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Note from Publisher National Council of Educational Research and Training (NCERT) developed Exemplar Problems in Science and Mathematics. The prime objective is to provide the students with number of quality problems to facilitate the concept of learning. Easy Marks NCERT Solutions to Exemplar Problems Biology-XI is mainly based on the idea to present the considerable requirements of the Exemplar Problems in a simple and detailed manner. Salient features of the book: ● Scientific and methodological solutions to the textual questions are provided. ● Multiple Choice Questions (MCQs) with explanation for understanding the concept better. ● The explanation of the answers are provided with diagram, wherever needed. ● Very Short, Short and Long Answer Type Questions are given to provide students with more practical problems. It has always been our endeavour to provide better quality material to the students. If there are any suggestions for the betterment of the book, we will certainly try to incorporate them.

CONTENTS 1. The Living World.............................................................................. 5 2. Biological Classification................................................................... 16 3. Plant Kingdom.................................................................................. 24 4. Animal Kingdom.............................................................................. 34 5. Morphology of Flowering Plants...................................................... 45 6. Anatomy of Flowering Plants........................................................... 56 7. Structural Organisation in Animals................................................... 67 8. The Unit of Life................................................................................ 78 9. Biomolecules..................................................................................... 88 10. Cell Cycle and Cell Division............................................................ 97 11. Transport in Plants............................................................................ 108 12. Mineral Nutrition.............................................................................. 124 13. Photosynthesis in Higher Plants....................................................... 134 14. Respiration in Plants......................................................................... 149 15. Plant Growth and Development........................................................ 160 16. Digestion and Absorption................................................................. 171 17. Breathing and Exchange of Gases.................................................... 181 18. Body Fluids and Circulation............................................................. 189 19. Excretory Products and Their Elimination....................................... 200 20. Locomotion and Movement.............................................................. 211 21. Neural Control and Coordination...................................................... 220 22. Chemical Coordination and Integration............................................ 227 ● Model Question Paper....................................................................... 237

1

The Living World

Multiple Choice Questions (MCQs) 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 Ans. (a) Will decrease Explanation: Number of common characters is maximum among members of a particular species. On the other hand, number of common characters is minimum among members of a particular kingdom. 2. Which of the following ‘suffixes’ used for units of classification in plants indicates a taxonomic category of ‘family’. (a) – Ales (b) – Onae (c) – Aceae (d) – Ae Ans. (c) – Aceae Explanation: You can consider the names of families, e.g. solanaceae, fabaceae, etc. 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 Ans. (c) Diversity of kinds of organisms and their relationships Explanation: In fact, the need for a proper classification system was felt because of huge diversity of organisms. Based on certain relationships, organisms were classified into different groups and sub-groups. 4. Genus represents (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 Ans. (c) Group of closely related species of plants and animals Explanation: Taxon genus is just above the taxon species. 5. The taxonomic unit ‘Phylum’ in the classification of animals is equivalent to which hierarchial level in classfication of plants (a) Class (b) Order (c) Division (d) Family Ans. (c) Division

5

Explanation: In animal kingdom, phylum comes just after the kingdom. Similarly, in the plant kingdom, division comes just after the kingdom. 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 Ans. (c) Collection of endemic and exotic living species Explanation: To understand this, you can visit the zoo at Delhi or Kolkata. You can also search in Google image and you will find giraffes; along with tigers and lions. Tigers and lions are endemic species while giraffe is an exotic species. 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 Ans. (c) Both (a) and (b) 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 organization (d) All of above Ans. (b) They share common genetic material but to varying degrees Explanation: In fact, the whole theory of evolution is based on similarity of genetic materials which indicates towards common ancestry for living organisms. Variations in similarity of genetic materials give biodiversity which we see all around us. 9. Which of the following is a defining characteristic of living organisms? (a) Growth (b) Ability to make sound (c) Reproduction (d) Response to external stimuli Ans. (d) Response to external stimuli Explanation: Rest of the characters may not be apparent at every instance of time. But response to external stimuli can always be confirmed as and when required. So, this is considered as a defining characteristic of living organisms. 10. Match the following and choose the correct option: A. Family (i) tuberosum B. Kingdom (ii) Polymoniales C. Order (iii) Solanum D. Species (iv) Plantae E. Genus (v) Solanaceae

