Marginal placentation, in which the ovules are borne along the fused margin of a single carpel, is found in
- A.Tomato
- B.Pea
- C.Mustard
- D.Sunflower
Correct answer
Explanation
The correct answer is B, the pea. The pea's ovary is made of one carpel whose two margins fuse to form a ridge, and the ovules are arranged in two rows along that ridge; this is marginal placentation, and it is why the pod opens to show a single row of seeds on each side. A is wrong because the tomato, like the lemon and China rose, shows axile placentation, in which a multicarpellary ovary is divided into chambers by septa and the ovules are borne on a central axis. C is wrong because mustard, like Argemone, shows parietal placentation, where the ovules develop on the inner wall of the ovary, which a false septum later divides into two chambers. D is wrong because the sunflower and marigold show basal placentation, with a single ovule at the base of the ovary.
Read the full article: Morphology of Flowering Plants: Root, Stem and Flower
Practice Questions
View allWhich of the following plants can survive in extremely saline conditions?
- A.Epiphytes
- B.Halophytes
- C.Xerophytes
- D.Hydrophytes
Show answer
Halophytes are plants of saline soils, chiefly the mangroves of tidal creeks and deltas such as Rhizophora and Avicennia, and their morphology is shaped by that habitat: they bear pneumatophores, negatively geotropic breathing roots that rise out of the waterlogged mud, along with stilt and prop roots for support and…
Read the full explanation →The potato is a modification of which plant organ?
- A.Root
- B.Stem
- C.Leaf
- D.Fruit
Show answer
The potato is an underground stem tuber, the swollen tip of an underground branch, and the proof is in its morphology: it bears nodes, the depressions called eyes, and each eye carries an axillary bud that can sprout into a new shoot.
Read the full explanation →The edible part of the carrot is a modified
- A.Conical taproot
- B.Fibrous root
- C.Stem tuber
- D.Adventitious root
Show answer
The carrot stores food in its primary root, which is broad at the top and tapers steadily to a point, and that shape is described as conical.
Read the full explanation →Prop roots, which hang from spreading branches and give them mechanical support, are a familiar feature of which tree?
- A.Maize
- B.Banyan
- C.Screw pine
- D.Rhizophora
Show answer
The banyan's horizontal branches grow so long and heavy that they send down thick aerial roots which reach the soil, thicken into pillars and carry the weight of the branch; these are called prop or pillar roots.
Read the full explanation →Pneumatophores, the negatively geotropic breathing roots, are characteristic of
- A.Mangrove plants such as Rhizophora
- B.Desert plants such as Opuntia
- C.Epiphytic orchids such as Vanda
- D.Parasitic plants such as Cuscuta
Show answer
The mud of a tidal swamp is waterlogged and almost free of oxygen, so these plants send up roots that grow vertically out of the soil into the air and take in oxygen through pores; such roots grow against gravity and are therefore called negatively geotropic.
Read the full explanation →