MODEL SUBJECTIVE QUESTIONS OF GYMNOSPERMS



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MODEL SUBJECTIVE QUESTIONS OF GYMNOSPERMS

1.  Describe life cycle of Gymnosperms.

2.  Describe kingdoms of life.

3.  Give affinities of gymnosperms.

4.  Discuss structures of root, stem and leaves of Cycas with labelled diagrams.

5.  Describe structures and development of ma!, and female cones of Cycas.

6.  Describe life cycle of cycas.

7.  Describe structures of stem and leaf of pinus.

8.  Describe structures and development of male and females cones of pinus.

9.  Describe life cycle of Pinus.

10.  Describe structure of Ephedra.

11.  Describe life cycle of Ephedra.



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SHORT QUESTIONS OF GYMNOSPERMS | Biology Boom



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SHORT QUESTIONS OF GYMNOSPERMS

1.  Give occurrence of Gymnosperms.

Ans: Gymnosperms are naked seeded plants. Gymnosperms are a group of ancient plants. They become dominant in the Jurassic period. Most of the gymnosperms are evergreen trees. Some shrubby plants are also found in this group. They have worldwide distribution. They are most abundant in the temperate region. The fossils of gymnosperms are found near coal and oil deposits.

2.  How do fertilization and seed formation occur in gym nos perms?

Ans: Pollen tube carries male gametes to egg (oosphere). Fertilization occurs and diploid oospore is formed. Oospore is the beginning of gametophyte generation. The oospore gives rise to the embryo. Prothalial tissues provide nourishment to developing embryo. Integument is transformed into the seed coat The unutilized prothalial cell becomes endosperm.

3.  What is meant by Ferns with seeds?

Ans: The primitive gymnosperms like Cycas are much identical with Pteridophytes (ferns). They were taken as Pteridophytes for long time. They were called Ferns with seeds.

4.  Give two resemblances between gymnosperms and pteridophytes.

Ans: Both have regular alternation sporophytic and the gametophytic generations. Their sporophyte is dominant and forms the main plant body. Gametophyte is reduced to prothellus. Both are heterosporous

5.  Give two differences between gymnosperms and pteridophytes.

Ans: There is no seed formation in the Pteridophytes. But present in gymnosperms. The male cells or sperms are carried by pollen-tube to the archegonia in the gymnosperms. But pollen tube is absent in Pteridophytes.

6.  Give two similarities between gymnosperms and angiosperms.

Ans:   They are similar in their external morphology, i.e., the
differentiation into root stem and leaves. Both have identical internal anatomy. Cambium is present in gymnosperm and dicot angiosperms.

7.  Give two differences between gymnosperms and angiosperms.
Ans:  The reproductive structures of angiosperms are flowers, those of gymnosperms are cones. In angiosperms, the seeds are enclosed by true carpels and at maturity, a carpel forms a fruit. It is absent in gymnosperms.
8. Name of order of gymnosperms.
Ans: Cycadofilicales, Bennettitales, Cycadales, Cordaitales, Ginokoales and Gnetales.

9. Which plant is called living fossil? Why?



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Ans: Cycas is called a living fossil. It has several characters
common with the Ptcridophytes.

10. What are coralloid roots? Give their advantage to plant.

Ans: Cycas produces coralloid roots. Coralloid roots are short tufts and dichotomously branched roots. These roots contain an endophytic alga in the inner part of their cortex. Sometimes, bacteria are also present in the cortex. Bacteria fix nitrogen.

11. What are transfusion tissues? Give their function.

Ans: Transfusion tissues are present around mid ribs. They cause lateral conduction in the leaf.
12. How is microspore germinate in Cycas?

Ans: The microspore cut off lateral prothalial cell towards one side of the spore. The larger cell then cuts off a small generative cell adjacent to the plothalial cell. It itself becomes tube cell. The microspore is liberated at this stage. Spores are dispersed by wind.

13. How does fertilization occur in Cycas?

Ans: Pollen grain reaches the archegonial chamber by pollination.
The wall of the pollen grain protrudes towards the archegonial chamber. The pollen grain bursts and release antherozoids into the archegonial chamber. Antherozoid enters the oosphere. Male nucleus unites with the oosphere nucleus. Fertilized oosphere secretes a thick wall and becomes the oospore. Oospore develops embryo.

14. Give occurrence and common species of pinus.

Ans: The genus Pinus has about 90 species. It has world wide in distribution. They are mostly present in the temperate regions. Four species of pinus are found in Pakistan: Pinus wallichiana; Pinus halepensis; Pinus roxburghii; Pinus gerardiana.

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Development of Embryo SAC or Female Gametophyte



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DEVELOPMENT OF EMBRYO SAC OR FEMALE GAMETOPHYTE

Types of embryo Sac Development

There we types of embryo sac development. The classification is based on:

  1. The number of 9 ses or spore nuclei entering into the formation of embryo sac Thus embryo sac may be monosporic, bisporic or tetrasporic tyr
  2. The number, arrangement, and chromosome number of the nuclei in the mature embryo sac.
  3. The total number of nuclear divisions occurring during megasporogenesis and development of female gametophyte.
  4. Monosporic, Normal or Polygonum Type

It is commonly found in plant. It is commonly called normal type. However, it was first clearly described in Polygonum. Therefore, it is also called as Polygonum type.

This embryo sac has four well-defined megaspores. One of which gives rise to the embryo sac. The functional megaspore enlarges. Its nucleus divides. A large vacuole is formed between the nuclei. Thus the daughter nuclei move to the micropylar and chalazal poles of the embryo sac. Each nucleus divides twice. Thus four nuclei are formed at each pole. One nucleus from each pole migrates to the centre of the embryo sac. The two nuclei fuse to form a diploid secondary nucleus. Three nuclei at micropylar end are surrounded by membranes. They form egg apparatus. The central cell enlarged arid become egg cell. The other two cells becomes synergid. Thus embryo sac is formed containing 8-nucleoli and later 7-celled during its development.

  1. Bisperic or Allium Type

This type of embryo sac is found in Allium. It is found in many monocot and dicot families. Two dyad cells are formed during first meiotic division duri-j. megasporogenesis. One of two dyad cell is abiyied The    of the surviving dyad cell towards the chalazal
end &lies to ft TM two haploid nuclei. These are called megaspore nuclei. These nuclei move towards opposite ends. These nuclei divide tw ice to form eight nuclei. One nucleus from each pole migrates to the centre of the embryo sac. Three nuclei at the upker end produce egg apparatus. The nuclei present at lower end form

antipodal cells. In this way 8- nucleate bisporic embryo sac develops.

types of embryo sacs

Tetrasporie Type

In this type of embryo sac wall is not formed after the meiotic nuclear division. All four haploid megapsore nuclei take part in the formation of the embryo sac. The resultant embryo sac• may be 8- nuceleate or 16-nucleate. Thus it has two types:

a)     Plunrnbago Type (8-Nucleate): In this case, the megaspore nuclei arrange themselves in a cross-like manner. One lies at the micropylar ends and the other lies at the chalazal end. The other two are present at each side of the embryo sac. Each nucleus divides once. Thus pairs of four nuclei are formed. One nucleus from each pair migrates to the centre. They fuse to form tetraploid secondary nucleus. The nucleus at micropylar and form the egg cell. The rest three nuclei degenerate. There are no antipodal cells and synergids.