6 n NCERT Exemplar Problems Biology–XI

Options (a) (i)-D, (ii)-C, (iii)-E, (iv)-B, (v)-A (b) (i)-E, (ii)-D, (iii)-B, (iv)-A, (v)-C (c) (i)-D, (ii)-E, (iii)-B, (iv)-A, (v)-C (d) (i)-E, (ii)-C, (iii)-B, (iv)-A, (v)-D Explanation: The order of taxa is as follows: Kingdom → Order → Family → Genus → Species Classification of potato: Kingdom: Plantae Order: Solanales Family: Solanaceae Genus: Solanum Species: tuberosum Ans. (a) (i)-D, (ii)-C, (iii)-E, (iv)-B, (v)-A

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? Ans. G Bentham and Joseph Dalton Hooker. Both are famous for their work on “classification of plants based on natural characteristics”. 2. What does ICZN stand for? Ans. ICZN stands for International Code for Zoological Nomenclature. 3. Couplet in taxonomic key means ________________ . Ans. Contrasting characters 4. What is a Monograph? Ans. A monograph contains information on any one taxon. A monograph provides work on primary research. 5. Amoeba multiplies by mitotic cell division. Is this phenomena growth or reproduction? Explain. Ans. After mitosis in Amoeba there is no growth in size of the organism rather two new organisms are formed. Hence, formation of new cells in Amoeba is reproduction. 6. Define metabolism. Ans. All the biological reactions in a living being are collectively called metabolism. Metabolism is of two types, viz. anabolism and catabolism. 7. Which is the largest botanical garden in the world? Name a few well known botanical gardens in India. Ans. The Royal Botanical Garden in Kew (London) is the largest botanical garden in the world. Some of the well known botanical gardens in India are as follows: (a) Indian Botanical Garden, Sibpur, Kolkata (b) Lloyad Botanical Garden, Darjeeling (c) Botanical Garden of FRI, Dehradun (d) National Botanical Garden, Lucknow



The Living World  n 7

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? Ans. It is true that a ball of snow increases in mass, volume and size; when it is rolled over. But in this case, the growth in size of the ball happens because of accumulation of material from outside. In case of growth in a living being, the growth happens because of accumulation of material from inside which is brought about by cell division and formation of new protoplasm. Thus, growth in a snowball is altogether different when compared to the growth in a living being. 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. Ans. Whenever we talk about biodiversity, we talk about all the life forms on the earth. In other words, the term ‘biodiversity’ is a universal term which encompasses all the organisms on the earth. But when we talk about a smaller geographical area; like an ecosystem or a particular habitat; then the term ‘diversity’ is used. So, the given example of the habitat shows diversity. 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. Ans. As per the ICBN, various hierarchies of units for classifying plants and suffixes used for such hierarchies are as follows: Hierarchy

Suffix

Kingdom

– Plantae

Division

– Phyta

Class

– Ae

Order

– Ales

Family

– Eae or – Ceae

Genus

Contains first name of organism which usually has Latin origin and written in italics.

Species

Contains second term of the scientific name which usually has Latin origin and written in italics.

