1.4 Exercise Problems

Q1. Why are living organisms classified?

Answer: A large variety of plants, animals, and microbes are found on earth. All these living organisms differ in size, shape, colour, habitat, and many other characteristics. As there are millions of living organisms on Earth, studying each of them is impossible. Therefore, scientists have devised mechanisms to classify all living organisms. These methods of classification are based on rules and principles that allow identification, nomenclature, and finally classification of an organism.
For example, based on certain principles, once an organism is identified as an insect, it will be given a scientific name and then grouped with other similar organisms. Thus, various groups or taxon include organisms based on their similarity and differences. Therefore, the biological classification helps in revealing the relationship between various organisms. It also helps in making the study of organisms easy and organized.

Q2. Why are the classification systems changing every now and then?

Answer: Millions of plants, animals, and microorganisms found on earth, have been identified by the scientists while many new species are still being discovered around the world. Therefore, to classify these newly discovered species, with new characters, new systems of classification have to be devised every now and then. This creates the requirement to change the existing systems of classification.

Q3. What different criteria would you choose to classify people that you meet often?

Answer: To classify a class of forty students, let us start the classification on the basis of the sexes of the students. This classification will result in the formation of two major groups- boys and girls. Each of these two groups can be further classified on the basis of the names of the students falling in these groups. Since it is possible that more than one student can have a particular name, these names can be further divided based on the surnames. Since there is still some chance that more than one student can have the same surname, the final level of classification will be based on the roll numbers of each student.

Q4. What do we learn from the identification of individuals and populations?

Answer: The knowledge of the characteristics of an individual or its entire population helps in the identification of similarities and dissimilarities among the individuals of same kind or between different types of organisms. It helps scientists to classify organisms in various categories.

Q5. Given below is the scientific name of Mango. Identify the correctly written name.
Mangifera Indica
Mangifera indica

Answer: In the binomial system of nomenclature, the generic name of a species always starts with a capital letter whereas the specific name starts with a small letter. Therefore, the correct scientific name of Mango is Mangifera indica.

Q6. Define a taxon. Give some examples of taxa at different hierarchical levels.

Answer: Each unit or category of classification is termed as a taxon. It represents a rank. For example, the basic level of classification is species, followed by genus, family, order, class, phylum or division, in ascending order. The highest level of classification is known as kingdom.

Q7. Can you identify the correct sequence of taxonomical categories?
(a) Species \(\rightarrow\) Order \(\rightarrow\) Phylum \(\rightarrow\) Kingdom
(b) Genus \(\rightarrow\) Species \(\rightarrow\) Order \(\rightarrow\) Kingdom
(c) Species \(\rightarrow\) Genus \(\rightarrow\) Order \(\rightarrow\) Phylum

Answer: The correct hierarchical arrangement of taxonomic categories in ascending order is Species \(\rightarrow\) Genus \(\rightarrow\) Family \(\rightarrow\) Order \(\rightarrow\) Class \(\rightarrow\) Phylum \(\rightarrow\) Kingdom Therefore, both (a) and (c) represent correct sequences of taxonomic categories. In sequence (b), species should be followed by genus. Therefore, it does not represent the correct sequence.

Q8. Try to collect all the currently accepted meanings for the word ‘species’. Discuss with your teacher the meaning of species in case of higher plants and animals on the one hand, and bacteria on the other hand.

Answer: In biological terms, species is the basic taxonomical rank. It can be defined as a group of similar organisms that are capable of interbreeding under natural conditions to produce fertile offspring. Therefore, a group of similar individuals that are respectively isolated form a species. Species can also be defined as groups of individuals that share the same gene pool.

Q9. Define and understand the following terms:
(i) Phylum
(ii) Class
(iii) Family
(iv) Order
(v) Genus

Answer: (i) Phylum: Phylum is the primary division of the kingdom. It includes one or more related classes of animals. In plants, instead of phylum, the term ‘division’ is used.
(ii) Class: Class is a taxonomic group consisting of one or more related orders. For example, the class, Mammalia, includes many orders.
(iii) Family: Family is a taxonomic group containing one or more related genera. In plants, families are categorized on the basis of vegetative and reproductive features.
(iv) Order: Order is a taxonomic group containing one or more families. For example, the order, carnivore, includes many families.
(v) Genus: Genus is a taxonomic group including closely related species. For example, the genus, Solanum, includes many species such as nigrum, melongena, tuberosum, etc

Q10. Illustrate the taxonomical hierarchy with suitable examples of a plant and an animal.

