1. What happens during alternation of generations in plants?

Question

2. What is the scientific explanation of a seed? What is the function of stoma/stomata in plants?

Answer 1

1. Alternation of Generations in Plants: Alternation of generations is a type of life cycle that occurs in plants (as well as some fungi and protists), comprising two distinct phases: the diploid sporophyte generation and the haploid gametophyte generation.

   • Sporophyte Generation: This is the diploid phase (2n), which develops from the fertilization of gametes. The sporophyte produces spores through meiosis, which are haploid (n) cells. These spores can grow into the next plant generation.

   • Gametophyte Generation: The haploid spores germinate and develop into the gametophyte phase, which produces gametes (sperm and eggs) through mitosis. When these gametes fuse during fertilization, they form a diploid zygote, which then develops into a new sporophyte, completing the cycle.

This alternation allows plants to reproduce both sexually and asexually and contribute to genetic diversity.

2. Scientific Explanation of a Seed: A seed is a reproductive structure in flowering plants (angiosperms) and some non-flowering plants (gymnosperms) that consists of an embryo, a source of stored food, and a protective outer covering.

   • Embryo: The developing plant that can grow into a new individual.
   • Stored Food: This provides the necessary nutrients for the embryo during its initial stages of growth until it can photosynthesize.
   • Seed Coat: This protective covering shields the embryo and food supply from environmental stresses and facilitates survival during dormancy.

Seeds are crucial for the reproduction and dispersal of flowering plants.

Function of Stoma/Stomata in Plants: Stomata are small openings located primarily on the surface of leaves, though they can also be found on stems and other parts of a plant. Each stoma is surrounded by a pair of guard cells that regulate its opening and closing.

• Gas Exchange: The primary function of stomata is to facilitate gas exchange, allowing carbon dioxide (CO2) to enter the leaf for photosynthesis and oxygen (O2) to exit as a byproduct.
• Transpiration: Stomata also play a crucial role in transpiration, the process by which water vapor is released from plant surfaces into the atmosphere. This process helps to maintain water and nutrient uptake through the roots and keeps the plant cool.
• Regulation of Water Loss: By regulating the size of the stomatal openings, guard cells help to optimize water loss and gas exchange, allowing the plant to adapt to its environment and maintain homeostasis.