4. 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? Ans. These variants are called biotypes. All biotypes are similar genetically

8 n NCERT Exemplar Problems Biology–XI

but they are different morphologically. The morphological difference happens because of the differences in abiotic factors like temperature, pH of soil, climate etc. The difference in abiotic factors is the result of different altitudinal gradients. 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? Ans. Following are the various steps of preparing herbarium: (a) Collection: This step involves collection of a particular species. (b) Pressing: This step involves spreading the specimen and pressing it between two sheets of paper so as to preserve most of the parts. (c) Drying: This step usually involves drying under the sun. (d) Poisoning: Sometimes, antifungal treatment needs to be given to the specimen to preserve it for longer duration. (e) Mounting: This step involves mounting the specimen over a herbarium sheet. (f) Labelling: This step involves writing full information and classification of the specimen. Different tools which need to be carried while collecting plants for the preparation of a herbarium are; digger and pruning knife, sickle, vasculum, polythene bags, old newspaper or magazine, blotting paper, plant press, field notebooks, herbarium sheets, glue, labels, etc. The preserved material should have thorough information and classification. This should include the names of division, order, family, genus and species. 6. What is the difference between flora, fauna and vegetation? Eichhornia crassipes is called as an exotic species while Rauvolfia serpentina is an endemic species in India. What do these terms exotic and endemic refer to? Ans. The sum of plant species in a given geographical area is called flora of that area. The sum of animal species in a given geographical area is called fauna of that area. The term ‘vegetation’ has wider scope than the term ‘flora’. Vegetation is often used for much wider geographical area than a particular ecosystem. In many cases, the term ‘vegetation’ is used for all the plants on the global scale. Endemic Species: A species which is found only in a particular geographical area is called the endemic species for that area. For example; Rauvolfia serpentina is found only in India. So, it is an endemic species in India. Exotic Species: A species which is not naturally found in a particular



The Living World  n 9

area but may be living because of careful selection and breeding or because of being imported is called an exotic species. For example, Eichhornia crassipes is native of other country but it was introduced in India. So, it is an exotic species in India. 7. A plant may have different names in different regions of the country or world. How do botanists solve this problem? Ans. There are many languages and even more dialects being spoken in different parts of the world. This means a plant may have different names in different regions of the country or world. This compounds the problem for anybody because nobody can remember all those names. To solve this problem, botanists have devised the system of binomial nomenclature so that a particular species can have unique name for the purpose of scientific study. A botanical name is usually composed of two terms, viz. genus name and species name. Care is taken to make a unique name for a particular species. 8. Brinjal and potato belong to the same genus Solanum, but to two different species. What defines them as seperate species? Ans. Brinjal and potato belong to the same genus Solanum because of certain common characters in them. Phyllotaxy, venation, inflorescence, etc. are some of the common characters in these plants which make them the member of the same genus. But breeding between a brinjal plant and a potato plant is not possible. Since capability to interbreed is the most defining criterion for members of a particular species; hence brinjal and potato are kept under separate species although they belong to the same genus. 9. Properties of cell organelles are not always found in the molecular constituents of cell organelles. Justify. Ans. No matter what is the function of a particular cell organelle; all the cell organelles are made up of more or less similar molecules. All the molecules come together in a particular fashion to build up a particular cell organelle. It is similar to the same brick making a small house or a big mansion of a factory. The constituents remain the same but the function and purpose of the finished product changes. Hence, properties of cell organelles are not always found in the molecular constituents of cell organelles. 10. The number and kinds of organism is not constant. How do you explain this statement? Ans. This question needs to be addressed from two perspectives, viz. number and variety. For any organism; the population cannot remain constant. In some of the generations, population can be more because of favourable conditions. In some other generations, population can be less because of unfavourable conditions. The kinds of organism cannot

10 n NCERT Exemplar Problems Biology–XI

be constant because evolution is a never ending process. In every era new species come into origin and some old species become extinct.

