Biological Classification

Multiple Choice Questions

Single Correct Answer Type

Q1. All eukaryotic unicellular organisms belong to
(a) Monera (b) Protista (c) Fungi (d) Bacteria
Ans: (b) Monera—Kingdom of prokaryotes
• All eukaryotic unicellular organisms belong to protista.
Q2. The five kingdom classification was proposed by
(a) R.H. Whittaker . (b) C. Linnaeus
(c) A. Roxberg (d) Virchow
Ans: (a) This phylogenetic classification was proposed by R.H. Whittaker (1969). He created new kingdom ‘Fungi’. The five kingdom classification are as follows: 1. Plantae, 2. Animalia, 3. Protista. 4. Monera and 5. Fungi.
Whittaker has used 5 criteria for the 5 kingdom classification and are as follows:
1. Reproduction,
2. Cell structure,
3. Phylogenetic relationships,
4. Mode of nutrition,
5. Thallus organisation

Q3. Organisms living in salty areas are called as
(a) Methanogens (b) Halophiles
(c) Heliophytes (d) Thermoacidophiles

Ans: (b)
• Halophiles: Bacteria living in extremely salty areas.
• Thermoacidophiles: Bacteria living in hot springs/deep sea water.
E.g.: Thermococcus
• Methanogens: Bacteria living in marshy areas and produce methane gas.
• Heliophytes: Sun loving plants

Q4. Naked cytoplasm, multinucleated and saprophytic are the characteristics of
(a) Monerans (b) Protists (c) Fungi (d) Slime moulds
Ans: (d) Slime moulds are saprophytic protists, without cell walls. The spores
of slime moulds possess true walls. Thalloid multinucleate body of a slime mould is called plasmodium. Spores are dispersed by air currents.
E.g.: Acellular slime mould—Physarum, Cellular slime mould—Dictyostelium.

Q5. An association between roots of higher plants and fungi is called .
(a) Lichen (b) Fern (c) Mycorrhiza (d) BGA
Ans: (c) Lichens are symbiotic associations, i.e. mutually useful associations, between algae and fungi. This relationship is best known as helotism.

Q6. A dikaryon is formed when
(a) Meiosis is arrested
(b) The two haploid cells do not fuse immediately
(c) Cytoplasm does not fuse
(d) None of the above
Ans: (b) In some fungi the fusion of two haploid cells immediately results in diploid cells (2n). However, in other fungi (ascomycetes and basidiomycetes), an intervening dikaryotic stage (n + n, i.e. two nuclei per cell) occurs. Such a condition is called a dikaryon and the phase is called dikaryophase of fungus. A dikaryotic cell has two dissimilar haploid nuclei.

Q7. Contagium vivum fluidum was proposed by
(a) D. J. Ivanowsky (b) M. W. Beijerinck
(c) Stanley (d) Robert Hooke
Ans: (b) D.J. Ivanowsky (1892) discovered the virus and has recognised certain microbes as causal organism of the mosaic disease of tobacco. M.W. Beijerinck (1898) demonstrated that the extract of the infected plants of tobacco could cause infection in healthy plants and called the fluid as Contagium vivum fluidum (infectious living fluid). W. M. Stanley (1935) first time showed that viruses could be crystallised and crystals consist largely of proteins.

Q8. Association between mycobiont and phycobiont are found in
(a) Mycorrhiza (b) Root (c) Lichens (d) BGA
Ans. (c) Association between mycobiont and phycobiont are found in lichens.

Q9. Difference between virus and viroid is
(a) Absence of protein coat in viroid but present in virus
(b) Presence of low molecular weight RNA in virus but absent in viroid
(c) Both (a) and (b)
(d) None of the above
Ans: (a) Viroids are smaller than viruses and the cause of potato spindle tuber disease, chrysanthemum stunt disease. It was found to be a free RNA and lacked the protein coat that is found in viruses, hence the name viroid.

Q10. With respect to the fungal sexual cycle, choose the correct sequence of events.
(a) Karyogamy, plasmogamy and meiosis
(b) Meiosis, plasmogamy and karyogamy
(c) Plasmogamy, karyogamy and meiosis
(d) Meiosis, karyogamy and plasmogamy
Ans: (c) The sexual cycle involves the following three steps:
1. Fusion of protoplasms between two motile or non-motile gametes called
plasmogamy.
• Plasmogamy is fusion of two haploid cells without nuclear fusion.
2. Fusion of two nuclei is called karyogamy.
3. Meiosis in zygote resulting in haploid spores.

Q11. Viruses are non-cellular organisms but replicate themselves once they infect the host cell. To which of the following kingdom do viruses belong to?
(a) Monera (b) Protista (c) Fungi (d) None of these
Ans: (d) Viruses did not find a place in classification since they are not truly ‘living’ if we understand living as those organisms that have a cell structure. Viruses are neither prokaryotes nor eukaryotes. They are inert outside their specific host cell and cannot multiply of their own because they lack cellular machinery to use its genetic material. Viruses can only multiply in host or living cell.

Q12. Members of Phycomycetes are found in
(1) Aquatic habitats
(ii) On decaying wood
(iii) Moist and damp places
(iv) As obligate parasites on plants Choose from the following options.
(a) None of the above (b) (i) and (iv)
(c) (ii) and (iii) (d) All of the above
Ans: (d) Members of Phycomycetes are found in aquatic habitats, on decaying wood, moist and damp places and as obligate parasites on plants.

Very Short Answer Type Questions
Q1. What is the principle underlying the use of cyanobacteria in agricultural fields for crop improvement?
Ans: Cyanobacteria (BGA) are autotrophic microbes. Cyanobacteria are widely distributed in aquatic and terrestrial environments. Nostoc, Ariabaena and Oscillatoria are BGA that can fix atmospheric nitrogen. These organisms can fix atmospheric nitrogen in specialised cells called heterocysts, e.g., Nostoc and Anabaena. In paddy fields cyanobacteria serve as an important biofertiliser. BGA also add organic matter to the soil and increase its fertility.

Q2. Suppose you accidentally find an old preserved permanent slide without a label. In your effort to identify it, you place the slide under microscope and observe the following features:
a. Unicellular ‘
b. Well defined nucleus
c. Biflagellate—one flagellum lying longitudinally and the other transversely.
What would you identify it as? Can you iiamethe kingdom it belongs to?
Ans: Dinoflagellates are unicellular eukaryotes. Most of them have two flagella; one lies longitudinally and the other transversely in a furrow between the wall plates. Dinoflagellates belongs to kingdom protista.

Q3. How is the five-kingdom classification advantageous over the two kingdom classification?
Ans: Two Kingdom system of classification with Plantae and Animalia kingdoms.
1. Two kingdom classification did not distinguish between the prokaryotes and eukaryotes. E.g.: It brought together the prokaryotic bacteria and blue green algae with other groups (like plant, fungi and animals) which were eukaryotic.
2. Two kingdom classification did not distinguish between the unicellular and multicellular organisms. E.g:: Chlamydomonas (unicellular) and Spirogyra (multicellular) were placed together under algae.
3. This system did not distinguish between autotrophic/photosynthetic (green algae and plants) and the heterotrophic/non-photosynthetic organisms (fungi).
Five Kingdom Classification:
1. Fungi were placed in a separate kingdom—kingdom fungi.
2. It has put together organisms which were placed in different kingdoms in earlier classifications.
Kingdom Protista brought together Chlamydomonas, Chlorella (earlier placed in algae within plants and both having cell walls) with Amoeba and Paramoecium (earlier plaeed in the animal kingdom and both lacking cell walls).
3. Animal and plant kingdoms become more homogenous than they are in the two kingdom classification. So, it is the advantageous over the two kingdom classification.

