Samacheer Kalvi 11th Bio Botany Solutions Chapter 9 Tissue and Tissue System

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Tamilnadu Samacheer Kalvi 11th Bio Botany Solutions Chapter 9 Tissue and Tissue System

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Samacheer Kalvi 11th Bio Botany Tissue and Tissue System Text Book Back Questions and Answers

Question 1.
Refer to the given figure and select the correct statement:
Samacheer Kalvi 11th Bio Botany Solutions Chapter 9 Tissue and Tissue System 4
(i) A, B, and C are histogen of shoot apex
(ii) A Gives rise to medullary rays
(iii) B Gives rise to cortex
(iv) C Gives rise to epidermis
(a) (i) and (ii) only
(b) (ii) and (in) only
(c) (i) and (iii) only
(d) (iii) and (iv) only
Answer:
(c) (i) and (iii) only

Question 2.
Read the following sentences and identify the correctly matched sentences.
(i) In exarch condition, the protoxylem lies outside of metaxylem.
(ii) In endarch condition, the protoxylem lie towards the centre.
(iii) In centarch condition, metaxylem lies in the middle of the protoxylem.
(iv) In mesarch condition, protoxylem lies in the middle of the metaxylem.
(a) (i), (ii) and (iii) only
(b) (ii), (iii) and (iv) only
(c) (i), (ii) and (iv) only
(d) All of these
Answer:
(c) (i), (ii) and (iv) only

Question 3.
In Gymnosperms, the activity of sieve tubes are controlled by:
(a) Nearby sieve tube members.
(b) Phloem parenchyma cells.
(c) Nucleus of companion cells.
(d) Nucleus of albuminous cells.
Answer:
(c) Nucleus of companion cells.

Question 4.
When a leaf trace extends from a vascular bundle in a dicot stem, what would be the arrangement of vascular tissues in the veins of the leaf?
(a) Xylem would be on top and the phloem on the bottom
(b) Phloem would be on top and the xylem on the bottom
(c) Xylem would encircle the phloem
(d) Phloem would encircle the xylem
Answer:
(a) Xylem would be on top and the phloem on the bottom

Question 5.
Grafting is successful in dicots but not in monocots because the dicots have:
(a) vascular bundles arranged in a ring
(b) cambium for secondary growth
(c) vessels with elements arranged end to end
(d) cork cambium
Answer:
(b) cambium for secondary growth

Question 6.
Why the cells of sclerenchyma and tracheids become dead?
Answer:

  • Scierenchyma and tracheids are cells which have a nucleus and cytoplasm (protoplasm) initially but it soon degenerates. They become dead cells.
  • Both give mechanical strength to the plant.
  • Tracheids being a part of xylem help to conduct water.

Question 7.
Explain sclereids with their types.
Answer:
Sclereids are dead cells, usually these are isodiametric but some are elongated too. The cell wall is very thick due to lignification. Lumen is very much reduced. The pits may simple or branched. Sclereids are mechanical in function. They give hard texture to the seed coats, endosperms etc., Sclereids are classified into the following types.

  1. Branchysclereids or Stone cells: Isodiametric sclereids, with hard cell wall. It is found in bark, pith cortex, hard endosperm and fleshy portion of some fruits. eg: Pulp of Pyrus.
  2. Macrosclereids: Elongated and rod-shaped cells, found in the outer seed coat of leguminous plants. eg: Crotalaria and Pisum sativum.
  3. Osteosclereids (Bone cells): Rod-shaped with dilated ends. They occur in leaves and seed coats. eg: seed coat of Pisum and Hakea.
  4. Astrosclereids: Star cells with lobes or arms diverging form a central body. They occur in petioles and leaves. eg: Tea, Nymphae and Trochodendron.
  5. Trichosclereids: Hair like thin-walled sclereids. Numerous small angular crystals are embedded in the wall of these sclereids, present in stems and leaves of hydrophytes. eg: Nymphaea leaf and Aerial roots of Monstera

Question 8.
What are sieve tubes? Explain.
Answer:

  1. Sieve tubes are long tube-like conducting elements in the pholem formed from a series of cells called sieve tube elements.
  2. The sieve tube elements are arranged one above the other and form a vertical sieve tube.
  3. The end wall contains a sieve plate.
  4. The sieve elements show nacreous thickenings on their lateral walls.
  5. They may possess simple or compound sieve plates.
  6. The function of sieve are believed to be controlled by companion cells.
  7. In a mature sieve tube, Nucleus is absent, it contains a lining layer of cytoplasm. A special protein
    (P. Protein= Pholem Protein) called slime body is seen in it.
  8. In mature sieve tubes, the pores in the sieve plate are blocked by a substance called callose (callose plug). The conduction of food material takes place through cytoplasmic strands. Sieve tubes occur only in the Angiosperm.

