6

Q1. Companion cells are closely associated with

• Sieve elements
• Vessel elements
• Trichomes
• Guard cells

Solution

Companion cells and sieve cells are derived from the same mother cell, and hence, they are in close association with each other. Sieve elements and companion cells are associated with each other through plasmodesmata.

Q2. Which of the following contributes the most to water conduction in plants?

• Sieve tubes
• Xylem vessels
• Trachea
• Sieve cells

Solution

Xylem vessels are xylem elements. Xylem is a complex permanent tissue which is responsible for the transportation of water and minerals from the roots to different parts of the plant.

Q3. Jute fibres are obtained from the  

• Secondary phloem  
• Pith  
• Xylem  
• Endodermis  

Solution

The phloem fibres of jute are of commercial importance. Phloem fibres, the phloem element, are generally absent in the primary phloem but present in the secondary phloem.  

Q4. The monocot stem lacks

• Tracheids
• Sieve tube
• Cambium
• None of the above

Solution

In a monocot stem, the cambium is absent; hence, the vascular bundles are known as closed type because they do not show any secondary growth.

Q5. Match the following and choose the correct option from below:           A. Meristem      (i) Photosynthesis, Storage     B. Parenchyma      (ii) Mechanical support     C. Collenchyma       (iii) Actively dividing cells     D. Sclerenchyma      (iv) Stomata     E. Epidermal tissue     (v) Sclereids        

• A-i, B-iii, C-v, D-ii, E-iv  
• A-iii, B-i, C-ii, D-v, E-iv  
• A-ii, B-iv, C-v, D-i, E-iii  
• A-v, B-iv, c-iii, D-ii, E-i  

Solution

      A. Meristem      (iii) Actively dividing cells (Meristems are responsible for the primary growth of plants.)     B. Parenchyma      (i) Photosynthesis, Storage (It is a simple permanent tissue consisting of chloroplasts.)     C. Collenchyma       (ii) Mechanical support (It is a simple permanent tissue which provides mechanical support to young parts which are growing.)     D. Sclerenchyma      (v) Sclereids (It is a form in which some sclerenchyma tissues are found. Sclereids are spherical, oval, cylindrical and highly thickened with narrow cavities. They are found in the fruit walls of nuts and pulps of guava and pear.)     E. Epidermal tissue     (iv) Stomata (They are present in the epidermal layer of leaves. They help plants in gas exchange and transpiration.)        

Q6. A conjoint and open vascular bundle will be observed in the transverse section of

• Monocot root
• Monocot stem
• Dicot root
• Dicot stem

Solution

In a dicot stem, the cambium is present between the xylem and phloem. It is termed the open vascular bundle. Also, the xylem and phloem are situated at the same radius within the bundle, and hence, it is conjoint.

Q7. The common bottle cork is a product of  

• Dermatogen  
• Phellogen  
• Xylem  
• Vascular cambium  

Solution

Cells of phellogen consist of deposits of suberin. Suberin is a water impervious, buoyant and fire-resistant substance which makes the phellogen a perfect commercial substance for making the common bottle cork.  

Q8. For union between stock and scion in grafting, which one is the first to occur?

• Formation of callus
• production of plasmodesmata
• differentiation of new vascular tissues
• regeneration of cortex and epidermis

Solution

The union of scion and stock leads to irregular, unorganized and undifferentiated mass of actively dividing cells known as callus

Q9. As the secondary growth proceeds in a tree, thickness of

• heartwood increases
• sapwood increases
• both increase
• both remain the same

Solution

As a result of continuous secondary growth, the older part of secondary xylem becomes non-functional. The function of secondary xylem is continuous by sapwood or alburnum. With addition of new outer rings of secondary xylem, more rings of sapwood changes into heartwood. So, the heartwood increases in diameter year after year but the sapwood remains in same thickness

Q10. A meristematic region present between the xylem and the phloem of open vascular bundles is called  

• Medullary ray  
• Pericycle  
• Pith  
• Intrafascicular cambium  

Solution

In a dicot root, the meristematic region present between the xylem and the phloem of open vascular bundles is called the intrafascicular cambium.  