Long Answer Type Questions 1. What is meant by living? Give any four defining features of life forms. Ans. A living organism is self replicating, evolving and self-regulating interactive system capable of responding to external stimuli. Growth, reproduction, nutrition, excretion, etc. are various characteristics of living beings. But most of these characteristics cannot be termed as defining features of life forms. Defining features of life form are: Growth is defined as an increase in mass. Plants grow throughout their life, while most of the animals grow up to a certain age only. But some non-living things also grow in mass, e.g. cloud or snowball. So, growth cannot be termed as the defining feature of life. Reproduction is the process by which a living being produces its own kind. Majority of organisms reproduce sexually, while many others reproduce asexually; by various methods. On the other hand, there are many living beings which do not reproduce at all, e.g. the worker bee in a beehive. But we consider it as a living being. So, reproduction cannot be termed as an all inclusive defining feature of life. As nonliving things cannot reproduce; so, reproduction can be termed as a defining feature of life (with certain exceptions). Metabolism involves various biochemical processes during which various molecules are formed and many others get broken down. Metabolic reactions cannot happen in a cell-free system. While some in-vitro reactions have been tried out in laboratories but they cannot be termed as real metabolisms. So, metabolism is one of the defining features of life. Structural organization which begins with cellular organization is another character of living beings. Some molecules come together and work in perfect synchronization to form a cell organelle and various cell organelles come together to form a cell. Eventually, cells end up forming the tissue; which become organs and finally the whole organism is formed. Cells are altogether different than their constituent organelles; in terms of characters and functions. Similarly; a tissue is entirely different than its component cells; in terms of functions. Similar demarcation and hierarchy of organization is not possible in non-living things. Hence, cellular organization is a defining feature of life. External stimuli can reach in various forms inside a living organism and the living being responds to each stimulus in a different way.



The Living World  n 11

This can be termed as consciousness to the environment. Such a consciousness is not possible in non-living things. Hence, response to external stimuli is a defining feature of life. 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? Ans. The scientist should look at various morphological features of the plant. He should begin with broad features; such as type of roots and venation. If fibrous roots are present then the plant may belong to monocotyledonous. In case of tap root, the plant may belong to dicotyledonous. This can be further confirmed with the presence of parallel or reticulate venation and number of cotyledons in the seeds. After that, the scientist should look at the type of phyllotaxy, inflorescence, etc. which will help in classifying the plant in order and family. If it is a flowering plant, then a detail study of various floral parts can give various clues about a particular family or order. Type of placentation can be studied by looking at the arrangement of seeds inside the fruits. Finally, arrangement of antheridium and gynoecium can help the scientist to confirm a particular family for the new species. The scientist also needs to rule out exact similarity with any other existing species before arriving at a unique name for the new species found. 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? Ans. (a) The common name of Brassica campestris linn is mustard. (b) The first part denotes the genus, while the second part denotes the species. (c) These names are written in italics to show their Latin origin. Moreover, it is a convention to write scientific name in italics. (d) The term ‘linn’ means that this species was first discovered and studied by Linnaeus. 4. What are taxonomical aids? Give the importance of herbaria and museums. How are Botanical gardens and Zoological parks useful in conserving biodiversity? Ans. Tools which help the scientists in studying about plants and animal species are called taxonomical aids. Taxonomical aids include either live species of plants or animals or preserved remains. In case of animals; museum specimens are kept under proper preservation. In case of plants, herbariums are used for keeping preserved specimens.

12 n NCERT Exemplar Problems Biology–XI

Importance of Herbarium: Herbarium works as a repository of specimens for future reference. This also includes detail information about classification of a particular specimen. In many cases, herbarium serves as a quick referral system while studying about a particular species or about a higher taxonomical level. Herbarium is convenient to make and easier to maintain. It is also easy to transport a herbarium. Importance of Museums: Museums have much wider collection of plants and animal specimens. Museums may also have skeletons of many extinct animals. Thus, a museum offers more options of finding rich information while studying about a plant or animal. Museums are usually maintained by educational institutions and thus they serve as important tool of study for students as well as for the scientists’ community. Role of Botanical and Zoological Parks in Conserving Biodiversity: Botanical and Zoological Parks serve the very important purpose of conserving the biodiversity. A botanical or zoological park is probably the most secure place for plants and animals to live in their natural habitat. Especially trained personnel take good care of plants and animal species. They also carry out selective breeding of various plants and animals to maintain the continuity of a particular species. Moreover, proper treatment is available in case some disease afflicts the plants and animals in such parks. Thus, it can be said that botanical and zoological parks play important role in conserving biodiversity. 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? Ans. Taxon: A level of biological classification is called a taxon, e.g. phylum, order, family, etc. Taxonomic Hierarchy: In taxonomy, different taxa have their own different levels. This means that a particular taxon will come only after another particular taxon. For example; species always comes after the genus and it can never be the other way around. Flow Chart of Plant Categories Kingdom → Division → Order → Family → Genus → Species Flow Chart of Animal Categories Kingdom → Phylum → Order → Family → Genus → Species In some cases, animals or plants are further classified into sub-groups; like super-class, class or sub-phylum. When we go up the taxonomic hierarchy; the number of common characters becomes lesser and lesser. For example; all members of a species will have the maximum number of common characters. On