Samacheer Kalvi 11th Bio Botany Solutions Chapter 9 Tissue and Tissue System 1

Question 9.
Distinguish the anatomy of dicot root from monocot root.
Answer:
The anatomy of dicot root from monocot root:
Samacheer Kalvi 11th Bio Botany Solutions Chapter 9 Tissue and Tissue System 2

Question 10.
Distinguish the anatomy of dicot stem from monocot stem.
Answer:
The anatomy of dicot stem from monocot stem:
Samacheer Kalvi 11th Bio Botany Solutions Chapter 9 Tissue and Tissue System 3

Samacheer Kalvi 11th Bio Botany Tissue and Tissue System Other Important Questions & Answers

I. Choose the correct answer. (1 Mark)

Question 1.
The National Medal of Science (1989) by the USA was awarded to
a) Nehemiah Grew
b) Katherine Esau
c) Schmidt
d) Clowes
Answer:
b. Katherine Esau

Question 2.
The study of internal structure and organisation of plant is called:
(a) plant taxonomy
(b) plant anatomy
(c) plant physiology
(d) plant ecology
Answer:
(b) plant anatomy

Question 3.
Stellate parenchyma occur in
a) Lilly Petiole
b) Nymphae leaves
c) Petioles of Banana & Canna
d) Petiole of Nerium
Answer:
c. Petiole of Banana & Canna

Question 4.
The term meristem is coined by:
(a) Nageli
(b) Robert
(c) Stevers
(d) Clowes
Answer:
(a) Nageli

Question 5.
Tracheids are chief water conducting element
a) Dicots
b) Monocots
c) Gymnoperms & Pteridophytes
d) Pteridophytes & Bryophytes
Answer:
c. Gymnosperms & Pteridophytes

Question 6.
Apical cell theory is proposed by:
(a) David brown
(b) Hofmeister
(c) Landmark
(d) Clowes
Answer:
(b) Hofmeister

Question 7.
The three tissue systems in plants are recognised by,
a) Julius von Sachs
b) Schuepp
c) Schleiden
d) Hartig
Answer:
a. Julius von Sachs

Question 8.
Which of the halogens gives rise to root cap?
(a) Plerome
(b) Periblem
(c) Dermatogen
(d) Calyptrogen
Answer:
(d) Calyptrogen

Question 9.
The type of collenchyma seen in Datura Nicotiana and Nerium is
a) Lacunar collenchyma
b) Lamellar collenchyma
c) Angular collenchyma
d) Fibrillar collenchyma
Answer:
c) Angular collenchyma

Question 10.
Parenchyma cells which stores resin, tannins, calcium carbonate and calcium oxalate are termed as:
(a) critoblast
(b) chromoblasts
(c) idioblasts
(d) astroblasts
Answer:
(c) idioblasts

Question 11.
Syncyte refers to
a) Parenchyma
b) Tracheids
c) Vessels
d) Fibres
Answer:
c. Vessels

Question 12.
Which of the following statement is not correct?
(a) Sclerenchyma is a dead cell
(b) It lacks protoplasm
(c) The cell walls of these cells are uniformly thickened
(d) Sclerenchyma are actively dividing cells
Answer:
(d) Sclerenchyma are actively dividing cells

Question 13.
Ribmeristem helps in the development of
a) Rhizodermis
b) Ground tissue
c) Vascular tissue
d) Cortex
Answer:
d. Cortex

Question 14.
Plant fibers are modified:
(a) sclerenchyma cells
(b) collenchyma cells
(c) parenchyma cells
(d) none of the above
Answer:
(a) sclerenchyma cells

Question 15.
Various types of stomata are recognised, on the basis of
a) the thickening on the walls of guard cells
b) the number of subsidiary cells around the guard cells
c) the opening and closing mechanism of the guard cells
d) the nature and structure of the guard cells
Answer:
b. the number of subsidiary cells around the guard cells

Question 16.
What type of xylem arrangement is seen in Selaginella sp?
(a) Endarch
(b) Exarch
(c) Centrarch
(d) Mesarch
Answer:
(c) Centrarch

Question 17.
In dicot stem, the following store starch, fatty substances, tannins, phenols, calcium oxalate crystals etc. is
a) Cortex
b) Pericycle
c) Medulla
d) Stele
Answer:
a. Cortex

Question 18.
In grasses the guard cells in the stoma are:
(a) bean-shaped
(b) irregular shaped
(c) dumbbell-shaped
(d) bell-shaped
Answer:
(c) dumbbell-shaped