b)     Fritillaria Type (8-Nucleate): This type of embryo sac occurs in a large number of genera. In this case, Three out of four megaspore nuclei are arranged in 3 + 1 fashion. Three nuclei migrate to the chalazal end. The remaining nucleus comes at the micropylar pole. The micropylar nucleus divides to form two haploid nuclei. The three chalazal nuclei fuse. The fusion nucleus ‘divides to form two triploid nuclei. Now the embryo sac contains four nuclei, two haploid micropylar nuclei and two triploid chalazal nuclei. Later each nucleus divides. Thus they produce four haploid nuclei at micropylar end and four triploid nuclei at chalazal end. One nucleus from each pole migrates to the centre. These fuse to forms a tetraploid secondary nucleus. The nuclei at micropylar end form egg apparatus. The nucleus at the chalazal end gives rise to antipodal cells.

c)      Pen.tea Type (16 Nucleate): In this case, 16 nuclei are arranged in quarters. One is present at each end of the embryo-sac and two are present at the sides. Three nuclei of each quarter become cells. The fourth nuclei of each quarter moves towards the center and act as polar nucleus. Therefore, there are four triads and four polar nuclei. One cell of the micropylar triad is the egg. It is the only functional cell.

d)     Drusa Type (16 Nucleate): In this case, one megaspore nucleus moves towards the micropylar. The remaining three megaspore nuclei move towards chalazal end. Each nucleus divides twice. Thus four nuclei are produced at micropylar end and twelve at chalazal end. One nucleus from each migrates towards the centre of the embryo sac. They fuse to form secondary nucleus. The three nuclei at micropylar end form egg apparatus. The eleven nuclei at chalazal end form antipodal cells.

e)     Adoxa Type (8-Nucleate): The four haploid megaspore nuclei

present in the cytoplasm undergo a mitotic division. They produce eight nuclei. These nuclei are arranged in typical manner. Three of them come at the micropylar end. Three comes at the chalazal end. And two come in the centre (fusion nucleus). Thus normal 8.nucleate seven celled embryo sac is formed.

0 Paperoma tye (16 Nucleate): In this case, each of four megaspores nuclei divides twice. They form 16 nuclei. These are uniformly distributed at the periphery of the embryo sac. Two nuclei at micropylar end form an egg and a Synergid. Eight of them fuse to form secondary nucleus. The remaining three stay at the periphery of the embryo sac.

DEVELOPMENT OF ENDOSPERM

The primary endosperm nucleus divides repeatedly. It forms polyploidy nutritive tissue called endosperm. There are two types of seeds for storage of food:

a)   Endospermic or albuminous seed: The endosperm supply food to the developing embryo. Such ..e,xls are called endospennic seeds. In plants like corn, wheat, the . idosperm tissue is present at the time of seed germination. So the .e are endospermic seeds.

b)   Non-endospermic or ex-albuminous sc. :ds: In some casts, the

endosperm is completely utilized by de eloping embryo. Such seeds are known as non-endosperrnic seeds. In beans and peas the endosperm tissue is completely digested by the developing embryo and stored in the cotyledons.

Formation of Endosperm

Endosperm is formed from the primary endosperm nucleus. Its formation starts before the formation of embryo. Primary endosperm nucleus is produced by fusion of monoploid polar nuclei (secondary nucleus) and a monoploid second male gamete. The endosnerm is thus triploid (3n). However in some case, it may be pentaploid (Penaea). It may be even 9n (Pepromia).

Structure of Endosperm

The cells of the endosperm are isodiametric. They store large quantity of food materials. The storage food is present in the form of starch granules, granules of proteins, or oils. In certain plants. the endosperm cells develop very thick hard walls of hemicelluloses. The parietal layer of the endosperm of grass functions like a cambium. This layer produces on its inside layers of thin-walled cells. These cells are packed with starch. The cells of outermost layer stops dividing. It is filled with aleurone grains. This layer is called aleurone layer. The cells of this layer secrete diastase and other enzymes. These enzymes digest the food stored in endosperm for developing embryo.

Structure of maize sad

Structure of maize sad

Types of Endosperm There are three types of endosperms on the basis of mode of development. These are nucelar type, cellular type and Helobial type.

  1. Nuclear Type: In this case, the primary endosperm nucleus divides by free nuclear divisions. Wall is not formed between them. A vacuole appears in the centre of the embryo sac. It increases in size and. Therefore, the nuclei are pushed to the periphery along the wall of the embryo sac. Later, walls develop between the nuclei. Thus cellular tissues are formed.
  1. Cellular Type: In this case, the primary endosperm nucleus divides and walls are formed between the daughter nuclei. These walls may be either transverse or longitudinal. It divides the embryo sac into two cells. Later, these cells divide by repeated divisions. It produces a tissue of irregularly arranged cells.
  2. Helobial Type: This type of endosperm occurs in the order Helobiales (Monocotyledons). In this case, first division of primary endosperm nucleus is followed by a transverse wall. This wall divides the embryo sac into a small chalazal chamber and a large micropylar chamber. Then the nuclei in each chamber divide by free nuclear divisions. But, there are few nuclear divisions in the calazal chamber. The endosperm in this

chamber degenerate. Walls develop between nuclei in micropylar chamber. It produces cellular endosperm.

Development of Embryo SAC

Mosaic Endosperm

Endosperm containing tissues of two different types is called mosaic endosperm. It occurs in plants like corn. In this case, endosperm lack of uniformity in the tissues. The endosperm contains patches of two different colours. It forms a sort of irregular mosaic pattern. The part of endosperm is starchy and part is sugary.

Perisperm

In this case, a part of nucellus may persist in embryo in the form of an apical cap. It acts as a nutritive tissue and called perisperm. It occurs in some dicots such as pepper and water-lily.

Hypothesis about the Nature of the Endosperm

There are different hypothesis about the nature of endosperm. These are:



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  1. Gametophytic nature: Endosperm is formed in the embryo sac by free nuclear division. Therefore, some botanists take it vegetative tissue of the female gametophyte. But this hypothesis is not accepted because it develops as a new structure after triple fusion.
  2. Sporophytic nature: The endosperm nucleus produced as a result of the fusion of second male gamete with the secondary nucleus. Therefore, some botanists consider it a sporophyte tissue homologous to embryo. But the product of this fusion is not a new plant. Therefore, this fusion cannot be regarded as fertilization. This fusion forms a simple triploid (3n) nutritive tissue, not an embryo.
  3. Special undifferentiated nature: According to this view, it is neither sporophytic tissue nor gametophytic tissue. But it is special undifferentiated triploid tissue. It provides nourishment to developing embryo in angiosperms. It is most accepted hypothesis.

DEVELOPMENT OF EMBRYO

Development of Dicot Embryo

The dewiopment of Capsella bursa-pastoris (Shepherd’s purse) embryo is taken as model organism for the study of development of embryo of dicots. Following developmental changes take place in the embryo Capsella hurca pctstoris.

