NCERT Exemplar Solutions for Class 11 Biology Chapter 2 Biological Classification

NCERT Exemplar Solutions for Class 11 Biology Chapter 2 Biological Classification

These Solutions are part of NCERT Exemplar Solutions for Class 11 Biology. Here we have given NCERT Exemplar Solutions for Class 11 Biology Chapter 2 Biological Classification.

VERY SHORT ANSWER QUESTIONS

Question 1.
What is the principle underlying the use of cyanobacteria in agricultural fields for crop improvement?
Solution:
Cyanobacteria are abfs to fix atmospheric nitrogen and make it available to the plants and thus are used in agricultural crop improvement.
This improves crop yield and also reduces the cost of application of nitrogen fertilisers, e.g., Anabena and Nostoc.

Question 2.
How is the five kingdom classification advantageous over the two kingdom classification?
Solution:
The five kingdom classification, proposed by RH whittaker is based upon cell structure, body structure (unicellular, multicellular), nutrition (autotrophic, heterotrophic) reproduction and habitat either aquatic, terrestrial, or aerial and phylogenetic relationship.
It is thus more useful as compared to two kingdom system of classification which does not distinguish between prokaryotes and eukaryotes and no other kingdom except plant and animal are identified.
Polluted water bodies have high growth of algae due to the presence of nutrient. These nutrients increase the rapid growth of water plants, i.e.,

Question 3.
Polluted water bodies have usually very high abundance of plants like Nostoc and Oscillitoria. Give reasons.
Solution:
algae especially Nostoc and Oscillitoria, etc., and result in colonies. These colonies are generally surrounded by a gelatinous sheath and leads to the formation of blooms in water bodies.

Question 4.
Are chemosynthetic bacteria autotrophic or heteroterophic?
Solution:
Chemosynthetic bacteria are capable of oxidising various inorganic substances such as nitrates, nitrites and ammonia and use the released energy for production of ATP and thus they are autotrophs and not heterotrophs.

Question 5.
The common name of a pea is simpler than its botanical (scientific) name Pisum sativum why then is the simpler common name not used instead of the complex scientific/botanical name in biology?
Solution:
The common or vernacular names cause confusion regarding the identification of specific specimen as they change with the change in place whereas the scientific names are in latin and universally accepted and understood. Scientific names are thus preferred over the common vernacular names.

SHORT ANSWER QUESTIONS

Question 1.
Diatoms are also called as ‘pearls of ocean’, why? What is diatomaceous earth?
Solution:

  1. Diatoms and desmids are included under chrysophytes, kingdom-Protista.
  2. These are the main producers in the ocean. They prepare food for themselves and for the other life forms in the ocean as were a siliceous shell known as frustule cores the body of diatoms, this is the reason they are also called as ‘pearls of ocean. ‘
  3. Diatomaceous earth’ is the accumulation of large deposits of diatoms that forms a siliceous covering extending for several 100 metres formed in billions of years.
  4. The material obtained from these deposits is used in polishing and filtration of oils and syrups.

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?
Discuss the mycilial structure in Agaricus and its soil borne nature.
Solution:
The fruiting bodies in Agaricus are known as basidiocarps. They form a concentric ring like structure from the mycelium present in the soil. These basidiocarps resemble button in shape and develop to form a ring like structure.
NCERT Exemplar Solutions for Class 11 Biology Chapter 2 Biological Classification 1.1
This fairy ring structure in Agaricus stimulate productivity in plants. This rings are the fruiting bodies of this fungus and the diameter of this fairy ring increases every year due to the spread of mycelium.

Question 3.
Neurospora an ascomycetes fungus has been •arsed 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 so important as a genetic tool?
Solution:
Neurospora fungus can be grown easily under laboratory conditions by providing ‘minimal medium’ like inorganic salts, carbohydrates source and vitamin (biotin) and thus was selected to be a very good tool in genetics. The mutations can be also easily introduced in the fungal cells and meiotic division can be easily seen under X-ray treatment.