Question 19.
Isobilateral leaf has
a) No distinction in to upperside and lower side
b) Stomata on both sides
c) Mesophyll not differentiated into Palisade & Spongy parenchyma
d) Mesophyll is differentiated into palisade & spongy parenchyma
Answer:
c. Mesophyll not differentiated into Palisade & Spongy parenchyma

Question 20.
The sunken stomata:
(a) reduce water loss by transpiration
(b) increase water loss by transpiration
(c) increase heat loss by evaporation
(d) neither reduce nor increase water loss by transpiration
Answer:
(a) reduce water loss by transpiration

Question 21.
In a cross-section of a leaf, the xylem and phloem in the midvein is
a) Facing the upper epidermis and lower epidermis respectively
b) Facing the lower epidermis and upper epidermis respectively
c) In the centre as successive concentric circles
d) Scattered all around the vascular bundle
Answer:
a. Facing the upper epidermis and lower epidermis respectively

Question 22.
In dicot stem, the hypodermis is generally:
(a) parenchymatous
(b) sclerenchymatous
(c) collenchymatous
(d) none of these
Answer:
(c) collenchymatous

Question 23.
Which one of the following is short-lived?
a) Proto phloem
b) Meta phloem
c) Primary phloem
d) Secondary phloem
Answer:
a. Proto phloem

Question 24.
Indicate the correct statement:
(a) Albuminous cells in gymnosperms are nucleated parenchyma cells.
(b) Albuminous cells in gymnosperms are nucleated collenchyma cells.
(c) Albuminous cells in gymnosperms are nucleated, thin-walled parenchyma cells.
(d) Albuminous cells in gymnosperms are nucleated sclerenchyma cells.
Answer:
(c) Albuminous cells in gymnosperms are nucleated, thin-walled parenchyma cells.

Question 25.
Bulliform cells are the modification of
a) Silica cells
b) guard cells
c) Subsidiary cells
d) Epidermal cells
Answer:
d. Epidermal cells

Question 26.
Which of the following statement is not correct?
(a) The outermost layer of the root is called the piliferous layer.
(b) The chief function of the piliferous layer is protection.
(c) Piliferous layer is made up of parenchyma cells with intracellular space.
(d) Piliferous layer is made up of parenchyma cells without intracellular space.
Answer:
(d) Piliferous layer is made up of parenchyma cells without intracellular space.

Question 27.
Trachea is other name of
a) Xylem vessel
b) Xylem tracheid
c) Xylem fibre
d) Phloem fibre
Answer:
a. Xylem vessel

Question 28.
Who discovered the Annular collenchyma?
(a) Clowes
(b) Sanio
(c) Nageli
(d) Duchaigne
Answer:
(d) Duchaigne

Question 29.
The main function of the xylem is:
(a) to conduct the minerals to various parts of plants
(b) to conduct oxygen to various parts of the plant body
(c) to conduct water and minerals from the root to the other parts of the plant body
(d) to conduct stored food to various parts of the plant body
Answer:
(c) to conduct water and minerals from the root to the other parts of the plant body

Question 30.
In maize the vascular bundles are:
(a) scattered
(b) concentric
(c) excentric
(d) radial
Answer:
(a) scattered

Question 31.
stomata in the leaves of a plant are used for:
(a) transpiration
(b) transpiration and gas exchange
(c) gas exchange
(d) none of the above
Answer:
(b) transpiration and gas exchange

Question 32.
Which of the statement is not correct?
(a) Palisade parenchyma cells are seen beneath the upper epidermis
(b) Palisade parenchyma cells contain more chloroplasts
(c) Palisade parenchyma cells are irregularly shaped
(d) The function of palisade parenchyma is photosynthesis
Answer:
(c) Palisade parenchyma cells are irregularly shaped

Question 33.
Spongy parenchyma cells are:
(a) irregularly shaped
(b) elongated cylindrical cells
(c) very lightly arranged cells
(d) with more number chloroplasts than palisade parenchyma
Answer:
(a) irregularly shaped

Question 34.
The main function of spongy parenchyma is:
(a) photosynthesis
(b) exchange of gases
(c) exchange of minerals
(d) water transport
Answer:
(b) exchange of gases

Question 35.
All mesophyll cells in monocot leaf are near:
(a) isodiametric and thick-walled
(b) irregular and thick-walled
(c) isodiametric and thin-walled
(d) irregular and thin-walled
Answer:
(c) isodiametric and thin-walled

Question 36.
Structurally, hydathodes are modified:
(a) cambium tissue
(b) parenchyma
(c) pith
(d) stomata
Answer:
(d) stomata

Question 37.
Hydathodes occurs in the leaves of:
(a) desert plants
(b) submerged aquatic plants
(c) floating aquatic weeds
(d) forest trees
Answer:
(b) submerged aquatic plants

Question 38.
The process of guttation is seen in:
(a) grasses
(b) dicot plants
(c) desert plants
(d) Nerium
Answer:
(a) grasses

Question 39.
Salt glands are present in:
(a) xerophytes
(b) hydrophytes
(c) halophytes
(d) merophytes
Answer:
(c) halophytes

Question 40.
The term sieve tubes is coined by:
(a) Schleiden
(b) Hanstein
(c) Tsehireh
(d) Hartig
Answer:
(d) Hartig

II. Answer the following. (2 Marks)

Question 1.
Define the tissue?
Answer:
A tissue is a group of cells that are alike in origin, structure, and function. The study of tissue is called Histology.

