Bihar Board 12th Biology Important Questions Short Answer Type Part 3

Bihar Board 12th Biology Important Questions Short Answer Type Part 3

BSEB 12th Biology Important Questions Short Answer Type Part 3

Question 1. What are the features of wild plants which are selected by man for his benefit?
Answer: Wild plants grow rapidly and produce a crop within a season, and wild plants store enough food reserves in their seeds to survive through drought.

Question 2. What is plant introduction?
Answer: When a plant species is carried from its place of origin to a new place and cultivated, it is termed as plant introduction. It is an important method for crop improvement.

Question 3. What is meristem culture?
Answer: Use of explant that contains pre-existing shoot meristems and produce shoots from them when cultured on a medium. Such a culture is called meristem culture.

Question 4. What is callus?
Answer: An unorganised mass of cells is called callus. It is usually produced by culturing explant in tissue culture laboratories. A superficial tissue developing in woody plants, usually through cambial activity, in response to wounding is also called callus. This tissue develops for protecting the injured surface.

Question 5. Who coined the term totipotency? What does it means?
Answer: German botanist Gottlieb Haberlandt 1902 coined the term totopotency. Totipotency is the ability or capability of a cell to give rise to a complete organism, when cultured in a suitable culture medium at appropriate temperature and aeration conditions.

Question 6. What are somatic hybrids? What are their common uses?
Answer: Somatic hybrids are produced by fusion of somatic cells of two varieties of species. They are produced by somatic hybridisation. The cell walls of plant cells are removed by digestion with a combination of pectinase and cellulase. The naked protoplasts of two ceils are induced to fuse by a solution of polyethylene glycol (PEG) and a brief high voltage current. Such protoplasts when transferred to suitable culture medium, develop cell walls and begin to divide. These are used for gene transfer, transfer of cytoplasm and production of allopolyploids.

Question 7. What are dedifferentiation and redifferentiation?
Answer:

1. Transformation of mature cells into meristematic cells leading to the formation of callus is called dedifferentiation.
2. Development of entire plants from the components cells of callus is called redifferentiation.

Question 8. Discuss the role of plant tissue culture in increasing food production.
Answer: Plant tissue culture plays various roles in increasing food production as:

• The callus culture and suspension culture is used to get cell biomass production.
• It may be used for biochemical isolation.
• It is used to regenerate plantlets.
• It is used for the production of transgenic plants.
• It is used for isolation of protoplasts.

Question 9. Elaborate as to how biotechnology can be helpful in achieving sustainable agriculture.
Answer: Biotechnology can be helpful in achieving sustainable agriculture through the use of biofertilizers, biopesticides, disease resistant and insect resistant varieties. Microorganisms are used to prepare butter, yogurt, cheese, idlis, dosa etc. Single cell protein (SCP) can be produced from algae, bacteria, microbes etc. It is done in yeasts. It provides a valuable protein rich supplement in human diet. Microbes are employed to enhance the availability of nutrients to crops.

Question 10. ‘Biotechnology can greatly promote human welfare, but it can also be misused to increase human sufferings.’ Comment on the statement.
Answer: Biotechnology is the wise use of organisms for human welfare. It can be misused in many ways:

• Biopotenting may cause problem to one country.
• Biopiracy – developing countries may be misused by exploiting bioresources.
• Bioweapons – may be fatal to use.
• Transgene – its introduction may violate the integrity of a species.

Question 11. Give a schematic representation of plant breeding.
Answer:

Question 12. Write a note on heterosis.
Answer: Heterosis is the reverse of inbreeding depression. When two unrelated individuals or lines are crossed, the performance of F₁ hybrid is often superior to both its parents.

Fig.: Meaning of heterosis. When phenotype of F₁ falls within range of parental values it represents dominance. Only when F₁ phenotype falls outside (on either side) of the parental range, it constitutes heterosis.

Question 13. A farmer adds Azotobacter culture to the soil before sowing maize. How does it increases the yield of maize?
Answer: Azotobacter is a free-living nitrogen fixing bacteria. It fixes atmospheric nitrogen in the soil and increases the fertility of soil. Maize plants cultivated in fertile soil result in increased yield.

