidermis	Equal on both, lower and upper epidermis.
Mesophyll	Made up of two types of tissues (a) Lower spongy parenchyma with large intercellular spaces. (b) Upper palisade parenchyma.	Only spongy parenchyma is present which has very small intercellular spaces.
Bundle sheath	Made up of parenchyma. Just above and below the vascular bundle some parenchymatous cells or collenchymatous cells are present (up to epidermis).	Made of parenchyma, but just above and below, the vascular bundles are found sclerenchymatous cells (up to epidermis).
Bulliform cells	Absent in dicot leaves. Bundle sheathAdaxial epidermis Xylem Dicot leaf	Present, particularly in grasses (monocot leaves). Upper Bundle sheath Cuticle Bulliform cells epidermis Mesophyll tissue

Answer

Palms, despite being monocotylednous plant show secondary growth, i.e., increase in girth. This is due to the division and enlargement of parenchymatous cells in the ground tissue. Thus, repeated divisions cause increase in girth of stem and this type of growth is referred to as diffused secondary growth.

Thinking Process

Presence of ovule is a characteristic feature of all angiosperms. It shows great variation in its attachment to the ovary.

Answer

Placenta are soft cushion like tissues with which the ovules are attached to the inner surface of ovary wall.

The arrangement of ovules within the ovary is known as placentation. The placentations are of different types, i.e., marginal, axile, parietal, basal and free central.

Marginal Placentation In this placentation, the placenta forms a ridge along the ventral suture of the ovary and the ovules are borne on this ridge forming two rows, as in pea.

Axile Placentation In this placentation, the ovules are borne on central axis and the marginal of placenta grow in word and fuse, thus making a multilocular ovary, as in China rose, tomato, etc.

Parietal Placentation In this placentation, the ovules develop on the inner wall of the ovary or on peripheral part. Ovary is one chambered but it becomes two chambered due to the formation of a false septum known as replam, e.g., mustard.

Free Central Placentation In this type of placentation, the ovules are present on the central axis of ovary and septa is absent so ovary is unilocular, as in Dianthus and Primose.

Basal Placentation In this placentation, the placenta develops at the base of ovary and a single ovule is attached to it, as in sunflower.

Thinking Process

Deciduous means ’tending to fall off. Leaves take up energy to maintain essential process for any plant. During peak hot summer/winter (adverse conditions) plants have to save energy to survive. So, they shed their leaves to conserve energy.

Answer

The process of shedding of leaves during hot summer or in autumn by deciduous plants is known as abscission. Anatomically, the cells of abscission zone are thin-walled and without deposition of lignin or suberin.

At the time of abscission, the middle lamella may dissolve between the cells of two middle layers but the primary wall remain intact. The middle lamella as well as the primary walls of the adjacent cells is dissolved. Ultimately the whole cells of middle layer found in the abscission layer gets dissolve completely.

Thus, there is separation of plant organ, i.e., leaf from the plant, wherever there is rainfall or wind.

Answer

Evergreen plant are those which has leaves persistent in all the four seasons. In contrast to deciduous plants which completely loose their foliage during winter or dry season. Pinus belonging to gymnosperms is an evergeen tree. The flowering plants under conditions of extreme cold shed their leaves and become dormant.

But Pinus due to the presence of bark, which is thick, needle-like leaves having sunken stomata, reduce the rate of transpiration. The cold areas are both physiologically and physically dry due to scanty rainfall, precipitation as snow, decreased root absorption at low temperature and exposed habitats.

But, Pinus is well adapted to such conditions. It continues to manufacture food during this period and grown to dominate other plants. This show that Pinus is an evergreen tree. It do not shed its leaves, i.e., needles under any condition.

Answer

A. If a plant cell is cut in different plane if result, in radial symmetry.

B. If a plant cell is cut in two equal halves it result in bilateral symmetry.

Answer

These terms mean as listed

Structure	Function	Diagram
Plasmodesmata
These are microscopic connecting channels between the two cells through the cell wall.	Allow communication and transport between two neighboring cells through the cell wall.
	Plasmodesmata allow molecules to travel between plant cells through the symplastic pathway.
Middle lamella
It is a layer in the cell wall mainly made of calcium pectate.	Performs the function of cementing between the two neighboring cells.
Secondary wall
It is a non-extensible layer made of hemicellulose fibers in the cell wall of plant cells.	Provides rigidity to the cell wall in plant cells.

Answer

Differences between the following

(a)

(b)

Stele	Vascular Bundle
Stele refers to conducting tissue or the central part of root or stem in plants. It comprises of vascular tissue, ground tissue and pith and limiting boundaries, i.e., endodermis and pericycle.	Vascular bundle comprises of vascular/conducting tissues xylem and phloem. Sometimes cambium is also included as in dicots.

(c)

Protoxylem	Metaxylem
It is the first or earlier formed xylem. Matures before the growth and differentiation of plant organs. Protoxylem elements are smaller in diameter. Tyloses absent in protoxylem vessels. Fibres are absent.	It is the later formed xylem. Matures after the growth and differentiation of plant organs. Metaxylem elements are broader and greater in diameter. Tyloses are generally present. Fibres may be present.

(d)

(e)

Open Vascular Bundle	Closed Vascular Bundle
Cambium present in between the xylem and phloem tissue.	Cambium is not present in between the xylem and phloem tissue.
Intrafascicular cambium between the phloem present. Occurs in the stems of dicots and gymnosperms. May be collateral or bicollateral. Xylem and phloem not in direct contact with each other due to cambial string. Intrafascicular cambium results in secondary growth. Cambial activity produces secondary phloem and secondary xylem that push primary phloem and primary xylem away from each other.	Intrafascicular cambium absent. Occurs in leaves and monocot stems. May be collateral or concentric. Xylem and phloem are in direct contact due to lack of cambial string. No such activity found. No such activity found.

(f)

Root Hair	Stem Hair
Root hairs are unicellular	Stem hairs are multicellular
	They are epidermal outgrowths known as trichomes.
It increases the surface area of root for absorption of water and minerals.	They help in preventing water loss due to transpiration.