HAVING gone thro­ugh a reasonable extent of astronomy, and a little of the history of science, we must move on.

Cells: All self-replicating forms of life, indeed all forms of life, are composed of cells; from single celled bacteria to whales and elephants comprising trillions of cells each.

Cells are microscopic but some, such as a hen’s eggs, are large. All basic functions of a living being are carried out at this level, such as synthesis of protein, extraction of energy nutrients and duplication wherever it is required. The common elements of cells include a thin plasma surrounding the cell nucleus which may be called its factory, or engine. Then, the nucleus containing genetic matter, and a viscous transparent material called cytoplasm, that is between the nucleus and membrane.

The genetic information in DNA molecules in the nucleus of a cell provide information on assembling or provide protein molecules. The cell is served well by the many different types of protein molecules. Some molecules serve by replicating genetic information by carrying out division of cells, changing the shape of cell, repairing cell structures or changing cell structures.

Other forms of molecules of the cell: hormones, digestive enzymes, antibodies, carriers of oxygen and other molecules in the blood. In short, it is the smallest component of an organism that may be said to be alive.

Besides the basic functions carried out at cellular level most cells perform highly specialised functions. For instance, gland cells secrete hormones, muscle cells contract, and nerve cells conduct electric signals and so on. Each part of the body, human or animal, is served by its own cells which keep that particular part alive. There are many dozen parts, and as many types of cells.

You will notice that the cell is the most basic component. It is another matter that humans, animals and trees each has been built with billions upon billions of cells. Cells are the most prolific items of nature, countless in number and variety and propensity, absolute marvel of Mother Nature. In fact, there is a lot more in the business of cells but we shall revert to it in due course. Now the cells for flora, or plants.

Plant cells are different from animal/human cells. They have a rigid cell wall made of cellulose, a tough material that provides shape to plant cell and consequently the plant itself. Contrarily, the animal cells are soft and pliable. Cells are the elementary particles of life for plants too.

Celsius: In much of the world, temperature is measured in degrees Celsius or Centigrade. Named after its creator, Anders Celsius from Sweden, in this scale, the freezing point of water is 0 and boiling point is 100. It is then called minus degrees Celsius.

We should be able to convert Celsius into Fahrenheit. But how? Just double the Celsius figure, then add 30. It will only give us an approximate figure. In the future I will give the more correct method for computation. For now, it is pretty handy for us.

Cenozoic: It is the last 65 million years of planet Earth’s history, from today backwards. The most recent era of geological time, describing the evolution of mammals, plants, birds, modern continents and glaciation. The disappearance of the great dinosaurs coincides with it, which occurred some 65 million years ago, after the dinos had ruled the planet for well above 150 million years before the advent of a large variety of mammals.

There are a few periods describing the Cenozoic itself, breaking it up further. In short, there is much more in the business of Cenozoic than an ordinary discussion can reveal. Going by the vast period of time for Earth’s history, Cenozoic describes a fairly short, albeit eventful period of time i.e. 65 million years!

Chandra’s limit: We have dealt with a major part of it in the past, not a long time ago. It deals with Black Holes. Subrahmanyan Chandrasekhar, a US based Indian calculated that a cold star of more than 1 1/2 times the mass of our Sun would not be able to support itself against its own gravity.

Chandra’s Limit, then, is the maximum possible mass of a stable star above which it must collapse and become a Black Hole. Our Sun, as such, will never end up as a Black Hole. Chandrasekhar earned a Nobel Prize for his ingenuity. It would still take some time before the relevant scientific community would accept his hypothesis. But that is the stuff of which scientific geniuses are made. Chandra was awarded the Noble a good 17 years after he first propounded his theory.