Question

29. Describe the adaptations of plants to life on land and explain how these adaptations have affected the success of each group in colonizing land. detail answer

Answer 1

Plants have evolved several adaptations to life on land. Plant adaptations to life on land include the development of many structures-

• A water repellent (waxy) cuticle that covers the outer surface of the plant and prevents drying out through evaporation. The cuticle also partially protects against radiation damage from UV light.
• Stomata to regulate water evaporation- stomata are pores or holes which allow for exchange of gases between the plant cells and the environment.Stomata are necessary in land plants because the waxy cuticle blocks free- flow of gases.
• Roots and root hairs essential for the absorption of nutrients and anchoring to the substrate. All land plants except Bryophytes have true roots.Bryophytes have root-like structures called rhizoids that anchor them to their substrate but are not involved in water absorption.
• Specialized cells to provide rigid support against gravity, specialized structures to collect sunlight.
• Alternation of haploid and diploid generations, sexual organs, a multicellular embryo protected by parental tissue, a vascular transport system.
• Regulation of gene expression is essential for the evolution of morphological diversity, including the establishment and perpetuation of developmental programs involved in plant adaptations to life on land.

All life started in the ocean and like animals, plants had to move to land. Cyanobacteria, bacteria that can photosynthesize were the first photosynthetic organisms to move to land which made land a more appealing place to live. When plants first colonized land , oxygen levels in the atmosphere were much lower than they are today, and carbondioxide levels were higher. Over time, as plants evolved new structures that allowed them to grow taller, wider and photosynthesize more, carbondioxide levels dropped dramatically. The adaptations like the alternation of generations (which is haplodiplontic: the haploid multicellular form known as gametophyte, is followed in the development sequence by a multiceellular diploid organism: the sporophyte. Gametophytes give rise to gametes by mitosis), a sporangium in which a spore is formed, a gametangium that produce haploid cells ( precursor cells give rise to gametes by mitosis) and apical meristem tissue in roots and shoots (elongation of the shoots and roots allows a plant to access additional space and resources.) etc helped plants in colonizing on land.