Q4. Polluted water bodies have usually veryhigh abundance of plants like Nostoc and Oscillitoria. Give reasons.
Ans: Polluted water bodies (Ponds, ditches and rivers etc.) have usually nutrient contents (such as nitrate, phosphates) domestic sewage primarily contains biodegradable organic matter. Presence of large amount of nutrients in waters also causes excessive growth of Planktonic (free floating algae) called an algal bloom, which imparts a distinct colour to water bodies.
Algal bloom causes deterioration of the water quality and fish mortality. Some bloom forming algae mainly Nostoc and Oscillitoria are extremely toxic to human beings and animals.

Q5. Are chemosynthetic bacteria—autotrophic or heterotrophic?
Ans: Chemosynthetic bacteria oxidise various inorganic substances such as nitrates, nitrites and ammonia and use the released energy for their ATP production. So chemosynthetic bacteria are autotrophic in nature.

Q6. The common name of 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?
Ans: As we know that pea (vernacular name or local name) is simpler than its botanical (scientific) name Pisum sativum. These local names would vary from place to place, even within a country. Probably one would recognise the confusion that would be created if we did not find ways and means to talk to each other, to refer to organisms we are talking about.
Hence, there is a need to standardise the naming of living organisms such that a particular organism is known by the same name all over the world.

Q7. A virus is considered as a living organism and an obligate parasite when inside a host cell. But virus is not classified along with bacteria or fungi. What are the characters of virus that are similar to non-living objects?
Ans: Virus are living organisms inside a host cell. But virus is not classified along with bacteria or fungi because they having an inert crystalline structure outside the living cell. They are inert outside their specific host cell and cannot multiply of their own because they lack cellular machinery to use its genetic material.

Q8. In the five kingdom system of Whittaker, how many kingdoms are eukaryotes?
Ans: In the five kingdom system of Whittaker, four kingdoms (Protista, fungi,
plantae and animalia) belong to eukaryotes.

Short Answer Type Questions

Q1. Diatoms are also called as ‘pearls of ocean’, why? What is diatomaceous earth?
Ans: The diatoms are the unique organisms, because of their distinctive cell walls. The walls are embedded with silica and thus the walls are indestructible. It show sculpturing and ornamentation that why Diatoms are also called as ‘Pearls of Ocean’.
Diatoms have left behind large amount of cell wall deposits in their habitat; this accumulation over billions of years is referred to as ‘diatomaceous earth’. Being gritty this soil is used in polishing, filtration of oils and syrups. Diatoms are the chief ‘producers’ in the oceans.

Q2. 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?
Ans: After heavy rains in forest, moisture and nutrients pass down in soil and activates the growth of mushroom mycelium. The basidiocarps of Agaricus (mushroom) arise from the mycelium present in the soil. They appear in a circle like a ring. As these basidiocarps resemble buttons and grow in rings, they are known as fairy rings.

Q3. Neurospora—an ascomycetes fungus has been used as a biological tool to understand the mechanism of plant genetics much in the same way as Drosophila has been used to study animal genetics. What makes Neurospora so important as a genetic tool?
Ans: Neurospora is used as a genetic tool because it is easy to grow and has a haploid life cycle that makes genetic analysis simple since recessive traits will show up in the offspring. Beadle and Tatum exposed Neurospora crassa to X-rays, causing mutations. This led them to propose the “one gene, one en2yme” hypothesis that specific genes code for specific proteins.

Q4. Cyanobacteria and heterotrophic bacteria have been clubbed together in Eubacteria of kingdom Monera as per the “Five Kingdom Classification” even though the two are vastly different from each other. Is this grouping of the two types of taxa in the same kingdom justified? If so, why?
Ans: Cyanobacteria and heterotrophic bacteria have been clubbed together in Eubacteria of Kingdom Monera as per the “Five Kingdom Classification” because they do not have nuclear envelope and membrane bound organelles. Their genetic material is naked. They have 70S type of ribosomes. So, cyanobacteria and heterotrophic bacteria are prokaryotes and belong, to Kingdom Monera.

Q5. 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?
Ans: An apothecium is a wide, open, saucer-shaped or cup-shaped fruit body. It is sessile and fleshy. A cleistothecium is a globose, completely closed fruit body with no special opening to the outside. Perithecium are flask shaped structures opening by a pore or ostiole (short papilla opening by a circular pore).

Q6. What observable features in Trypanosoma would make you classify it under Kingdom Protista?
Ans: Trypanosoma is classified under the Kingdom Protista because it is unicellular eukaryotes. It has well defined nucleus with nuclear envelope, membrane bound organelles, 80S ribosomes and flagella with 9 + 2 organisation.

Q7. Fungi are cosmopolitan, write the role of fungi in your daily life.
Ans: Dough which is used for making bread, is fermented by fungi Saccharomyces cerevisiae (Baker’s yeast).
Roquefort cheese are ripened by growing a specific fungi on them, which gives them a particular flavour.
Microbes mainly yeasts used for the production of beverages like wine, beer, whisky, brandy or rum. For this purpose the yeast (Saccharomyces cerevisiae) used for fermenting malted cereals and juices to produce ethanol and commonly called Brewer’s yeast

Antibiotics produced by Fungi:

1.	Penicillin	Penicillium notatum and Penicillium chrysogenum
2.	Griseofulvin	Penicillium griseofulvum
3.	Cephalosporin	Cephalosporium acremonium
4.	Gentomycin	Micromonospora purpurea

• Cyclosporin A is produced by Trichoderma polysporum (Fungus). Cyclosporin A is used as an immunosuppressive agent in organ transplant patients.
• Statins produced by Monascus purpureus(Yeast). Statins used as blood- cholesterol lowering agent.
• Mushrooms, morels (Morchella) and truffles are edible fungi.
• Fungi causes several diseases in plants and animals including human beings.

Long Answer Type Questions
Q1. 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.
Ans: Asexual reproduction is by the production of different types of spores, the most common being the zoospores. They are flagellated (motile) and on germination gives rise to new plants.
Types of asexual reproduction:
1. Zoospores: Motile and formed in favourable condition.
2. Aplanospores: Thin walled, non-motile and formed in unfavourable condition.
3. Hypnospore: Thick walled, non-motile and formed in unfavourable condition.
4. Akinete: Under unfavourable condition, entire cell becomes thick.
5. Palmella stage: In condition of drought, protoplast is surrounded by gelatinous covering.

