Biological Classification Test - 8

Azolla plays a very important role in rice production. Azolla and its nitrogen-fixing partner, Anabaena, have been used as green manure to fertilize i rice paddies and increase production. With the help of Azolla, rice can be grown year after year, several crops i a year, with little or no decline in productivity; hence no rotation of crops is necessary.

Prokaryotic cells have a disorganized nucleus, with circular DNA  devoid of histones. 

Eukaryotic DNA is linear and is associated with basic proteins called histones.

A virus is an organism that can be considered both living and non-living. It can be considered as living when it is inside any host (bacterium) as the virus infects the host cell and replicates inside it making several copies of it. When it is outside the host cell, it is non- living as it can not carry out its life- processes of either reproducing or digestion etc. 

Agrobacterium tumefaciens, is soil borne gram -negative bacteria that causes crown galls on most of the dicot leaves. It contains a plasmid also called the Ti (tumor inducing) plasmid, which is used widely in genetic engineering/recombinant DNA technology  for creating transgenic plants or genetically modified plants.

Eukaryotic cilia are made up of tubulin protein. Cilia have a core of 2 microtubules and around there are 9 doublet microtubules. These are not at all hair like structures.

The atmospheric nitrogen is not available for the plants. By the process of nitrogen fixation, atmospheric nitrogen is converted into ammonia and made available for plants. The nitrogen fixer soil organisms belong to bacteria. Examples of free-living nitrogen-fixing bacteria include cyanobacteria, Azotobacter, Clostridium. Examples of symbiotic nitrogen-fixing bacteria include Rhizobium, Bradyrhizobium.

Euglena is connecting link between animals and plants. Euglena contains chlorophyll, yet it resembles animals, because it, feeds like animals in the absence of sunlight. It resembles the ancestral form which the plants and animals evolved.

The function of contractile vacuole in protozoa is hydrostatic or osmoregulatory. The mechanism which is assumed to effect water regulation is the contractile vacuole. The vacuole periodically increases in volume (diastole) to get filled with water and contracts (systole) to discharge its water content to the surrounding environment and this is the basic mechanism of osmoregulation, e.g., Amoeba.

Amoeba is an unicellular organism also known as amoeboid, which has the capacity to modify its body by expanding and revoking pseudopods. It is unicellular and can be seen in fresh water. This single cell performs overall function of the body such as collects the food, oxidizes it, supplies energy, excretes waste products and helps in the reproduction. Carbon dioxide and ammonia are the main waste products of amoeba and they are excreted out through the body by the process called diffusion with the help of contractile vacuole. The waste formed in the cytoplasm of amoeba gets in to the contractile vacuole. Then the contractile vacuole enlarges and moves to the periphery of plasma membrane and finally it bursts out. Thus the discharge of waste products directly in to the sea.

The most well known examples of yeast fermentation are in the production of alcoholic drinks and the leavening of bread. For their participation in these two processes, yeasts are of major importance in the food industry. Varieties of the Saccharomyces cervisiae genus are the most common yeasts in fermented foods and beverages.