Question

In orthotropous ovule, the micropyle and chalaza are
A. Parallel to funiculus
B. At the right angles of funiculus
C. Oblique angle to funicles
D. In straight line with funiculus

Answer 1

Polygonum, Piper, Rumex, etc. are common examples of orthotropous ovules. This form of ovule in angiosperms is a primitive characteristic.

Complete Answer:
- The ovule is an oval-shaped multicellular structure which derives from the placenta and lies inside the ovary chamber.
- Each chamber can comprise one or more ovules. A fully developed ovule comprises the stalk or funicle and the body.
- The placenta is attached to one end of the funicle and the other to the body of the ovule. The stage at which the funicle is bound to the body is called a hilum. The ovule’s body shows two ends: the basal end, the chalaza, and the upper end, the micropylar end.

Now, let us find the solution from the options-
Option A: In orthotropous ovules, the micropyle and chalaza does not lie parallel to funiculus. Therefore, the option A is incorrect.

Option B: It is observed in amphitropous ovule. In an orthotropous ovule, the micropyle and chalaza are not at the right angle to funicles. Therefore, the option B is incorrect.

Option C: In orthotropous ovules, the micropyle and chalaza does not does not find an oblique angle to funiculus. Therefore, the option C is incorrect.

Option D: When the funicle, chalaza, and the micropyle come to lie on one vertical line, the ovule is shown to be orthotropous. Therefore, the option D is correct.

Thus, the correct answer is option D In straight line with funiculus.

Note: In orthotropous ovules, the body is straight such that the chalaza, where the nucellus and integuments are joined, are both aligned with the funicle that connects the ovule to the placenta, and the micropyle.