NCERT Exemplar Class 11 Biology Solutions The Living World
NCERT TEXTBOOK QUESTIONS SOLVED
Multiple Choice Questions
1.As we go from species to kingdom in a taxonomic hierarchy, the number of common characteristics
(a) will decrease
(b) will increase
(c) remain same
(d) may increase or decrease.
2.Which of the following ‘suffixes’ used for units of classification in plants indicates a taxonomic category of’Family’?
(c) – Aceae
Soln. (c) : The name of a plant Family is formed by adding the suffix-‘aceae’ to the stem of a legitimate name of an included genus, e.g., Rosaceae from Rosa, Linaceae from Linum and Cucurbitaceae from Cucurbita.
3.The term ‘systematics’ refers to
(a) identification and study of organ systems
(b) identification and preservation of plants and animals
(c) diversity of kinds of organisms and their relationship
(d) study of habitats of organisms and their classification.
Soln. (c): Systematics is the branch of study of diversity of organisms and all comparative and evolutionary relationship between them.
(a) an individual plant or animal
(b) a collection of plants or animals
(c) group of closely related species of plants or animals
(d) none of these.
Soln. (C) : Genus refers to a taxonomic category which comprises a group of closely related’plants and animals. E.g., Panthem leo is lion. Panther a is a Genus which has less common characters than Species.
5.The taxonomic unit’Phylum’in the classification of animals is equivalent to which hierarchial level in classification of plants?
(a) Class (b) Order
(c) Division (d) Family
Soln. (c) : Phylum/Division is a taxonomic category higher than that of Class and lower than that of Kingdom. The term Phylum is used for animals while the term Division is used for plants. A Division or Phylum is formed of one or more classes. The Phylum Chordata of animals contains various classes such as Aves, Reptilia, Amphibia, Cyclostomata, Chondrichthyes, Osteichthyes, Mammalia, etc. The Division Angiospermae of plants consists of two classes- Dicotyledoneae and Monocotyledoneae.
6.Botanical gardens and zoological parks have
(a) collection of endemic living species only
(b) collection of exotic living species only
(c) collection of endemic and exotic living species
(d) collection of only local plants and animals.
Soln. (cY: Botanical gardens and zoological parks are specialised places where living plants are grown and living animals are kept (where they can reproduce too) respectively. Both, endemic (local) as well as exotic (foreign to that place) species are kept in these places. They can be used for scientific studies. Botanical garden at Kew, England and National Zoological Park, Delhi are some famous examples. .
7.Taxonomic key is one of the taxonomic tools in the identification and classification of plants and animals. It is used in the preparation of
(a) monographs (b) flora
(c) both (a) and (b) (d) none of these
Soln. (c): Flora is a book containing information as to the habitat, climate, seasonal changes, distribution, description and index of plants found in a specific area. Monograph is treatise having all information about a particular taxon like Family or Genus.
8. All living organisms are linked to one another because
(a) they have common genetic material of the same type
(b) they share common genetic material but to varying degrees
(c) all have common cellular organisation
(d) all of the above.
Soln. (b): All organisms share common generic material, i.e., DNA and RNA. However, it can vary to certain degrees.
9.Which of the following is a defining characteristic of living organisms?
(b) Ability to make sound
(d) Response to external stimuli
10.Match the following and choose the correct option.
Family (i) tuberosum
Kingdom (ii) Polemoniales
Order (iii) Solanum
Species (iv) Plantae
Genus (v) Solanaceae
(i) -D, (ii)-C, (iii)-E, (iv)-B, (v)-A
(i) -E, (ii)-D, (iii)-B, (iv)-A, (v)-C
(i) -D, (ii)-E, (iii)-B, (iv)-A, (v)-C
(i) -E, (ii)-C, (iii)-B, (iv)-A, (v)-D
Very Short Answer Type Questions
1.Linnaeus is considered as Father of Taxonomy. Name two other botanists known for their contribution to the field of plant taxonomy?
Soln. Carolus Linnaeus developed binomial nomenclature, he is known as Father of Taxonomy. Two other botanists who gave their contribution to the field of plant taxonomy are John Ray (author of Historia generalis plcmtarum and gave term species) and A.P. de candolle (introduced the term taxonomy).
2.What does ICZN stand for?
Soln. ICZN stands for International Code of Zoological Nomenclature.