Q2. Apart from chlorophyll, algae have several other pigments in their chloroplast. What pigments are found in blue-green, red and brown algae that are responsible for their characteristic colours?
Ans: Apart from chlorophyll, algae have several other pigments in their chloroplast like carotenoids, xanthophylis (fucoxanthin) and r-phycoerythrin. In blue- green algae phycocyanin and r-phycoerythrin pigments are present beside chlorophyll a.
• Brown algae possess chlorophyll a, c, carotenoids and xanthophylls. They vary in colour from olive green to various shades of brown depending upon the amount of the xanthophyll pigment, fucoxanthin present in them.
• Red algae possess chlorophyll a, d and phycoerythrin in their body. The members of rhodophyceae are commonly called red algae because of the predominance of the red pigment, r-phycoerythrin in their body.

Q3. Make a list of algae and fungi that have commercial value as source of food,
chemicals, medicines and fodder.
Ans:
A. Economic importance of Algae:
1. Many species of Porphyra, Laminaria and Sargassum are among the 70 species of marine, algae used as food. Chlorella and Spirullina are unicellular algae, rich in proteins and are used as food supplements even by space travellers.
2. Certain marine brown and red algae produce large amounts of hydrocolloids (water holding substances) or phycocolloids, e.g.: algin (brown algae) and carrageen (red algae) are used commercially. Agar, one of the commercial products obtained from Gelidium and Gracilaria are used to grow microbes and in preparations of ice-creams and jellies.
3. Bromine is obtained from red algae Polysiphonia. Macrocystis is the source of Potash. Laminaria and Fucus are the source of Iodine.
B. Economic importance of Fungi:
1. Mushrooms, morels (Morchella) and truffles are edible fungi.
2. Microbes mainly yeasts used for the production of beverages like wine, beer, whisky, brandy or rum. For this purpose the yeast {Saccharomyces cerevisiae) used for fermenting malted cereals and juices to produce ethanol and commonly called Brewer’s yeast.
• Cyclosporin A is produced by Trichoderma polysporum (Fungus). Cyclosporin A is used as an immunosuppressive agent in organ transplant patients.
• Statins produced by Monascus purpureus (Yeast). Statins used as the blood-cholesterol lowering agent.

Penicillin	Penicillium notatum and Penicillium chrysogenum
Griseofulvin	Penicillium griseofulvum
Cephalosporin	Cephalosporium acremonium
Gentomycin	Micromonospora purpurea

Q4. ‘Peat’ is an important source of domestic fuel in several countries. How is ‘peat’ formed in nature?
Ans: Species of Sphagnum, a moss, provide peat that have long been used as fuel and because of their capacity to hold water as packing material for trans-shipment of living material. Peat forms when plant material decaying fully by acidic and anaerobic conditions. Peat is soft and easily compressed. Under pressure, water in the peat is forced out. Upon drying, peat can be used as fuel.

Q5. Biological classification is a dynamic and ever evolving phenomenon which keeps changing with our understanding of life forms. Justify the statement taking any two examples.
Ans: Kingdom Protista brought together Chlamydomonas, Chlorella (earlier placed in algae within plants and both having cell walls) with Amoeba and Paramoecium (earlier placed in the animal kingdom and both lacking cell walls). Five kingdom classification has put together organism (like Chlamydomonas and Amoeba) which were placed in different kingdoms in earlier classifications. This change happened because the criteria for classification changed. 

LIVING WORLD

Multiple Choice Questions

Single Correct Answer Type

Q1. 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) 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.

Q2. 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)
(a) —Ales —» Order (plant) .
(b) —Onae —» Class (plant)
(c) —Aceae —> Family (plant)
(d) —Ae —> Phylum (plant)

Q3. The term ‘systematics’ refers to
(a) Identification and classification of plants and animals •
(b) Nomenclature and identification of plants and animals
(c) Diversity of kinds of organisms and their relationship

(d) Study of habitats of organisms and their classification
Ans: (c) Human beings were, since long, not only interested in knowing more about different kinds of organisms and their diversities, but also the relationships among them. This branch of study was referred to as systematics. Systematics takes into account evolutionary relationships between organisms.

Q4. 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) Genus comprises a group of related species which has more characters in common in comparison to species of other genera.

Q5. The taxonomic unit ‘Phylum’ in the classification of animals is equivalent to which hierarchical level in classification of plants?
(a) Class (b) Order (c) Division (d) Family
Ans: (c) Classes comprising animals like fishes, amphibians, reptiles, birds along with mammals constitute the next higher category called Phylum. All these classes are included in the phylum chordata. In case of plants, classes with a few similar characters are assigned to a higher category called Division.

Q6. 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) Botanical gardens and zoological parks have collection of endemic and exotic living species.

Q7. 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) .
• Flora contains the actual account of habitat and distribution of plants
of a given area. These provide the index to the plant species found in a particular area. . .
• Manuals are useful in providing information for identification of names of species found in an area. Monographs contain information on any one taxon, i.e. any one genus or family at a particular time. They also help in correct identification.

Q8. 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 the above
Ans: (b) All living organisms—present, past and future are linked to one another by the sharing of the common genetic material, but to varying degrees.

Q9. Which of the following is a defining characteristic of living organisms?
(a) Growth (b) Ability to make sound
(d) Reproduction (d) Response to external stimuli 
Ans. (d) Response to external stimuli is a defining characteristic of living organisms.

Q10. Match the following and choose the correct option.

A.	Family	(0	tuberosum
B.	Kingdom	(ii)	Polymoniales
C.	Order	(iii)	Solarium
D.	Species	(iv)	Plantae
E.	Genus	(v)	Solanaceae

Options:
(a) D—(i), C—(ii), E—(iii), B—(iv), A-(v)
(b) E—(i), D—(ii), B—(iii), A—(iv), C-
(c) D-C), E—(ii), B—(iii), A—(iv), C-(v)
(d) E—(i), €—(ii), B—-(iii), A-(iv), D-(v)
Ans: (a)

D.	Species	(i)	tuberosum
C.	Order	(ii)	Polymoniales
E.	Genus	(iii)	Solatium
B.	Kingdom	(iv)	Plantae
A.	Family	(v)	Solanaceae

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.
Ans: 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? 
Ans: ICZN stand for International Code of Zoological Nomenclature.

Q3. Couplet in taxonomic key means .
Ans: 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?
Ans: 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.
Ans: In single-celled organisms, we are not very clear about the usage of these two terms—growth and reproduction.

Q6. Define metabolism.
Ans: The sum total of all the chemical reactions occurring in our body is metabolism.

Q7. Which is the largest botanical garden in the world? Name a few well known botanical gardens in India.
Ans: Largest famous botanical garden of world is Royal Botanical Garden, Kew (London), England. Largest botanical garden of India is Indian Botanical Garden, Sibpur, Howrah, Kolkata, West Bengal. National Botanical Research Institute is situated at Lucknow (India).

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?
Ans: 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. ‘

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. –
Ans: 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.
Ans:

Taxon	Suffixes
Kingdom T	No definite suffix
Division T	phyta/spermae
Class T	nae/opsida
Order r	ales
Family T	aceae
Genus T	No definite suffix
Species	No definite suffix

 

Q8. Brinjal and potato belong to the same genus Solarium, but to two different species. What defines them as separate species?
Ans. “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.
Ans. 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.

