Development Of Fruits - SS3 Biology Past Questions and Answers - page 2

The structure of fruits plays a vital role in plant reproduction and seed dispersal. Fruits are the mature ovaries of flowering plants and typically consist of three main layers: the outer epicarp, the middle mesocarp, and the inner endocarp. This layered structure protects the seeds within and aids in their dispersal. Furthermore, the fleshy or dry nature of the fruit influences the mode of seed dispersal, with animals often assisting in dispersal through ingestion and transportation, while wind and water play a role in other fruit types.

 

Fruits can be classified based on their development into three main types: simple fruits, aggregate fruits, and multiple fruits. 

Simple Fruits: These develop from a single ovary of a single flower. They can be further categorized into fleshy fruits, such as berries (e.g., tomatoes, grapes) and drupes (e.g., peaches, cherries), as well as dry fruits like nuts (e.g., acorns, chestnuts) and capsules (e.g., poppy, milkweed).

Aggregate Fruits: These form from multiple ovaries within a single flower, and each ovary develops into a small individual fruit, called a fruitlet. Examples include strawberries, raspberries, and blackberries.

Multiple Fruits: These develop from a cluster of flowers closely packed together, where each flower contributes to the fruit structure. Pineapples and figs are examples of multiple fruits.

Fruit dispersal mechanisms are crucial for the survival and distribution of plant species. There are several methods of fruit dispersal: 

Animal Dispersal: Many fruits have evolved to attract animals with their appealing colours, smells, and flavours. Animals eat the fruits, and the seeds pass through their digestive systems unharmed. The seeds are then deposited in different locations, promoting the growth of new plants. Examples include berries consumed by birds and fleshy fruits eaten by mammals.

Wind Dispersal: Some fruits, like dandelions and maple keys, have adapted to disperse their seeds through the wind. These fruits are lightweight and often have structures like wings or tufts that allow them to be carried far away from the parent plant.

Water Dispersal: Plants growing near water bodies have fruits designed to float and survive in water. The flowing water carries these fruits to new areas, aiding in the expansion of the plant population. Coconut is an excellent example of a fruit dispersed by water.

Explosive Mechanism: Certain plants possess fruits that explode when they ripen, forcefully ejecting the seeds to a distance. The sudden release of pressure helps in spreading the seeds away from the parent plant. Examples include touch-me-not (Mimosa pudica) and violets (Viola spp.).