Answer: The arrangement of various taxa in a hierarchical order is called taxonomic hierarchy. In this hierarchy, species is present at the lowest level whereas kingdom is present at the highest level.

Classification of a plant
As an example, let us classify Solanum melongena (Brinjal).
Kingdom – Plantae
Division – Angiospermae
Class – Dicotyledonae
Order – Solanales
Family – Solanaceae
Genus – Solanum
Species – melongena
Classification of an animal
As an example, let us classify Columba livia (Blue rock Dove).
Kingdom – Animalia
Phylum – Chordata
Class – Aves
Order – Columbiformes
Family – Columbidae
Genus – Columba
Species – livia

Exemplar Section

VERY SHORT ANSWER TYPE QUESTIONS 

Q1. Linnaeus is considered as Father of Taxonomy. Name two other botanists known for their contribution to the field of plant taxonomy?

Answer: Natural system of classification for flowering plants was given by George Bentham and Joseph Dalton Hooker, in three volume of Genera Plantarum.

Q2. What does ICZN stand for?

Answer: ICZN stand for International Code of Zoological Nomenclature.

Q3. Couplet in taxonomic key means ____.

Answer: The keys are based on the contrasting characters generally in a pair called couplet. It represents the choice made between two opposite options. This results in acceptance of only one and rejection of the other.

Q4. What is a Monograph?

Answer: Monographs contain information on any one taxon, i.e. any one genus or family at a particular time.

Q5. Amoeba multiplies by mitotic cell division. Is this phenomena growth or reproduction? Explain.

Answer: In single-celled organisms, we are not very clear about the usage of these two terms-growth and reproduction. Amoeba growth through mitosis is the same as reproduction since it divides to give rise to the new individual. Mitosis is responsible for growth.

Q6. Define metabolism.

Answer: The sum total of all the chemical reactions occurring in our body is metabolism. Metabolism is defined as the total of all biochemical reactions taking place within any living organism to sustain and maintain life.

Q7. Which is the largest botanical garden in the world? Name a few well known botanical gardens in India.

Answer: The world’s largest botanical garden is situated in London which is known as Kew Royal Gardens. Other known botanical gardens are:
1. Sanjay Gandhi Jaivik Udyan in Patna
2. Hyderabad Botanical Garden
3. NTR Garden, Hyderabad
4. Botanical Garden Sarangpur
5. Cubbon Park, Bangalore

SHORT ANSWER TYPE QUESTIONS

Q1. 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?

Answer: No, this is not comparable to growth as seen in living organisms. Non-living objects like snow ball also grow if we take increase in body mass as a criterion for growth. However, this kind of growth exhibited by non-living objects is by accumulation of material on the surface (accretion). In living organisms, growth is from inside. ‘ This happens due to the extrinsic growth by the deposition of the same material.

Q2. In a given habitat we have 20 plant species and 20 animal species. Should we call this as ‘diversity’ or ‘biodiversity’? Justify your answer.

Answer: In a given habitat we have 20 plant species and 20 animal species. We can call this as ‘biodiversity’. Each different kind of plant, animal or organism that we see, represents a species. This refers to biodiversity or the number and types of organisms present on earth.

Q3. 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.

Answer: The hierarchy followed in plants:
Species \(\rightarrow\) Genus \(\rightarrow\) Family \(\rightarrow\) Order \(\rightarrow\) Class \(\rightarrow\) Division \(\rightarrow\) Kingdom Suffixes used by botanists are as follows:

Taxon Suffix
a) Division -phyta
b) Class -ae
c) Order-ales
d) Family -aceae

Q4. 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?

Answer: These variants are called the ‘ecotypes’. Plants show changes in morphological features in response to the altitudinal gradient.

Q5. 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?