  1. First division of Oospore: Its oospore increases in size. It divides transversely in two cells. The cell toward the microphyll end is called suspensor cell. The cells towards other side is called embrymial cell. Embryonal cell forms the major portion of embryo.
  2. Formation of suspensor and radicle: The suspensor cell undergoes few transverse divisions. It produces short filament of cells called suspensor. The first cell of suspensor enlarges very much. It becomes basal cell. It pushes the embryo down into the developing endosperm. Suspensor also acts as conductive tissues for the nutrients. The last cell of suspensor adjacent to embryonal cell is called hypophysis. Hypophysis divides further to form radicle.

Ages of development of capsella bursa pastorts

  1. Formation of octant: They embryonal cell increases in size. It divides by three divisions. Two divisions are vertical and one division is transverse. These divisions form eight groups of cells called octant or pro-embryo. The four octants towards the chalazal end are the epibasal or anterior octant. The other four octants which are adjacent to suspensor are hypobasal or posterior octant.

11. Formation of cotyledons and plumule: The epibasal cells further divides to fora two cotyledons and plumule. Further divisions occur in the cotyledonary cells and bibbed mass of cells is formed. These lobes are primary cotyledons. The plumule and epicotyl is produced in the notch between two depressions. Therefore, plumule in dicot is terminal in origin.

12. Formation of bypocotyl: The hypobasal octants divide to form mass of cells called hypocotyl. Hypocotyl is elongated. It carries radicle at its tip.

13. Folding of embryo: The developing embryo increase in size. Therefore, it become curved or folded in different ways. The way of folding of embryo in seed is characteristic feature of each plant.

14. Formation of basic layers of meristem: Two successive divisions occur in octants. It produces three layers. The outer layer is called dermatogen, middle is called periblem and central one is called plerome. Dermatogen gives rise to epidermis. Periblem gives rise to cortical portion. Plerome forms the stele in the centre.

Development of Monocot Embryo The development of Sagittaria sagittifolia embryo is taken as model organism for the study ofembryology of monocots. It undergoes following changes:

  1. Its zygote divides by a transverse wall into a terminal and a basal cells

2. The basal does not divide further. It enlarges to form a vesicular cell. The terminal cell divides transversely to form proembryo.

3. The proembryo upper, middle and basalupper, middle and basalThe lowermost cell of the proembryo divides by a longitudinal wall. It then divides by transverse and longitudinal walls. Thus

9

eight cells are formed. These are arranged in two tiers. Each containing four cells.

  1. Each of the eight cells undergoes periclinal division and form dermatogen. Thus the entire region grows. It differentiates into a single terminal cotyledon.
  2. The middle cell of the proembryo undergoes a transverse division and two cells are formed. The lower of these two cells give rise to lateral shoot apex. The upper cell forms the hypocotyl, the tip of the root and a short suspensor. The suspensor is composed of 3-6 cells.

Apomixis

or Abnormal Embryonal Development

Apomixis includes all those cases of embryonal development in which the normal process of fertilization is not involved. Certain species of the following genera show different cases of apomixis Iris. Pea, Lilium, Malus, Crepis, Hypericum and Ulmas. Apomixes includes apogamy, apospory and parthenogenesis:

  1. Apogamy: The development of embro from any cell of the gametophyte without the normal process of fertilization is called apogamy.
  2. Apospory: The development of an embryo-sac from the

sporophytic cell, generally the nucellar cells, without undergoing the usual meiosis or reduction division is known as apospory. In apogamous cases the normal oosphere or one of the synergids, or one of the antipodal cells may develop into an embryo without the inyolvement of normal fertilization. If the cells involve involved are haploid then the embryo would also be haploid. The resulting plants are generally sterile. If such are diploid then the embryo and the resulting plant would also be diploid. It will be fertile pant.

  1. Parthenogenesis: The development of a gametophytic cell or oosphere without undergoing fertilization is also known as parthenogenesis. It occurs in banana.

Polyembryony

Production of more than one embryo in an ovule is known as polyembryony. It is very rare in the Angiosperms. Citrus is a very good example showing different cases of polyembryony. There are different forms of polyembryony. These are:

1. Cleavage polyembryony. In this case, more than one embryo

may be produced from a single oospore. In such cases, all the embryos may not survive till the maturation of the seed due to the mutual competition.

  1. Adventitious polyembryony: More than one embryo may be produced in a single ovule due to the development of certain nucellar cells. These cells changes into embryos in addition to the normal embryo which develops from the oospore. Such cases are known as Adventitious polyembryony. In the case of Citrus upto ten embryos have been recorded in the mature seed.
  2. Sometimes, an ovule contains more than one functional megaspores. They develop into embryo sacs and oosphere. These oosphere are fertilized and produce more than one embryos.
  3. Sometimes, embryos may develop from synergids or antipodal. Embryo from oospore is also there. Thus polyembryo are formed.

Development of Seed and Fruit

The stimulus of fertilization leads to the development of embryo and endosperm in the. It also stimulates enormous changes in the ovule. These changes leading to the development of seed, and in the ovary wall resulting in the formation of fruit.

Development of seed

The ovule increases in size during development of embryo. Its integument becomes thin, dry and hard and forms testa. In certain seeds it may be differentiable into two layers. The inner one is generally thin and membranous. It is known as the tegmen. Tegemn represents the inner integument. The developing embryo may or may not utilize the whole of the endosperm. Thus endospermic or non endosperinic seeds may formed. In certain seeds a small amount of the nucellus persists as a nutritive tissue known as the perisperm. In the non endospermic seeds the cotyledons become massive. They contain the stored food material. This food is utilized by the embryo during the germination of the seed. In case of endospermic seeds the persisting endosperm is utilized by the embryo during the germination of the seed. In certain seeds outgrowths of variable sizes are produced. These outgrowths form aril or earuncle. A scar left on the seed. It represents the point of attachment of the ovule. It is known as the hilum.

Development of Fruit

The stimulus of fertilization also causes changes in the ovary wall. It becomes the fruit wall or pericarp. The ovary wall may become dry and hard giving rise to dry fruit. Or it may become soft and fleshy giving rise to the fleshy fruits. The development of the fruit from the ovary wall is one of the chief characteristics of Angiosperms. The development of the fruit ensures the protection and maturation of the seed. It also provides an efficient means of seed dispersal. In certain cases otter parts of the flower such as calyx or thalamus may also take part in the formation of the fruit. It some extreme cases, the whole inflorescence may be involved. Such fruits are called pseudocarps. Examples of these types are pear, apple, pineapple, strawberry, fig, mulberry etc. In certain plants the fruits may be produced even without the process of fertilization. Such fruits are generally seedless and are known as parthenocarpic fruits.

