Question

Bacteria cannot be seen with the naked eyes, but these can be seen with the help of a microscope. If you have to carry a sample from your home to your biology laboratory to demonstrate the presence of microbes under a microscope, which sample would you carry and why?

Answer 1

Hint: Bacteria are single celled, microscopic organisms that exist in every environment. They are organisms with simple structure and complex behaviour. They show extensive metabolic diversity.

Complete answer:
- Bacteria live both inside and outside the living organisms. They have various modes of nutrition. They can be photosynthetic autotrophs, chemosynthetic autotrophs or heterotrophic in nature.
- Curd is a great source of bacteria as it contains millions of lactic acid bacteria that coagulate and digest milk proteins.
- Similarly tap water contains millions of bacteria that can be easily studied under the microscope. It contains approximately 80,000 bacteria in 1 ml of water that can be studied by observing under a microscope.
- So for studying the presence of microbes under a microscope, we can carry either curd or tap water.

Additional information:
- Bacteria lack nuclear membranes and are also devoid of plastids, mitochondria, and advanced flagella.
- They reproduce primarily through asexual modes of reproduction like binary fission. Some also show protosexual phenomenon.
- It belongs to kingdom Monera which is divided into two major groups- the Eubacteria or true bacteria and the Archaebacteria or primitive bacteria.
- Eubacteria are ubiquitous in nature i.e. they occur everywhere and anywhere.
- Archaebacteria are primitive and most primitive prokaryotes that are living under most primitive conditions like very high temperature, very high salt concentrations. They are termed as living fossils because they can survive the geological changes successfully.
- They can withstand the temperature upto 78 degrees centigrade while some psychrophilic bacteria can survive upto very low temperature as low as -19 degrees centigrade.

Note: Bacteria are very small and their size generally ranges from 0.2-1.5 mm in length. Dialister pneumonsites are the smallest bacteria while Spirillum volutans is the longest bacterium.