I: | Intercalary meristem is a primary meristem and contributes to the formation of the primary plant body. |
II: | Cork cambium is a lateral meristem and produces secondary tissues. |
1. | Only I is correct |
2. | Only II is correct |
3. | Both I and II are correct |
4. | Both I and II are incorrect |
1. | Heart wood does not conduct water but it gives mechanical support to the stem. |
2. | Autumn wood or late wood has a large number of xylary elements having vessels with wider cavities. |
3. | Phloem fibers are generally absent in the primary phloem |
4. | Gymnosperms lack sieve tubes and companion cells |
1. | Phloem parenchyma is absent in most of the dicotyledons |
2. | Vessels are the characteristic feature of gymnosperms |
3. | The radial conduction of water takes place by the ray parenchymatous cells |
4. | The first formed phloem consists of bigger sieve tubes and is referred to as protophloem |
1. | They help in absorption of water and minerals. |
2. | They help in preventing water loss due to transpiration. |
3. | They help in transpiration of water, the biological process by which water is lost in the form of water vapour from the aerial parts of the plants. |
4. | They allow interchange of gases between the internal tissue and the atmosphere. |
1. | Secondary growth does not occur in monocotyledons |
2. | The cells of secondary cortex are parenchymatous |
3. | Bark refers to all the tissues exterior to the vascular cambium, therefore it does not include secondary phloem |
4. | In the dicot root, the vascular cambium originates from the tissue located just below the phloem bundles, a portion of pericycle tissue, above the protoxylem forming a complete and continuous wavy ring, which later becomes circular |
1. | A - Adaxial epidermis | 2. | B - Phloem |
3. | C - Mesophyll | 4. | D - Abaxial epidermis |
a. | In roots, xylem and phloem in a vascular bundle are arranged in an alternate manner along the different radii. |
b. | Conjoint closed vascular bundles do not possess cambium. |
c. | In open vascular bundles, cambium is present in between xylem and phloem. |
d. | The vascular bundles of dicotyledonous stem possess endarch protoxylem. |
e. | In monocotyledonous root, usually there are more than six xylem bundles present. |
In old trees the greater part of secondary xylem is dark brown and resistant to insect attack due to :
a. | secretion of secondary metabolites and their deposition in the lumen of vessels. |
b. | deposition of organic compounds like tannins and resins in the central layers of stem. |
c. | deposition of suberin and aromatic substances in the outer layer of stem. |
d. | deposition of tannins, gum, resin and aromatic substances in the peripheral layers of stem. |
e. | presence of parenchyma cells, functionally active xylem elements and essential oils. |
Choose the correct answer from the options given below
1. (b) and (d) Only
2. (a) and (b) Only
3. (c) and (d) Only
4. (d) and (e) Only