Question 4.
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?
Discuss the type of fruiting bodies formed by ascomycetes fungus and differentiate accordingly on the basic of there structures.
Solution:
Ascomycetes consist of sporangial sac called ascus. Asci (singular-ascus) may occur freely or in aggregated form with dikaryotic mycelium to form the fruitification bodies called ascocarps.
The fruitification formed by asci include the following :
(i) Apothecium is cup like structure, e.g., Peziza.
NCERT Exemplar Solutions for Class 11 Biology Chapter 2 Biological Classification 1.2
(ii) Perithecium is flask shaped, e.g., Neurospora
NCERT Exemplar Solutions for Class 11 Biology Chapter 2 Biological Classification 1.3
(iii) Cleistothecium is closed with a slit, e.g., Penicilium
NCERT Exemplar Solutions for Class 11 Biology Chapter 2 Biological Classification 1.4

Question 5.
What obsrevable features in Trypanosoma would make you classify it under kingdom- Protista?
Discuss cell structure of Trypanosoma also discuss its different strain brief.
Solution:
Trypanosoma is included under flagellated protozoans on the basis of locomotary organ. It resembles Protisia in the following characters.
NCERT Exemplar Solutions for Class 11 Biology Chapter 2 Biological Classification 1.5
(i) It is unicellular.
(ii) It reproduces asexually i.e., by binary fission.
(iii) Possess centrally located nucieus and also contain an prominent nucleus endosome.
(iv) Reserve food material is in the form of granules.

LONG ANSWER QUESTIONS

Question 1.
Algae are known to reproduce asexually by variety of spores under different environmental conditions. Name these spores and the conditions under which they are produced.
Solution:
Asexual reproduction in algae is very common mean of reproduction. Algae and their spores exhibit significant diversity and vary greatly in their level of specialisation. Asexual reproduction by spores and their types include:
(i) Zoospores are mobile flagellated spores. In this protoplasm of each vegetative cell undergoes repeated longitudinal division either into 2 or 4, rarely 8 or 16 daughter protoplasts. Before the onset of division the parent cell loses its flagella.

  • Each daughter protoplast after the last series of division secretes a cell wall and a neuromotor apparatus that develops two flagella, eyespots and contractile vacuoles.
  • Each of the daughter cell thus formed resembles the parent cell in all aspects except the small size.
  • Under favourable conditions formation of zoospores is very common.
    NCERT Exemplar Solutions for Class 11 Biology Chapter 2 Biological Classification 1.6

(ii) Aplanospores are the non-motile spores. They are formed asexually within a cell, in which protoplast withdraws itself from the parent wall, rounds up and develops into aplanospores which germinate either directly or may divide to produce zoospores.
NCERT Exemplar Solutions for Class 11 Biology Chapter 2 Biological Classification 1.7

(iii) Hypnospores- In this, the protoplasm withdraws from the cell wall, rounds up and develops a thick wall under unfavourable conditions. These resting spores are called as hypnospores. Due to presence of haematochroma they are red in colour e.g., Vancheria, Ulothrix.
(iv) Akinetes are special vegetative thick walled cells present in the filaments which remain under dormant state and resume germination under favourable conditions. They can also withstand unfavourable condition as Spirogyra.
(v) Statospores are thick walled spores ‘ produced in diatoms.
(vi) Neutral spores are the protoplast, of vegetative cells directly functioning as spores (e.g., Ectocarpus).

Question 2.
Apart from chlorophyll, algae have several other pigments in their chloroptast. What pigments are found in blue, green, red and brown algae, that are responsible for their characteristic colours?
Solution:

  • All photosynthetic organisms comprise of one or more organic pigments that are capable of absorbing visible, radiations, which will initiate the photochemical reaction of photosynthesis.
  • The three major classes of pigments found in plants and algae are the chlorophylls, the carotenoids and the phycobilins.
  • Carotenoid and phycobilins are called accessory pigments since, the quanta absorbed by theese pigments can be transferred to chlorophyll.
  • The diversity of light harvesting pigments in alga implies that the common ancestor was primitive and that no close affinity exist between blue, green, red, brown, golden brown and green algae.
    NCERT Exemplar Solutions for Class 11 Biology Chapter 2 Biological Classification 1.8

 