10. The number and kinds of organism is not constant. How do you explain this statement?
Ans. 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.
Ans: Growth, reproduction, cellular organisation, ability to sense environment and mount a suitable response, metabolism, ability to self-replicate, self-organise, interact and emergence are unique features of living organisms.
Some other characteristics of living organisms are life-span, movements, adaptations, variations and homeostasis, etc. Living organisms are self- replicating, evolving and self-regulating interactive systems capable of responding to external stimuli.
1. Metabolism: 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.
2. Cellular Organisation: All living organisms are composed of cells and products of cells. Hence, cellular organization of the body is the defining feature of life forms.
3. Consciousness: Perhaps, the most obvious and technically complicated feature of all living organisms is this ability to sense their surroundings or environment and respond to these environmental stimuli which could be physical, chemical or biological. All organisms, from the prokaryotes to the most complex eukaryotes can sense and respond to environmental cues.
All organisms handle chemicals entering their bodies. All organisms ‘ therefore are aware of surroundings. Plants respond to external factors like light, water, temperature, other organisms, pollutants, etc. Photoperiod affects reproduction in seasonal breeders, both plants and animals. Consciousness, therefore, becomes the defining property of living organisms.
4. Interactions: 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.

Q2. A scientist has come across a plant which he feels is a new species. How will he go about its identification, classification andnomenclature? .
Ans: Obviously, nomenclature or naming is only possible when the organism is described correctly. This is identification. Reference collections of plant specimens are collected into herbarium and identified. Most plant parts are dried, pressed, mounted on herbarium sheets and stored.

 . Classification is the process by which anything is grouped into convenient categories based on some easily observable characters. The earliest systems of classification used only gross superficial morphological characters such as habit, colour, number and shape of leaves, etc. They were based mainly on vegetative characters or on the androecium structure (system given by Linnaeus). Such systems were artificial.
• Natural classification systems is based on natural affinities among the organisms and consider, not only the external features, but also internal features, like ultra-structure, anatomy, embryology and phytochemistry. Natural system of classification for flowering plants was given by George Bentham and Joseph Dalton Hooker, in three volume of Genera Plantarum.
• At present phylogenetic classification systems basad on evolutionary relationships between the various organisms are acceptable. This assumes that organisms belonging to the same taxa have a common ancestor. First phylogenetic system was proposed by Engler and Prantlin monograph ‘Die NaturlichenPflanzenFamilien’.
• In order to facilitate the study, number of scientists have established procedures to assign a scientific name to each known organism. This is acceptable to biologists all over the world. The system of providing scientific names is called Binomial nomenclature.
• Each name has two components—the Generic name and the specificepithet. This system of providing a name with two components is called Binomial nomenclature. This naming system given by Carolus Linnaeus is being practiced by biological all over the world. This naming using a two word format was found convenient.

Q3. Brassica compestris 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. 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?
Ans: Taxonomic studies of various species of plants, animals and other organisms are useful in agriculture, forestry, industry and in general in knowing our bio-resources and their diversity. ,
• Herbarium is a store house of collected plant specimens that are dried, pressed and preserved on sheets. Further, these sheets are arranged according to a universally accepted system of classification.
• The herbarium sheets carry a label providing information about date and place of collection, English, local and botanical names, family, collector’s name, etc. Herbaria also serve as quick referral systems in taxonomical studies.
• Biological museums are generally set up in educational institutes such as schools and colleges. Museums have collections of preserved plant and animal specimens for study and reference. Specimens are preserved in the containers or jars in preservative solutions. Plant and animal specimens may also be preserved as dry specimens.
• Insects are preserved in insect boxes after collecting, killing and pinning. Larger animals like birds and mammals are usually stuffed and preserved. Museums often have collections of skeletons of animals too.
• Biodiversity conservation may be in-situ as well as ex -situ. However when there are situations where an animal and plant is endangered or threatened and need urgent measure to save it from extinction, ex-situ conservation is the desirable approach.
• In ex-situ conservation threatened animals and plants are taken out from natural habitat and placed in special place where they can be protected and given special care. Zoological park, botanical garden and wildlife safari park serve these purpose.

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? 
Ans: 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.

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?
Ans: 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.
Ans: 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?
Ans: 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?
Ans: 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.
Ans: 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.

human health

 Chapter 8 Human Health and Diseases

Multiple Choice Questions
Single Correct Answer Type
1. The term ‘Health’ is defined in many ways. The most accurate definition of the health would be

(a) Health is the state of body and mind in a balanced condition
(b) Health is the reflection of a smiling face
(c) Health is a state of complete physical, mental and social well-being
(d) Health is the symbol of economic prosperity.
Answer. (c) Health is not just the absence of disease. It is a state of complete physical, mental, social and psychological well-being.

2. The organisms which cause diseases in plants and animals are called
(a) Pathogens (b) Vectors (c) Insects (d) Worms
Answer. (a) A wide range of organisms belonging to bacteria, viruses, fungi protozoans, helminthes, etc., could cause diseases in man. Such disease causing organisms are called pathogens.

3. The chemical test that is used for diagnosis of typhoid is
(a) ELISA-Test (b) ESR-Test
(c) PCR-Test (d) Widal-Test
Answer. (d) The chemical test that is used for diagnosis of typhoid is Widal-Test.

4. Diseases are broadly grouped into infectious and non-infectious diseases. In the list given below, identify the infectious diseases.
i. Cancer ii. Influenza

iii. Allergy iv. Small pox
(a) i and ii (b) ii and iii –
(c) iii and iv (d) ii and iv
Answer. (d)

5. The sporozoites that cause infection, when a female Anopheles mosquito bites a person being are formed in
(a) Liver of person (b) RBCs of mosquito .
(c) Salivary glands of mosquito (d) Intestine of mosquito
Answer. (d) The sporozoites that cause infection, when a female Anopheles mosquito bites a person being are formed in intestine of mosquito.

6. The disease chikunguniya is transmitted by
(a) House flies (b) Aedes mosquitoes
(c) Cockroach (d) Female Anopheles
Answer. (b) Dengue and chikunguniya are transmitted by Aedes mosquitoes.

7. Many diseases can’be diagnosed by observing the symptoms in the patient. Which group of symptoms are indicative of pneumonia?
(a) Difficulty in respiration, fever, chills, cough, headache
(b) Constipation, abdominal pain, cramps, blood clots
(c) Nasal congestion and discharge, cough, sorethroat, headache
(d) High fever, weakness, stomach pain, loss of appetite and constipation.
Answer. (a)

• Difficulty in respiration, fever, chills, cough, headache: Pneumonia
• Constipation, abdominal pain, cramps, blood clots: Amoebiasis
• Nasal congestion and discharge, cough, sorethroat, headache: Common cold
• High fever, weakness, stomach pain, loss of appetite and constipation: Typhoid

8. The genes causing cancer are
(a) Structural genes (b) Expressor genes
(c) Oncogenes ’ (d) Regulatory genes
Answer. (c) Oncogenes are the cancer causing genes.