Fruit Formation

 

 

 

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MULTIPLE CHOICE QUESTIONS OF GYMNOSPERMS



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MULTIPLE CHOICE QUESTIONS OF GYMNOSPERMS

1.  Which of the followings is correct for vascular bundle of
gymnosperms?

(a) Stele           (b) Exarch        (c) Collateral (d) Conjoint

2.  Secondary growth occurs by the activity of:

(a) Phloem       (c) Xylem        (c) Cambium (d) Bark

3.  Which of the followings is absent in the xylem of gymnosperms?

(a) Trachieds (b) Parenchyma (c) Fibers         (d) Vessels

4.  Bark is produced by the activity of:

(a) Phloem       (c) Xylem        (c) Cambium (d) Phellogen

5.  Generative cell represents the reduced:

(a) Antheridium(b) Archegonium(c) Oogonium (c) Antherozoids

6.  The unutilized prothalial cell becomes:

(a) Endosperm (b) Archegonium(c) Oogonium (c) Antherozoids

7.  Adventitious root system is found in:

(a) Pteridophytes(b) Gymnosperm (c) Bryophyte(d) All

8.  Endosperm in gymnosperm is:

(a) Haploid      (b) Diploid         (c) Triploid rd) None

9.  Endosperm in Angiosperms is:

(a) Haploid      (b) Diploid         (c) Triploid   (d) None

10.  Ovule is absent in:

(a) Pteridophytes(b) Gymnosperm (c) Angiosperm (d) All

11.  Egg is present in:

(a) Ovule         (b) Venter           (c) Neck       (d) None



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12.  Which of the following is called living fossil?

(a) Ephedra      (b) Pinus          (c) Cycas        (d) Ginko

13.  The outer most layer of the sporogenous tissue forms the

(a) Tapetum     (b) Spores        (c) Neck         (d) Wall

14.  Megasporangium is:

(a) Pollen sac (b) Ovule           (c) Seed          (d) Venter

Answers

1. (c) 2. (c) 3. (d) 4. (d) 5. (a) 6. (a) 7. (a) 8. (a)

9. (c)    10. (a) 11. (b) 12. (c) 13. (a) 14. (b) 15. (a)

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Apiaceae (Umbelliferae) Carrot Family | Biology Boom



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Appendix

Apiaceae (Umbelliferae) Carrot Family

Diagnostic characters

  1. Habits: Annual or perennial herbs rarely shrubs.
  2. Roots: Tap root, branched, sometimes, tuberous due to presence of stored food.
  3. Stem: Herbaceous stem, erect or prostate with swollen nodes.
  4. Leaves: Petiolate, Alternate, simple, exstipulate, reticulate venation. Usually sheathing at the base.
  5. Inflorescence: Cymose, umbel (old name of family Umbelliferae derive from umbel), simple or compound. Umbel is surrounded by thin leafy bracts involure and involucel.
  6. Flower: Ped ici I late, ebracteate, actinomorphic, Regular, complete, hermaphrodite; epigynous with a disc, pentamerous, sometimes, outer petal of marginal flowers of umbel are enlarged. Therefore, the flowers are irregular and zygomorphic.
  7. Calyx: 5 sepals, adnate to ovary, superior, free.
  8. Corolla: 5, free, often bifid, unequal velvate or imbricate, superior.
  9. Stamens: 5 Stamens, free, alternating with petals, anther versatile, superior.
  10. Carpel: Bicarpillary, syncarpous, ovary inferior, bilocular with single pendulous ovule in each loeulus, style two, stigma two, placentation parietal.
  11. Fruits: Cremocarp, oblong, ridged.
  12. Seed: Albuminous seed

Floral formula and Floral Diagram

ED or t, , Kg or C5, A1. ‘Cm.

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Economic importance

  1. Food: This family has many vegetables like carrot, parsely, parsnip and sowa.
  2. Fodder: Several members of this family are important as forage plants for cattle and horses. Some of these plants are carrot, wild parsely, cow-parnip, angelicas etcs.
  3. Codiments: Many members of this family are used as condiments. For example, Fercula (Hing), Carum (Ajwan), Cuminum (Zira), Foeniculum (Saunf), coriandrum (Dhania) and peucedanum (Sowa). Volatile oils, resins etc are produced in the bark, leaves, and fruits give the plant their fragrance.
  4. Medicinal: This family has many medicinal plants. For example, Ligusticum (Lovage- Ajwain), Ferula (Hing), Foeniculum (Saunf), Anethum (Dill or Sowa) are used in many drugs for digestive disorders.. Hing is obtained from resinous gum produced from the roots of Ferula asafetida in Afghanistan and Iran. Centella or Hydrocotyle (Brahmin booti) is useful for brain work.
  5. Poisons: Several members of this family give acrid watery juice. It has narcotic effects in animals. Among these, the most important is conium (Hemlock). Every part of this plant especially fresh leaves and fruits contain a volatile oily alkali called conine. It is much poisonous. Its few drops can kill some small animals. It acts on nervous system. Therefore, its small doze is effective for cancerous and nervous disorders. Several

British species like Oenanthae, Cicuta and Aethusa are also poisonous. Their fleshy roots are very deadly to all kinds of livestock. These are also fatal to human.

  1. Oil: Oil is obtained from coriander (Dhania) and Centella (Brahmi). These are used as hair oil.
  2. Ornamental plants: Several plants are cultivated domestically as ornamental plants like blue lac flower or didicans (Trachymene), Angeica (Angelica), sea holly (Eryngium) and cow parsnip (Heraclaeum).

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Distribution pattern

This family is commonly known as carrot or parsely family. It is a large family. It contains about 200 genera and 2900 species. Most of its members are oily or aromatic. They are Wia:.ly distributed. They are mos.. abundant in the north temperate and sub-tropical regions. They are mostly absent from tropics.

important Species

  1. Daucus carota, Carrot (Gajar)
  2. Foeniculum vulgaris Fennel-Saul&
  3. Coriandrum sativum, Corriander-Dhania
  4. Apium graveoloens, Celery —Ajmud

TAKHITAJAN CLASSIFICATION SYSTEM



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Armen Leonovich Takhtajan or Takhtajian (June 10, 1.910 — November 13, 2009) was a Soviet-Armenian botanist. He was one of the most important figures in 20th  century plant evolution and systematics and biogeography. His interests included morphology of flowering plants, paleobotany, and the flora of the Caucasus (Russia). He was born in Shushi. Takhtajan worked at the Komarov Botanical Institute in Leningrad. He developed his 1940 classification scheme for flowering plants. This classification emphasized phylogenetic relationships between plants. His system did not become known to botanists in the West until after 1950. In the late 1950s he began a correspondence and collaboration with the prominent American botanist Arthur Cronquist. – The plant classification scheme of Cronquits was heavily influenced by his collaboration with Takhtajan and other botanists at Komarov. Takhtajan was a member of the Russian Academy of Sciences, as well as a foreign associate of the U.S. Sciences since 1971. He was also the academician of the Academy of Sciences of the Armenian SSR, the president of the Soviet All-Union Botanical Society (1973) and the International Association for Plant Taxonomy (1975). He was a member of the Finnish Academy of Science and Literature (1971), the German Academy of Naturalists “Leopoldina” (1972) and other scientific societies. He is an author of works on the origin of flowering and paleobotanics. He developed a system of higher plants. He worked on the “Flora of Armenia” (vol. 1-6, 1954-73) and “Fossil flowering plants of the USSR “(v. 1, 1974) books.

Features

I. His system is based on phylogenetic system of classification. This system has greatly influenced all recent systems of classification.

