Palm is a monocotyledonous plant, yet it increases in girth. Why and how?
Increase in diameter of the stem inpalm is accomplished by primary thickening meristem. This meristem originates below
the region of attachment of the young leaf primordia by periclinal divisions of the cells.In longitudinal section, it appears in the formof a flat or concave zone of several layersof rectangular cells oriented parallel to thesurface of the stem. At first the young stem , increases mainly in width by the activity of theprimary thickening meristem but in later stagesit is also responsible for the increase in height of the young stem. In some palms expansion of the ground tissue continues in the older part of the stem where parenchyma cells undergo division and cell expansion and the intercellular spaces, also increase in size. This type of growth is called diffused secondary growth.
Trunks of some of the aged tree species appear to be composed of several fused trunks. Is it a physiological or anatomical abnormality? Explain in detail.
Arrange the following in the sequence you would find them in a plant starting from the periphery—phellem, phellogen, phelloderm.
Cork cambium forms tissues that form the cork. Do you agree with this statement? Explain.
The lawn grass (Cyandon dactylon) needs to be mowed frequently to prevent its overgrowth. Which tissue is responsible for its rapid growth?
Arrange the following in the sequence you would find them in a plant starting from the periphery – phellem, phellogen, phelloderm.
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 |
Options:
(a) A—(i), B—(iii), C—(v), D—(ii), E—(iv)
(b) A—(iii), B—(i), C—(ii), D—(v), E—(iv)
(c) A—(ii), B—(iv), C—(v), D—(i), E—(iii)
(d) A—(v), B—(iv), C—(iii), D—(ii), E—(i)
While eating peach or pear it is usually seen that some stone like structures get entangled in the teeth, what are these stone like structures called?
Trunks of some of the aged tree species appear to be composed of several fused trunks. Is it a physiological or anatomical abnormality? Explain in detail.
Protoxylem is the first formed xylem. If the protoxylem lies next to phloem what kind of arrangement of xylem would you call it?
Plants require water for their survival. But when watered excessively, plants die. Discuss.
What is present on the surface of the leaves which helps the plant prevent loss of water but is absent in roots?
Below is a list of plant fibres. From which part of the plant these are obtained?
(a) Coir
(b) Hemp
(c) Cotton
(d) Jute
The transverse section of a plant material shows the following anatomical features – (a) the vascular bundles are conjoint, scattered and surrounded by a sclerenchymatous bundle sheath, (b) phloem parenchyma is absent. What will you identify it as?
Each of the following terms has some anatomical significance. What do these terms mean? Explain with the help of line diagrams.
a. Plasmadesmoses/Plasmodesmata
b. Middle lamella
c. Secondary wall
The cross-section of a plant material showed the following features when viewed under the microscope.
a. The vascular bundles were radially arranged.
b. Four xylem strands with exarch condition of protoxylem.
To which organ should it be assigned?
The cross-section of a plant material showed the following features when viewed under the microscope.
(a) The vascular bundles were radially arranged.
(b) Four xylem strands with exarch condition of protoxylem.
To which organ should it be assigned?
Plants require waterfortheir survival. But when watered excessively, plants die. Discuss.
What part of the plant would show the following?
a. Radial vascular bundle
b. Polyarch xylem
c. Well developed pith
The lawn grass (Cynodon dactylon) needs to be mowed frequently to prevent its overgrowth. Which tissue is responsible for its rapid growth?
Cut a transverse section of young stem of a plant from your school garden and observe it under the microscope. How would you ascertain whether it is a monocot stem or a dicot stem ? Give reasons.
Epidermal cells are often modified to perform specialised functions in plants. Name some of them and function they perform.
Distinguish between the following:
(a) Exarch and endarch condition of protoxylem
(b) Stele and vascular bundle
(c) Protoxylem and metaxylem
(d) Interfasicular cambium and intrafasicular cambium
(e) Open and closed vascular bundles
(f) Stem hair and root hair. .
While eating peach or pear it is usually seen that some stone like structures get entangled in the teeth, what are these stone like structures called?
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 cell |
Options:
(a) A—(iii), B—(iv), C—(i), D—(ii)
(b) A—(i), B—(ii), C—(iii), D—(iv)
(c) A—(iii), B—(ii), C—(iv), D—(i)
(d) A—(iii), B—(ii), C—(i), D—(iv)
Below is a list of plant fibres. From which part of the plant these are obtained
a. Coir b. Hemp
c. Cotton d. Jute
Epidermal cells are often modified to perform specialized functions in plants. Name some of them and function they perform.
Product of photosynthesis is transported from the leaves to various parts of the plants and stored in some cell before being utilised. What are the cells/ tissues that store them?
Protoxylem is the first formed xylem. If the protoxylem lies next to phloem what kind of arrangement of xylem would you call it?
Trunks of some of the aged tree species appear to be composed of several fused trunks. Is it a physiological or anatomical abnormality? Explain in detail.
Explain the process of secondary growth in the stems of woody angiosperms with the help of schematic diagrams. What is its significance?