Questions and Answers

The transverse section of a plant material shows the following anatomical features – (a) the vascular bundles are conjoint, scattered and surrounded by a sclerenchymatous bundle sheaths. (b) phloem parenchyma is absent. What will you identify it as?

Cut a transverse section of young stem of a plant from your school garden and observe it under the microscope. How would you ascertain whether it is a monocot stem or a dicot stem? Give reasons.

Draw illustrations to bring out the anatomical difference between (a) Monocot root and Dicot root (b) Monocot stem and Dicot stem

In a pinnately compound leaf, the leaflets are arranged along the sides of a common axis called the rachis, as seen in neem. In a palmately compound leaf, the leaflets are attached at a common point at the tip of the petiole, as in silk cotton.

(a) In racemose inflorescence, the main axis continues to grow and the flowers are borne laterally in an acropetal succession, e.g., mustard. In cymose inflorescence, the main axis terminates in a flower and the subsequent growth is by lateral branches, which also end in flowers, showing basipetal succession, e.g., jasmine. (b) An apocarpous ovary has multiple free carpels, e.g., lotus. A syncarpous ovary has multiple carpels that are fused together, e.g., mustard.

(a) Aestivation is the mode of arrangement of sepals or petals in floral buds with respect to the other members of the same whorl. (b) Placentation refers to the arrangement of ovules within the ovary. (c) Actinomorphic flowers are those which can be divided into two equal halves in any radial plane passing through the center, e.g., mustard. (d) Zygomorphic flowers can be divided into two similar halves only in one particular vertical plane, e.g., pea. (e) A superior ovary is one where the ovary is positioned above the other floral parts, e.g., mustard. (f) A perigynous flower has the ovary situated at the center and other floral parts are located on the rim of the thalamus at the same level, e.g., rose. (g) Epipetalous stamens are those where stamens are attached to the petals, as in brinjal.

Phyllotaxy refers to the arrangement of leaves on the stem or branch. The three types are: Alternate phyllotaxy, where a single leaf grows at each node in an alternate manner, as in sunflower; Opposite phyllotaxy, where a pair of leaves arises at each node and lie opposite to each other, as in guava; Whorled phyllotaxy, where more than two leaves arise at a node and form a whorl, as in Alstonia.

[Diagrams are to be drawn as per NCERT textbook illustrations.]

A typical flower of Solanaceae (e.g., Solanum nigrum) is described as: Actinomorphic, bisexual, pentamerous; calyx 5, united; corolla 5, united; androecium 5, epipetalous; gynoecium bicarpellary, syncarpous, ovary superior, axile placentation. Floral formula: ⚥ K(5) C(5) A5 G(2). [Floral diagram to be drawn as per NCERT guidelines.]