Answer: For preparing a herbarium sheet, the paper is cut in the desired length \(\rightarrow\) say, \(29 \times 41 cm\).)
The dried specimen is taken and mounted on the sheers with the help of glue. You may use sellotape if desired.
Labels are out underneath each specimen.
Collections tools will include:
1. Digger
2. Knife and Scissors
3. Newspaper
4. Blotting sheet
5. Plant press
6. Notebook
7. Magnifying glass

The information that will be provided:
1. The scientific name of the specimen
2. Taxonomical details
3. Common name
4. Collector’s name
5. Place of collection
6. Date and Time

Q6. 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?

Answer: Flora is a plant life occurs in a particular region or time.
Fauna is the total number of animals found in a particular region or time Vegetation is a term used for plant forms which do not include particular taxa or botanical characteristics
Exotic species is any species of a plant living in any other place except its native and endemic species which are restricted to a particular area.

Q7. A plant may have different names in different regions of the country or world. How do botanists solve this problem? 

Answer: They have given a scientific name for each plant and animals. It became the common name throughout the world. Example: Mango is scientifically termed as Mangifera indica. Mango is called as Aam in India. But the scientific term is common.

Q8. Brinjal and potato belong to the same genus Solanum, but to two different species. What defines them as seperate species?

Answer: In terms of reproduction, these two species varies. They share the same genus but they remain different species.  “Species is a group of potentially interbreeding groups that are reproductively isolated from other such groups”. Brinjal and potato belong to the same genus Solarium, but to two different species as they are reproductively isolated

Q9. Properties of cell organelles are not always found in the molecular constituents of cell organelles. Justify.

Answer: All living phenomena are due to underlying interactions. Properties of tissues are not present in the constituent cells. Similarly, properties of cellular organelles are not present in the molecular constituents of the organelle but arise as a result of interactions among the molecular components comprising the organelle. These interactions result in emergent properties at a higher level of organization. This phenomenon is true in the hierarchy of organisational complexity at all levels.

Q10. The number and kinds of organism is not constant. How do you explain this statement?

Answer: The number and kinds of organisms are variable according to the seasonal changes like, population of certain insects increases during rainy season. The IUCN Red List (2004) documents the extinction of 784 species (including 338 vertebrates, 359 invertebrates and 87 plants) in the last 500 years.

LONG ANSWER TYPE QUESTIONS

Q1. What is meant by living? Give any four defining features of life forms.

Answer: The ability of an object which can self-replicate and self regulate is known as Living.
The 4 defining characteristics are:
i) Growth
ii) Reproduction
iii) Metabolism
iv) Consciousness

Growth: There are two types. Extrinsic and intrinsic growth. Which is deposited on the outer surface and one is inside the cell
Reproduction: Biological process in which an organism gives rise to individuals similar to themselves. The process is of two types. Asexual and sexual reproduction.
Metabolism: It is the total of all chemical & biological reactions occurring simultaneously inside the cells. It is two types catabolism and anabolism. One involves the breakdown of molecules and one is building up of biomolecules
Consciousness: Ability of the body to sense & respond to the external stimuli.

Q2. A scientist has come across a plant which he feels is a new species. How will he go about its identification, classification and nomenclature.

Answer: A new identify species can be easily classified by taxonomic aids. The scientist has to do comparative studies of the morphological & anatomical features with the features of existing plants present in the taxonomical aids and according to binomial nomenclature given by Carl Linnaeus, the species can be classified. Some of the taxonomical aids that can be used are flora, manuals, monographs, catalogues etc.

Q3. 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?

Answer: a. Mustard
b. The first word in a biological name represents the genus while the second component denotes the specific epithet.
c. Both word in a biological name, when handwritten, are separately underlined, or printed in italics to indicate their Latin origin.
d. Name of the author appears after the specific epithet, i.e. at the end of the biological name and is written in an abbreviated form, e.g., Brassica compestris Linn. It indicates that this species was first described by Linnaeus.

Q4. What are taxonomical aids? Give the importance of herbaria and museums. How are Botanical gardens and Zoological parks useful in
conserving biodiversity?

Answer: Collection of information, techniques, procedures which helps to identify & classify an individual is called taxonomic aids.

Importance of herbarium
a) Collection of dried, pressed & preserved plants in sheets is called herbarium.
b) These sheets are arranged systemically according to the accepted system of classification.
c) It is used to provide information about flora.
d) It is used to study the morphology of plants.
e) Hence its comparative studies are used in the identification of unknown plants.

