NCERT Book Class 11 Biology Chapter 8 Cell: The Unit of Life

UNIT 3
CELL: STRUCTURE AND FUNCTIONS

Chapter 8 Biology is the study of living organisms. The detailed description of
Cell: The Unit of Life their form and appearance only brought out their diversity. It is the
cell theory that emphasised the unity underlying this diversity of forms,
Chapter 9 i.e., the cellular organisation of all life forms. A description of cell
Biomolecules structure and cell growth by division is given in the chapters comprising
this unit. Cell theory also created a sense of mystery around living
Chapter 10 phenomena, i.e., physiological and behavioural processes. This mystery
Cell Cycle and was the requirement of integrity of cellular organisation for living
Cell Division phenomena to be demonstrated or observed. In studying and
understanding the physiological and behavioural processes, one can
take a physico-chemical approach and use cell-free systems to
investigate. This approach enables us to describe the various processes
in molecular terms. The approach is established by analysis of living
tissues for elements and compounds. It will tell us what types of organic
compounds are present in living organisms. In the next stage, one can
ask the question: What are these compounds doing inside a cell? And,
in what way they carry out gross physiological processes like digestion,
excretion, memory, defense, recognition, etc. In other words we answer
the question, what is the molecular basis of all physiological processes?
It can also explain the abnormal processes that occur during any
diseased condition. This physico-chemical approach to study and
understand living organisms is called ‘Reductionist Biology’. The
concepts and techniques of physics and chemistry are applied to
understand biology. In Chapter 9 of this unit, a brief description of
biomolecules is provided.