Important Questions for Class 11 Biology Chapter-2- Biological Classification

Biological classification is the process of grouping living organisms. The five kingdom classification was proposed by R.H.Whittaker. He named the kingdoms as Monera, Protista, Fungi, Plantae and Animalia. He classified them on the basis of cell structure, thallus organization, reproduction, mode of nutrition, etc.

Q.1. What advantages does the five-kingdom classification have over the two-kingdom classification?

A.1. The advantages of five kingdom classification over two kingdom classification are as follows:

  • It is based upon cell structure

  • It is based upon the body structure

  • Nutrition

  • Way of living

  • Phylogenetic relationship

More to Read: Five Kingdoms Classification

Q.2. Why are cyanobacteria used in agricultural fields for crop improvement?

A.2. Cyanobacteria have the ability to fix atmospheric nitrogen and make it available to the plants. This improves the crop yield. That is why cyanobacteria are used in agricultural fields.
Also read: Crop Improvement

Q.3. The chemosynthetic bacteria are autotrophic or heterotrophic?

A.3. Autotrophs

Q.4. What similarities do a virus and non-living objects share?

A.4. A virus is considered living inside the host but non-living when outside the host. This is because:

  • Inert nature

  • Inability to reproduce

  • No cellular organization

  • It cannot grow and divide

Q.5. Why do polluted water bodies have an abundance of Nostoc and Oscillatoria?

A.5. The nutrients present in the polluted water bodies enhance the growth of algal plants such as Nostoc and Oscillatoria.

Q.6. Name the eukaryotic kingdoms in the five-kingdom classification proposed by Whittaker.

A.6. The eukaryotic kingdoms in the five-kingdom classification are:

  • Protista

  • Fungi

  • Animalia

  • Plantae

Q.7. What is the nature of the cell wall in diatoms?

A.7. The cell wall of diatoms forms two thin overlapping cells. It is made up of silica.

Q.8. Who proposed the five kingdom classification?

A.8. R.H.Whittaker

Q.9. What is the difference between a virus and a viroid?

A.9. A virus contains DNA or RNA as the genetic material and a protein coat whereas the viroids do not have a protein coat but RNA as genetic material.

Q.10. State the uses of heterotrophic bacteria and archaebacteria which are economically important.


Heterotrophic Bacteria

  • They maintain the fertility of the soil by nitrogen fixation, ammonification and nitrification. Eg., Rhizobium

  • The milk products such as cheese, curd are obtained by bacteria.


  • Biogas is produced by methanogens from animal dung.

Short Answer Type Questions

Q.1 What is diatomaceous earth? Why are diatoms referred to as ‘pearls of the ocean’?

A.1. The accumulation of large deposits of diatoms that forms a covering of silica extending over several 100m for billions of years. Diatoms are the main producers in the ocean. They prepare food for themselves as well as other life forms in the ocean. Their body is made up of siliceous shell known as a frustule.

Q.2. Explain the myth of ‘fairy rings’ created by the mushrooms after heavy rains in the forest.

A.2. The mycelium of the mushroom absorbs nutrients from the soil. The nutrients in the centre get exhausted and grow in diameter thereby forming a circle. These rings are the fruiting bodies of the fungus and are known as ‘fairy ring’.

Q.3. Why is Neurospora an important genetic tool?

A.3. Neurospora can be grown easily under laboratory conditions by providing organic salts, carbohydrates and vitamin. Under X-ray treatments, mutations can be introduced easily in the Neurospora cells and meiotic division is easily visible.

Q.4. What is the role of fungi our daily lives?

A.4. The role of fungi in our daily life are as follows:

  • Few fungi such as Agaricus compestris are highly rich in nutrients and are used as food.

  • The saprophytic fungi act upon dead and decaying matter and convert the complex substances into simpler ones that are absorbed by the plants in the form of nutrients.

  • Some fungi possess the soil binding capacity and make the soil good for cultivation. For eg., Mucor, Absidia, etc.

  • They provide resistance against pests.

  • Fungi are used in alcohol and yeast preparation due to their fermentation property. For eg., Saccharomyces

Q.5. What features of Trypanosoma make it fall under the kingdom Protista?

A.5. Trypanosoma falls under the kingdom Protista due to the following reasons:

  • They are unicellular.

  • The nucleus is centrally located and the nucleus contains an endosome.

  • Reserve food material is granulated.

  • They reproduce asexually by binary fission.

Read More: Binary Fission

Q.6. The ascomycetes produce fruiting bodies like apothecium, perithecium, or cleistothecium. What are the differences between these three fruiting bodies?

Apothecium Perithecium Cleistothecium
It is a cup-shaped structure. It is the ascigerous fruitification of lichens. Eg., Peziza It is a flask-shaped structure. Eg., Neurospora It is a closed ascocarp. Eg., Penicillin

Q.7. Cyanobacteria and heterotrophic bacteria are very different from each other but fall under eubacteria of kingdom Monera. Is this type of grouping justified?

A.7. They are introduced in the same kingdom due to a few similarities they share:

  • They do not possess a well-defined nucleus.

