Question

Select one of the following important features distinguishing Gnetum from Cycas and Pinus and showing affinities with angiosperms.

• A. Perianth and two integuments
• B. Presence of vessel elements and absence of archegonia
• C. Absence of resin duct and leaf venation
• D. embryo development and apical meristem

Answer 1

The correct option is B

Presence of vessel elements and absence of archegonia

The correct option is B.

Explanation of the correct option:

1. Gnetum is an evergreen family of Gnetaceae comprising shrubs, trees, lianas, etc.
2. Cycas plants belong to the ancient order Cycadophyta.
3. Pinus is known as a coniferous tree belonging to the family Pinaceae.
4. One of the distinguishing features of these plants is that they have vessel elements in their vascular system.
5. The presence of vessels in the wood of Gnetum distinguishes it from Cycas and Pinus.
6. Vessel elements are cells found in the xylem.
7. Vessels help in the transport of water across the plant.
8. The other distinguishing feature of these plants is the absence of archegonia.
9. Archegonia's absence shows affinity with the angiosperms.
10. Archegonia is the female gametophyte in plants.

Explanations of the incorrect options:

Option A:

1. The perianth is known as the collection of the calyx (sepals) and corolla (petals) on the outer side of the flower.
2. Whereas integuments are the tough outer covering of a plant that develops into the seed coat.
3. This is an incorrect option.

Option C:

1. Leaf venation signifies the arrangement of veins of the vascular tissues in the leaf of a plant.
2. Resin ducts are found in leaves, stems, roots, etc., located in the phloem of the vascular bundles.
3. This is an incorrect option.

Option D:

1. Apical meristem of a plant help in the growth of shoot and root tips.
2. Embryo development is the process of growth of the embryo into fruit and seed.
3. This is an incorrect option.

Final answer: The important features distinguishing Gnetum from Cycas and Pinus and showing affinities with angiosperms are the presence of vessel elements and the absence of archegonia.