3.Couplet in taxonomic key means .
Soln. Couplet in taxonomic key means pair of contrasting character.
4.What is a monograph?
Soln. Monograph is treatise having all information about a particular taxon like Family or Genus.
5.Amoeba multiplies by mitotic cell division. Is this phenomena growth or reproduction? Explain.
Soln. Amoeba (unicellular organism) multi-plies by simple mitotic cell division giving rise to two daughter Amoebae. Here reproduction is synonymous with growth i.e., increase in number of cells. ‘
Soln. Metabolism (Gk. metabole – change) is the sum total of all chemical reactions occurring in an organism due to specific interactions amongst different types of molecules within the interior of cells. Metabolism includes catobolism (breakdown reaction) and anabolism (building up reactions).
7.Which is the largest botanical garden in the world? Name a few well known botanical gardens in India.
Soln. Main Botanical Garden, Moscow is largest garden spread over an area of 900 acres. A few well known botanical gardens in India are – Indian Botanical Garden Sibpur (Kolkata), Lloyd Botanical Garden (Darjeeling) and National Botanical Garden (Lucknow).
Short Answer Type Questions
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?
Soln. Growth is characteristic feature of all living organisms. Increase in mass and increase in number of individuals are twin characteristics of growth. Living organisms show internal growth due to addition of materials and formation of cells inside the body.
The ball of snow is non-living object. While rolling over snow, it gathers more snow on its surface, so it increases in size by physical process, not by biological process. So, the growth of snow ball cannot be compared to growth seen in living organisms.
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.
Soln. Biodiversity is the occurrence of a wide variety of life forms differing in morphology, size, colour, anatomy, habitats and habits. In a gixjen habitat, the 20 plant species and 20 animal species habitat, shows biodiversity of that given habitat. Diversity is broader term habitat which can be applied to any area.
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.
Soln. ICBN has specified certain rules and principles in order to facilitate the study of plants by botanists. Hierarchy of units of classification botanists follow while classifying plants and different ‘Suffixes’ used for the units are as follows:
4.A plant species shows several morphological
variations in response to altitudinal gradient. Whengrownundersimilarconditionsofgrowth, the morphological variations disappear and all the variants have common morphology. What are these variants called?
Soln. 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. These variants are called ecotype. It is a group of genetically similar plant showing similarity when grown in same environmental and geographical regions. The same’environment provide them the similar abiotic factors like soil, pH, temperature etc. When they grown in two different
geographical regions, they are exposed to different abiotic characters thus, it affects their growth and development bringing changes in their external morphological features but, they have the same genetic constitution.
5.How do you prepare your own herbarium sheets? What are the different tools you carry with you while collecting plants for the preparation of a herbarium? What information should a preserved plant material on the herbarium sheet provide for taxonomical studies?
Soln. We can prepare our own herbarium sheets by following steps.
(i) First, for herbaceous species the entire plant with intact parts is collected and for others, shoots having flowers, leaves and fruits are selected and cut with the help of pruning knife.
(ii) The collected material is placed in polythene bags or vasculum.
(iii) The collected specimens are spread over magazine or newspaper sheets. Care is taken to spread the leaves properly and to separate the petals so as to expose the essential organs. If the specimen is longer than the sheet, the same can be gently bent in n or w form.
(iv) Magazine and newspaper sheets are now put inside the press.
(v) Details of collection should be jotted down in the field notebook. For this every collected material is given a number. The details include plant size, branching, root system and specialised underground organ, flower colour, topography and date of collection.
Tools for collecting plants for the preparation of a herbarium are as follows: Digger and pruning knife, sickle with long handle, vasculum, polythene bags, magazines or newspapers, blotting papers, plant press, field notebook, herbarium sheets, glue, labels, small transparent polythene bags.
Preserved plant material on the herbarium sheet provide following information for taxonomical studies:
(i) Provides information about the local flora as well as flora of distant areas.
(ii) It provides information about the ecology of different places.
(iii) It depicts the morphological variations fohnd in species.
6.What is the difference between flora, fauna and vegetation? Eichhornia crassipes is called as an exotic species while Rauwolfia serpentina is an endemic species in India. What do these terms exotic and endemic refer to?
