Since the dawn of civilisation, there have been many attempts to classify the living organisms. The classification was done instinctively based on the use of the organisms for human benefits and not on any scientific criteria.
(a) Who was the first to classify organisms on a scientific basis?
(b) How did he classify plants?
(c) How did he classify animals?

Linnaeus classified aU organisms into two kingdoms Plantae and Animalia; this system was used till recently. But now it has been found that the two kingdom system of classification is inadequate.
(a) Give four reasons to justify that the two-kingdom system of classification is inadequate.
(b) Who proposed the five-kingdom classification?

(a) Name the four groups of bacteria (A-D) shown in the figure given above.
(b) Name one disease caused by bacteria (i) in plants and (ii) in human beings, respectively.

Though the bacterial cell structure is very simple, they are very complex in their behaviour. Bacteria as a group show the most extensive metabolic diversity.
(a) Mention the different modes of nutrition shown by bacteria.
(b) How do Archaebacteria differ from other eubacteria?

The diagram of a Nostoc filament is shown above. Answer the following questions.
(a) Identify the cell labelled 'A'. What is its significance?
(b) Name the pigment that gives them the characteristic blue-green colour.
(c) What type of nutrition is exhibited by them?
(d) Why does the ground become slippery during rainy season?

Kingdom Protista is an artificial assemblage of unicellular eukaryotic organisms and its boundaries are not well-defined. This kingdom forms a link with other kingdoms, Plantae, Animalia and Fungi.
(a) Mention two characteristics in which certain protists resemble plants.
(b) Slime moulds resemble fungi in certain aspects and animals in some other aspects. Mention one feature each of fungi and animals, in which slime moulds resemble them.
(c) Mention two features in which protozoans resemble Animalia.

Two organisms of Kingdom Protista are shown above.
(a) Identify the organisms (A) and (B) and assign them to their respective phyla.
(b) Write any two differences between them.

(a) Identify the two fungi shown above.
(b) Name the respective class, which each of them belongs to.
(c) Write two differences between their sexual spores.

Kingdom Plantae includes all eukaryotic chlorophyUbearing, autotrophic organisms. A few members are parasites or partially heterotrophic like insectivorous plants.
(a) Name two insectivorous plants.
(b) Give an example of a parasitic plant.
(c) All plant cells have a cell wall. What is it mainly made of?
(d) What is meant by alternation of generations?

A diagram of a bacteriophage is given above.
(a) Label the parts A, B, C and D marked in the diagram.
(b) Why did viruses not find a place in the classification?