The Living World  n 13

the other hand, all members of a genus will have a lesser number of common characters. The number of individuals increases as we go up the taxonomical hierarchy. 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 refering to? What would the friend explain to him? Ans. Key is an important tool to study a taxonomic category. A key is composed of two contrasting characters. These characters generally occur in pairs and such a pair is called a couplet. While studying a key; either of the contrasting characters is rejected or accepted. Thus, a choice is made between the two contrasting characters in a key. Each statement in the key is called a lead. It is important to note that a key is usually analytical in nature. Moreover, separate keys need to be used for different taxonomic categories. Keys help in step-bystep identification of a particular organism. For example; presence or absence of notochord gives us a clue whether the organism belongs to vertebrate or invertebrate. Similarly, presence of absence of lungs tells us if the organism belongs to tetrapoda or pisces. 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. Ans. Metabolism involves various biochemical processes during which various molecules are formed and many others get broken down. All organisms exhibit metabolism, e.g. protozoans, algae, fungi, bacteria, etc. Metabolic reactions cannot happen in a cell-free system. While isolated in-vitro reactions carried out in laboratories cannot be termed as metabolism because they are conducted in controlled environment and are simulated. But such reactions can be termed as living reactions because they are the reactions going inside a living system. 8. Do you consider a person in coma-living or dead? Ans. When it comes to human beings, it is very difficult to define the living state. A person may lie in coma for several years. By technical definition, the person is alive because he is not brain-dead. However, most of his vital organs have stopped functioning. Such a person is kept alive with life support system. A heart and lung machine works continuously to perform the function of oxygenation and circulation. A dialysis unit may be in place to perform the function of kidneys. The person gets nutrition through intravenous fluids. Since the person is in comma so he is not exhibiting consciousness to his environment. In other words, he is not exhibiting response to stimuli; which is one of the defining criteria for life.

14 n NCERT Exemplar Problems Biology–XI



Since the person is being kept alive because of life support system; metabolic activities are going on. Hence, the person can be considered as dead. But we should not forget that once he is put off the life support system; he will become brain-dead immediately and will be dead by technical definition. So, this is a difficult question whether a person in comma is dead or alive. 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? Ans.

Whole moong dal Broken moong dal (i) The whole seed is intact. (i) Seed is broken into pieces. (ii) Seed is capable of carrying (ii) Respiration does not take out respiration. place. (iii) Under favourable (iii) This will never be able to circumstances; the seed will germinate. undergo changes and would germinate to produce a new plant. (iv) This is a living thing. (iv) This is a non-living thing. 10. Some of the properties of tissues are not the constituents of its cells. Give three examples to support the statement. Ans. It is indeed true that some of the properties of tissues are not the constituents of its cells. Following three examples support this statement: (a) A muscle tissue is capable of contraction but all its constituent cells may not be capable of doing so. (b) The skeletal system is composed of bones and cartilage. A bone is hard and lightweight but its constituents may exhibit similar property. (c) Blood is capable of carrying oxygen but WBCs are not capable of doing in spite of being the constituents of blood. qqq



The Living World  n 15

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