9. In malignant tumors, the cells proliferate, grow rapidly and move to other . parts of the body to form new tumors. This stage of disease is called
(a) Metagenesis (b) Metastasis
(c) Teratogenesis (d) Mitosis
Answer. (b) In malignant tumors, the cells proliferate, grow rapidly and move to other parts of the body to form new tumors. This stage of disease is called metastasis.

10. When an apparently healthy person is diagnosed as unhealthy by a psychiatrist, the reason could be that
(a) The patient was not efficient at his work
(b) The patient was not economically prosperous
(c) The patient shows behavioural and social maladjustment
(d) He does not take interest in sports
Answer. (c) When an apparently healthy person- is diagnosed as unhealthy by a psychiatrist, the reason could be that the patient shows behavioural and social maladjustment.

11. Which of the following are the reason(s) for Rheumatoid arthritis? Choose the correct option.
i. The ability to differentiate pathogens or foreign molecules from self cells increases
ii. Body attacks self cells
iii. More afitibodies are produced in the body
iv. The ability to differentiate pathogens or foreign molecules from self cells is lost
(a) i and ii (b) ii and iv (c) iii and iv (d) i and iii
Answer. (b) Rheumatoid arthritis is an autoimmune diseases in which

• Body attacks self cells
• The ability to differentiate pathogens or foreign molecules from self cells is lost

12. AIDS is caused by HIV. Among the following, which one is not a mode of transmission of HIV?
(a) Transfusion of contaminated blood
(b) Sharing the infected needles
(c) Shaking hands with infected persons
(d) Sexual contact with infected persons
Answer. (c) Mode of transmission of HIV:

• Transfusion of contaminated blood
• Sharing the infected needles
• Sexual contact with infected persons

13. ‘Smack’ is a drug obtained fipm the
(a) Latex of Papaver somniferum (b) Leaves of Cannabis sativa
(c) Flowers of Datura (d) Fruits of Erythroxylum coca
Answer. (a)

• ‘ Smack’ is a drug obtained from the latex of Papaver somniferum.
• Smack are brown sugar, the common name of Heroin.
• Heroin is obtained by acetylation of morphine.

14. The substance produced by a cell in viral infection that can protect other cells from further infection is N
(a) Serotonin (b) Colostrum
(c) Interferon (d) Histamine
Answer. (c) The substance produced by a cell in viral infection that can protect other cells from further infection is interferon.

15. Transplantation-of tissues/organs to save certain patients often fails due to rejection of such tissues/organs by the patient. Which type of immune response is responsible for such rejections?
(a) Auto-immune response (b) Humoral immune response
(c) Physiological immune response (d) Cell-mediated,immune response
Answer. (d) Transplantation of tissues/organs to-save certain patients often fails due to rejection of such tissues/organs by the patient. Cell-mediated immune response is responsible for such rejections.

16. Antibodies present in colostrum which protect the new bom from certain diseases is of
(a) Ig G type (b) Ig A type (c) Ig D type (d) Ig E type
Answer. (b) Antibodies present in colostrum which protect the new bom from certain diseases is of Ig A type.

17. Tobacco consumption is known to stimulate secretion of adrenaline and nor¬adrenaline. The component causing this could be
(a) Nicotine (b) Tannic acid (c) Curaimin (d) Catechin
Answer. (a) Tobacco consumption is known to stimulate secretion of adrenaline and nor-adrenaline. The component causing this could be nicotine. Morphine, cocaine, codeine and nicotine are all alkaloids.

18. Anti-venom against’snake poison contains
(a) Antigens (b) Antigen-antibody complexes
(c) Antibodies (d) Enzymes
Answer. (c) Anti-venom against snake poison contains antibodies.

19. Which of the following is not a lymphoid tissue?
(a) Spleen (b) Tonsils (c) Pancreas (d) Thymus
Answer. (c) Spleen, Tonsils and Thymus are lymphoid tissue while pancreas is mixed gland.

20. Which of the following glands is large sized at birth but reduces in size with ageing?
(a) Pineal (b) Pituitary (c) Thymus (d) Thyroid
Answer. (c) Thymus glands is large sized at birth but reduces in size with ageing.

21. Haemozoin is a
(a) Precursor of hemoglobin
(b) Toxin released from Streptococcus infected cells
(c) Toxin released from Plasmodium infected cells
(d) Toxin released from Haemophilus infected cells ’
Answer. (c) Haemozoin is a toxin released from Plasmodium infected cells.

22. One Of the following is not the causal organism for ringworm.
(a) Microsporum (b) Trichophyton
(c) Epidermophyton (d) Macrosporum
Answer. (d) Microsporum, Trichophyton and Epidermophytonare the causal organism for ringworm while Macrosporum is a brown alga.

23. A person with sickle cell anemia is
(a) More prone to malaria (b) More prone to typhoid
(c) Less prone to malaria (d) Less prone to typhoid.
Answer. (c) A person with sickle cell anemia is less prone to malaria.

Very Short Answer Type Questions
1. Certain pathogens are tissue/organ specific. Justify the statement with suitable examples.
Answer. Salmonella typhi causes typhoid and infects small intestine while intestinal endoparasite causes amoebic dysentery and infects large intestine.

2.The immune system of a person is suppressed. In the ELISA test, he was found positive to a pathogen.
a. Name the disease the patient is suffering from.
b. What is the causative organism?
c. Which cells of body are affected by the pathogen?
Answer. a. Acquired Immuno Deficiency Syndrome (AIDS)
b. Human Immuno deficiency virus (HIV)
c. Helper T-lymphocytes (TH or T4)

3. Where are B-cells and T-cells formed? How do they differ from each other?
Answer. Both B-cells and T-cells are formed in bone marrow. B-cells matures in bone marrow while T-cells matures in thymus. B-cells provides humoral immunity and T-cells provides cell mediated immunity (CMI).

4. Given below are the pairs of pathogens and the diseases caused by them. Which out of these is not a matching pair and why?
(a) Virus – common cold (b) Salmonella – typhoid
(c) Microsporum – filariasis (d) Plasmodium – malaria
Answer. Pair is mismatched. Microsporum causes ringworm disease.

5. What would happen to immune system, if thymus gland is removed from the body of a person?
Answer. Thymus is the primary lymphoid organ. In thymus gland, immature lymphocytes differentiate into antigen-sensitive lymphocytes. If thymus gland is removed from the body of a person, his immune system becomes weak. As a result the person’s body becomes prone to infectious diseases,

6. Many microbial pathogens enter the gut of humans along with food. What are the preventive barriers to protect the body from such pathogens? What type of immunity do you observe in this case?
Answer. (i) The mucus coating of the epithelium lining of the gut helps in trapping microbes entering the body.
(ii) Saliva in the mouth and hydrochloric acid in gastric juice secreted by stomach prevent microbial growth. This type of immunity is innate immunity.

7. Why is mother’s milk considered the most appropriate food for a new born infant?
Answer. Mother’s milk is considered as the most appropriate food for a new born infant because the yellowish fluid colostrum secreted by mother during the initial days of lactation has abundant antibodies (IgA) to protect the infant.

