Plant Morphology: 20 MCQs with answers

Taproot system

Dicots usually develop a taproot system where the primary root grows directly downward and lateral roots arise from it.

Node

Nodes are the points on the stem where leaves and axillary buds are attached. Internodes are the segments between nodes.

Lamina (blade)

The lamina, or leaf blade, is the broad, flat portion of the leaf that is primarily responsible for photosynthesis.

Peepal

Reticulate venation, where veins form a network, is typical of dicot leaves like peepal. Wheat, maize, and bamboo are monocots with parallel venation.

Bisexual

A bisexual flower contains both male (stamens) and female (carpels) reproductive organs, such as in Hibiscus.

Phyllotaxy

Phyllotaxy is the pattern of leaf arrangement on a stem, which can be alternate, opposite, or whorled.

Petiole

The petiole is the stalk that connects the leaf blade to the stem. Rachis is the axis of a compound leaf.

Calyx

The calyx, composed of sepals, is the outermost whorl of a flower, protecting the inner parts in the bud stage.

True

The root cap is a thimble-like structure that covers the root tip and protects it from damage as the root grows through soil.

Region of elongation

Cells in the region of elongation undergo rapid enlargement, which pushes the root tip forward into the soil.

Carrot root

Carrot is a modified taproot, not a stem. Potato, ginger, and onion are stem modifications (tuber, rhizome, and bulb respectively).

Colocasia (taro)

Colocasia has a corm, which is a modified underground stem that stores food. Sweet potato, radish, and turnip are root modifications.

On a common axis (rachis)

In pinnately compound leaves, leaflets are attached along a common axis called the rachis, as seen in neem and rose.

Nodular root

Nodular roots, as in legumes, contain symbiotic bacteria (Rhizobium) that fix atmospheric nitrogen.

Aestivation

Aestivation refers to the arrangement of sepals and petals in relation to each other in a flower bud, such as valvate, twisted, or imbricate.

Papaya

Papaya has unisexual flowers—male and female flowers occur on separate plants. Hibiscus, mustard, and China rose have bisexual flowers.

False

Leaflets of a compound leaf do not have axillary buds; only the entire leaf has an axillary bud at its base on the stem.

Placentation

Placentation refers to the arrangement of ovules within the ovary. Aestivation is the arrangement of sepals/petals, phyllotaxy is leaf arrangement, and inflorescence is flower arrangement.

Free central

In free central placentation, the ovules are borne on a central axis and the ovary is unilocular without septa, as seen in Dianthus.

Perianth

When sepals and petals are similar and not distinguishable, they are collectively called the perianth, as in onion and tulip.