C) Mosses.
Further Explanation-
Almost half a billion years ago, the first plants arrived as life forms on Earth, during the Ordovician period, and during this period, simpler forms of life were constantly in the process of evolving. The first land plants were non-vascular and did not have an elaborate or branched root system. They could exist in the harshest of conditions. The environmental conditions changed rapidly in the course of the next 35 million years, when Carbon dioxide levels in the atmosphere reduced drastically, leading to the First Ice Age. The constant lowering of temperatures on the Earth made it extremely difficult for most living creatures to adapt to, resulting in mass extinction.
Scientists explain that the evolution of plant life to vascular plants with an elaborate root system was responsible for the Ice Ages. The roots extracted nutrients from the soil, altering the chemical composition of the rocks, that sucked carbon dioxide from the atmosphere. Also, mosses had a minor role in the Ice Age, as they grew easily on rock surfaces and helped in breaking them down. The effect of mosses on rocks was almost the same as that of a vascular plant with an elaborate root system. In the course of time, these simpler plant structures developed a complex novel structure and reproduction mechanisms. Plant reproduction needed the protection of embryo so that seeds could be formed. The first plant forms that developed an elaborate root system lacked all the plant components in its truest form, and the connection between modern plant life forms can traced back to a common ancestor, whose remains might be found in a fossilized form.
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Answer Details-
Grade- Secondary School.
Chapter- The evolution of life on Earth.
Subject- Geography.
Additional Remarks- This chapter provides information with the evolution and development of life on Earth, the various periods and the environmental changes that shaped the Earth’s landscapes till the present Ages.
Keywords-
Evolution, vascular plants, elaborate root system, Ice Age, Carbon dioxide levels, the chemical composition of rocks, weathering, fossils.