Soln. Flora is all the plant life normally present in a given habitat at a given time. Fauna is all the animal life normally present in a given habitat at a given time. Vegetation is the assemblages of plant species and the ground cover they provide. It is broad and general term used for a plant forms which does not include particular taxa or any botanical characteristics.
Exotic is a species of organism that is not native to a locality, having been moved there from its natural range by humans or other agents. Endemic is describing a plant or animal species that is restricted to one or few localities in its distribution. Endemic species are usually confined to island and are vulnerable to extinction. Eichhornia crassipes is native of Amazonian basin but it was introduced in India, so it is a exotic species in India. Rauwolfia serpentina is found only in India, so it is an endemic species found only in India.
7. A plant may have different names in different regions of the country or world. How do botanists solve this problem?
Soln. Botanist solved this problem of naming plants by International Code for Botanical Nomenclature (ICBN), which is based on agreed principles and criteria, provided by acceptable biologists all over the world and International Conferences which are held from time to time to update the codes and resolve the controversies, if any. They developed a universal scientific name for each organism. Each scientific name has two components – the ‘generic name and the specific epithet. This system of providing a name with two components is called binomial nomenclature.
This naming system given by Carious Linnaeus is being practised by biologists all over the world e.g., Scientific name of Mango is Mangifera indica.
8. Brinjal and potato belong to the same genus Solanum, but to two different species. What defines them as separate species?
Soln. Genus is a group or assemblage of related species which resemble one another in certain correlated characters. Brinjal and potato belongs to same genus Solanum but they are different species Solanum melongena and Solanum tuberosum respectively. The basic criterion for defining two different species is that they cannot interbreed and produce fertile offspring. Potato and brinjal neither actually nor potentially interbreed, thus they are defined as separate species.
9.Properties of cell organelles are not always found in the molecular constituents of cell organelles. Justify.
Soln. Cell, the basic structural and functional unit is composed of many cell organelles, i.e., ER, Golgi apparatus, ribosomes, mitochondria, chloroplasts etc, each with a specific function. Each of these organelles are made up of various molecules such as proteins, lipids, enzymes, metallic ions like Mg2+, Ca2+, Mn2+, Na+ etc. which helps in the functioning, of cell organelles. Molecular constituent like proteins (60-70%), lipids (25-30%), RNA (5-7%), DNA, Mn2+, ETS, ATP synthetase etc. found in mitochondria function together in a coordinated way to carry out cellular respiration and release energy, thus making it power house of the cell. Thus, the molecular constituents of a cell organelle, forms the basis of its functioning irrespective of its individual molecular properties.
10 .The number and kinds of organism is not constant. How do you explain this statement?
Soln. The number and kinds of organism change dramatically as one moves from one place to the next because of the following reasons:
(i) Environmental variability : Climate, food supply and interaction with other organisms affect organisms and causes changes in their number and kind.
(ii) population of reproductively compatible organisms that have similar biological properties, no species can be found everywhere.
(iii) Evolutionary change : Species do not stay the same over time, they are in constant state of change as individuals. They are able to survive and reproduce within certain environments become more frequent, while others less capable die or fail to produce offspring. Sometimes organisms evolved to adapt environment.
(iv) Continental drift : The locations of landmasses across earth’s surface have not remained the same, but have changed slowly over the cause of earth’s history. Therefore, the condition experienced by organisms change over long period of earth’s history. Ecological limitation : Every organism has a limited range of condition that must be met in order to allow it to live and reproduce. Since a species is a
Long Answer Type Questions
1.What is meant by living? Give any four defining features of life forms.
Soln. The objects exhibiting growth, development, responsiveness and other characteristics of life are called as living.
Four defining feature of life forms are as follows:
(i) Consciousness : It is awareness of the surroundings and response to external stimuli. The external stimuli can be physical, chemical or biological. The stimuli are perceived by sense organs in higher animals, e.g., eyes, ears, nose. All organisms, from primitive prokaryotes to most advanced and complex eukaryotes, are able to sense and respond to environmental factors. Organisms also handle chemicals entering their bodies.
(ii)Metabolism : All organisms operate a network of thousands of chemical
reactions. The sum total of all chemical reactions occurring in an organism due to specific interactions amongst different types of molecules within the interior of cells is called metabolism (Gk. metabole â€” change).
