Tag: structure of ovule

Questions Related to structure of ovule

A nutritive inner region of integument is?

botany asexual and sexual reproduction in plants structure of male and female reproductive structures structure of ovule gynoecium

  1. Amphithecium

  2. Endothecium

  3. Endothelium

  4. Endostomium

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Correct Option: C
Explanation:
In some plants, which have unitegmic and tenuinucellate ovules, nucellus degenerates at an early stage of ovule development. In such cases, the innermost layer of the integument becomes specialized and forms a tissue around the embryo sac that performs the nutritive function for the embryo sac. This specialized tissue is called the Endothelium. Therefore, a nutritive inner region of the integument is Endothelium.
So, the correct answer is C

The point at which funiculus touches the ovule is

botany asexual and sexual reproduction in plants structure of male and female reproductive structures structure of ovule gynoecium

  1. Chalaza

  2. Hilum

  3. Raphe

  4. Endothelium

Show answer
Correct Option: B
Explanation:
•Chalaza is portion of the ovule which is opposite to the region of attachment of nucellus, integuments and funiculus.
•Hilum is a structure by which body of ovule is attached to the funiculus. 
•Raphe is a ridge showing the fusion of funiculus with the body of ovule.
•Endothelium is a specialized tissue present around the embryo sac which is formed by the specialization of integuments to perform the nutritive function of nucellus in the ovules in which nucellus degenerates at an early stage.
So, the correct answer is B.

Out of linear tetrad which one is the functional megaspore

botany asexual and sexual reproduction in plants structure of male and female reproductive structures structure of ovule gynoecium

  1. Micropylar

  2. Any of the middle ones

  3. Chalazal

  4. Any of the four

Show answer
Correct Option: C
Explanation:
Megaspore mother cell undergoes meiosis to form four haploid megaspores which are arranged in a linear tetrad. Out of these four megaspores, only one remains functional that develops into embryo sac or the female gametophyte and the rest three degenerate. The megaspore that remains functional can either be micropylar or chalazal depending upon the species. For example, in Polygonum, chalazal megaspore is functional while in Oenothera, micropylar megaspore is functional. Since Polygonum type embryo sac is the most common type of embryo sac found in Angiosperms, the functional Megaspore is generally the chalazal one. 
So, the correct answer is C.

Orthotropous ovules occur in

botany asexual and sexual reproduction in plants structure of male and female reproductive structures structure of ovule gynoecium

  1. Pisum sativum

  2. Solanum nigrum

  3. Polygonum

  4. Helianthus

Show answer
Correct Option: C
Explanation:
Orthotropous ovule is the simplest and primitive type of ovule. In this type of ovule, micropyle, chalaza and funiculus lie in one vertical plane. Example of plants with orthotropous ovules are, Polygonum, Piper nigrum, Piper betel and all gymnosperms.
So, the correct answer is C.

A mass of parenchymatous tissue forming the bulk of ovule is

botany asexual and sexual reproduction in plants structure of male and female reproductive structures structure of ovule gynoecium

  1. Obturator

  2. Female gametophyte

  3. Nucellus

  4. Endosperm

Show answer
Correct Option: C
Explanation:
Obturator is a structure of ovule that is associated with directing the growth of pollen tube towards the micropyle. It may originate either from the placenta or funiculus or even both.
Female gametophyte is the embryo sac. It is a 7-celled structure consisting of egg apparatus (comprising of egg cell and two synergids), a large central cell and three antipodal cells.
Nucellus is the central part of ovule in which embryo sac is present. It is a mass of parenchymatous cells and forms the major part of the ovule. 
Endosperm is the nutritive structure formed from triple fusion that provides nutrition to the developing embryo.
Hence, from all the options given in the question, the mass of parenchymatous cells forming bulk of ovule is nucellus.
So, the correct answer is C.

Secondary nucleus formed by the fusion of two polar nuclei is also called

botany asexual and sexual reproduction in plants structure of male and female reproductive structures structure of ovule gynoecium

  1. Vegetative nucleus

  2. Definitive nucleus

  3. Generative nucleus

  4. Primary endosperm nucleus

Show answer
Correct Option: B
Explanation:
The secondary nucleus formed by the fusion of two polar nuclei is also called definitive nucleus. Vegetative nucleus and Generative nucleus are present in the young pollen grain when the Microspore divides mitotically to form a large vegetative cell and a small generative cell. Primary endosperm nucleus is formed by the fusion of male gamete with a diploid secondary nucleus.
So, the correct answer is B.