Question 14. What are mutations?
Answer: Mutation is a sudden and heritable change in a character of an organism. It may arise due to a change in (i) chromosome structure, (ii) chromosome number, (iii) base sequence of the concerned gene. Mostly mutations are non-expressive. These may be spontaneous (natural) or induced by mutagens like physical mutagens (X-rays, gamma rays, etc.), chemical (EMS., sodium azide etc.)

Mutation, breeding is used in plant breeding to develop improved varieties.

Question 15. What is the difference between conventional agriculture practices and modern agriculture practices?
Answer: Conventional agriculture practice includes the use of locally available good quality seeds, compost, manure and biofertilizers, this was more ecofriendly. Modern agricultural practices are causing ecological damage due to enormous exploitation of natural resources and un-manageable amount of byproducts and wastes, which are continuously polluting the atmosphere.

Question 16. Insulin is extracted from which micro-organism?
Answer: Insulin producing genes from human beings have been introduced into bacteria E. Coli, E. Coli produces insulin which is known as humulin.

Question 17. Name a water fern that is an excellent biofertilizer for rice cultivation. What helps the fern to do so?
Answer: Azolla – Anabaena symbiosis is a cyanobacterial biofertilizer, for rice cultivation. It fixes atmospheric nitrogen which is consumed by growing rice crops.

Question 18. What is Integrated Pest Management?
Answer: Integrated Pest Management is an important step taken by government which involves the harmovious application of various ‘Cultural controls’ to insure environmental pollution and proper maintenance of ecological balance.

Question 19. Differentiate between manure and biofertilizers.
Answer:

Manure	Biofertilizer
1. Manures represent the partially decayed wastes and are added to soil.	1. Biofertilizers include the organisms which enrich the soil nutrients due to their biological activity.
2. They increase the fertility aeration and water holding capacity of soil.	2. They may or may not contribute in maintaining the form of soil.
3. Green manures add many kinds of nutrient elements used by crops. Chemical fertilizers are required to be added to soil.	3. One or few nutrients are made available to crops by biofertilizers. They add to the fertility of soil and reduce the demand of chemical fertilizers.

Question 20. Write a note on Mycorrhiza.
Answer: Mycorrhiza are symbiotic association between fungus and roots of higher plants. It is of two types: Ectomycorrhiza and Endomycorrliza.
1. Ectomycorrhiza – Here, fungal mycelia form mantle on root surface. From the mantle, fungal hyphae penetrate into cortex of root as well as into the soil. This leads to increase in surface area for absorption of water and minerals (N, P and K). Fungal hyphae in soil further solubilise some insoluble organic compounds which are easily absorbed by plants. Ectomycorrhizae have been found in oaks, pines, Fagus and Eucalyptus.

2. Endomycorrhiza – Here, fungus does not form a mantle on root surface, instead it produces loosely interwoven hyphae. Some of these mycelia penetrate into soil still others enter into cortex of root.

Question 21. What is the biological significance of ectomycorrhizae in peach orchards?
Answer: The ectomycorrhizae has following functions in peach orchards:

• Absorption of water
• Solubilisation of complex organic molecules into simple inorganic nutrients
• Protection of plants from attack of disease causing pathogens, etc.

Question 22. Write two main drawbacks of using chemical weedicides? What are Bioherbicides?
Answer: Herbicides are those chemicals which are used to control the weeds (unwanted plants in crop fields).
Drawbacks of use of chemical weedicides:

• Improper use of herbicides may damage the crops.
• They encourage the growth of resistant weeds.

Bioherbicide involves the biological control of Weeds by some living organisms. It involves the use of insects feeding on a specific weed or use of certain micro-organisms which will cause disease in weeds.

Question 23. How is Lactic acid produced? Write down its uses.
Answer: Lactic acid – It was the first organic acid to be produced from microbial fermentation of lactose (milk sugar). Fermenting agents are bacteria (e.g. Streptococcus lactis and Lactobacillus species) and fungi (e.g. Rhizopus). The acid derived from fungal sources is costlier but is of high purity.