8. What are interferons? How do interferons check infection of new cells?
Answer. Interferons are natural proteins produced by the cells of immune system in
response to foreign agents such as viruses, tumor cells and parasites and protect non-infected cells from further infection. Interferons inhibit the viral replication within host cells, activate natural killer cells and macrophages, increases antigen presentation to lymphocytes, and induce the resistance of host cells to viral infection. When the antigen is presented to matching T-cells’ and B-cells, these cells multiply and remove the foreign substance.

9. In the figure, structure of an antibody molecule is shown. Name the parts A, B and C. Show A, B and C in the diagram.

Answer. A:—Constant region of heavy chain,
B—Constant region of light chain,
C—Variable region of light and heavy chain

10. If a regular dose of drug or alcohol is not provided to an addicted person, he shows some withdrawal symptoms. List any four such withdrawal symptoms.
Answer. The withdrawal symptoms are:
a. Anxiety b. Shakiness c. Nausea d. Sweating

11. Why is it that during changing weather, one is advised to avoid closed, crowded and air-conditioned places like cinema halls etc.?
Answer. During changing weather, one is advised to avoid closed, crowded and air- conditioned placed like cinema halls, etc., because during this period the infectious agents are more humerous and prevalent to which we are more vulnerable.

12. The harmful allele of sickle cell anemia has not been eliminated from human population. Such afflicted people derive some other benefits. Discuss.
Answer. The harmful alleles get eliminated from population over a period of time, yet sickle cell anaemia is persisting in human population because SCA is a harmful condition which is also a potential saviour from malaria.
Those with the benign sickle trait possess a resistance to malarial infection. The pathogen that causes the disease spends part of its cycle in the red blood cells and triggers an abnormal drop in oxygen levels in the cell. In carriers, this drop is sufficient to trigger the full sickle-cell reaction, which leads to infected cells being rapidly removed from circulation and strongly limiting the infection’s progress. These individuals have a great resistance to infection and have a greater chance of surviving outbreaks. This resistance to infection is the main reason the SCA allele and SCA disease still exist. It is found in greatest frequency in populations where malaria was and is still often a serious problem.

13. Lymph nodes are secondary lymphoid organs. Explain the role of lymph nodes in our immune response.
Answer. Lymph nodes are small solid structures located at different points along the lymphatic system. Lymph nodes trap the microorganisms or other antigens, which happen to get into the lymph and tissue fluid. Antigens trapped in the lymph nodes are responsible for the activation of lymphocytes present there and cause the immune response.

14. Why is an antibody molecule represented as H2 L2 ?
Answer. Each antibody molecule is made of the two heavy chains (H2 ) and two light chains (L2 ), hence represented as H2 L2 .

15. What does the term ‘memory’ of the Immune system mean?
Answer. When body encounters a pathogen for the first time produce a response called 1° response. 1° response is of low intensity. When body encounters the same pathogen subsequently then body elicits 2° response. 2° response is highly intensified. This is due to the fact that our body have memory of the first encounter.

16. If a patient is advised Anti Retroviral Therapy, which infection is he suffering from? Name the causative organism.
Answer. The patient is suffering from AIDS. The causative organism for AIDS is HIV (Human Immuno deficiency Virus).

Short Answer Type Questions
1. Differentiate between active immunity and passive immunity.
Answer.

2. Differentiate between benign tumor and malignant tumor.
Answer.

• Benign tumors normally remain confined to their original location and do not spread to other parts of the body and cause little damage.
• Malignant tumors are a mass of proliferating cells called neoplastic or tumor cells. Neoplastic cells grow very rapidly, invading and damaging the surrounding normal tissues. As these cells actively divide and grow they also starve the normal cells by competing for vital nutrients.
• Cells sloughed from such tumors reach distant sites through blood, and wherever they get lodged in the body, they start a new tumor there. This property called metastasis is the most feared property of malignant tumors.

3. Do you consider passive smoking is more dangerous than active smoking? Why?
Answer. Yes, passive smoking is also dangerous as the active smoking because the person is exposed to the same harmful effects of smoking like emphysema, bronchitis, lung cancer, urinary bladder cancer or even peptic ulcer.

4. “Prevention is better than cure”. Comment.
Answer. Prevention is better than cure is true as in same cases the disease is non- curable like AIDS and Hepatitis-B, and in some cases’ the treatment causes financial problems in the family.

5. Explain any three preventive measures to control microbial infections.
Answer. (i) Maintenance of personal and public hygiene is very important for
prevention and control of many infectious diseases. Measures for personal hygiene include keeping the body clean; consumption of clean drinking water, food, vegetables, fruits, etc. Public hygiene includes proper disposal of waste and excreta; periodic cleaning and disinfection of water reservoirs, pools, cesspools and tanks and observing standard practices of hygiene in public catering.
(ii) In cases of air-borne diseases such as pneumonia and common cold, in addition to the above measures, close contact with the infected persons or their belongings should be avoided.
(iii) For diseases such as malaria and filariasis that are transmitted through insect vectors, the most important measure is to control or eliminate the vectors and their breeding places. This can be achieved by avoiding stagnation of water in and around residential areas, regular cleaning of household coolers, use of mosquito nets, introducing fishes like Gambusia in ponds that feed on mosquito larvae, spraying of insecticides in ditches, drainage areas and swamps, etc. In addition, doors and windows should be provided with wire mesh to prevent the entry of mosquitoes.

6. In the given flow diagram, the*replication of retrovirus in a host is shown. Observe and answer the following questions.
(a) Fill in (1) and (2).
(b) Why is the virus called retrovirus?
(c) Can the infected cell survive while viruses are being replicated and released?

Answer. (a) 1. Viral DNA is produced by reverse transcriptase.
2. New viral RNA is produced by infected cell.
(b) HIV is called retrovirus because it forms DNA from RNA by reverse transcription.
(c) Yes, infected cell can survive while viruses are being replicated and released.

7. “Maintenance of personal and public hygiene is necessary for prevention and control of many infectious diseases”. Justify’ the statement giving suitable examples.
Answer. Measures for personal hygiene include keeping the body clean; consumption of clean drinking water, food, vegetables, fruits, etc. Public hygiene includes proper disposal of waste and excreta; periodic cleaning and disinfection of water reservoirs, pools, cesspools and tanks, and observing standard practices of hygiene in public catering. These measures are particularly essential where the infectious agents are transmitted through food and water such as typhoid, amoebiasis and ascariasis.

8. The following table shows certain diseases, their causative organisms and symptoms. Fill the gaps.

Answer.

9. The outline structure of a drug is given below.

(a) Which group of drugs does this represent?
(b) What are the modes of consumption of these drugs?
(c) Name the organ of the body which is affected by consumption of these drugs.
Answer. (a) Cannabinoids
(b) Generally taken by inhalation and oral ingestion
(c) Affect the cardiovascular system of the body

10. Give the full form of CT and MRI. How are they different from each other? Where are they used?
Answer. CT (computed tomography) and MRI (magnetic resonance imaging) are very useful to detect cancers of the internal organs. Computed tomography uses X-rays to generate a three-dimensional image of the internals of an object. MRI uses strong magnetic fields and non-ionising radiations to accurately detect pathological and physiological changes in the living tissue.