Question 2.
What are idioblasts?
Answer:
Parenchyma cells which store resin, tannins, crystals of calcium carbonate, calcium oxalate are called idioblasts.

Question 3.
Mention any, two characters of meristematic tissue.
Answer:
Two characters of meristematic tissue:

  1. The meristematic cells are isodiametric and maybe, oval, spherical or polygonal in shape.
  2. They have generally dense cytoplasm with a prominent nucleus.

Question 4.
Differentiate between Histogen theory of Root apex and shoot apex.
Answer:

  • According to Histogen theory, the Root apex has 4 distinct regions, such as Dermatogen, Periblem Plerome and Calyptrogen whereas shoot apex has only three regions, except calyptrogen.
  • Calyptrogen in root gives rise to root cap or calyptra.

Question 5.
What is mean by carpus?
Answer:
It is the inner zone of shoot apex that forms cortex and stele of the shoot.

Question 6.
Explain apical cell theory?
Answer:
Apical cell theory is proposed by Nageli. The single apical cell or apical initial composes the root meristem. The apical initial is tetrahedral in shape and produces root cap from one side. The remaining three sides produce epidermis, cortex and vascular tissues. It is found in vascular cryptogams.

Question 7.
What is meant by angular collenchyma?
Answer:
It is the most common type of collenchyma with irregular arrangement and thickening at the angles where cells meet., eg: Hypodermis of Datum and Nicotiana.

Question 8.
What is “Bundle cap” or “Hard bast”?
Answer:
In Dicot stem, in each vascular bundle, a few layers of sclerenchyma cells occur in patches outside the phloem, known as bundle cap or hard bast, providing mechanical strength.

Question 9.
What is Filiform Sclereids?
Answer:
The sclereids are present in the leaf lamina of Olea europaea. They are very much elongated fibre like and about 1mm length.

Question 10.
Distinguish between Libriform fibres and Fibre tracheids.
Answer:
Between Libriform fibres and Fibre tracheids:

Libriform fibres

Fibre tracheids

1. These fibres have slightly lignified secondary walls with simple pits. These fibres are long and narrow.1. These are shorter than the libriform fibres with moderate secondary thickenings in the cell walls. Pits are simple or bordered.

Question 11.
What is the special significance of radial arrangement in roots?
Answer:

  • In Roots, xylem and phloem are arranged in different radii, alternating each other, this is known as Raidal arrangement.
  • This condition helps the water molecules to move upwards and sidewards along xylem since the roots branch off to give secondary and tertiary roots.

Question 12.
What is meant by endarch type of xylem arrangements?
Answer:
Protoxylem lies towards the .centre and metaxylem towards the periphery this condition is called Endarch. It is seen in stems.

Question 13.
What are the types of cells present in phloem?
Answer:
Phloem consists of four types of Cells:

  1. Sieve elements
  2. Companion cells
  3. Phloem parenchyma
  4. Phloem fibres.

Question 14.
Define epiblema?
Answer:
It is made up of a single layer of parenchyma cells which are arranged compactly without intercellular spaces. It is devoid of epidermal pores and cuticles. Root hair is always single-celled, it absorbs water and mineral salts from the soil. Another important function of the piliferous layer is protection.

Question 15.
Notes on Albuminous cells (or) Strasburger cells
Answer:

  • They are cytoplasmic nucleated parenchyma associated with sieve cells of Gymnosperm.
  • They are analogous to companion cells of phloem, seen in Angiosperms.

Question 16.
Notes on Casparian stripes and passage cells
Answer:

  • There is a band like structure, made of suberin and lignin present in the raidal and inner tangential walls of endodermal cells of roots
  • Their main function, is to prevent the re-entry of water in to the cortex from the xylem.
  • Passage cells are the cells of the endodermis opposite to the protoxylem elements, with out Casparian stripes, help in the radial diffusion of water into xylem of roots.

Question 1 7.
Mention any two functions of the epidermal tissue system in plants.
Answer:
Two functions of epidermal tissue system in plants:

  1. This system in the shoot checks excessive loss of water due to the presence of a cuticle.
  2. The epidermis protects the underlying tissues.

