Why are xylem and phloem called complex tissues?
A group of different types of cells which perform common function is called complex tissue. Xylem and phloem are called complex tissues as all cells that work as a unit for a common function have different structural organisation. Xylem has four types of cells-tracheids, vessels, xylem parenchyma and xylem fibres. Phloem consists of sieve tube elements, companion cells, phloem parenchyma and phloem fibres. Xylem is associated with conduction of water and minerals from roots to top of plants and phloem is responsible for transport of organic food.
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.
Arrange the following in the sequence you would find them in a plant starting from the periphery – phellem, phellogen, phelloderm.
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.
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?
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.
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)
The lawn grass (Cyandon dactylon) needs to be mowed frequently to prevent its overgrowth. Which tissue is responsible for its rapid growth?
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?
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?
What is present on the surface of the leaves which helps the plant prevent loss of water but is absent in roots?
Epidermal cells are often modified to perform specialised functions in plants. Name some of them and function they perform.
Deciduous plants shed their leaves during hot summer or in autumn. This process of shedding of leaves is called abscission. Apart from physiological changes what anatomical mechanism is involved in the abscission of leaves.
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)
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?
Write the precise function of:
a. Sieve tube
b. Interfasicular cambium
c. Collenchyma
d. Aerenchyma
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
Assume that a pencil box held in your hand, represents a plant cell. In how many possible planes can it be cut? Indicate these cuts with the help of line drawings.
A transverse section of the trunk of a tree shows concentric rings which are known as growth rings. How are these rings formed? What is the significance of these rings?
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?
Which part of the plant would show the following:
(a) Radial vascular bundle
(b) Polyarch xylem
(c) Well developed pith
Plants require waterfortheir survival. But when watered excessively, plants die. Discuss.
Write the precise function of
(a) Sieve tube
(b) Interfascicular cambium
(c) Collenchyma
(d) Aerenchyma
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?
What part of the plant would show the following?
a. Radial vascular bundle
b. Polyarch xylem
c. Well developed pith
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?
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.