Uses: Lactic acid is used in confectionery, fruit juices, essence, pickles, canned vegetables and fish products. It is also employed as mordant in tanning, printing of wool, plastic and pharmaceuticals.

Question 24. Write the fermentation reactions for the production of alcohol.
Answer:

Question 25. Why are leguminous plants cultivated as green manure crop?
Answer: Leguminous plants possess root nodules where atmospheric nitrogen is fixed by symbiotic bacteria – Rhizobium. The fixed nitrogen fertilizes the soil. Moreover, the green plants provide manure by their death and decay.

Question 26. How can age-sex structure of a population be deficted in a pyramid diagram?
Answer: The age structure of a given population refers to the proportion of individuals of different ages within that population. Many functional aspects of the individuals are related to age. For example, infants, below one year of age, and older people have higher mortality rates than individuals of other ages. In addition, the proportion of reproductively active males and females in a population influences the population growth. The number of female individuals in active reproductive age (usually 15 – 44 years) influences the birth rates within a population.

Age-sex structure of a population can be depicted in the form of a pyramid diagram by plotting the percentage of population of each sex in each age class.

The age-sex structure of the developed world gives a steeper pyramid, which represents a nearly stable population. A rapidly growing population, like that of India, is represented by a much less steep pyramid.

The population planning policies have succeeded only marginally.

Question 27. Briefly outline the reasons for human population explosion.
Answer: Population explosion refers to increase in human population at an alarming rate.
It is because:

• Agricultural production has increased and starvation deaths have declined.
• Medical services have brought down mortality due to fatal diseases and epidemics.

Question 28. Why is increasing food production considered only a temporary solution for a growing population?
Answer: Malthus had stated that “Population, when unchecked increases in geometrical ratio, while the food supply at the best increase in an arithmetical ratio, hence population tends to increase upto the limits of means of subsistence”. Advances in biotechnology has led to increase in food production but it is considered as temporary solution because the environment can support population upto a certain limit. If the current trend of growth counting, the other available natural resources will become too meagre to meet the needs. This will lead to number of socio-economic problems.

Question 29. What do evolutionary biologists believe that the ‘success’ of mammals is largely due to their ability to maintain a constant body temperature and thrive whether they live in Antarctica or in the Sahara desert?
Answer: The mechanism used by most mammals to regulate their body temperature are similar to the ones that humans use. Human being maintain a constant body temperature of 37°C. In summer, when outside temperature is more than our body temperature, we sweat profusely. The resulting evaporate cooling, similar to what happens with a desert cooler in operation, brings down the body temperature. In winter when the temperature is much lower than 37°C, we start to shiver, a kind of exercise which produces heat and raises the body temperature.

Question 30. Why is temperature regarded as the most ecologically relevant enviromental factor?
Answer: The average temperature on land varies seasonally, decreases progressively from the equator towards the poles and from plains to the mountain tops. It ranges from subzero levels in polar areas and high altitude to > 50°C in tropical deserts in summer. Where average temperature exceed 100°C there are unique habitats such as thermal springs and deep-sea hydrothermal vents. Due to this variation in temperature mango trees cannot grow in temperature countries like Canada and Germany and snow leopards are not found in Kerala.

Question 31. Name the major biomes of India.
Answer: Major biomes of India:

1. Tropical rain forests
2. Deciduous forests
3. Desert
4. Seacoast

Question 32. What are the key elements that lead to variation in the physical and chemical conditions of different habitats?
Answer: The most important key elements are temperature, water, light and % soil. However, the physico-chemical (abiotic) components alone do not characterise the habitat of an organism completely; the habitat includes biotic components also – pathogens, parasites, predators and competitors of the organisms with which they interact constantly.

Question 33. Explain in brief the importance of light
Answer: Plants produce through photosynthesis, which is possible only when sunlight is available as a source of energy. Many species of small plants, growing in forests are adopted to photosynthesis optionally under very low conditions because they are constantly overshadowed by tall, canopied trees. