THE BIG WORLD OF

TOPIC AT GLANCE…

What are microorganisms???

Where are microorganisms found???

What are various groups of microorganisms???

How are microorganisms both beneficial and harmful to

us???

How does food go bad???

What are the common methods of preserving food???

What is the role of various microorganisms in nitrogen

cycle in nature???

WHAT ARE MICROORGANISMS???

“Microorganisms” is derived from Greek words

micros (small) and organismos (organisms).

They are too small and can be seen with the help of

microscope.

Also called as microbes.

They can be unicellular (single-celled) as well as

multicellular (multi-celled).

The study of microorganisms is known as

microbiology.

WHERE ARE THEY PRESENT???

They are found everywhere– in water, in soil and in air.

Dessert soil lack them because of hot and dry climate but found near roots of plants and dead leaves.

They have heterotrophic mode of nutrition.

Parasitic microorganism causing diseases in host are known as pathogens.

TYPES OF MICROORGANISMS

Bacteria

Algae

Protozoa

Fungi

BACTERIA

Simplest unicellular organisms.

Exist singly or in chains or groups.

A thick outer wall (spore)help them to survive in unfavourable conditions.

Three types of bacteria:

Bacillus (rod-shaped)

Coccus (spherical-shaped)

Spirillus (spiral-shaped)

ALGAE

Plant-like organisms having cell walls.

Contains chlorophyll, therefore, can make food through photosynthesis.

Autotrophs but lack roots, stem and leaves.

They can be unicellular or multicellular.

Seaweeds are largest algae.

They are found in water bodies and moist places.

PROTOZOA

It means first animal.

They are unicellular organisms.

Exist in water and soil.

They have various locomotory organs like pseudopodia, cilia and flagella.

They digest their food in compartments called vacuoles.

FUNGI

They have saprophytic

mode of nutrition.

They obtain nutrients fro

dead and decaying

organic matter.

Examples:

Mushroom (Agaricus)

Moulds (Rhizopus)

Yeast (Unicellular Fungi)

VIRUS

Virus means poison in Latin.

They can be helpful as well as harmful.

They are the link between living and non-living.

They are alive only when it enters cells of a living

plant or animal energy of the host cell to remain

alive.

FRIENDLY MICROORGANISMS

Microorganisms play vital role in our lives.

Ways in which they are beneficial to us:

In decomposition and recycling

In increasing soil fertility

In food chains

In food-making processes

In water treatment plants

In production of energy-giving fuels

For making antibiotics

For making vaccines

In science and technological fields

HARMFUL MICROORGANISMS

Microorganisms more than the harm the y cause to us than for their uses.

Microorganisms causing diseases are called pathogens.

They make their way into our body through the following ways:Through air

Through food and water

Through direct contact

Through carriers

Through cuts and wounds on skins

FOOD PRESERVATION

The process of treatment food to slow down or to

stop the growth of microorganisms that spoil food is

known as food preservation.

Food spoilage by microorganisms is a disagreeable

change in food.

Common methods of food preservation:

Using natural preservatives (salt)

Using food grade chemical preservation (heating)

By refrigeration and freezing (pasteurization)

By drying and dehydration (canning)

NITROGEN CYCLE

Nitrogen cycle is a cycle in which atmospheric

nitrogen is converted from its gaseous form into

usable form and returned to the atmosphere

through stages that involves microorganisms.

STAGES OF NITROGEN CYCLE

Nitrogen fixation

Nitrogen assimilation

Ammonification

Nitrification

Denitrification

OVERVIEW

THANK YOU

Made by:

Rahul Chawla

VIII B