  1. His system of classification is inspired by Hans Hallier’s earlier theories.
  2. He published preliminary diagram of phylogeny of orders of Angiosperms.
  3. One of his main innovations was subdivision of both monocots and dicots into subclasses. These are widely accepted as a major advancement in angiosperm classification.
  1. Takhtajan system of classification* is synthetic, integrated and based on all available data. This data includes recent studies in embryology, cytology, genetics, comparative anatomy, photochemistry and molecular data. It is also based on cladistic analysis of many texa.
  2. The book of Armen Takhtajan, “Diversity and classification of flowering plant” includes interafamilial classification (subfamilies and tribes).
  3. Armen Takhtajan traveled extensively throughout the world. He studied floristic composition of different regions. His book, “Floristic regions of the World”, contains floristic division of whole of the world. It also listed endemic families and genera. He also provided endemic species of each region.
  4. He put forward various examples of parallelism and convergent evolution from angiospermic families. He used molecular data and available contemporary record to organism these species into their respective families.
  5. Peter Steven, one of his critic has tested the hypothesis of Takhtajan by DNA analysis and found her classification perfect.
  6. The Takhtajan system is similar to the Cronquist system. But it has greater complexity at the higher levels. He favors smaller orders and families. It allows character and evolutionary relationships to be more easily grasped.
  7. The Takhtajan classification system remains influential. It is used, for example, by the Montreal Botanical Garden. It is recognized throughout the world.
  8. Armen Takhtajan has age of more than 100 years (June 10, 1910 — November 13, 2009). It is very long life span. He spent most of life in study of plants. He interacted with many famous botanists of the world. Therefore, his classification system unique in chalacter. It is formed as result of hard work of more than 80 years.
  9. In this system the flowering plants are divided into two classes:

a)   Class Magnoliopsida (or Dicotyledons) includes 8 subclasses, 126 orders, c. 440 families, almost 10,500 genera, and no less than 195,000 species;

b)Class Liliopsida (or Monocotyledons) includes 4 subclasses, 31 orders, 120 families, more than 3,000 genera, and about 65,000 species.

. He wrote 20 books and more than 300 scientific papers, many of which were ground-breaking, from his 1943 paper Correlations of Ontogenesis and Phylogenesis in Higher Plants, in which he unveiled his theories on macroevolution as a result of changcs in developmental timing, through to his books Floristic Regions of the World and Diversity and Classification of Flowering Plants.

Taxa developed by Takhtajan

The Takhtajan system of flowering plant classification treats flowering plants as a division (phylum), Magnoliophyta,. It has two classes. These two classes are subdivided into subclasses, and then superorders, orders, and families. The two classes are:

a)    ,Magnoliopsida (dicots): It has following subclasses:

Subclass Asteridae

Subclass Caryophy I I idae

Subclass Dilleniidae

Subclass Hamamel id idae

Subclass Magnoliidae

Subclass Rosidae

b)  Liliopsida (monocots): It has following st.’Iclasses:

Subclass Alismatidae

Subclass Arecidae

Subclass Cornmelinidae

Subclass Liliidae

Subclass Zingiberidae

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Characteristics of Wood | Biology Boom



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CHARACTERISTICS OF WOOD

Wood is a I41 fibrous tissue found in many plants. It has been used for centuries ice noth fuel and as a construction material. It is composed of 2 natural composite of cellulose fibers (which are strong in tensio .) embedded in a matrix of lignin. Lignin resists compression. W md is produced as secondary xylem in the stems of trees. In a living tree it transfers water and nutrients to the leaves and other growing tissues. It has a support function, enabling woody plants to reach large sizes or to stand up for themselves.

  1. Formation

Wood is yielded by trees. A tree increases in diameter by the formation of new woody layers between the existing wood and the inner bark. It envelops the entire stem, living branches, and roots. Technically this is known as secondary growth. Secondary growth takes place by the cell division in the vascular cambium, a lateral meristem, and subsequent expansion of the new cells.

  1. Growth rings

In some areas like Pakistan, there are clear seasons. Here growth can occur in a discrete annual or seasonal pattern, leading to growth rings. These rings can be clearly seen on the end of a log. These are also visible on the other surfaces. If these seasons are annual these growth rings are called as annual rings. Where there is no seasonal difference growth rings may be indistinct or absent. In some cases, there are differences within a growth ring. Wood is divided into two types on the basis of type of growth rings:

a) Early wood or springwood: The part of a growth ring nearest

the center of the tree arc formed early in the growing season. Growth is rapid during these seasons. They are composed of wider elements. It is lighter in color than that near the outer portion of the ring. It is known 3S early wood or springwood.

h) Late wood or summer wood; The outer portion formed later in the season is then known as fir: latewood or suminerwood.

  1. Knots

A knot is a particular type of imperfection in a piece of wood. It will affect the technical properties of the wood. It makes the wood imperfect. But knots may be exploited for artistic effect. In a longitudinally sawn plank, a knot will appear as a roughly circular solid piece of wood. The grains of the rest of the wood flow around this piece of wood. Within a knot, the direction of the wood (grain direction) is up to 90 degrees different from the grain direction of the re ular wood.

1

Heartwood and sapwood

a)     Heart wood: Heartwood (or “xylem”) is wood that as a result of tylosis become more resistant to decay. Tylosis is the deposition of chemical substances (a genetically programmed process). Once heartwood formation is complete, the heartwood is dead. Some uncertainty still exists as to whether heartwood is truly dead, as it can still chemically react to decay organisms. Usually heartwood looks different; in that case it can be seen on a cross-section. Heartwood may (or may not) be much darker than living wood. It may (or may not) be sharply distinct from the sapwood. However, other processes, such as decay, can discolor wood, even in woody plants. The term heartwood derives from its position and not from any vital importance to the tree. A tree can thrive with its heart completely decayed.

b)     Sapwood: Sapwood is the younger, outermost wood. In the growing tree it is living wood. Its principal functions are to conduct water from the roots to the leaves. It also store up and give back aecording to the season the reserves prepared in the leaves. All xylem tracheids and vessels have lost their cytoplasm and the cells are therefore functionally dead in sapwood. All wood in a tree is first formed as sapwood. The more leaves a tree bears and the more vigorous its growth, the larger the volume of sapwood required. Hence trees making rapid growth in the open have thicker sapwood for their size than trees of the same species growing in dense forests. Sometimes trees grown in the open may become of considerable size, 30 cm or more in diameter, before the formation of heartwood. Some species begin to form heartwood very early in life. Therefore, they have only a thin layer of live sapwood. But in others the change comes slowly. Thin sapwood is characteristic of such species as chestnut, black locust, mulberry, osage-orange, and sassafras. But it is thick in maple, ash, hickory, hackberry, beech, and pine. Some others never form heartwood.

Wood showing annual growth rings

Hard and soft woods

There is a strong relationship between the properties of wood and the properties of the particular tree that yielded it. For every tree species there is a range of density for the wood it yields. There is a rough correlation between density of a wood and its strength (mechanical properties). For example, mahogany is a medium-dense hardwood. It is excellent for fine furniture crafting, making it useful for model building. The densest wood may be black ironwood.

It is common to classify wood as either softwood or hardwood.

a)     The wood from conifers (e.g. pine) is called softwood.

b)   The wood from dicotyledons (usually broad-leaved trees, e.g. oak) is called hardwood.