Question 18.
Define chlorenchyma?
Answer:
Sometimes in the young stem, chloroplasts develop in peripheral cortical cells, which is called chlorenchyma.

Question 19.
What is meant by Casparian strips?
Answer:
In true root endodermis, radial and inner tangential walls of endodermal cells possess thickenings of lignin, suberin, and some other carbohydrates in the form of strips they are called Casparian strips.

Question 20.
What are albuminous cells?
Answer:
The cytoplasmic nucleated parenchyma is associated with the sieve cells of Gymnosperms. Albuminous cells in Conifers are analogous to companion cells of Angiosperms. It also called Strasburger cells.

Question 21.
Write down the function of Collenchyma
Answer:

  • It give mechanical strength to young plant parts.
  • It resists bending of stems (helps Cucurbita in bending)
  • It prevents tearing of leaves.
  • It perform photosynthesis when it contain chlorophyll
  • It can also store food material

Question 22.
Define stele?
Answer:
All the tissues inside the endodermis comprise the stele. This includes pericycle, vascular system, and pith.

Question 23.
What is meant by cambium?
Answer:
Cambium consists of brick-shaped and thin-walled meristematic cells. It is one to four layers in thickness. These cells are capable of forming new cells during secondary growth.

Question 24.
Define silica Cells?
Answer:
Some of the epidermal cells of the grass are filled with silica. They are called silica cells.

Question 25.
What is piliferous layer?
Answer:

  • The outermost layer of the root is known as piliferous layer or Epiblema.
  • It is made up of single layer of parenchyma cells which are arranged compactly without intercellular spaces.
  • It is devoid of epidermal pores and cuticle.
  • It has root hairs originating from small cells known as trichoblast. .
  • Function: It is absorptive and protective in function.

III. Answer the following. (3 Marks)

Question 1.
Explain apical cell theory.
Answer:
Apical cell theory is proposed by Hofmeister (1852) and supported by Nageli (1859). A single apical cell is a structural and functional unit. This apical cell governs the growth and development of the whole plant body. It is applicable in Algae, Bryophytes, and in some Pteridophytes.

Question 2.
Explain histogen theory.
Answer:
Histogen theory is proposed by Hanstein (1868) and supported by Strassburger. The shoot apex comprises three distinct zones.

  1. Dermatogen: It is the outermost layer. It gives rise to the epidermis.
  2. Periblem: It is a middle layer. It gives rise to the cortex.
  3. Plerome: It is the innermost layer. It gives rise to stele.

Question 3.
Classify meristems based on their position?
Answer:
Based on their position there are three types.

1. Apical meristem:

  • Present in the apices of root and shoot
  • Responsible for increase in the length of the plant
  • This kind of growth is called primary growth.

2. Inter calary meristem:

  • Occurs between the mature tissues
  • responsible for elongation of internodes. E.g grass

3. Lateral meristem

  • Occurs along the longitudinal axis of stem and root
  • It is responsible for secondary tissues and thickenings of stem & root
  • E.g. Vascular cambium & Cork cambium (Phellogen)

Question 4.
Explain the term “sclereids”.
Answer:
Sclereids are dead cells, usually these are isodiametric but some are elongated too. The cell wall is very thick due to lignification. Lumen is very much reduced. The pits may simple or branched. Sclereids are mechanical in function. They give hard texture to the seed coats, endosperms etc.

Question 5.
Explain briefly about plant fibres.
Answer:
Fibres are very much elongated sclerenchyma cells with pointed tips. Fibres are dead cells and have lignified walls with narrow lumen. They have simple pits. They provide mechanical strength and protect them from the strong wind. It is also called supporting tissues. Fibres have a great commercial value in cottage and textile industries.

Question 6.
Write briefly about xylem fibres.
Answer:
The fibres of sclerenchyma associated with the xylem are known as xylem fibres. Xylem fibres are dead cells and have lignified walls with narrow lumen. They cannot conduct water but being stronger provide mechanical strength. They are present in both primary and secondary xylem. Xylem fibres are also called libriform fibres.
The fibres are abundantly found in many plants. They occur in patches, in continuous bands and sometimes singly among other cells. Between fibres and normal tracheids, there are many transitional forms which are neither typical fibres nor typical tracheids. The transitional types are designated as fibre – tracheids. The pits of fibre – tracheids are smaller than those of vessels and typical tracheids.

Question 7.
Explain companion cells.
Answer:
The thin walled, elongated, specialized parenchyma cells, which are associated with die sieve elements, are called companion cells. These cells are living and they have cytoplasm and a prominent nucleus. They are connected to the sieve tubes through pits found in the lateral walls. Through these pits cytoplasmic connections are maintained between these elements. These cells are helpful in maintaining the pressure gradient in the sieve tubes. Usually the nuclei of the companion cells serve for the nuclei of sieve tubes as they lack them. The companion cells are present only in Angiosperms and absent in Gymnosperms and Pteridophytes. They assist the sieve tubes in the conduction of food materials.

