What is the primary function of the endosperm?

The primary function of the endosperm is to provide nutrition to the developing embryo. It is a nutrient-rich tissue, typically triploid ($3n$), formed from the primary endosperm nucleus (PEN) after triple fusion. In some seeds, like castor or maize, it persists in the mature seed (albuminous seeds) and nourishes the embryo during germination. In others, like pea or bean (non-albuminous seeds), the embryo completely consumes the endosperm during development, storing food in its cotyledons instead. Its timely development ensures a ready food supply for the growing embryo.

How do true fruits differ from false fruits? Provide examples.

True fruits develop exclusively from the ripened ovary of a flower, with no other floral part contributing significantly to the fruit's structure. Examples include mango, tomato, and pea. In contrast, false fruits, also known as accessory fruits, develop not only from the ovary but also involve other floral parts like the thalamus, receptacle, or calyx, which become fleshy and edible. Classic examples of false fruits are apple and pear (where the thalamus forms the main edible part), strawberry (thalamus), and cashew (pedicel).

What is parthenocarpy, and why is it significant?

Parthenocarpy is the phenomenon where fruits develop without fertilisation. As a result, these fruits are typically seedless. This process can occur naturally, as seen in bananas, or can be induced artificially by applying plant growth hormones like auxins. Parthenocarpy is significant because it allows for the production of seedless fruits, which are often preferred by consumers for their convenience and ease of consumption. It also has commercial importance in horticulture for increasing fruit yield and quality.

Explain the difference between albuminous and non-albuminous seeds.

Albuminous (or endospermic) seeds are those in which a significant portion of the endosperm persists in the mature seed, serving as the primary nutritive tissue for the embryo. Examples include castor, maize, and wheat. Non-albuminous (or exalbuminous) seeds, on the other hand, are those where the endosperm is completely consumed by the developing embryo during its growth. In these seeds, the food reserves are stored primarily in the cotyledons, which become fleshy. Examples include pea, bean, and groundnut.

What is the fate of the integuments of the ovule after fertilisation?

After fertilisation, the integuments, which are the protective layers surrounding the ovule, undergo significant changes to develop into the seed coat. The outer integument typically forms the testa, which is the outer, often tough and protective layer of the seed coat. The inner integument forms the tegmen, which is usually a thinner, inner layer. The seed coat provides crucial protection to the delicate embryo and stored food reserves inside the seed, safeguarding it from mechanical injury, desiccation, and pathogen attack until conditions are favorable for germination.

How does the zygote ensure it receives adequate nutrition during its development into an embryo?

The zygote employs a clever strategy to ensure it receives adequate nutrition: it typically begins to divide and develop into an embryo only after a certain amount of endosperm has already formed. The endosperm, being a nutrient-rich tissue, is developed from the primary endosperm nucleus (PEN) and serves as the primary food source. This sequential development ensures that a ready supply of nourishment is available for the rapidly growing and differentiating embryo, preventing starvation and supporting its complex developmental stages from a single cell to a multicellular plantlet.

Post-fertilisation Structures and Events

Biology

NEET UG

Version 1Updated 21 Mar 2026

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Post-fertilisation structures and events encompass the entire sequence of developmental changes that occur in a flower subsequent to the successful fusion of male and female gametes (fertilisation). This critical phase initiates the transformation of the ovule into a seed and the ovary into a fruit, ensuring the protection and dispersal of the nascent embryo. These events are orchestrated by compl…

Quick Summary

Post-fertilisation events are the crucial developmental changes occurring in a flower after successful double fertilisation, leading to the formation of seeds and fruits. The fertilised ovule transforms into a seed, while the ovary matures into a fruit.

Key transformations include the zygote developing into an embryo, the primary endosperm nucleus (PEN) forming the nutritive endosperm, and the ovule integuments hardening into the protective seed coat.

The ovary wall differentiates into the pericarp, the fruit wall. Endosperm development can be nuclear, cellular, or helobial, providing food for the embryo. Embryo development proceeds through globular, heart-shaped, and mature stages, forming the plumule, radicle, and cotyledons.

Seeds are classified as albuminous (with persistent endosperm) or non-albuminous (food stored in cotyledons). Fruits can be true (from ovary only) or false (involving other floral parts), and some develop without fertilisation (parthenocarpic), resulting in seedless fruits.

These processes are vital for plant propagation, protection, and dispersal of the next generation.

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Key Concepts

Endosperm Development and Types

The endosperm is crucial for embryo nutrition and develops from the triploid Primary Endosperm Nucleus (PEN).…

Embryo Development (Embryogeny)

The zygote, formed by syngamy, develops into an embryo. This process, called embryogeny, ensures the…

Seed Structure and Types

A seed is a fertilised ovule, containing an embryo, stored food, and a protective seed coat. Its structure…

**Ovule

\rightarrow

Seed**

**Ovary

\rightarrow

Fruit**

**Integuments

\rightarrow

Seed Coat (Testa, Tegmen)**

**Ovary Wall

\rightarrow

Pericarp**

**Zygote (

2n

)

\rightarrow

Embryo (

2n

)**

**Primary Endosperm Nucleus (PEN,

3n

)

\rightarrow

Endosperm (

3n

)**

**Nucellus (

2n

)

\rightarrow

Perisperm (if persistent, e.g., black pepper)**

Endosperm Types — Nuclear (free nuclei), Cellular (walls form), Helobial (intermediate).

Seed Types — Albuminous (endosperm present, e.g., castor, maize), Non-albuminous (endosperm absent, food in cotyledons, e.g., pea, bean).

Fruit Types — True (from ovary only, e.g., mango), False (other floral parts, e.g., apple, strawberry), Parthenocarpic (seedless, without fertilisation, e.g., banana).

To remember the fate of floral parts after fertilisation:

Old Ovaries Form Fruits. Old Ovules Start Seeds. Inner Integuments Turn To Tegmen. Outer Integuments Turn To Testa. Zygotes Evolve Embryos. PEN Ends Endosperm.