These names are a bit misleading, as hardwoods are not necessarily hard, and softwoods are not necessarily soft. The well-known balsa (a hardwood) is actually softer than any commercial softwood. Conversely, some softwood (e.g. yew) are harder than many hardwoods.

  1. Color

Some species show a distinct difference between heartwood and sapwood. In these species, natural color of heartwood is darker than that of the sapwood. Very frequently the contrast is conspicuous. This is produced by deposition of chemical substances in the heartwood. A dramatic color difference does not mean a dramatic difference in the mechanical properties of heartwood and sapwood. Some experiments on very resin( us Longleaf Pine specimens indicate an increase in strength, due to the resin. It increases the strength when wood is dry. Such resin-sat irated heartwood is called fat lighter. Structures built of fat lighter are r Dt attacked by termites. But they are very flammable. Stumps of old ilngleaf pines are often dug and split into small pieces. These are sold as kindling for fires. Stumps thus dug may actually remain a century or more since being cut. Abnormal discoloration of wood often denotes a diseased condition, indicating unsoundness. The black check in western hemlock is the result of insect attacks.

  1. Structure

Wood is a heterogeneous, hygroscopic, cellular and anisotropic material. It is composed of cells. Theircell walls are composed of micro-fibrils of cellulose (40% — 50%) and hemicelluloses (15% — 25%) impregnated with lignin (15% — 30%). The cells are mostly of one kind, tracheids. They are much more uniform in structure than that of most hardwoods. There are no vessels (“pores”) in coniferous wood such as one sees so prominently in oak and ash. The structure of hardwoods is more complex. The water conducting capability is depends on vessels. In some cases (oak, chestnut, ash) vessels are quite large and distinct. But in others (buckeye, poplar, willow) it is too small to be seen without a hand lens. Such woods are divided into two large classes, ring-porous and diffuse-porous.



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a)    Ring porous species:. In ring-porous species, the larger vessels

or pores are localized in the part of the growth ring formed in spring. Thus they form a region of more or less open and porous tissue. The rest of the ring, produced in summer, is made up of smaller vessels. It is composed of much greater proportion of wood fibers. These fiber are the elements which give strength and toughness to wood. But the vessels are a source of weakness. Such wood is present in ash, black locust, catalpa, chestnut, elm, hickory, mulberry, and oak,

b)    Diffused porous woods: In this case, the pores are evenly sized. Therefore, water conducting capability is scattered throughout the growth ring instead of being collected in a band or row. Examples of this kind of wood are basswood, birch, buckeye, maple, poplar, and willow. Intermediate groups: Some species, such as walnut and cherry, are on the border between the two classes, forming an intermediate group.

  1. Early wood and latewood in softwood

In temperate softwoods there often is a marked difference between latewood and early wood. The latewood will be denser than that .formed early in the season. When examined under a microscope the cells of dense latewood are very thick-walled. They have very small cell cavities. But those formed first in the season have thin walls and large cell cavities. The strength is in the walls, not the cavities. Thus there is greater the proportion of latewood the greater the density and strength. In choosing a piece of pine the principal thing to observe is the comparative amounts of early wood and latewood. The width of ring is not nearly so important as the proportion and nature of the latewood in the ring.

a) Early v ad and latewood in ring-porous woods: In the case of

the ring-porous hardwoods there seems to exist a pretty definite relation between the rate of growth of timber and its properties. Generally, if there is more rapid growth or the wider the rings of growth, the heavier, harder, stronger, and stiffer the wood. This, it must be remembered, applies only to ring-porous woods such as oak, ash, hickory, and others of the same group, and is, of course, subject to some exceptions and limitations.

b) Earlywood_and latewood in diffuse-porous woods: In the

diffuse-porous woods, the demarcation between rings is not always so clear. In some cases, it is almost (if not entirely) invisible to the unaided eye. Conversely, when there is a clear demarcation there may not be a noticeable difference in structure within the growth ring. In diffuse-porous woods, the vessels or pores are even-sized, so that the water conducting capability is scattered throughout the ring instead of collected in the early wood. The effect of rate of growth is, therefore, not the same as in the ring-porous woods, approaching more nearly the conditions in the conifers.

  1. Monocot wood

Some structural material roughly resembles ordinary, dicot or conifer wood. These are produced by a number of monocot plants. These also are called wood. Its example is bamboo. It is a member of the grass family. It has considerable economic importance. Large culms are widely used as a building and construction material. Another major plant group is called wood are the palms. Of much less importance are plants such as Pandanus, Dracaena and Cordyline. With all this material, the structure and composition of the structural material is quite different from ordinary wood.

10. Water content

Water occurs in living wood in three conditions, namely: I. In the cell walls

  1. In the protoplasmic contents of the cells.
  2. As free water in the cell cavities and spaces.

In heartwood it occurs only in the First and last forms. Wood that is thoroughly air-dried retains from 8-16% of water in the cell walls. The oven-dried wood also retains a small percentage of moisture. The water contents make the wood softer and more pliable. A similar effect is in the softening action of water on paper or cloth. Within certain limits, the greater the water content, the greater its softening effect.

11. Uses of wood

1. Fuel: Wood has a long history of being used as fuel. It is stills used as fuel in rural areas of the world. Hardwood is preferred er softwood because it creates less smoke and burns longer.

  1. Construction: Many buildings are made and decorated with wood. Wood is an important construction material. Wood remains in common use today in boat construction. Wood to be used for construction work is commonly known as lumber in North America. Elsewhere, lumber is called as felled trees. New domestic housing in many parts of the world today is commonly made from timber-framed construction. Engineered wood products are becoming a bigger part of the construction industry. They may be used in both residential and commercial buildings as structural and aesthetic materials. In buildings made of other materials, wood will still be found as a supporting material. It is especially used in roof construction, in interior doors and their frames, and as exterior cladding. Wood is also commonly used as shuttering material.
  1. Engineered wood: Wood used in construction includes products such as glued laminated timber (glulam), laminated veneer lumber (LVL), parallam and I-joists. These products allow the use of smaller pieces. They may also be selected for specific projects such as public swimming pools or ice rinks Wood will not deteriorate in the presence of certain chemicals. These engineered wood products are more environmentally friendly. They are sometimes cheaper, than building materials such as steel or concrete.- Wood unsuitable for construction is broken down mechanically (into fibers or chips) or chemically (into cellulose). It is used as a raw material for other building materials such as chipboard, engineered wood, hardboard, medium-density fiberboard(MDF), oriented strand board (OSB). Such wood derivatives are widely used. Wood fibers are an important component of most paper. Cellulose is used as a component of some synthetic materials. Wood derivatives can also be used for kinds of flooring, for example laminate flooring.
  1. Next generation wood products: Further developments include new lignin glue applications, recyclable food packaging, rubber tire replacement applications, anti-bacterial medical agents, and high strength fabrics or composites. As scientists and engineers further learn and develop new techniques to extract various components from wood.
  1. Furniture and utensils: Wood has always been used extensively for furniture, including chairs and beds. Also for tool handles and cutlery, such as chopsticks, toothpicks, and other utensils, like the wooden spoon.
  2. In the arts: Wood has long been used as an artistic medium. It has been used to make sculptures and carvings for millennia. Examples include the totem poles carved by North American indigenous people from conifer trunks. Certain types of musical instruments, such as those of the violin family, the guitar, the clarinet and recorder, the xylophone, and the marimba, are made mostly or entirely of wood.
  3. Sports and recreational equipment: Many types of sports equipment are made of wood, or were constructed of wood in the past. For example, cricket bats are typically made of white willow. The baseball bats are legal for use in Major League Baseball. These are frequently made of ash wood or hickory
  4. Medicine: In January 2010 Italian scientists announced that wood could be used to become a bone substitute. It is likely to take at least five years.