  • DNA lies freely in the cytoplasm.

  • The ribosomes are 70S type.

  • The nucleus does not have a nucleolus and a nuclear membrane.

Also read: Kingdom Monera

Q.8. Name a few plants that are partially heterotrophic.

A.8. Partial heterotrophs are mentioned below:

  • Loranthus and Viscum are partial stem parasites with leathery leaves. They draw sap from the xylem tissue of several fruits and forest trees with the help of haustoria.

  • The insectivorous plants trap the insects and digest them by the proteolytic enzymes secreted by the epidermis of the leaves.

Q.9. What do you understand by ‘phycobiont’ and ‘mycobiont’?

A.9. The algal component of the lichens is known as phycobiont, while the fungal component is known as mycobiont. Both the algae and the fungi live in symbiotic association with each other. The algae prepare food for the fungi and the fungi, in turn, provides shelter and absorbs nutrients from the soil.

Q.10. Are viruses living or non-living?

A.10. Viruses are known as the connecting link between the living and the non-living. The features that classify them as living and non-living are mentioned below:


  • They possess a non-cellular organization.

  • They are inactive outside the body of a host.

  • Lack of respiration

  • The absence of cell metabolism.

  • They can be crystallized and precipitated.


  • They possess genetic material.

  • They can undergo mutation.

  • They can grow and multiply when inside the host.

  • They are obligate parasites and attack specific hosts.

Explore More: Viruses

Long Answer Type Questions

Q.1. Give an account of the asexual reproduction by spores in algae.

A.1. Asexual reproduction in algae involves the formation of several kinds of spores.

  • Zoospores- Motile, naked spores with two, four or many flagella. For eg., Chlamydomonas possess biflagellate zoospores, Ulothrix possess quadriflagellate zoospores and Oedogonium possess multiflagellate zoospores.

  • Aplanospores- These spores are non-motile. They may be formed either singly or by the division of protoplast to form several aplanospores. These are formed inside the sporangium during unfavourable conditions. Eg., Microspora.

  • Tetraspores- Tetraspores are produced by diploid plants of some algae. These are a special type of haploid aplanospores formed within tetrasporangium.

  • Akinetes- These are thick-walled spore-like structures with abundant food reserves. They can survive under unfavourable conditions.

  • Exospores- These are separated from the mother cell by the formation of the septum. They are formed near the end of the mother cell. Eg., Chamaesiphon

  • Endospores- The mother protoplast divides and forms the endospores. They are also known as conidia or gonidia. These are formed to survive under unfavourable conditions. Eg., Dermocarpa

Q.2. What are the characteristic features of euglenoids?

A.2. The characteristic features of euglenoids are:

  • They are unicellular protists, commonly found in freshwater.

  • The cell membrane is rich in proteins and is known as a pellicle.

  • Two flagella are present on the anterior end of the body.

  • They possess a small light-sensitive eyespot.

  • They are autotrophic because of the presence of photosynthetic pigment chlorophyll. However, in the absence of light, they behave as heterotrophs.

  • They are known as the connecting-link between plants and animals because they possess features common to both plants and animals.

Q.3. How is ‘peat’ naturally formed?

A.3. Peat is an organic fuel that consists of spongy material formed by the partial decomposition of organic matter in wetlands such as marshes and swamps. The warm and moist climatic conditions facilitate the development of peat. The main producers of peat Sphagnum mostly occur in bogs. This plant gets accumulated over a period of time and gets hardened thereby converting into peat. It is used in the production of ethyl alcohol, tar, ammonia, etc. It is also used for the purpose of covering roots during transportation.

Q.4. Enlist the various algae and fungi that have commercial values in medicines, food, and chemicals.

A.4. Algae:

Medicines Food Chemicals
Corollina-cures worm infection Porphyra, Rhodymenia, Chondrus Phycolloids- includes agar, carageen in and funori
Polysiphonia- antibacterial property Laminaria, Alariam, Macrocystis, sargassum Alginic acid- phycocolloid obtained from laminaria
Sodium laminarin sulphate- coagulant Edible brown algae used as fodder Nerocystis, fucus, sargassum
Chlollera, Cualerpa- antibiotic extraction Chlamydomonas, Chlollera, Scenedesmus-sewage oxidation
Durvillea- Vermifuge properties Ulva, Caulerpa, Enteromorpha Ointments, toothpaste, creams, cosmetics, etc.
Ascophyllum- antibiotic properties Used as salts in obtaining emulsions


Medicines Food Chemicals
Penicillin Aspergillus oryzae- fermentation, Saccharomyces roxii- yeast Aspergillus niger
Baccatin-A Monoasus purpureus-food colourings Aspergillus niger and P.purpurogenum
Penicillium citrinin Penicillium comemberti, Penicillin roqueforti-cheese production Awentil and Mucur- production of citric acid
Claviceps purpurea P.glacum, A.gallomyces

For more information on any other biological concepts, keep exploring BYJU’S website. You can also download BYJU’S app for further reference.

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Photoperiodism was first characterized in