Question 8.
Distinguish between meristematic tissue and permanent tissue.
Answer:
Between meristematic tissue and permanent tissue:

Meristematic tissue

Permanent tissue

1. Cells divide repeatedly1. Do not divide
2. Cells are undifferentiated2. Cells are fully differentiated
3. Cells are small and Isodiametric3. Cells are variable in shape and size
4. Intercellular spaces are absent4. Intercellular spaces are present
5. Vacuoles are absent5. Vacuoles are present
6. Cell walls are thin6. Cell walls maybe thick or thin
7. Inorganic inclusions are absent7. Inorganic inclusions  are present

Question 9.
Write down the differences between tracheids and fibres.
Answer:
The differences between tracheids and fibres:

Tracheids

Fibres

1. Not much elongated1. Very long cells
2. Posses oblique end walls2. Posses tapering end walls
3. Cell walls are not as thick as fibtres3. Cell wall are thick and lignified
4. Possess various types of thickenings4. Possess only pitted thickenings
5. Responsible for the conduction and also mechanical support5. Provide only mechanical support

Question 10.
What is the significance of companion cells.
Answer:

  • The companion cell and sieve tube originated from the same mother cell, so it remain associated with sieve elements.
  • The nucleus of sieve tube got degenerated in the course of development and the nucleus of the companion cell takes control of the functions of sieve tube.
  • They are connected to sieve tube through pits found on lateral walls.
  • Companion cells are absent in sieve cells of Gymnosperms & Pteridophytes.

Question 11.
Explain the term trichomes.
Answer:
There are many types of epidermal outgrowths in stems. The unicellular or multicellular appendages that originate from the epidermal cells are called trichomes. Trichomes may be branched or unbranched and one or more one celled thick. They assume many shapes and sizes. They may also be glandular (eg: Rose, Ocimum) or non – glandular.

Question 12.
What do you understand about hypodermis in plant tissue system.
Answer:
One or two layers of continuous or discontinuous tissue present below the epidermis, is called hypodermis. It is protective in function. In dicot stem, hypodermis is generally collenchymatous, whereas in monocot stem, it is generally sclerenchymatous. In many plants collenchyma form the hypodermis.

Question 13.
What is meant by pith?’
Answer:
The central part of the ground tissue is known as pith or medulla. Generally this is made up of thin walled parenchyma cells with intercellular spaces. The cells in the pith generally stores starch, fatty substances, tannins, phenols, calcium oxalate crystals, etc.

Question 14.
What is the main cause of guttation in plants?
Answer:

  • Hydathodes discharge liquid water with various dissolved substances from the interior of the leaf to the surface. This process is called guttation.
  • The main cause for this is root pressure, during night when root pressure is high, watery drops ooze out with the assistance of special structures called hydathodes. Eg. Grasses, tomato etc.

Question 15.
What is meant by stele in plant stem?
Answer:
The central part of the stem inner to the endodermis is known as stele. It consists of pericyle, vascular bundles and pith. In dicot stem, vascular bundles are arranged in a ring around the pith. This type of stele is called eustele.

Question 16.
Apical meristem is subterminal in root unlike Apical meristem of stem – why?
Answer:

  • According to Hanstein and strasburgur (1868) the stem apex has only 3 zones, where as the root apex has 4 zones in the meristem. The 4 th zone is calyptrogen giving rise to root cap.
  • So in the root apex is subterminal due to the presence of root cap or calyptra.

Question 17.
Explain the mesophyll layer of the leaf.
Answer:
The ground tissue that is present between the upper and lower epidermis of the leaf is called mesophyll. Here, the mesophyll is not differentiated into palisade and spongy parenchyma. All the mesophyll cells are nearly isodiametric and thin walled. These cells are compactly arranged with limited intercellular spaces. They contain numerous chloroplasts.

Question 18.
Mention any three differences between stomata and hydathodes.
Answer:
Stomata:

  1. Occur in epidermis of leaves, young stems.
  2. Stomatal aperture is guarded by two guard cells.
  3. The two guard cells are generally surrounded by subsidiary cell.