Importance of museums
It consists of a collection of preserved plants & animal used for study & references.
Many museums publish journals, research papers to make available the results of research in their collection.

Q5. 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?

Answer: Taxon is a taxonomic group of plants and animals with similar traits of any ranking. These taxonomic groups/categories are distinct biological entities and not merely morphological aggregates. Classification is not a single step process but involves hierarchy of steps in which each step represents a rank or category. Since the category is a part of overall taxonomic arrangement, it is-called the taxonomic category and all categories together constitute the taxonomic hierarchy.
\(
\begin{array}{|c|l|}
\hline \text { Taxon } & \text { Suffixes } \\
\text { Kingdom } & \text { No definite suffix } \\
\uparrow & \\
\text { Division } & \text { phyta/spermae } \\
\uparrow & \\
\text { Class } & \text { nae/opsida } \\
\uparrow & \\
\text { Order } & \text { ales } \\
\uparrow & \\
\text { Family } & \text { aceae } \\
\uparrow & \\
\text { Genus } & \text { No definite suffix } \\
\uparrow & \\
\text { Species } & \text { No definite suffix } \\
\hline
\end{array}
\)
As we go higher from species to kingdom, the number of common characteristics goes on decreasing. Lower the taxa, more are the characteristics that the members within the taxon share. Higher the category, greater is the difficulty of determining the relationship to other taxa at the same level. As we go higher from species to kingdom, the number of individuals goes on increasing.

Q6. 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?

Answer: In reference of this question, ‘Key’ Stands for taxonomic keys. Key is the taxonomical aid used for identification of plants and animals based on the similarities and dissimilarities. The keys are based on the contrasting characters generally in a pair called couplet. It represents the choice made between two opposite options. This results in acceptance of only one and rejection of the other. Each statement in the key is called a lead. Separate taxonomic keys are required for each taxonomic category such as family, genus and species for identification purposes. Keys are generally analytical in nature.

Q7. 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.

Answer: All-living organisms are made of chemicals.

• There are thousands of metabolic reactions occurring simultaneously inside all living organisms, be they are unicellular or multicellular. The sum total of all the chemical reactions occurring in our body is metabolism. All plants, animals, fungi and microbes exhibit metabolism.
• No non-living objects exhibit metabolism. Metabolic reactions can be demonstrated outside the body in cell free system. An isolated metabolic reaction(s) outside the body of an organism, performed in a test tube is neither living nor non-living. ‘
  Hence, while metabolism is a defining feature of all living organisms without exception, isolated metabolic reactions in vitro are not living things but surely living reactions.

Q8. Do you consider a person in coma-living or dead?

Answer: Human being is the only organism who is aware of himself, i.e. has self-consciousness. We sense our environment through our sense organs (like ear, nose, eye, etc.). When it comes to human beings, it is all the more difficult to define the living state. We observe patients lying in coma in hospitals virtually supported by machines which replace heart and lungs. The patient is otherwise brain-dead. The patient has no self-consciousness. So on this basis the person is considered as dead, but there are thousands of metabolic reactions occurring in the body, hence on the basis of metabolism the person is considered as living. So we can say that the person that lying in coma is neither living nor dead.

Q9. 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?

Answer: Whole moong daal has intact embryo which respire at slow rate during dormancy phase. When whole moong daal absorb water it resumes growth and germinate to form a new plant. Broken moong daal does not have intact embryo, so it cannot respire and do not germinate/grow. As whole moong daal can grow hence it is living while broken moong daal cannot grow hence non-living.

Q10. Some of the properties of tissues are not the constituents of its cells. Give three examples to support the statement.

Answer: Bone is a specialised connective tissue which is made up of osteocytes (bone cells). Bones provide mechanical support which is not provided by osteocytes.

• Dry surface of skin is a compound epithelium tissue that is made up of epithelial cells. Epithelial tissue protect skin from chemical and mechanical stresses while this property is not found in epithelial cells.
• Blood is a specialised connective tissue which is made up of RBCs, WBCs and Platelets. Blood help in the transport of nutrients inside the body while blood cells do not play a role in transport of nutrients.