The most common type of ovule is

botany asexual and sexual reproduction in plants structure of male and female reproductive structures structure of ovule gynoecium

  1. Orthotropous

  2. Hemitropous

  3. Anatropous

  4. Campylotropous

Show answer
Correct Option: C
Explanation:
•Orthotropous ovule is the simplest and primitive type of ovule. In this type of ovule, micropyle, chalaza and funiculus lie in one vertical plane.
•Hemianatropous ovule- The body of ovule is turned through 90° and micropyle and chalaza lie in a straight line but funiculus is at right angle or 90° with both these two.
•Anatropous ovule is the most common type of ovules, which occurs in more than 80% of angiospermic families. The body of ovule is rotated by 180° and micropyle comes near to the funiculus. Chalaza and micropyle lie in the straight line but hilum is at 90° to micropyle.
•Campylotropous ovule- In this type of ovule, the length of funiculus becomes increased and it covers the whole ovule.
So, the correct answer is C.

Name the type of ovule in which hilum, chalazal and micropyle come to lie nearby.

botany asexual and sexual reproduction in plants structure of male and female reproductive structures structure of ovule gynoecium

  1. Campylotropous

  2. Amphitropous

  3. Both A and B

  4. Hemitropous

Show answer
Correct Option: C
Explanation:

• Campylotropous ovule- This type of ovule is similar to Anatropous ovule but the curvature is less than that of an anatropous ovule. Micropyle is near to the funiculus. Chalaza and micropyle lie in the straight line but hilum is at 90° to the micropyle.

• Amphitropous ovule- The body of ovule gets curved along with the embryo sac in such a way that it becomes horseshoe-shaped.
• Hemianatropous ovule- The body of ovule is turned through 90° and micropyle and chalaza lie in a straight line but funiculus is at a right angle or 90° with both these two.
Hence, it is in Campylotropous and Amphitropous ovule in which Hilum, chalaza, and micropyle come to lie nearby. 
So, the correct answer is C.

Archesporium of ovule is

botany asexual and sexual reproduction in plants structure of male and female reproductive structures structure of ovule gynoecium

  1. Single celled derived from nucellar epidermis

  2. Single celled derived from nucellar hypodermis

  3. Multicellular derived from nucellar epidermis

  4. Multicellular derived from nucellar hypodermis

Show answer
Correct Option: B
Explanation:

In the ovule or megasporangium, during the process of megasporogenesis, a hypodermal cell functions as a archesporium cell and becomes more prominent because of large size, denser cytoplasm and large nucleus. In tenuinucellate ovules, archesporial cell directly functions as megaspore mother cell while in crassinucellate ovules, archesporial cell divides periclinally to form an outer parietal cell and inner primary sporogenous cell that functions as megaspore mother cell.

Hence, a single hypodermal cell in the Nucellus functions as the archesporium.
So, the correct answer is B.

Ovule is inverted with body fused to funicle, micropyle lying close to hilum and facing the placenta. It is?

botany asexual and sexual reproduction in plants structure of male and female reproductive structures structure of ovule gynoecium

  1. Hemitropous

  2. Orthotropous

  3. Anatropous

  4. Campylotropous

Show answer
Correct Option: C
Explanation:

•Hemianatropous ovule- The body of ovule is turned through 90° and micropyle and chalaza lie in a straight line but funiculus is at right angle or 90° with both these two.

•Orthotropous ovule is the simplest and primitive type of ovule. In this type of ovule, micropyle, chalaza and funiculus lie in one vertical plane.
•Anatropous ovule is the most common type of ovules, which occurs in more than 80% of angiospermic families. The body of ovule is rotated by 180° and micropylar comes near to the funiculus. Chalaza and micropyle lie in the straight line but hilum is at 90° to micropyle. The body of ovule is fused to funiculus on one side, thus forming a ridge called Raphe.
•Campylotropous ovule- This type of ovule is very similar to the Anatropous ovule but the curvature is less than the Anatropous ovule.
Hence, the properties given in the question match those of Anatropous ovule.
So, the correct answer is C.