Hydathodes:

  1. Occur at the tip or margin of leaves that are grown in moist shady place.
  2. Aperture of hydathodes are surrounded by a ring of cuticularized cells.
  3. Subsidiary cells are absent.,

Question 19.
What are halophiles? Explain briefly.
Answer:
Halophiles:

  1. Plants that grow in salty environment are called Halophiles.
  2. Plant growth in saline habitat developed numerous adaptations to salt stress. The secretion of ions by salt glands is the best-known mechanism for regulating the salt content of plant shoots.
  3. Salt glands typically are found in halophytes. (Plants that grow in saline environments)

IV. Answer in detail.

Question 1.
Explain Histogen theory, Korper Kappe Theory and Quiescent Centre Concept with diagrams.
Answer:
Histogen Theory: Histogen theory is proposed by Hanstein (1868) and supported by Strassburger. The histogen theory as appilied to the root apical meristem speaks of four histogen in the meristem. They are respectively

  1. Dermatogen: It is a outermost layer. It gives rise to root epidermis.
  2. Periblem: it is a middle layer. It gives rise to cortex.
  3. Plerome: It is innermost layer. It gives rise to stele.
  4. Calyptrogen: it gives rise to root cap.
    Samacheer Kalvi 11th Bio Botany Solutions Chapter 9 Tissue and Tissue System 9

Korper Kappe Theory: Korper kappe theory is proposed by Schuepp. There are two zones in root apex – Korper and Kappe.

  1. Korper zone forms the body.
  2. Kappe zone forms The cap.

This theory is equivalent to tunica corpus theory of shoot apex.The two divisions are distinguished by the type of T (also called Y divisions). Korper is characterised by inverted T division and kappe by straight T divisions.
Samacheer Kalvi 11th Bio Botany Solutions Chapter 9 Tissue and Tissue System 10

Quiescent Centre Concept: Quiescent centre concept was proposed by Clowes (1961) to explain root apical meristem activity. These centre is located between root cap and differentiating cells of the roots. The apparently inactive region of cells in root promeristem is called quiescent centre. It is the site of hormone synthesis and also the ultimate source of all meristematic cells of the meristem.
Samacheer Kalvi 11th Bio Botany Solutions Chapter 9 Tissue and Tissue System 11

Question 2.
Describe the structure and function of different kinds of parenchyma tissues?
Answer:
Samacheer Kalvi 11th Bio Botany Solutions Chapter 9 Tissue and Tissue System 12
Parenchyma is generally present in all organs of the plant. It forms the ground tissue in a plant. Parenchyma is living tissue and made up of thin-walled cells. The cell wall is made up of cellulose. Parenchyma cells may be oval, polyhedral, cylindrical, irregular, elongated, or armed. Parenchyma tissue normally has prominent intercellular spaces. Parenchyma may store various types of materials like water, air, ergastic substances. It is usually colourless. The turgid parenchyma cells help in giving rigidity to the plant body. Partial conduction of water is also maintained through parenchymatous cells. Occasionally Parenchyma cells which store resin, tannins, crystals of calcium carbonate, calcium oxalate are called idioblasts. Parenchyma is of different types and some of them are discussed as follows.

Types of parenchyma:
(i) Aerenchyma: Parenchyma which contains air in its intercellular spaces. It helps in aeration and buoyancy.
eg: Nymphae and Hydrilla.
Samacheer Kalvi 11th Bio Botany Solutions Chapter 9 Tissue and Tissue System 13

(ii) Storage Parenchyma: parenchyma stores food materials. eg: Root and stem tubers.
Samacheer Kalvi 11th Bio Botany Solutions Chapter 9 Tissue and Tissue System 14

(iii) Stellate Parenchyma: Star-shaped parenchyma. eg: Petioles of Banana and Canna.
Samacheer Kalvi 11th Bio Botany Solutions Chapter 9 Tissue and Tissue System 15

(iv) Chlorenchyma: Parenchyma cells with chlorophyll. The function is photosynthesis, eg: Mesophyll of leaves.
Samacheer Kalvi 11th Bio Botany Solutions Chapter 9 Tissue and Tissue System 16

(v) Prosenchyma: parenchyma cells became elongated, pointed, and slightly thick-walled. It provides mechanical support.
Samacheer Kalvi 11th Bio Botany Solutions Chapter 9 Tissue and Tissue System 17

Question 3.
Describe the types of tracheids with a diagram.
Answer:
Samacheer Kalvi 11th Bio Botany Solutions Chapter 9 Tissue and Tissue System 18
Types of secondary wall thickenings in tracheids and vessels:
Tracheids are dead, dignified, and elongated cells with the tapering end. Its lumen is broader than that of fibres. In cross-section, the tracheids are polygonal. There are different types of cell wall thickenings due to the deposition of secondary wall substances. They are annular (ring-like), spiral (spring-like), scalariform (ladder-like) reticulate (net-like), and pitted (uniformly thick except at pits). Tracheids are imperforated cells with bordered pits on their sidewalls. Only through this conduction takes place in Gymnosperms. They are arranged one above the other. Tracheids are chief water-conducting elements in Gymnosperms and Pteridophytes. They also offer mechanical support to the plants.

