Plant Morphology: 18 MCQs with answers

Plumule

The plumule grows upward to form the shoot system (stem, leaves, flowers), while the radicle forms the root system.

Stem

Stems are characterized by nodes (where leaves attach) and internodes (spaces between nodes). Roots lack these features.

Photosynthesis

Photosynthesis is primarily carried out by leaves. Roots anchor, absorb, and store, but they are not the main photosynthetic organs.

Protect the flower bud

The calyx consists of sepals, which are typically green and protect the flower bud before it opens.

seed

The ovule becomes the seed, while the ovary develops into the fruit.

Flower

Flowers are reproductive organs. Vegetative organs include roots, stems, and leaves.

False

The stem is negatively geotropic, meaning it grows upward, away from gravity. Roots are positively geotropic.

Mangrove pneumatophores

Mangroves have pneumatophores, which are root modifications that help in gaseous exchange in waterlogged soil. Carrot is for storage, banyan for support, and potato is a stem.

base

Racemose inflorescence shows acropetal succession, meaning flowers open from bottom to top, so the oldest are at the base.

Stem

In plants like grapevines, tendrils are modified stems that help in climbing. Leaves can also be modified into tendrils (e.g., pea), but the question asks for the most likely part; in the source, stem tendrils are mentioned.

Ginger

Ginger is a rhizome, an underground stem modification. Carrot and sweet potato are roots, and banyan prop roots are roots.

Bears nodes and internodes

Roots do not have nodes and internodes; that is a feature of stems. Roots are positively geotropic and hydrotropic and lack leaves.

True

In cymose inflorescence, the main axis terminates in a flower, which opens first and is therefore the oldest. Younger flowers develop below.

cymose

In cymose inflorescence, the main axis ends in a flower (definite growth), and subsequent flowers develop below it. Racemose has indefinite growth.

Onion – bulb (stem)

Onion is a bulb, which is an underground stem modification. Potato is a tuber (stem), sweet potato is a root, and carrot is a root.

It determines the method of propagation

Knowing that a potato is a stem (with buds/'eyes') tells farmers they can propagate it vegetatively by planting pieces of the tuber. This is a practical application of morphology.

The organ is a modified stem because it bears scaly leaves with axillary buds and lacks a root cap.

The presence of scaly leaves with axillary buds is a definitive characteristic of stems (modified underground stems like rhizomes or tubers). Roots do not bear leaves or buds. Additionally, roots have a root cap, which is absent here. Therefore, the organ is a modified stem.

It is a cymose inflorescence with basipetal succession.

The description matches a cymose inflorescence, where the main axis terminates in a flower, limiting further growth. In cymose inflorescences, the oldest flower is at the tip and younger flowers arise below, which is basipetal succession (from apex to base). In contrast, racemose inflorescences have acropetal successio…