Q.Can an unfertilised, apomictic embryo sac give rise to a diploid embryo? If yes, then how?

Parthenocarpy is the development of fruit without fertilisation, giving seedless fruits; banana is the classic example.

Fertilisation normally triggers the ovary to develop into a fruit and the ovules into seeds. In parthenocarpic fruits, the ovary develops into a fruit WITHOUT fertilisation occurring, so the fruit is seedless. Commercially important parthenocarpic fruits include banana (and it can be indu …

Parthenocarpic fruits are seedless precisely because they develop without fertilisation of the ovary.

Assertion (A) is correct: parthenocarpic fruits (e.g. seedless banana, and seedless grapes or watermelon obtained by auxin treatment of the ovary) do not contain seeds. Reason (R) is also correct and directly explains why: parthenocarpy is the development of a fruit from the ovary without fertilisation taking place. Since fertilisation (fusion of male and female gametes) is what norm …

Parthenocarpy is the formation of a fruit without fertilization, typically producing seedless fruit.

Parthenocarpy is defined as the development of a fruit from the ovary without the occurrence of fertilization, and such fruits are usually seedless (e.g., bananas, some grape varieties). It can occur naturally or can be induced artificially through application of growth hormones like auxins. Parthenogenesis (c) refers to development of an embryo from an unfertilized egg (seen in some animals), polyembryony (a) is the occurrence of more than one embryo in a single seed, and apomixis (d) i …

Parthenocarpy is the development of a fruit from the ovary without fertilization, giving seedless fruit.

Parthenocarpy refers to the development of the ovary into a fruit without the ovules being fertilized. Since fertilization does not occur, no seeds are formed, resulting in a seedless fruit — e.g., banana. Parthenocarpic fruit development can occur naturally or be artificially induced (e.g., by application of growth hormones). Apomixis is a different phenomenon, where seeds are produced without the fusion of gametes (asexual reproduction that mimics sexual re …

Banana fruit develops without fertilisation (parthenocarpy), giving the commercially valuable seedless fruit.

Parthenocarpy is the development of a fruit from the ovary without fertilisation having occurred, so the resulting fruit is typically seedless. It can occur naturally or be induced artificially by applying growth hormones such as auxins to unpollinated/unfertilised flowers.

…

Parthenocarpy uncouples fruit development from fertilisation, so the ovary matures into a fruit even though no seeds are formed.

Definition and mechanism

Normally, fertilisation of the egg cell (and the resulting hormonal changes) triggers the ovary wall to develop into a fruit while the fertilised ovules develop into seeds. In parthenocarpy, the ovary develops into a fruit without fertilisation occurring, so the fruit lacks seeds. It can occur naturally in some species or can be induced artificially by applying growth hormones such as auxins to unpollinated flowers, which mimic the hormonal trigger normally provided by fertilisation.

Examples and significance

…

Fruits that develop without fertilisation are called parthenocarpic fruits; the process is parthenocarpy.

Normally, after double fertilisation the ovary develops into the fruit and the ovules develop into seeds. In some plants, however, the ovary can swell and mature into a fruit even when fertilisation has NOT occurred. Such seedless fruits are called parthenocarpic fruits, and the phenomenon is called parthenocarpy.

…

Apomixis = production of seeds without fertilisation — an asexual method that outwardly resembles sexual reproduction, giving clonal (parent-identical) seeds.

Concept

Normally a seed forms only after fertilisation of the egg. In apomixis, however, seeds are formed without fertilisation — for example, the diploid egg cell or another cell of the ovule develops directly into an embryo without meiosis and syngamy. The resulting seeds are genetically identical to the mother plant (clones).

Significance

• Seen in some Citrus, in the family Asteraceae, and in many grasses. …

A fruit that develops from the ovary without fertilisation is a parthenocarpic fruit — option (iii). Such fruits are seedless.

Concept

Normally, after double fertilisation the ovule becomes the seed and the ovary matures into the fruit. Parthenocarpy is the development of the fruit from the ovary without fertilisation, so no true seed is formed. This can occur naturally or be induced by spraying growth hormones such as auxins and gibberellins.

Why the other options are wrong

• (i) False fruit — a fruit in which tissue other than the ovary (e.g. the thalamus in apple) contributes to the flesh; fertilisation has still occurred.
• (ii) True fruit — a fruit that develops from the ovary after normal fertilisation. …

Apomixis, a form of asexual reproduction that mimics seed formation without fertilisation, occurs in some Asteraceae and grasses.

Apomixis is the production of seeds without the fusion of gametes (no fertilisation). It is a form of asexual reproduction that mimics sexual seed formation. In NCERT, apomixis is described in several species of Asteraceae and in grasses, where the diploid egg cell forms without meiosis a …

Fruit development in the complete absence of fertilisation, producing a seedless fruit, is called parthenocarpy.

Normally a fruit develops from the ovary only after fertilisation has occurred, and the fertilised ovules inside develop into seeds. In some plants, however, the ovary enlarges into a fruit without any fertilisation taking place — since no zygote or embryo forms, no seeds are produced, so the resulting fruit is seedless. This phenomenon is called parthenocarpy. It can occur naturally (e.g. banana, seedless grapes, some varieties of cucumber) or can be induced artificially by applying growth hormones such as auxins to the unpollinated pistil/stigma.

The other options describe different phenomena and are ruled out:

• Apomixis (b): seeds are formed without the fusion of gametes — an asexual mode of seed formation that mimics sexual reproduction (common in some grasses, Citrus, Asteraceae). It still produces seeds, unlike parthenocarpy. …