Biology Class 11 NCERT Solutions: Chapter 5 Morphology of Flowering Plants Part 2 (For CBSE, ICSE, IAS, NET, NRA 2022)
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Q: 6. Differentiate between
(A) Racemose and cymose inflorescence
(B) Fibrous roots and adventitious roots
(C) Apocarpous and syncarpous ovary
Answer:
| Racemose Inflorescence | Cymose Inflorescence | ||
| (1) | Younger flowers are present at the tip while older flowers are arranged at the base of this inflorescence. Such an arrangement is called acropetal succession. | (1) | Younger flowers are present at the base of the inflorescence, while older flowers are present at the top. Such an arrangement is called basipetal succession. |
| (2) | The main axis in Racemose inflorescence continues to grow and produce flowers laterally. | (2) | The main axis in cymose inflorescence has limited growth, which later terminates into a flower. |
| (3) |  | (3) |  |
| Fibrous Root | Adventitious Root | ||
| (1) | In monocots, the primary root, which develops from the radicle of the seed, is short-lived and is replaced by a large number of roots arising from the base of the stem. | (1) | These roots arise from any part of the plant other than the radicle of seeds. |
| (2) | It is found in wheat and other cereals. | (2) | It is found in banyan, Monstera, and other plants. |
| (3) |  | (3) |  |
| Apocarpous Ovary | Syncarpous Ovary | ||
| (1) | The Flowers with Apocarpous Ovary have more than one carpel. These Carpels are free | (1) | The flowers with syncarpous ovary have more than one carpel. However, these carpels are fused |
| (2) | It is found in lotus and rose flowers. | (2) | It is found in the flowers of tomato and mustard. |
| (3) |  | (3) |  |
Q: 7. Draw the labelled diagram of the following:
(i) Gram seed
(ii) V. S. of maize seed
Answer:
(i) Gram seed
(ii) V. S. of maize seed
Q: 8. Describe modifications of stem with suitable examples
Answer:
Stems of various plants have undergone modifications to perform different functions.
Underground stems or storage stems:
Examples: Rhizomes, Corms, tubers
In ginger and banana, the underground stem is called a rhizome. The underground stem in Colocasia (arbi) is known as corm. Rhizomes and corms are underground stems, modified for the storage of food. Also, these stems help in vegetative reproduction of these plants. The tips of the underground stem in potato plants become swollen due to the accumulation of food. The potato is a tuber that helps in the storage of food and bears eyes on it. Subtended by a leaf scar, these eyes bear buds that give rise to new plants.
Supportive stems
Example: tendril
The stem in some weak plants bear thin, slender, and spirally-coiled structures called tendrils that help the plant get attached to nearby structures for support. Tendrils are found in cucumbers, melons, and other members of the family Cucurbitaceous.
Protective stems
Example: Thorns
The stem in bougainvillea and citrus plants (like lemon and orange) bear sharp, pointed structures called thorns, which provide protection to the plant from herbivores.
Photosynthetic stems
Example: Opuntia
The stem in the Opuntia is green. It carries out the process of photosynthesis in the absence of leaves.
Others stem modifications
In some plants, underground stems such as grasses spread in the soil and help in perenation. These stems are called runners.
The short lateral stem called the offset in some aquatic plants (such as Eichhornia) bears leaves and tufts of roots at the node and gives rise to new plants.