PGLAW 2018 Panjab University Entrance Exam With Answers

The correct answer is B: Carbon, Hydrogen, Nitrogen.

Carbon, hydrogen, and nitrogen are the primary elements that make up the building blocks of life, such as amino acids, nucleotides, and lipids. These molecules are essential for the formation of proteins, DNA, and cell membranes, which are the key components of living cells.

It is widely believed that the first living organisms on Earth arose from non-living matter through a process known as abiogenesis or chemical evolution. This process involved the gradual assembly of organic molecules from simpler inorganic compounds such as water, methane, and ammonia, which were abundant on the early Earth.

Carbon, hydrogen, and nitrogen were particularly important in this process, as they have unique properties that allow them to form strong covalent bonds and a wide range of organic compounds. Over time, these organic molecules became more complex, eventually giving rise to the first living cells.

While other elements such as oxygen, calcium, and phosphorus are also important for life, they were not primarily responsible for the origin of life on Earth.