Question 3.
Make a list of algae and fungi that have commercial value as source of food, chemicals, medicines and fodder.
Solution:
Algae
Around 70 species of marine ailgae are used for food, chemical and medicinal purpose.
NCERT Exemplar Solutions for Class 11 Biology Chapter 2 Biological Classification 1.9
Fungi
The role of fungi was established in early history. Since, the beginning of cultivation yeast have been used in making of bread and alcohol. The discovery of penicillin that marked the beginning of a new approach to microbial dis eases in human health.
Products of fungi in medicine, chemical and food include.
Around 70 species of marine aigae are used for food, chemical and medicinal purpose.
NCERT Exemplar Solutions for Class 11 Biology Chapter 2 Biological Classification 1.10

We hope the NCERT Exemplar Solutions for Class 11 Biology at Work Chapter 2 Biological Classification, help you. If you have any query regarding NCERT Exemplar Solutions for Class 11 Biology at Work Chapter 2 Biological Classification, drop a comment below and we will get back to you at the earliest.

NCERT Exemplar Solutions for Class 11 Biology Chapter 1 The Living World

NCERT Exemplar Solutions for Class 11 Biology Chapter 1 The Living World

These Solutions are part of NCERT Exemplar Solutions for Class 11 Biology. Here we have given NCERT Exemplar Solutions for Class 11 Biology Chapter 1 The Living World.

VERY SHORT ANSWER QUESTIONS

Question 1.
Couplet in taxonomic key means……. .
Solution:
Couplet in taxonomic key is a pair of a contrasting characters used as tool foi” identification to aid in identification of a newly discovered organism.

Question 2.
What is a monograph?
Solution:
Monograph is a specialised work of documenting information on a particular taxon, /. e., family or genus or on aspect of subject, usually by a single author.
The main purpose of monograph is to present primary research and original work.

Question 3.
Amoeba multiplies by mitotic cell division. Is this phenomena growth or reproduction? Explain.
Solution:
Amoeba multiplies by simple mitotic cell divisions giving rise to two daughter Amoebae. Growth here is synchronous with reproduction, i.e., increases in number.

Question 4.
Define metabolism.
Solution:
Metabolism is the sum total of all biological reactions occurring in any living cell, which are controlled absolutely by enzymes. These reactions are of two types breaking down reactions (catabolism, e.g., cell ‘ respiration) and synthesing reactions (anabolism,
e.g., photosynthesis).

Question 5.
Which is the largest botanical garden in world? Name a few well known botanical gardens in India.
Solution:
A botanical garden is dedicated to collection, cultivation and display of wide range of plants labelled with their botanical names.
The largest botanical garden in the world is Royal Botanical Garden (in Kew, London). In India the famous well known botanical gardens are
(i) National Botanical Garden (NBG) Lucknow, UP.
(ii) Botanical Garden of FRI, Dehradun (UK).
(iii) Lloyd Botanical Garden, Daijeeling.
(iv) Indian Botanical Garden, Sibpur, Kolkata.

SHORT ANSWER QUESTIONS

Question 1.
A ball of snow when rolled over snow increases in mass, volume and size. Is this comparable to growth as seen in living organisms? Why?
Solution:

  1. Living organisms, grow, have metabolism and respond to external stimuli and reproduce as well. These characteristics are not shown by non-living objects.
  2. In biological terms growth is characteristic feature of all living organisms. It relates to increase in size by accumulation of protoplasm in the cell thus resulting in increase in the size of the cell.
  3. Increase in number of cell by cell division on other hand results in the size of individual organism.
  4. Snow is an inanimate (non-living) object, while rolling over, it gathers more snow on its surface thus, it increases in size by physical phenomenon but not by biological phenomenon.
  5. This growth cannot be thus compared to that seen in living organisms.

Question 2.
In a given habitat we have 20 plant species and 20 animal species. Should we call this as ‘diversity or biodiversity’? Justify your answer.
Solution:
There are existing 20 plant species and 20 animal species in the given habitat. They will exhibit the biodiversity in that given habitat because diversity refers to variation in a broad term and can be applied to any area whereas biodiversity is a degree of variation of life forms within a specified area.