Question 4.
Compare the different types of plant tissues.
Answer:
The different types of plant tissues:
Samacheer Kalvi 11th Bio Botany Solutions Chapter 9 Tissue and Tissue System 5

Question 5.
Compare the vascular tissues of plants.
Answer:
The vascular tissues of plant:
Samacheer Kalvi 11th Bio Botany Solutions Chapter 9 Tissue and Tissue System 6

Question 6.
Draw and label the various parts of T.S. of dicot root.
Answer:
Draw and label the various parts of T.S. of dicot root:
Samacheer Kalvi 11th Bio Botany Solutions Chapter 9 Tissue and Tissue System 8

Question 7.
Explain Any two Root Apex organisation theories.
Answer:
The root apex is dome-shaped structure. It is subterminal because it is cov^ed by root cap.
Theories – explaining the organization of root apex.
1. Histogen theory:

  • Hanstein (1868) – proposed the theory
  • Root apex consists of four halogens.

Example:

  • Dermatogen – gives rise to epidennis of root
  • Periblem – gives rise to cortex
  • Plerome – inner most layer, gives rise to stele
  • Calyptrogen – gives rise to root cap in monocots

Question 8.
Draw and label the various parts of monocot stem.
Answer:
The various parts of monocot stem:
Samacheer Kalvi 11th Bio Botany Solutions Chapter 9 Tissue and Tissue System 7

Question 9.
Explain the various parts of sunflower leaf with neat diagram.
Answer:
1. Anatomy of a Dicot Leaf – sunflower Leaf: Internal structure of dicotyledonous leaves reveal epidermis, mesophyll and vascular tissues.

2. Epidermis: This leaf is generally dorsiventral. It has upper and lower epidermis. The epidermis is usually made up of a single layer of cells that are closely packed. The cuticle on the upper epidermis is thicker than that of lower epidermis. The minute opening found on the epidermis are called stomata. Stomata are more in number on the lower epidermis than on the upper epidermis.

A stomata is surrounded by a pair of bean shaped cells are called guard cells. Each stoma internally opens into an air chamber. These guard cells contain chlotroplasts. The main function of epidermis is to give protection to the inner tissue called mesospyll. The cuticle helps to check transpiration. Stomata are used for transpiration and gas exchange.

3. Mesophyll: The entire tissue between the upper and lower epidermis is called mesophyll (GK meso = in the middle, phyllome = leaf). There are two regions in the mesophyll. They are palisade parenchyma and spongy parenchyma. Palisade parenchyma cells are seen beneath the upper epidermis. It consists of vertically elongated cylindrical cells in one or more layers. These are compactly arranged and are generally without intercellular spaces. Palisade parenchyma cells contain more chloroplasts than spongy parenchyma cells.

The function of palisade parenchyma is photosynthesis. Spongy parenchyma lies below the palsied parenchyma. Spongy cells are irregularly shaped. These cells are very loosly arranged with numerous airspaces. As compared to palisade cells, the spongy cells contain number of chloroplasts. Spongy cells facilitate the exchange of gases with the help of air spaces. The air space that is found next to the stomata is called respiratory cavity or substomatal cavity. Å

4. Vascular tissue: Vascular tissue are present in the veins of leaf. Vascular bundles are conjoint collateral and closed. Xylem is present towards the upper epidermis, while the phloem towards the lower epidermis. Vascular bundles are surrounded by a compact layer by a parenchymatous cell called bundle sheath or border parenchyma.

Xylem consists of metaxylem and protoxylem elements. Protoxylem is present towards the upper epidermis, while the phloem consists of sieve tubes, companion cells and phloem parenchyma. Phloem fibres are absent. Xylem consists of vessels and xylem parenchyma. Tracheids and xylem fibres are absent.
Samacheer Kalvi 11th Bio Botany Solutions Chapter 9 Tissue and Tissue System 19
Solution To Activity
Text Book Page No. 10
Question 1.
Cell lab: Students prepare the slide and identify the different types tissues.
Answer:
Preparing a slide of plant tissue.
Objective:

  1. Using hand cutting method to make thin slice of dicot root.
  2. To make slide and stain of plant sample.
  3. To observe the plant sample under microscope.

Materials:

  1. A young dicot root
  2. Compound microscope
  3. Slide
  4. Cover slip
  5. Eosin stain

Method:

  1. Place 2 cm of young dicot root on a glass slide or plate.
  2. Cut thin slices of the root through the region of maturation.
  3. Stain it with Eosin.
  4. Fix one or two of the sections in a slide and put a cover slip.
  5. To observe the sample under a compound microscope and record the parts of the sample.

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