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Which one of the following represents an ovule, where the embryo sac becomes horse-shoe shaped and the funiculus and micropyle are close to each other -
A
Amphitropous
B
Anatropous
C
Circinotropous
D
Atropous
Detailed Solution
Ovules are classified by the orientation of the body of the ovule with respect to the funicle.
In an amphitropous ovule, the body of the ovule is curved so much that the nucellus and the embryo sac also become curved, taking a horse-shoe shape.
The micropyle comes to lie close to the funicle (hilum).
Examples: Lemna, Papaver and some members of Alismataceae.
In an anatropous ovule (the most common type) the body is inverted so that the micropyle lies close to the funicle, but the embryo sac is straight.
In an atropous (orthotropous) ovule the micropyle, chalaza and funicle lie in one straight line, and in a circinotropous ovule the funicle coils around the ovule.
So the ovule described is amphitropous.
In an amphitropous ovule, the body of the ovule is curved so much that the nucellus and the embryo sac also become curved, taking a horse-shoe shape.
The micropyle comes to lie close to the funicle (hilum).
Examples: Lemna, Papaver and some members of Alismataceae.
In an anatropous ovule (the most common type) the body is inverted so that the micropyle lies close to the funicle, but the embryo sac is straight.
In an atropous (orthotropous) ovule the micropyle, chalaza and funicle lie in one straight line, and in a circinotropous ovule the funicle coils around the ovule.
So the ovule described is amphitropous.