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SUBJECTIVE QUESTIONS OF STRUCTURE OF PLANTS PARTS



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SUBJECTIVE QUESTIONS OF STRUCTURE OF PLANTS PARTS

1.  Describe structure of root.

2.  Give secondary growth in root.

3.  Compare monocots and dicot roots

4.  Describe structure of stem.

5.  Compare monocot and dicot stems.

6.  Discuss primary growth in stem.

7.  Discuss secondary growth in stem.

8.  What is periderm? How is it formed?

9.  Describe structure of leaf.

10. What is meristem? Give its structure and forms.

11.  Discuss arrangement of meristem in shoot apex.

12.  Discuss organization in root apex.



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SHORT QUESTIONS OF STRUCTURE OF PLANT PARTS



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SHORT QUESTIONS OF STRUCTURE OF PLANT PARTS

1.  Differentiate between tap and adventitious roots.

Ans: Tap root arise from the embryo. Adventitious root develops from other mature tissues of plant like stem etc.

2.  What are root hairs? Give their functions.

Ans: A root hair starts its growth as a small papilla on the outer wall. The nucleus and cytoplasm migrate into the papilla. The papilla grows and attains maximum size. Its wall becomes rigid due to deposition of pectic substances.

3.  What is endodermis and Casparian strips?

Ans: The inner most layer of the cortex is distinct and well developed in primary roots. It is called endodermis. The cells of this layer are rectangular in outline. A band of suberin develops all around the cell in the middle of the transverse and radial walls. This suberin band is called casparian strip.

4.  What is pericycle?

Ans: The outer most part of the stele consists of one or more layers of parenchymatous cells. The outer laer of this parenchyma is called pericycle.

5.  What type of phloem are found in roots?

Ans: The phloem strands alternate with the ridge of the xylem and have the same number. In each phloem, the protophloem elements are present towards the outside and metaphloem are present towards the inner side. Phloem consists of Sieve tube elements, parenchyma and few fibers.

6.  What is root cap?

Ans: Root cap is present at the tip of the root. It protects the underlying apical meristem. Root caps also help in penetration of root in soil. Root cap also controls the geotropic response of root. Central cells of root caps in many parts form a constant stricture called columella.

7.  What is Cork cambium or phellogen?

Ans: The stress of secondary growth ruptures the whole cortex. Therefore, the cork cambium arises in the pericycle. Sometimes, new cork cambium arises in deeper layers. It sloughs off the old periderm in the form of bark. Lenticels are not produced in the,periderm of roots.

8.  What is phelloderm?

Ans: The cork cambium also produces some phelloderm (Parenchyma cells) towards the inner side. But this phelloderm is not clearly differentiated. It merges with outer part of the non-functional phloem and remaining pericycle.

9.  What are medullary rays? Give their function.

Ans: The strips of ground tissues between the adjacent vascular are called medullary rays or pith rays. Medullary rays connect the pith with cortex.

10.  Differentiate between Collateral and Bicollateral xylem.

Ans: Collateral: In this case, xylem is present towards the inner side and phloem is present towards the outer side of vascular bundle. Bicollateral: In this case, phloem is present on both side of xylem.

11.   What are Concentric bundles?

Ans:   In this case, on type of vascular tissue (xylem or phloem) completely surround the other type of tissue.

12.  Differentiate between Amphicribral and Amphivasal.

Ans:   Amphicribral: In this case, xylem is completely surrounded by phloem. These vessels are found in fruits, flowers and ovules of certain plants. Amphivasal: In this case. phloem is completely surrounded by xylem. These vessels are found in certain member of family Liliaceae.

13.  Differentiate between protophloem and metaphloem.

Ans: The phloem present towards the outside are called protophloem. The sieve tubes of protophloem are narrow and stretched. They are often non-functional. The phloem present towards the inner side is called metaphloem. They are functional.

14.  What is open type vascular bundle?

Ans: .Vascular bundles having cambium between xylem and phloem are called open type.

15.  What is vascular cambium? Give its function.

Ans:   A narrow strip of meristematic cells is present between the xylem and phloem in the vascular bundles of dicots and gymnosperms. This strip of meristematic cells is called vascular cambium. This cambium becomes active at the start of secondary growth.

16.  What is fascicular cambium?

Ans: The fascicular cambium is present between xylem and phloem tissues. The vascular cambium of the bundles is not continuous with adjacent kindles. The parenchyma cells of the medullary rays are present in between the• fascicular cambium.

17.  What are fusiform and ray initials?



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Ans: Fusiform initials: They are wedge like. They are many times longer than broad. and have narrow pointed ends. Ray initials: They are nearly isodiametric. They are found in vertical rows. The derivatives of ray initials give rise to rays.

18.  Differentiate between sap and heart woods.

Ans: Sap wood: The narrow peripheral functional part of the secondary xylem is called sap wood. Heart wood: The major central nonfunctional part forms the heart wood. The elements of heartwood undergo certain morphological changes. These changes include deposition of tannins and lignification of their walls.

19.  What are annual rings? How are they formed?

Ans:  The activity of the vascular cambium is not of uniform throughout the years in many plants. The cambium is most active during the spring. It produces wide and loosely dispersed tracheal elements. It is called spring wood. The activity of cambium slows down during the autumn. It produces narrow and closely placed tracheal elements. It forms autumn wood. This difference of spring wood and autumn wood produces annual rings.

20.  What is periderm?

Ans: The continuous secondary growth cause rupturing of the protective layer or epidermis. A secondary protective tissue is produced on the surface of the stem. This protective tissue is called periderm.

21.  What are lenticels? How are they formed?

Ans:   The phellogen produces a group of loosely placed cells at certain points. These loosely placed cells are called lenticels. They have no or slight suberization on their walls. Lenticels Vary in size from minute microscopic to clearly visible spots.

22.  Differentiate between Biracial and Isolateral leaves.

Ans:   In flattened leaves, the palisade layer is restricted to the upper side. Such leaves are called bifacial or dorsiventral. If the palisade is present on both sides of the spongy tissue, then the leaf is called isolateral.

23.  What are centric leaves?

Ans: The palisade forms a continuous ring around the spongy tissue in narrow and cylindrical leaves. Such leaves are called centric leaves.

24.  Differentiate between apical and intercalary meristems.

Ans: The meristems present at the tips of roots and shoot are called apical meristems. The meristem situated at the bases of internodes is called intercalary meristem.

