Tiêu đề Ex-3 Morphology of Flowering Plants.pdf ✅

MORPHOLOGY OF FLOWERING PLANTS 99 Ans. (c) Sol. The upward growth of the parts of plants away from the force of gravity i.e., against the gravitational force is called negative geotropism. This is observed in the roots of Rhizophora. The unequal distribution of auxin (a class of plant hormones present in stems, buds, and root tips of the plant) is the cause of geotropism. Modifications of stem 6. Axillary tendrils are found in (a) Cucumber (b) Pumpkins (c) Watermelon (d) All of these Ans. (d) Sol. Cucumber, pumpkins, and watermelon have a very weak aerial stem, so their aerial stem is modified into tendrils. They are thread-like sensitive structures that can coil around support and help the plant in climbing. 7. A lateral branch with short internodes and each node bearing a rosette of leaves and a tuft of roots is found in (a) Pistia and Chrysanthemum (b) Eichhornia and Citrus (c) Pistia and Eichhornia (d) None of the above Ans. (c) Sol. Pistia and Eichhornia are both aquatic plants. An interesting modification of stems is found in these plants, namely offset. This modification shows a lateral branch with short internodes and each node bearing a rosette of leaves and a tuft of roots. The function of this offset (modification of stem) is to form the plant species by propagation. 8. Match the column I and II, and choose the correct combination from the options given. Column I Column II a. Colocasia 1. Flattened stem b. Watermelon 2. Stem thorn c. Opuntia 3. Storage stem d. Euphorbia 4. Stem tendril e. Bougainvillea 5. Fleshy cylindrical stem (a) a-3, b-4, c-5, d-1, e-2 (b) a-3, b-2, c-1, d-5, e-4 (c) a-4, b-2, c-5, d-1, e-3 (d) a-3, b-4, c-1, d-5, e-2 Ans. (d) Sol. -Colocasia is the modified underground stem because they reproduce through tubers that store food in the form of starch. -Watermelon have modified axillary buds that form thin, leafless, and spirally coiled branches and it helps the weak plant stem to climb the support referred to as stem tendrils. -Opuntia and Euphorbia have a weak stem so it is modified into phylloclade which is flat (Opuntia), fleshy (Euphorbia), cylindrical, and green colored that helps in photosynthesis. -Bougainvillea develops stem thorns as the axillary buds do not grow normally and develop into a hard structure called thorns. 9. Vegetative propagation in mint occurs by (a) runner (b) offset (c) rhizome (d) sucker Ans. (d) Sol. Sucker is a non- green slender stem branch which arises from the underground base of erect shoots or crowns. It is a mode of vegetative propagation. The leaf 10. A simple leaf can be differentiated from the pinnae of a compound leaf on the basis of presence or absence of (a) number of pinnae (b) shape of lamina (c) axillary bud (d) lateral buds Ans. (c) Sol. The axillary bud is an embryonic shoot located in the axil of a leaf. A simple leaf can be differentiated from the pinnae of a compound leaf on the basis of presence or absence of axillary bud. The leaflets resemble leaves in having a base, stalk, and blade, but they do not have axillary buds and stipules. 11. Which of the following is an incorrect statement? (a) Palmately compound leaves resemble fingers of a palm (b) All leaflets of palmately compound leaves are attached to a common point (c) Neem leaves have a continuous lamina (d) Silk cotton leaf is classified as a palmately compound leaf Ans. (c) Sol. Leaves may be simple or compound. In simple leaves, the lamina (leaf blade), lamina is entire or when incised, the incisions do not touch the midrib. When the incisions of the lamina reach up to the midrib breaking it into a number of leaflets, the leaf is called compound. In neem, lamina is not continuous, it has a pinnately compound leaf.