Q11. Which of the following is nucleated?  

• Vessel  
• Sieve cell  
• Tracheid  
• Companion cell  

Solution

Companion cells are specialised parenchymatous cells.     They help in maintaining the pressure gradient in the sieve tubes.     Nuclei of the companion cells control the function the sieve tubes.  

Q12. Vascular cambium produces

• primary xylem and primary phloem
• secndary xylem and secondary phloem
• primary xylem and secondary phloem
• secondary xylem and primary phloem

Solution

Cells of vascular cambium produces secondary phloem on the outside and secondary xylem on the inner side. Youngest xylem layer occur inner to vascular cambium  while oldest layer of secondary xylem is found outside the primary xylem or towards pith. In phloem, youngest layer of secondary phloem lies outside the vascular cambium while oldest layer is towards outside, inner to primary phloem.

Q13. In land plants, the guard cells differ from other epidermal cells in having  

• Cytoskeleton  
• Mitochondria  
• Endoplasmic reticulum  
• Chloroplasts  

Solution

In terrestrial plants, the epidermal cells are meant for protection. Guard cells contain chloroplasts. Hence, apart from the regulation of the opening and closing of stomata, they also carry out the process of photosynthesis.  

Q14. Grafting is successful in dicots but not in monocots because the dicots have

• Vascular bundles arranged in a ring
• Cambium for secondary growth
• Vessels with elements arranged end to end
• Cork cambium

Solution

The cambium possesses the ability to form secondary xylem and phloem. It is present in dicots and absent in monocots. In case of grafting, it is very important that the plant should form primary and secondary tissue for its survival. Hence, grafting is successful in dicots.

Q15. The opening in the core tissue which permits the exchange of gas between the atmosphere and the internal tissue is called

• Complementary tissue
• Periderm
• Lenticel
• Bark

Solution

The phellogen cuts off closely arranged parenchymatous cells on the outer side of cork cells. These parenchymatous cells rupture forming lenticels. Lenticels permit the exchange of gases between the outer atmosphere and the internal tissue of the stem.

Q16. In an annual ring, the light-coloured part is known as  

• Early wood  
• Late wood  
• Heart wood  
• Sap wood  

Solution

In an annual ring, the light-coloured part is known as early wood or spring wood. It is formed when the cambium is active. It consists of more number of xylary elements with wider cavities. This wood is lighter in colour with low densities.  

Q17. Casparian thickenings are found in the cells of

• Pericycle of the root
• Endodermis of the root
• Pericycle of the stem
• Endodermis of the stem

Solution

In a dicotyledonous root, the endodermal cells consist of a water-impermeable, waxy material called suberin in the form of casparian strips. A Casparian strip is a band of cell wall material deposited radially and tangentially in endodermal cells.

Q18. Ground tissues include

• All tissues external to the endodermis
• All tissues except the epidermis and vascular bundles
• Epidermis and cortex
• All tissues internal to endodermis

Solution

Ground tissues include all tissues except epidermis and vascular bundles.

Q19. In a woody dicotyledonous tree, which of the following parts will mainly consist of primary tissues?

• Stem and root
• All parts
• Shoot tips and root tips
• Flowers, fruits and leaves

Solution

Meristematic tissue is responsible for the increase in length of the plant and the formation of primary tissues. The apical meristem is present at shoot tips and root tips. In a woody dicotyledonous plant, the growth involves an increase in the length of stems, their girth and formation of new leaves.

Q20. Consider the following statements     1. In a dicot root, the vascular bundles are collateral and endarch.     2. The innermost layer of the cortex in a dicot root is the endodermis.     3. In a dicot root, the phloem masses separated from the xylem by parenchymatous cells are known as the conjunctive tissue.     Which of the statements given above are true?  

