Question

What is the direction of micropyle in anatropous ovule?
A.Left
B.Right
C.Upward
D.Inverted

Answer 1

Micropyle is a minute opening found on the covering or the integuments of the ovule in plants. The pollen enters inside the ovule through the micropyle.

Complete answer:
In seed bearing plants, ovule is the female reproductive part that grows into the seed after fertilization. The ovule consists of three parts which are female gametophyte, nucellus and the integuments. Integuments are the protective layer of the seed which develops into seed coat after fertilization. Nucellus is found inside the ovule which functions as the megasporangium and provides nutrients to the female gametophyte. The integuments have a minute pore which is called micropyle through which the pollen tube containing the pollen grain will enter. These pollen grains will fuse with the female gamete to form embryo.
The orientation of ovule is different for different sets of plants. It can be anatropous, amphitropous or orthotropous. Anatropous is the main type of orientation found in flowering plants or gymnosperms. In this the ovule is completely inverted that is, 180 degree orientation from the stalk. The chalazal end will be at the top and micropyle will be very close to hilum. The orientation of the funicle will be parallel to the ovule and very close to the micropyle. Now let's analyze the options to find the correct answer.

Option A) the orientation of the micropyle is not towards the left in an anatropous ovule. Therefore this is an incorrect option
Option B) the orientation of the micropyle is not towards right in an anatropous ovule. Therefore this is an incorrect option
Option C)the orientation of the micropyle is upward in an anatropous ovule. Therefore this is an incorrect option
Option D) The micropyle is inverted in an anatropous ovule. Therefore this is the correct option

Hence, the correct answer is option (D)

Note: Amphitropous ovule is the one in which the inverted ovule has turned 90 degree on its stalk.The embryo and embryo sac is curved and becomes horse-shoe shaped.
Orthotropous ovule is the one in which the ovule is aligned straight with micropyle, chalaza and hilum in a straight line with chalaza on the bottom. This type of orientation is found in all gymnosperms.