Fruit, False Fruit and Seedless Fruits (Leaving Cert Biology): Revision Notes

Fruit, False Fruit and Seedless Fruits

Fruit

• Fruits develop after fertilisation, as the ovary enlarges to protect and nourish the seeds.
• The ovules develop into seeds.
• As the seed develops, the surrounding ovary becomes the fruit.
• Fruit formation is stimulated by growth regulators (auxins) produced by seeds.
• Types of fruits:
  • Succulent fruits swell with water as well as food (e.g., plums, oranges).
  • Dry fruits just swell with food (e.g., beans).
• The wall of the ovary becomes the wall of the fruit, known as the pericarp.
• Fruits are designed to protect the seed and to help in seed dispersal.
• Once the fruit forms, the rest of the flower parts die and fall away.

False Fruits

• Some fruits like apples, pears, and strawberries are known as false fruits.
• They do not develop from the ovary.
• False fruits develop when the receptacle swells with food and water.

Seedless Fruits

• Seedless fruits are fruits produced without seeds. It is a form of virgin birth (no fertilisation).
• This process is called parthenocarpy.
  • Bananas, oranges, grapes, and pineapples can be produced without seeds.
  • Seedless fruits can be formed genetically naturally or by breeding programmes.
• Seedless fruit formation:
  • Natural parthenocarpy:
  • Occurs naturally due to genetic factors.
  • Examples: bananas, pineapples.
  • Artificial parthenocarpy:
  • Triggered by spraying plants with growth regulators (e.g., auxins, gibberellins).
  • Examples: Seedless cherries, peppers, apricots.
• Commercial applications:
  • Ethene gas is used to remove the green colour from fruits and ripen the fruits.
  • Carbon dioxide stops fruits from ripening, allowing long-term storage (e.g., over winter).