• (a) is true, but (b) and (c) are false.  
• (b) is true, but (a) and (c) are false.  
• (a) is false, but (b) and (c) are true.  
• (c) is false, but (a) and (c) are true.  
• (c) is true, but (a) and (b) are false.  

Solution

1. In a dicot root, the vascular bundles are open and endarch.     2. The innermost layer of the cortex in a dicot root is the endodermis.     3. In a dicot root, the phloem masses separated from the xylem by parenchymatous cells are known as the conjunctive tissue.   

Q21. Phellogen and phellem respectively denote

• Cork and cork cambium
• Cork cambium and cork
• Secondary cortex and cork
• Cork and secondary cortex

Solution

Phellogen and phellem denote cork cambium and cork, respectively. The phellem develops from the phellogen.

Q22. The cork cambium, cork and secondary cortex are collectively called

• Phelloderm
• Phellogen
• Periderm
• Phellem

Solution

The cork cambium, cork and secondary cortex are collectively called periderm.

Q23. Identify the tissue system from among the following:

• Parenchyma
• Xylem
• Epidermis
• Phloem

Solution

The epidermis is the tissue which is the outermost covering of the plant body. The cells are elongated and compactly arranged and form a continuous layer. The cells are parenchymatous with a small amount of cytoplasm and a large vacuole.

Q24. How does a dicot leaf differ anatomically from a monocot leaf?

• Parallel venation
• Differentiation of palisade and spongy parenchyma
• Stomata only on the upper side
• Stomata on both sides

Solution

In a dicot stem, the mesophyll layer is differentiated into the palisade parenchyma and spongy parenchyma. In monocots, there is no such differentiation.

Q25. A bi-collateral vascular bundle is characterized by

• phloem being sandwitched between xylem
• transverse splitting of vascular bundle
• longitudinal splitting of vascular bundle
• xylem being sandwitched between phloem

Solution

Bi-collateral vascular bundles are conjoint bundles having phloem both on the outer and inner side of xylem. Example- Cucurbita

Q26. In a dicotyledonous stem, the sequence of tissues from the outside to the inside is  

• Phellem - Pericycle - Endodermis - Phloem  
• Phellem - Phloem - Endodermis - Pericycle  
• Phellem - Endodermis - Pericycle - Phloem  
• Pericycle - Phellem - Endodermis - Phloem  

Solution

Phellem - Endodermis - Pericycle - Phloem     From the periphery to the pith of the cell, because the phellem is formed due to the activity of the cork cambium located in the cortex outside the endodermis. The pericycle is the layer present on the inner side of the endodermis. The phloem is located in vascular bundles on the inner side of the pericycle.  

Q27. Which one of the following statements pertaining to a plant structure is correct?  

• Cork lacks stomata, but lenticels carry out transpiration.  
• Passage cells help in the transfer of food from the cortex to the phloem.  
• Sieve tube elements possess cytoplasm but no nuclei.  
• The shoot apical meristem has a quiescent centre.  

Solution

Sieve tube elements are the phloem elements. They are long tube-like structures arranged longitudinally. They are in association with the companion cells. The end walls are perforated in a sieve manner to from sieve plates.     Each cell lacks a nucleus, but it has a large vacuole and the peripheral cytoplasm.  

Q28. Abnormal secondary growth occurs in

• Dracaena
• ginger
• wheat
• sunflower

Solution

In Dracaena, large secondary growth in thickness occurs that begins with formation of secondary meristematic tissue

Q29. Radial conduction of water takes place by  

• Vessels  
• Vessels and tracheids  
• Phloem  
• Ray parenchyma cells  

Solution

Ray parenchyma cells are the cells of xylem parenchyma. They are present in wood rays and transport water laterally within the stem.  

