NCERT Class 11-Biology: Chapter –2 Biological Classification Part 3

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Question 8:

In the five kingdom system of Whittaker, how many kingdoms are eukaryotes?

Answer:

In the five-kingdom system of Whittaker, four kingdoms are eukaryotes which are as follows:

(a) Protista

(b) Fungi

(c) Plantae

(d) Animalia

Short Answer Type Questions

Question 1:

Diatoms are also called as ‘pearls of ocean’, why? What is diatomaceous earth?

Answer:

The diatoms are the unique organisms, because of their distinctive cell walls. The walls are embedded with silica and thus the walls are indestructible. It show sculpturing and ornamentation that why Diatoms are also called as ‘Pearls of Ocean’. Diatoms have left behind large amount of cell wall deposits in their habitat; this accumulation over billions of years is referred to as ‘diatomaceous earth’. Being gritty this soil is used in polishing, filtration of oils and syrups. Diatoms are the chief ‘producers’ in the oceans.

Question 2:

There is a myth that immediately after heavy rains in forest, mushrooms appear in large number and make a very large ring or circle, which may be several metres in diameter. These are called as ‘Fairy rings’. Can you explain this myth of fairy rings in biological terms?

Answer:

After heavy rains in forest, moisture and nutrients pass down in soil and activates the growth of mushroom mycelium. The basidiocarps of Agaricus (mushroom) arise from the mycelium present in the soil. They appear in a circle like a ring. As these basidiocarps resemble buttons and grow in rings, they are known as fairy rings.

Question 3:

Neurospora - an ascomycetes fungus has been used as a biological tool to understand the mechanism of plant genetics much in the same way as Drosophila has been used to study animal genetics. What makes Neurospora as important as a genetic tool?

Answer:

Neurospora fungus was selected to be a very good tool in genetics because this fungus can be grown easily under laboratory conditions by providing ‘minimal medium’ like inorganic salts, carbohydrates source and vitamin (biotin)

Also under X-ray treatment the mutations can be easily introduced in the fungal cell and meiotic division can be easily seen.

Question 4:

Cyanobacteria and heterotrophic bacteria have been clubbed together in Eubacteria of kingdom Monera as per the “Five Kingdom Classification” even though the two are vastly different from each other. Is this grouping of the two types of taxa in the same kingdom justified? If so, why?

Answer:

As per the “Five Kingdom Classification” cyanobacteria that are autotrophic organisms are clubbed together with heterotrophic bacteria in Eubacteria of kingdom Monera. This grouping of the two types of taxa in the same kingdom is correct. This is because both cyanobacteria and heterotrophic bacteria are unicellular and prokaryotes.

Question 5:

At a stage of their cycle, ascomycetes fungi produce the fruiting bodies like apothecium, perithecium or cleistothecium. How are these three types of fruiting bodies different from each other?

Answer:

The fruiting body of ascomycetes is called ascocarp. Ascocarp can be divided into three types, namely apothecium perithecium and clestothecium.

  • Apothecium is a saucer-shaped structure. It is open from the upper side.

  • Perithecium is a flask-shaped structure. It has a pore-like opening.

  • Cleistothecium is a closed structure. It has no opening.

Question 6:

What observable features in Trypanosoma would make you classify it under kingdom Protista?

Answer:

The following observable features in Trypanosoma would make us classify it under the kingdom Protistai. Unicellular

ii. Well defined nucleus

iii. Membrane bound organelles

iv. The presence of Flagella.

Question 7:

Fungi are cosmopolitan, write the role of fungi in your daily life.

Answer:

Role of Fungi

Fungi are cosmopolitan in occurrence being present in air, water, soil, over and inside animals and plants. The branch of biology dealing with the study of fungi is known as Mycology

(i) Few fungi are used as nutritious and delicious food. e.g., Agaricus compestis

(ii) Saprophytic fungi lives upon dead organic matter and breaks complex substances into simple ones, that are absorbed by plants as nutrients

(iii) Some fungi like Absidia, mucor and Rhizopus possess soil binding properties and make the soil good for cultivation

(iv) They also provide pest resistance, e.g., empusa, Ferinosa etc.

(v) Yeast (Saccharomyces) has the property of fermentation, thus used in alcohol and dough preparation.

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