Question

The most common type of ovule is
(a)Orthotropous
(b)Hemitropous
(c)Anatropous
(d)Campylotropous

Answer 1

Hint: The female germ cells of a plant present inside a small body called ovule develops into a seed after fertilization. In the most common type of ovule, raphe is present and the whole ovule body is inverted on its stalk.

Complete answer:
The most common type of ovule is the anatropous ovule found in Angiosperm. An ovule is a small body that contains the female germ cells of a plant. After fertilization, this ovule develops into a seed. Anatropous ovules are those ovules that are completely inverted on its stalk which means the ovule body is turned back 180 degrees on its stalk. For example, Helianthus and Tridax.

Additional information:
-The micropyle comes near to the funiculus because of 180 degrees rotation. This keeps the chalaza and micropyle in a straight line but the hilum will be at 90 degrees to the micropyle.
-As the body of the ovule is fused with the funiculus on one side, a ridge is also present there.
-Campylotropous ovule: In the campylotropous ovule, the length of the funiculus is highly increased and as a result, it covers the entire ovule.
-Orthotropous ovule: In the orthotropous ovule, the micropyle, chalaza, and funiculus lie in the same vertical plane. This is the most primitive and simplest type of ovule.
-Hemianatropous ovule: In the hemianatropous ovule, the ovule body is turned by 90 degrees because of this the chalaza and micropyle lie in a straight line but the funicle lies at 90 degrees to both of these structures.

So, the correct answer is,’ Anatropous’.

Note:
-The orthotropous ovule is found in members of Polygonaceae e.g., Polygonum, Rumex, etc., and Piperaceae e.g., Piper nigrum, Piper betel.
-In an anatropous ovule, the body of the ovule is fused with the funiculus on one side.
-The anatropous ovule occurs in more than 80% of the plants of angiosperms families.