Q30. Cells of this tissue are living and show angular wall thickening. They also provide mechanical support. The tissue is

• Xylem
• Sclerenchyma
• Collenchyma
• Epidermis

Solution

Collenchyma is a simple permanent tissue. The cells are thickened at the corners due to the deposition of cellulose, hemicelluloses and pectin. It provides mechanical support to the young growing parts of the plant.

Q31. Some vascular bundles are described as open because these  

• Are surrounded by pericycle but not endodermis  
• Are capable of producing secondary xylem and phloem  
• Possess conjunctive tissue between xylem and phloem  
• Are not surrounded  

Solution

In open vascular bundles, the cambium which is present between the xylem and phloem possesses the capacity to produce the secondary xylem and phloem.  

Q32. At maturity, which of the following is non-nucleated?  

• Palisade cell  
• Sieve cell  
• Companion cell  
• Cortical cell  

Solution

Sieve cells which are found in sieve tube elements of the phloem lack a nucleus when they mature. However, nuclei are present in young cells.  

Q33. Cork tissue arises from  

• Periderm  
• Phellogen  
• Phelloderm  
• Phellem  

Solution

When the stem continues to grow in girth, the outer cortical and epidermal cells need to be replaced. Hence, the meristematic tissue called phellogen develops in the cortical region. The cells of the outer region of the phellogen develop into cork, while the cells of the inner region develop into phellem.  

Q34. In grasses, certain adaxial epidermal cells along the veins modify themselves into large empty, colourless cells called  

• Bulliform cells  
• Companion cells  
• Guard cells  
• Subsidiary cells  
• Albuminous cells  

Solution

In grasses, certain adaxial epidermal cells along the veins modify themselves into large empty, colourless cells called bulliform cells. These cells are responsible for the curling of leaf surfaces in grass.  

Q35. The waxy material deposited in the casparian strip of the endosperm is

• Pectin
• Suberin
• Cellulose
• Lignin
• Hemicellulose

Solution

Suberin is a water-impermeable waxy material which deposits in the cell walls of the endodermal cells.

Q36. Periderm is produced from

• Cork cambium
• Pro-cambium
• Secondary cortex
• Vascular cambium

Solution

The cork cambium is a meristematic tissue which develops to replace the outer cortical and epidermal cells. Its outer cells differentiate into the phellem and the inner cells differentiate into the phelloderm. The cork cambium along with the phellem and phelloderm is called the periderm.

Q37. Match the following and choose the correct option from below:     A. Cuticle     (i) Guard cells     B. Bulliform cells     (ii) Single layer     C. Stomata     (iii) Waxy layer     D. Epidermis     (iv) Empty colourless cells        

• A-iii, B-iv, C-i, D-ii  
• A-i, B-ii, C-iii, D-iv  
• A-iii, B-ii, C-iv, D-i  
• A-iii, B-ii, C-i, D-iv  

Solution

A. Cuticle     (iii) Waxy layer (Present on the epidermal layer in leaves.)     B. Bulliform cells     (iv) Empty colourless cells (They are adaxial epidermal cells found in grasses.)     C. Stomata     (i) Guard cells (Two bean-shaped guard cells are present on either side of the stoma and they control the opening and closing of stoma.)     D. Epidermis     (ii) Single layer (The epidermis forms the outermost covering of the plant body; it is usually single layered.)        

Q38. Closed vascular bundles lack

• Ground tissue
• Conjunctive tissue
• Cambium
• Pith

Solution

In case of a closed vascular system, the cambium is absent between the xylem and phloem.

Q39. Which of the following is true?  

• Vessels are unicellular and with narrow lumen.  
• Vessels are multicellular and with wide lumen.  
• Tracheids are unicellular and with wide lumen.  
• Tracheids are multicellular and with narrow lumen.  

Solution

Vessels are xylem elements. Each xylem vessel is made of many cells called vessel chambers. Because the vessels are devoid of protoplasm, they have a wide lumen.  

Q40. Intercalary meristem leads in

• Secondary growth
• Primary growth
• Apical growth
• Secondary thickening
• Secondary over growth

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