Question

Explain two novel (new) characteristics that all land plants have, and how these characteristics are beneficial when living on land

Answer 1

Two novel characteristics found in all land plants is the alternation of generations, a sporangium in which the spores are formed, a gametangium that produces haploid cells, and meristem tissue in roots and shoots.

a) Alternation of generations: It in simpler words implies to a type of life cycle in which subsequent generations of plants alternate between diploid and haploid organisms. Alternation of generations is also known as metagenesis.It is the type of life cycle that comprises of distinct haploid sexual and diploid asexual stages in which. In these a multicellular haploid gametophyte with n number of chromosomes alternates with a multicellular diploid sporophyte with 2n chromosomes which is made up of n pairs. A sporophyte produces haploid spores by meiosis by reducing the number of chromosomes to half i.e from 2n to n.There are two main stages of Alternation of Generations.

1)Sporophyte Generation:

In sphoeopgytic generation two haploid gametes fuse together to form a diploid zygote. And this results in the formation of sporophyte. The sporophyte is formed by the process of mitosis.when it matures , the sporophyte develops reproductive organs known as sporangia. These sporangia are used to create haploid spores. These spores are released and are thus carried away by air and water and they develop into a gametophyte

2)Gametophyte Generation

This is the next stage in the alternation of generations. The spore is newly formed and has half the DNA as the parent organism. This spore undergoes mitosis number of times to form a gametophyte. The gametophyte creates gametes. These gametes are produced by gametangia. These gametes are then transferred between plants or spilled or carried away in the environment.When a gamete encounters a gamete of the opposite sex, it fuses with it to form a zygote which eventually becomes a sporophyte.

b) Meristem: It is found at the tips of shoots and roots.it gives rise to all the specialized tissues of the organism. Earlier researchers found that plants don not grow much off the ground. To develop into a bigger size, each plant captured more light by developing shoots. It was found that land plants found more rigid molecules in their stems as air was less supportive than water in terms of necessary elements for growth.