What is lichen? Write some important characters of lichens.

       Lichens are a specific group of primitive plants. A lichen is compost of two different components which are algae and fungi.
Both the components are involved in matual beneficial relationship. The algal component of lichen is known as phycobiont and the fungal component is known as mycobiont. The organisation neither resembles algae nor fungi but it is a symbiotic association. The fungal partner absorbs water, mineral nutrients and supplies those to the algal partner which can synthesize food materials.
   
        Some important characters of lichens are as follows:

1. Lichens are the composite association of algae and fungi.

2. Lichens reproduce both by asexual and sexual methods. Only the fungal component is involved in sexual reproduction.

3. The male sex organ is termed as spermogonium and the female sex organ is termed as carpogonium.

4. The growth of lichens is very slow.

5. The lichens are able to survive in high temperature and dry conditions for a long time.

6. Some species of lichens are used to produce medicines. Lobaria, Evernia, Peltigera etc. are used in whooping cough.

What is bacteria?

       Bacteria are very small and simplest type of microorganisms. They do not have true nucleus. The bacteria are found to be present in everywhere, i.e., in air,water,soil and particularly in all such habitats which are usually rich in ogranic contents.
       The bacteria was first discovered by Anton Von Leeuwenhoek in the year 1675.

      Following are some characters of bacteria:

a. Bacteria are microscopic organisms, with average diameter ranging from 0.5 micron to 1.5 micron in case of sperical bacteria whereas rod shaped filamentous forms are about 0.5 micron yo 1.5 microns in length and 0.2 to 1 micron in width.

b. Bacteria are unicellular organisms.

c. Bacteria are mostly saprophytes, some are parasites and a very few are autotroph.

d. Bacteria possess a definite cell wall surrounding the inner protoplasm.

e. Bacteria are prokaryotic organisms, i.e., they do not have a true nucleus.

f. Except ribosome and mesosome other cell organelles are not present.

g. Reproduction takes place by means of spore formation and cell division.

What is mitosis cell division?

Mitosis cell division is a kind of cell division in which the newly developed cells contain same number of chromosomes with their parent cell.
     Mitosis cell division is also known as somatic cell division as it takes place in somatic cells i.e., in body cells of plants and animals. 

What is Botany?

     Botany is the branch of biology that deals with the study of plants from scientific point of view. Botany is also known as plant science.

What is prop root?

Q. Define prop root.

Answer. Prop roots are roots which arise from the horizontal branches of the stem and hang in the air. These roots grow in length and penetrate the soil and ultimately act as pillars supporting the main stem.
Example: Banyan tree.

What is virus? Mention some characteristics features of Viruses.

        Viruses are very small infectious particles composed of a protein coat and a nucleic acid core.They can reproduce within the host cell only by using the biochemical mechinary of the hosts.
     
        Viruses are found to show some specific characteristics studying wchich one can't fix whether viruses are living or non-living.
        Some of the characteristics features of Viruses are under mentioned:

1. Viruses are granular and can be observed under electron microscope only.

2.Viruses are host specific.

3.They produce characteristic symptoms on specific hosts.

4. They contain genetic material which may be either DNA or RNA.

5. They are infectious.

6.They are in between living and non-living as they show different characters some of which belongs to living beings and some characters belong to non-living things.

7. Most of the viruses can't be seperated using bacterial filters.

8. They show response to change in humidity and temperature.