Chapter 2: Biological Classification

Zoospores are thin-walled spores that are motile and flagellated. They are produced under favourable conditions

Aplanospores are thin-walled non-motile spores and produced under unfavourable condition.

Hypnospores are thick-walled spores and produced under unfavourable condition.

Akinites are from the vegetative cells, thick cell wall. It is formed under unfavourable condition.

Hormogonia are the fragments of filaments formed due to breakage of thallus due to the formation of mucilaginous filled necridia. It is formed under unfavourable conditions.

Blue-green algae phycocyanin and r-phycoerythrin pigments are present beside chlorophyll a

Brown algae possess chlorophyll a, c, carotenoids and xanthophylls. They are olive green in colour.

Red algae possess chlorophyll a, d and phycoerythrin in their body

1. Importance of algae

Algae is used as food in many species like Porphyra, laminaria etc. Chlorella and spirulina are unicellular algae rich in protein

Some kind of marine algae produce a large number of hydrocolloids and used commercially. Example like agar obtained from delirium and gracilaria are used to grow microbes in ice creams.

2. Importance of fungi

There are edible fungi like mushrooms

Yeast is used in the [production of alcohol and also for fermenting malted cereals juices to produce ethanol.

Cyclosporin A is an immunosuppressive agent in organ transplant patients.

Statins are produced by Monascus purpureus and used as a blood-cholesterol reducing agent.

Peat is formed from the wetland vegetation especially from the Sphagnum (bog moss).

Sphagnum likes to grow in acidic nature in the bog, due to the acidity the complete degradation of the cell could not take place due to the presence of less number of bacteria. Sphagnum uptakes water from the dead hyaline pores and holds a great amount of water. Due to the fossilization of Sphagnum, Peat is formed.

C. Linnaeus classified the organisms based on morphological characters like Plantae and Animalia.

But it was not sufficient as there were certain organisms claimed by both botanist and zoologist. Later R.H. Whittaker proposed five kingdom classification system. Euglena and slime moulds were given place under kingdom Protista. Blue-green algae and bacteria were been placed under Monera. In 1977 Carl Woese proposed six kingdom classification. In this classification, the Kingdom Monera was split into two more domains i.e. Eubacteria and Archebacteria this was done based on some major differences in the cell wall. Many more organisms like virus, viroids and prions are there without being classified under any kingdom. Hence it can be said that the biological classification is an ever-evolving phenomenon.

NCERT Exemplar Solutions for Class 11 Biology Chapter 2 have answers to questions in the NCERT Exemplar book. This page also comprises questions on biological classification and other important questions prepared by subject experts at BYJU’S. Practising these exemplar solutions will boost students’ confidence in attempting the Class 11 annual exam and entrance examinations.

The process of classification by which scientists group different living organisms is called Biological Classification. Some of the different characteristics of an organism are based on similarities observed on the basis of physical characteristics. The more similar physical characteristics an organism shares with one another, the more likely they are to be grouped together. Different organisms are primarily classified into seven different ranks, which are given below:

• Phylum
• Class
• Kingdom
• Species
• Family
• Genus
• Order

1. Kingdom Monera
2. Kingdom Protista
3. Kingdom Fungi
4. Kingdom Plantae
5. Kingdom Animalia
6. Viruses, Viroids and Lichens.