Tag: cell theory

A microscope is an instrument used to see objects that are too small to see by naked eyes. It consists the lens which magnifies the image of cells. 

In the beginning of the 19th century, Theodor Schwann (1839) established cell theory and postulated that cell is the basic unit of life. 

The cell was first discovered by Robert Hooke in 1665. He gave 60 'observations' in detail of various objects under a coarse, compound microscope. One observation was from very thin slices of bottle cork. Hooke discovered a multitude of tiny pores that he named "cells". He described a honeycomb like network of cellulae (latin for storage rooms) in cork slices.

Resolving power is the ability to distinguish two close objects as distinct. It is calculated by the formula 0.61 wavelength/ numerical aperture, where  numerical aperture is the light collecting ability of lens. It is clear that resolving power will be more if wavelength is less and numerical aperture is more. Thus, the correct answer is option A.

Total magnification is calculated as (ocular lens magnification) * (objective lens magnification). With an ocular lens of 10x, the possible total magnifications are 10*10=100x, 10*20=200x, 10*30=300x, and 10*43=430x. 10x is not possible as the minimum magnification is 100x.

Antonie van Leeuwenhoek, known as the father of microbiology, developed simple microscopes with single lenses that could achieve magnifications of up to 300 times.

Pond water is a rich habitat containing various microorganisms, including bacteria and protozoa, which are commonly observed under a light microscope.

Antonie van Leeuwenhoek used single-lens microscopes, which he made, to make the first observations of bacteria and protozoa. His extensive research on the growth of small animals such as fleas, mussels, and eels helped disprove the theory of spontaneous generation of life.

Bacteria are extremely small and require high magnification to be seen clearly; therefore, the 100x objective lens (often used with oil immersion) is necessary.

Both Scanning Electron Microscopes (SEM) and Transmission Electron Microscopes (TEM) utilize electron beams to image specimens at high resolution.