Question 3.
International Code of Botanical Nomenclature (ICBN) has provided a code for classification of plants. Give hierarchy of units of classification, botanists follow while classifying plants and mention different ‘suffixes’ used for the units.
Solution:
ICBN has specified certain rules and principles in order to facilitate the study of plants by botanists. It helps in correct positioning of any organism newly discovered through the pressure of proper identification and nomenclature.
The taxonomic hierarchy, which is used while
classifying any plant given below
Kingdom-Plan tae
Division-phyta
Class-ae
Order-ales
Family-eae/ceae
Genus-First name of organism usually Latin word and written in italics.
Species-Second word of scientific name, also written in italics.

Question 4.
What are hormone receptors? What are the modes of their action ?A plant species shows several morphological variations in response to altitudinal gradient. When grown under similar conditions of growth, the morphological variations disappear and all the variants have common morphology. What are these variants called?
Solution:
These morphological variants are called bio types. It includes group of genetically similar plants showing similarity when grown in same environmental and geographical regions. The same environment provides them the similar abiotic factors like soil, pH, temperature, etc.
When growth in two different geographical regions, they are exposed to different abiotic characters which affects their growth, and development bringing changes in their external morphological features but, their genetic constitution remain same.

Question 5.
What is the difference between flora, fauna and vegetation? Eichhornia crassipes is called as an exotic species, while Rauwoljia serpentina is an endemic species in India. What do these terms exotic and endemic refer to?
Solution:
Following are the difference between flora, fauna and vegetation
NCERT Exemplar Solutions for Class 11 Biology Chapter 1 The Living World 1.1

Question 6.
Brinjal and potato belong to the same genus Solamim, but to two different species. What defines them as seperate species?
Solution:
Genus is a taxonomic rank used in bionorr.’al nomenclature comprising of a group of related species sharing few common characters.
Solanum is the largest genus of flowering plants which includes few economically important plants, e.g., potato, tomato, tobacco and brinjal. All these plants show some common morphological structures related to vegetative and reproductive similarities. So, they are are included in the same common genus Solanum.

Question 7.
The number and kinds of organism is not constant. How do you explain this statement? Change is law of nature.
Solution:
The number and kind of organisms is not constant, because of the following reasons new organism are added due to mechanisms of.
(i) sexual reproduction
(ii) mutation
(iii) evolution
The number of organisms get reduced due to
(i) environmental threats
(ii) loss of habitat
(iii) anthropogenic activities

LONG ANSWER QUESTIONS

Question 1.
Brassica campestris Linn
(a) Give the common name of the plant.
(b) What do the first two parts of the name denote?
(c) Why are they written in italics?
(d) What is the meaning of Linn written at the end of the name?
Solution:
Brassica campestris Linn
(a) The common name of Brassica compestris Linn is mustard.
(b) The first part of the name denotes the genetic name and the second part is the species name of the plant.
(c) According to ICBN, all scientific names are comprised of one genetic name followed by a species name, which require to be always written in italics. It is a rule of bionomial nomenclature.
(d) Linn means Linnaeus. He was the first to discover the plant. He identified, named and classified the plant, so the plant is named after him by adding suffix ‘Linn’, after the scientific name B. campestris.

Question 2.
What are taxonomical aids? Give the importance of herbaria and museums. How are Botanical gardens and Zoological parks useful in conserving biodiversity?
Solution:
The aids which help in identification, classification and naming of a newly discovered organisms (plant or animal) the taxonomic aids.
It could be in the form of a preserved document like herbaria or specimen kept at museums or scientific institutions. Other aids include written document like monography, taxonomic keys, couplets, etc.
A new organism found can be studied while comparing it with living plants and animals living in protected areas like Botanical gardens, Zoological parks, etc. Botanical gardens helps in conservation of plants by
(i) Plant species growing important local and keeping record of them.
(ii) Growing and maintaining species that rare are and endangered.
(iii) Supplying seeds for different aspects of botanical research.
Zoological parks contribute in conserving biodiversity by
(i) Providing natural environment and open space to animals.
(ii) Providing home to different native and exotic wild animals.
(iii) Rescue of endangered species.
(iv) Facilitating breeding animal and releasing them free. Thus, both botanical gardens and zoological parks play an important role in conservation of biodiversity.

We hope the NCERT Exemplar Solutions for Class 11 Biology at Work Chapter 1 The Living World, help you. If you have any query regarding NCERT Exemplar Solutions for Class 11 Biology at Work Chapter 1 The Living World, drop a comment below and we will get back to you at the earliest.