Labeled Diagram of an Anatropous Ovule (NEET Biology)

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Draw a diagram of an anatropous ovule and label six parts other than the gametophyte.

Hint:  In this state, the micropyle is positioned near the funicular attachment. This is the developmental phase when the egg is prepared for fertilization by the sperm from a pollen grain.

Complete answer:

In an anatropous ovule, the plant’s ovule is positioned in an inverted orientation, causing the micropyle to bend down toward the funiculus to which the ovule is attached. The chalazal end is situated at the upper position. The ovule serves as the female reproductive structure of the plant and ultimately develops into a seed following fertilization.

Structure of ovule:

Funicle: A small structure that links the ovule to the placenta.

Hilum: The attachment point where the ovule’s body merges with the funicle.

Nucellus: The main body of the ovule, composed of a mass of parenchymatous cells known as nucellus, which can vary in thickness. The cells of the nucellus are rich in nutrients.

Integuments: The nucellus is encased by one or two or multiple protective layers called integuments. In higher dicots, the ovule contains a single integument, whereas in monocots or primitive dicots, two integuments are present.

Chalaza: This is the region where the integuments originate, typically located at the opposite end from the micropyle, representing the basal part of the ovule.

Micropyle: A small opening found in the integuments at one end, located opposite the chalazal end.

Note:

 In the amphitropous condition, the anatropous arrangement of the ovule is rotated 90 degrees.

  • Within the ovule, the megaspores remain and divide by mitosis to form the haploid female gametophyte.
  • The nucellus is structurally and functionally similar to the megasporangium.

 

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