25.  Differentiate between protoderm and procambium.

Ans: Protoderm: This is the surface layer. Its cells are differentiated into epidermal systems. Procambium: They are also called provascular tissues. Their cells form different parts of vascular systems at maturity.

26.  What is Lateral Meristems? Where is it present.

Ans: The cylinders of dividing cells present in the vascular and cork tissue of the plants are called lateral meristems. Lateral meristems are present in dicots and gymnosperms. Vascular and cork cambium are the example of lateral meristem.

27.  Differentiate between pericinal and anticlinal divisions.

Ans: Periclinai: In this case, cell division is parallel to the axis. these divisions are also called tangential. Anticlinal: In this case, cell division occurs at right angles to the surface.

28.  What is Histogen theory?

Ans: This theory was put forward by Hanstein. According to this theory the apical meristematic tissues are divided into three zones: Dermatogens. Periblem and Plerome.

29.  What is Tunica-Corpus theory?

Ans: This theory was given by Schmidt. Histogen theory was discarded due to lack of cytological proof. Therefore, Tunica corpus theory was put forward. According to this concept, the dividing cells in the apical meristem are arranged in two zones: Tunica, Corpus.

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MULTIPLE CHOICE QUESTIONS AND FILL IN BLANKS OF STRUCTURE OF PLANTS PARTS



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MULTIPLE CHOICE QUESTIONS AND FILL IN BLANKS OF STRUCTURE OF PLANTS PARTS

1.  Casparian strips are present in

(a) Cortex          (b) Epidermis (c) Stele                (d) Endodermis

2.  The outer most part of the stele consists of one or more layers of parenchymatous cells. The outer layer of this parenchyma is called:

(a) Cortex          (b) Epidermis ‘ (c) Stele              (d) pericycle

3.  The type of arrangement in which protoxylem lies towards the outside and metaxylem lies towards the inside is called:

(a) Mesarch       (b) Endarch        (c) exarch          (d) None

4.  The case in which xylem is present towards the inner side and phloem is present towards the outer side of vascular bundle is:

(a) Collateral      (b) Bicollateral (c) Concentric (d) Blare])

5.  The case in which one type of vascular tissue (xylem or phloem) completely surround the other type of tissue is:

(a) Collateral      (b) Bicollateral (c) Concentric (d) Diarch

6.  Endodermis is present in:

(a) Monocot       (b) Dicot            (c) Gymnosperm (d) None4

7.  Cambium is absent in:

(a) Monocot       (b) Dicot            (c) Gymnosperm (d) None

8.  The leaves in which palisade layer is restricted to the upper side is:

(a) Bifacial         (b) Isolateral      (c) Centric          (d) None

9.  The leaves in which palisade is present on both sides of the spongy tissue:

(a) Bifacial         (b) lsolateral      (c) Centric          (d) None

10.  Cortex is formed form:

(a) Plerome       (b) Dermatogen (c) Periblem       (d) None

11.  Pith is formed form:

(a) Plerome        (b) Dermatogen (c) Periblem       (d) None

12.  Root cap is present on:

(a) Primary root (b) Secondary (c) Tertiary          (d) All

13.  One or more layers of cortex below the epidermis become thick wall to form

(a) Exodermis  (b) Stele               (c) Endodermis (d) Pith

plant-parts

 

14.  Casparian strips have compound:

(a) Cellulose      (b) Lignin           (b) Subrin          (d) Cutin

15.  The outer layer of this parenchyma is called:

(a) pericycle       (b) Endodermis (c) Stele             (d) None

16.  A parenchymatous sheet of tissues separates the phloem strands from xylem and it becomes:

(a) Pericycle       (b) Endodermis (c) Stele             (d) Cambium

17.  The cells of root caps in many parts form a constant structure called:

(a) Stele            (b) Strip             (e) Medulla        (d) columella

18.  The number of xylem or phloem bundles in monocot is from:

(a) 12 to 20       (b) 15 to 20       (c) 17 to 20       (d) 12 to 30

19.  The number of protoxylem or phloem bundles in dicot is from:

(a) 2 to 9           (b) I to 5           (c) 2 to 5           (d) 2 to 8

20.  Which is incorrect for monocot root?

(a) The pericycle gives rise to lateral roots. (b) Cambium is absent.

(c)     The pith is present.

(d)    Secondary growth does not occur

21.  Pith is composed of:

(a) Collenchyma (b) Parenchyma (c) Sclerenchyma (d) None

22.  Which is correct for dicot root?

(a)    Vascular bundles are scattered irregularly in ground tissues.

(b)    The vascular bundles are open.

(c)     Cambium is absent.

(d)    There is no hard bast.

23.  Secondary growth includes the formation of secondary vascular tissues and:

(a) periderm       (b) Plerume       (c) Epidermis (d) Cortex



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24.  Suberization occurs in:

(a) Cortex          (b) Cork             (c) Xylem           (d) Phloem

25.  The walls of epidermal cells of leaves of the xerophytic plants undergo:

(a) Suberization (b) lignification (c) Cutinization  (d) None

Answers:
1. (d)  2. (d)  3. (c)  4. (a)  5. (c)  6. (b)  7. (a)  8. (a)
  9. (b)  10. (c)  11. (a)  12. (a)  13. (a)  14. (b)  15. (a)  16. (d) 17. (d)  18. (a)  19. (c)  20. (a)  21. (b)  22. (b)  23. (a)  24. (b)  25. (b)

 

Fill in blanks:

1.  The inner most layer of the cortex is distinct and well developed
in primary roots. It is called______

2.  A band of suberin develops all around the cell in the middle of the transverse and radial walls. This suberin band is called
________ strip.

3.  The outer most part of the stele consists of one or more layers of parenchymatous cells. The outer layer of this parenchyma is
called ________

4.  In case _____ xylem is present towards the inner side and phloem is present towards the outer side of vascular bundle.

5.  In case_________ , phloem is present on both side of xylem.

6.   In case of__________ bundles, on type of vascular tissue (xylem or phloem) completely surround the other type of tissue.

7.  Vascular bundles having cambium between xylem and phloem are called _______ type.

8.  A narrow strip of meristematic cells is present between the xylem and phloem in the vascular bundles of dicots and gymnosperms. This strip of meristematic cells is called vascular………..

9.  The phellogen produces a group of loosely placed cells at certain points. These loosely placed cells are called ____

10.  The tissues in which the cells are undifferentiated and capable of division are called ______

11.  The meristems present at the tips of roots and shoot are called _____ meristems.

12.  The meristem situated at the bases of intemodes is called ______ meristem.                                                       •

13.  One or More layers of cortex below the epidermis become thick wall to form_______

14.  The outer layer of this parenchynfa is called ____

15.  Cells of root caps in many parts form a constant structure called…………..

16.  The number of xylem or phloem bundles in monocot is 12 to 20.

17.  Secondary growth includes the formation of secondary vascular
tissues and ________

18.  The walls of epidermal cells of leaves of the xerophytic plantsundergo……………

 

Answer:
I. endodermis    2. casparian    3 pericycle
4. Collateral     5. Bicollateral    6. Concentric
7. open     8. cambium    9. lenticels
10. meristem     11. apical    12. intercalary
13. exodermis     14. pericycle    15. columella
16. periderm     17. lignification
 

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