Grade 11 : Biology - Morphology of Plants (Set 2)

Explanation:In dicotyledonous plants, direct elongation of the radicle leads to the formation of the primary root, which grows inside the soil and bears lateral roots. This constitutes the tap root system (e.g., Mustard plant).

Explanation:In monocotyledonous plants such as wheat, the primary root is short-lived and is replaced by a large number of roots originating from the base of the stem, forming a fibrous root system.

Explanation:Roots that develop from parts of the plant other than the radicle (such as stems or leaves) are called adventitious roots (e.g., Grass, Monstera, and Banyan tree).

Explanation:Very fine and delicate, thread-like structures called root hairs arise from the epidermal cells of the region of maturation. They absorb water and minerals from the soil.

Explanation:Stem tendrils develop from axillary buds, are slender and spirally coiled, and help plants to climb, such as in gourds (cucumber, pumpkins, watermelon) and grapevines.

Explanation:Underground stems of potato, ginger, turmeric, zaminkand, and colocasia are modified to store food and act as organs of perennation to tide over conditions unfavourable for growth.

Explanation:When the veinlets form a network, the venation is termed reticulate, which is a characteristic feature of dicotyledonous plants.

Explanation:In alternate type of phyllotaxy, a single leaf arises at each node in alternate pattern, as seen in China rose, mustard, and sunflower plants.

Explanation:In opposite type of phyllotaxy, a pair of leaves arises at each node and lie opposite to each other, as in Calotropis and guava plants.

Explanation:If more than two leaves arise at a node and form a whorl, it is called whorled phyllotaxy, as seen in Alstonia.

Explanation:In racemose type of inflorescence, the main axis continues to grow continuously and flowers are borne laterally in an acropetal succession.

Explanation:In cymose type of inflorescence, the main axis terminates in a flower, hence growth is limited. The flowers are borne in a basipetal order.

Explanation:When a flower can be divided into two equal radial halves in any radial plane passing through the centre, it is actinomorphic (radial symmetry), e.g., mustard, datura, chilli.

Explanation:When a flower can be divided into two similar halves only in one particular vertical plane, it is zygomorphic (bilateral symmetry), e.g., pea, gulmohur, bean, cassia.

Explanation:In hypogynous flowers, the gynoecium occupies the highest position while other parts are situated below it. The ovary in such flowers is said to be superior (e.g., Mustard, China rose, Brinjal).

Explanation:In marginal placentation, the placenta forms a ridge along the ventral suture of the ovary and the ovules are borne on this ridge forming two rows, as in pea.

Explanation:When the placenta is axial and the ovules are attached to it in a multilocular ovary, the placentation is called axile (e.g., China rose, tomato, lemon).

Explanation:In parietal placentation, the ovules develop on the inner wall of the ovary or on peripheral parts (e.g., Mustard and Argemone).

Explanation:In mango and coconut, the fruit is known as a drupe. They develop from monocarpellary superior ovaries. In coconut, the mesocarp is fibrous.

Explanation:In plants such as gram, pea, and bean, the endosperm is completely consumed during embryo development before seed maturation; hence, these seeds are non-endospermic (exalbuminous).