(iii) Homeostasis : A favourable internal environment suitable for the functioning of body organs is present in every living being. It is quite different from the external environment. Changes in external environment do not have much impact on the internal environment as the living beings have a self regulated system to adjust and maintain the internal environment. The phenomenon is called homeostasis (Gk. homois â€” alike, stasis â€” standing.
(iv) Cellular organisation : Each living being is a complex entity which is formed of one or more cells. Cells work together to form tissues, tissues form organs, organs form organ systems and various organ system form the complete organism. So, cell is the basic unit of every living organism.
2.A scientist has come across a plant which he feels is a new species. How will he go about its identification, classification and nomenclature.
Soln. New species of plant can be identified with the help of taxonomic keys, catalogues, monographs, floras and manuals.
(i) Key is booklet containing list of characters and their alternates which are helpful in identification of various taxa â€” class, order, family, genus and species.
(ii) Catalogue is list or register that enumerates methodically all the species found in a particular place, often with brief description aiding identification.
(iii) Monograph is treatise having all information about a particular taxon like family or genus.
(iv) Flora is a book containing information as to the habitat, climate, seasonal changes, distribution, description and index of plants found in a specific area.
(v) Manual is handy book containing instructions as to occurrence, collection and identification of species found in a particular area.The scientist has to study the morphological and anatomical characters of the plant parts, compare the characteristic features with the similar information available in the scientific literature and after that he can decide the exact systematic position of the plant, name it according to the rules of binomial nomenclature and fix it’s systemic position.
3. 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?
Soln.(a) Common name of Brassica campestris is mustard or sarson.
(b) The first part of this name denotes the generic name and the second part denotes the species name of the plant.
(c) According to ICBN, all scientific names are comprised of one generic name followed by a species name, which have to be written in italics always. It is a rule of binomial nomenclature.
(d) Linn means Linnaeus was the first to discover this plant. He identified, named and classified the plant, so credit is given to him by adding suffix ‘Linn’, after the scientific name B. campestris Linn.
4. What are taxonomical aids? Give the importance of herbaria and museums. How are Botanical gardens and Zoological parks useful in conserving biodiversity?
Soln. Techniques, procedures and stored information that are useful in identification and classification of organisms are called taxonomic aids.
Importance of herbaria:
(i) It provides information about the local flora as well as flora of distant areas.
(ii) Herbaria are used for correct and authentic identification of unknown plants.
(iii) It provides information about the ecology of different places.
(iv) The information is useful in locating wild varieties and relatives of economically Important plants. The same is helpful in breeding programmes for evolving newer and better varieties.
(v) It depicts the morphological variations found in species.
– (vi) Information is obtained as to the season of flowering of various plants.
(vii)It serves as a quick referal system for taxonomic studies.
Importance of museums are as follows:
(i) Standard museums have collections of plants and animals of various areas.
(ii) Museums provide information not only about the local fauna and flora but also of other areas.
(iii) They are used to deposit type specimens whenever new taxa are described.
(iv) They are important centres for taxonomic studies like important members of various taxa, their important characteristics, study and identification of various organisms.
Botanical gardens and Zoological parks are ex situ mode of biodiversity conservation. They have seed banks, tissue culture facilities and other ex-situ technologies to conserve biodiversity. They have well managed captive breeding programmes. As a result many animals which have become extinct in the wild continue to be maintained in zoological parks. Captive breeding is also resorted to in those cases where the number of surviving individuals is so small that there is no realistic chance of in situ survival. As the number increases in captive breeding, the individuals are selectively released in the wild. By this method Californian Candor (Gymnogyps californicus) and Black-Footed Ferret (Mustela nigripes) have been saved from extinction. Ginkgo tree (Ginkgo biloba) has been saved by selective breeding followed by channelling into trade of nature lovers. Therefore, botanical gardens and zoological parks can be used to restock depleted populations, reintroduce species in the wild and restore degraded habitats.
5.Define a taxon. What is meant by taxonomic hierarchy. Give a flow diagram from the lowest to highest category for a plant and an animal.
What happens to the number of individuals and number of shared characters as we go up the taxonomical hierarchy?
Soln. Taxonomic unit in the biological system of classification is called taxon (plural
taxa). It represents a rank. Any category i.e., Kingdom, Phylum, Class, Order, Family, Genus, Species is taxon.