11. Many secondary metabolites of plants have medicinal properties. It is their misuse that creates problems. Justify the statement with an example.
Answer. Several plants, fruits and seeds having hallucinogenic properties and have been used for hundreds of years in folk-medicine, religious ceremonies and rituals all over the globe. When these are taken for a purpose other than medicinal use or in amounts/frequency that impairs one’s physical, physiological or psychological functions, it constitutes drug abuse.

12. Why cannabinoids are banned in sports and games?
Answer. As these days cannabinoids are being abused by some sports persons to increase their performance, that is why cannabinoids are banned in sports and games.

13. What is secondary metabolism?
Answer. Secondary metabolism is a term for pathways and small molecule products of metabolism that are not absolutely required for the survival of the organism. Examples of the products include antibiotics and pigments.

14. Drugs and alcohol give short-term ‘high’ and long-term ‘damages’. Discuss.
Answer. Curiosity, need for adventure and excitement, and experimentation, constitute
common causes, which motivate youngsters towards drug and alcohol use.
A child’s natural curiosity motivates him/her to experiment. This is complicated further by effects that might be perceived as benefits, of alcohol or drug use. Thus, the first use of drugs or alcohol may be out of curiosity or experimentation, but later the child starts using these to escape facing problems. Of late, stress, from pressures to excel in academics or examinations, has played a significant role in persuading the youngsters to try alcohol and drugs. The perception among youth that it is ‘cool’ or progressive to smoke, use drugs or alcohol, is also in a way a major cause for youth to start these habits. Television, movies, newspapers, internet also help to promote this perception. Other factors that have been seen to be associated with drug and alcohol abuse among adolescents are unstable or unsupportive family structures and peer pressure.

15. Diseases like dysentery, cholera, typhoid etc., are more common in overcrowded human settlements. Why?
Answer. Diseases like dysentery, cholera, typhoid etc., are more common in overcrowded human settlements because these are infectious diseases that can transmitted from one person to another. In overcrowded settlements there is more chances of transmission of disease from one person to other.

16. From which plant cannabinoids are obtained? Name any two cannabinoids. Which part of the body is effected by consuming these substances?
Answer. Cannabinoids are obtained from the inflorescence of the plant Cannabis sativa. Marijuana, hashish, charas, ganja are some of the cannabinoids. These chemicals interact with cannabinoid receptors of the body, mainly present in the brain. Cardiovascular system is affected adversely.

17. In the metropolitan cities of India, many children are suffering from allergy/ asthma. What are the main causes of this problem? Give some symptoms of allergic reactions.
Answer. Allergy is the exaggerated response of the immune system of certain antigens present in the environment. In metropolitan cities life style is responsible for lowering of immunity and sensitivity to allergens. More polluted environment increases the chances of allergy in children. Some symptoms of allergic reactions are sneezing, watery eyes, running nose and difficulty in breathing.

18. What is the basic principle of vaccination? How do vaccines prevent microbial infections? Name the organism from which hepatitis B vaccine is produced.
Answer. The principle of vaccination is based on the property of ’memory’ of the immune system. In vaccination, a preparation of antigenic proteins of pathogens or inactivated/live but weakened pathogens is introduced into the body. The antigens generate the primary immune response by producing antibodies. The vaccines also generate the memory B-cells and T-cells. When the vaccinated person is attacked by the same pathogens, the existing memory B-cells or T-cells recognise the antigen quickly and overwhelm the invaders with massive production of lymphocytes and antibodies. Hepatitis B vaccine is produced from yeast.

19. What is cancer? How is a cancer cell different from the normal cell? How do normal cells attain cancerous nature?
Answer. An abnormal and uncontrolled division of cells is termed as Cancer. The cancerous cells are different from the normal cells in the following ways.

In our body, the growth and differentiation of cells is highly controlled and regulated. The normal cells show a property called contact inhibition.
The surrounding cells inhibits uncontrolled growth and division of cells. The normal cells lose this property and become cancerous cells giving rise to masses of cells called tumors. Transformation of normal cells into cancerous cells is induced by some physical, chemical and biological agents (carcinogens).

20. A person shows strong unusual hypersensitive reactions when exposed to certain substances present in the air. Identify the condition. Name the cells responsible for such reactions. What precaution should be taken to avoid such reactions?
Answer. Allergy. Mast Cells are responsible for such reactions. To avoid such reactions following precautions must be taken:
(i) The use of drugs like antihistamine, adrenalin and steroids quickly reduce the symptoms of allergy.
(ii) Avoid contact with substances to which a person is hypersensitive.

21. For an organ transplant, it is an advantage to have an identical twin. Why?
Answer. Very often, when some human organs like heart, eye, liver, kidney fail to
function satisfactorily, transplantation is the only remedy to enable the patient to live a normal life. Then a search begins—to find a suitable donor.
Grafts from just any source—an animal, another primate, or any human beings cannot be made since the grafts would be rejected sooner or later. Tissue matching, blood group matching are essential before undertaking any graft/transplant and even after this the patient has to take immuno-suppresants all his/her life. The body is able to differentiate ‘self ’ and ‘nonself’ and the cell-mediated immune response is responsible for the graft rejection. In an identical twin there is no chance of rejection of transplanted organ, so it is advantageous.

22. What are lifestyle diseases? How. are they caused? Name any two such diseases.
Answer. Lifestyle diseases are defined as diseases linked with the way people live their life. This is commonly caused by alcohol, drug and smoking abuse as well as lack of physical activity and unhealthy eating. Diseases that impact on our lifestyle are heart disease, stroke and obesity.

23. If there are two pathogenic viruses, one with DNA and other with RNA, which would mutate faster? And why?
Answer. Both DNA and RNA are able to mutate. In fact, RNA being unstable, mutate at a faster rate. Consequently, viruses having RNA genome and having shorter life span mutate and evolve faster.

Long Answer Type Questions
1. Represent schematically the life cycle of a malarial parasite.
Answer.

2. Compare the life style of people living in the urban areas with those of rural areas and briefly describe how the life style affects their health.
Answer. Urban areas
The social environment: Urban environments are more likely to see higher rates of crime and violencfc. ‘
The physical environment: In densely populated urban areas, there is often a lack of facilities and outdoor areas for exercise. In addition, air quality is often lower in urban environments which can contribute to chronic diseases such as asthma. In the developing world, urban dwellers often live in large slums which lack basic sanitation and utilities such as water and electricity. Access to health and social service: Persons of lower socioeconomic status are more likely to live in urban areas and are more likely to lack health insurance. The high prevalence of individuals without health insurance or citizenship creates a greater burden on available systems.
Rural areas
The social environment: Rural dwellers have significantly poorer health status than urban elders. Also, rural residents smoke more, exercise less, have less nutritional diets.
The physical environment: Rural women especially less educated women, are more sedentary than urban women. While poor air quality and crime rates are likely to be less of an issue in rural areas, insufficiencies in the built environment make it difficult for rural residents to exercise and maintain healthy habits.
Access to health and social seryice: Evidence indicates that rural residents have limited access to health care. Some rural areas have a higher proportion of uninsured and individually insured residents than urban areas.