Hierarchy of categories is the classification of organisms in a definite sequence of categories (taxonomic categories) in a descending order starting from kingdom and reaching upto species or on ascending order from species to kingdom.
It is also called Linnaean hierarchy, as it was first proposed by Linnaeus. The hierarchy includes seven obligate categories. Kingdom, division (for plants) or phylum (for animals), class, order, family, genus and species. The categories are arranged in ascending sequence, keeping the species at the top.
Fig.: Taxonomical hierarchy showing
arrangement in ascending order
Number of individuals increases and number of shared characters decreases as we go up the taxonomical hierarchy i.e., from the lowest ran (species) to highest rank (kingdom).
6.A student of taxonomy was puzzled when told by his professor to look for a key to identify a plant. He went to his friend to clarify what ‘Key’ the professor was referring to? What would the friend explain to him?
Soln. Identification of a plant is a scientific process. His friend explained that his professor was referring to biological keys. Key or taxonomic key is an artificial analytic device having a list of statements with dichotomic table of alternate characteristics which is used for identifying organisms. Usually a couplet or two contrasting characters are used. The one present in the organism is chosen while the other is rejected. Each statement of the key is called lead. The concept of key was introduced by Lamarck. Separate taxonomic keys are used for each taxonomic category like Fatnily, Genus and Species.
Keys are used as reference to help in identification of a newly discovered plant.
7.Metabolism is a defining feature of all living organisms without exception.
Isolated metabolic reactions in vitro are not living things but surely living reactions. Comment.
Soln. All organisms operate a network of thousands of chemical reactions. The sum total of all chemical reactions occurring in an organism due to specific interactions amongst different types of molecules within the interior of cells is called metabolism (Gk. metabole â€”change). Metabolism is defining property of living beings because all activities of an organism including growth, movements, development, responsiveness, reproduction, etc. are due to metabolism. No nonliving object shows metabolism. However, metabolic reactions can be carried out outside the body of an organism in cell free systems. Such reactions are neither living nor nonliving. The isolated in vitro metabolic reactions can, however, be called biological reactions or living reactions as they involve biochemicals.
8.Do you consider a person in coma-living or dead?
Soln. Consciousness is the defining property of living organisms. The word coma comes from the greek word coma which means “deep sleep”. Coma is a state of unconsciousness in which a person cannot be awakened and fails to respond to any stimuli or perform any voluntary action. The person is still alive, but the brain is functioning at its lowest stage of alertness. The various causes of coma are severe injury to head, infection in brain, overdose of some medicine, stroke or some illness. A person in coma has brain dead but , they are living, as they require nourishment and maintenance Glassgow coma scale is a numerical system to estimate a patient’s level of consciousness. The higher the score, the greater the level of consciousness.
9.What is the similarity and dissimilarity between “whole moong daal” and “broken moong daal” in terms of respiration and growth? Based on these parameters classify them into living or nonliving?
Soln. Whole moong daal contains seed coat, embryo (which has two part cotyledon and tigellum) and endosperm. If all necessary conditions are provided to whole moong daal they show germination. During germination they -exhibit growth and respiration. Broken moong daal does not contain all parts like whole moong daal. They cannot germinate even all necessary conditions for germination is provided. So they do not exhibit growth. Respiration generally starts during germination therefore broken moon daal does not show respiration. Whole moong daal is living during germination whereas broken moong daal is non-living. ‘
10.Some of the properties of tissues are not the constituents of its cells.
Give three examples to support the statement.
Soln. Living beings has multiple level of organisation. Each level of organisation has its own properties, which are not found in its constituents.
Examples of three tissues supporting the statement are as follows:
(i) Cardiac muscle tissue : It is a contractile tissue present only in heart. Cell junctions fuse the plasma membrane of cardiac muscle cells and make them stick together. When one cell receives a signal to contract its neighbours also starts to contract. It means a single cell cannot contract, while there are some fusion points, which allow the cells to contract as a unit.
(ii)Blood : It is a fluid connective tissue. The individual components of blood i.e., RBCs, WBCs and platelets have different properties but as a unit they make the blood, a tissue serving many functions.
(iii)Bone : It is a hard connective tissue that forms the framework of the body. The individual cells inside the bone do not have this property.
(iv)Nervous system: Many neurons make nervous system, but individual nerve cell ‘cannot perform the function of control and coordination.