3. Why do some adolescents start taking drugs? How can this be avoided?
Answer. The reasons why adolescents and youngsters take to consumption of drugs are:
(i) Curiosity of child motivates him/her to experiment.
(ii) Need for adventure and excitement.
(iii) Peer group pressure
(iv) Desire to do more physical and mental work.
(v) To overcome frustration and depression, due to failure in examinations or in other activities.
(vi) Unstable or unsupportive family structures.
The following measures can be taken to avoid taking drugs:
(i) Avoid undue pressure on child to perform beyond his/her capability in studies, sports ox any other activities.
(ii) Education and counselling are very important to face problem of stress and failure in life.
(iii) Seeking help from parents, elders and peers. This would help the young to share their feelings and concern.
(iv) Looking for danger signs and taking appropriate measures to treat them.
(v) Seeking professional and medical help for de-addiction and rehabilitation.

4. In your locality, if a person is addicted to alcohol, what kind of behavioural changes do you observe in that person? Suggest measures to overcome the problem.
Answer. The immediate adverse effects of drugs and alcohol abuse are manifested in the form of reckless behaviour, vandalism and violence. Excessive doses of drugs may lead to coma and death due to respiratory failure, heart failure or cerebral hemorrhage. A Combination of drugs or their intake along with alcohol generally results in overdosing and even deaths. The most common warning signs of drug and alcohol abuse among youth include drop in academic performance, unexplained absence from school/college, lack of interest in personal hygiene, withdrawal, isolation, depression,, fatigue, aggressive and rebellious behaviour, deteriorating relationships with family and friends, loss of interest in hobbies, change in sleeping and eating habits, fluctuations in w’eight, appetite, etc. There may even be some far-reaching implications of drug/alcohol abuse. If an abuser is unable to get money to buy drugs/alcohol he/she may turn to stealing. The adverse effects are just not restricted to the person who is using drugs or alcohol. At times, a drug/ alcohol addict becomes the cause of mental and financial distress to his/her entire family and friends.
The age-old adage of‘prevention is better than cure’ holds true here also. It is also true that habits such as smoking, taking drug or alcohol are more likely to be taken up at a young age, more during adolescence. Hence, it is best to identify the situations that may push an adolescent towards use of drugs or alcohol, and to take remedial measures well in time. In this regard, the parents and the teachers have a special responsibility. Parenting that combines with high levels of nurturance and consistent discipline, has been associated with lowered risk of substance (alcohol/drugs/tobacco) abuse. Some of the measures mentioned here would be particularly useful for prevention and control of alcohol and drugs abuse among adolescents.

5. What are the methods of cancer detection? Describe the common approaches for treatment of cancer.
Answer. Cancer detection and diagnosis: Early detection of cancers, is essential as it allows the disease to be treated successfully in many cases. Cancer detection is based on biopsy and histopathological studies of the tissue and blood and bone marrow tests for increased cell counts in the case of leukemias. In biopsy, a piece of the suspected tissue cut into thin sections is stained and examined under microscope (histopathological studies) by a pathologist. Techniques like radiography (use of X-rays), CT (computed tomography) and MRI (magnetic resonance imaging) are very useful to detect cancers of the internal organs. Computed tomography uses X-rays to generate a three-dimensional image of the internals of an object. MRI uses strong magnetic fields and non-ionising radiations to accurately detect pathological and physiological changes in the living tissue.

• Antibodies against cancer-specific antigens are also used for detection of certain cancers. Techniques of molecular biology can be applied to detect genes in individuals with inherited susceptibility to certain cancers. Identification of such genes, which predispose an individual to certain cancers, may be very helpful in prevention of cancers. Such individuals may be advised to avoid exposure to particular carcinogens to which they are susceptible (e.g., tobacco smoke in case of lung cancer).
• Treatment of cancer: The common approaches for treatment of cancer are surgery, radiation therapy and immunotherapy. In radiotherapy, tumor cells are irradiated lethally, taking proper care of the normal tissues surrounding the-tumor mass. Several chemotherapeutic drugs are used to kill cancerous cells. Some of these are specific for particular tumors. Majority of drugs have side effects like hair loss; anemia, etc. Most cancers are treated by combination of surgery, radiotherapy and chemotherapy. Tumor cells have been shown to avoid detection and destruction by immune system. Therefore, the patients are given substances called biological response modifiers such as a-interferon which activates their immune system and helps in destroying the tumor.

6. Drugs like LSD, barbiturates, amphetamines, etc., are used as medicines to help patients with mental illness. However, excessive doses and abusive usage are harmful. Enumerate the major adverse effects of such drugs in humans.
Answer. Drugs like barbiturates, amphetamines, benzodiazepines, and other similar drugs, that are normally used as medicines to help patients cope with mental illnesses like depression and insomnia, are often abused. Morphine is a very effective sedative and painkiller, and is very useful in patients who have undergone surgery. Several plants, fruits and seeds having hallucinogenic properties have been used for hundreds of years in folk-medicine, religious
ceremonies and rituals all over the globe. When these are taken for a purpose other than medicinal use or in amounts/frequency that impairs one’s physical, physiological or psychological functions, it constitutes drug abuse. ,

7. What is Pulse Polio-Programme of Government of India? What is OPV? Why is it that India is yet to eradicate Polio?
Answer. Pulse Polio is an immunisation campaign established by the government of India to eliminate poliomyelitis (polio) in India by vaccinating all children under the age of five years against the polio virus. The project fights poliomyelitis through a large-scale pulse vaccination programme and monitoring for polio cases.

•  In 1995, following the Global Polio Eradication Initiative of the World Health Organization (1988), India launched Pulse Polio immunisation program with Universal Immunization Program which aimed at 100% coverage.
• The last reported cases of wild polio in India were in West Bengal and Gujarat on 13 January 2011. On 27 March 2014, the World Health Organization (WHO) declared India a polio free country, since no cases of wild polio had been reported in for three years.
•  Polio vaccines are the vaccines used to prevent poliomyelitis (polio).One type uses inactivated poliovirus and is given by injection (IPV), while the other type uses weakened poliovirus and is given by mouth (OPV). The World Health Organization recommends all children be vaccinated against polio. The two vaccines have eliminated polio from most of the world. The oral polio vaccine was developed by Albert Sabin and came into commercial use in 1961. _

8. What are recombinant DNA vaccines? Give two examples of such vaccines. Discuss their advantages.
Answer. A recombinant vaccine is a vaccine produced through recombinant DNA technology. This involves inserting the DNA encoding an antigen that stimulates an immune response into bacterial or mammalian cells.
Recombinant DNA technology has allowed the production of antigenic polypeptides of pathogen in bacteria or yeast. Vaccines produced using jthis approach allow large scale production and hence greater availability for immunisation, e.g., hepatitis B vaccine (Recombivax HB) produced from yeast. As of June 2015 one human DNA vaccine had been approved for human use, the single-dose Japanese encephalitis vaccine called IMOJEV, released in 2010 in Australia.
Advantages of recombinant DNA vaccines:
1. No risk for infection
2. Ease of development and production
3. Stability for storage and shipping
4. Cost-effectiveness
5. Expression and purification of recombinant proteins
6. Long-term persistence of immunity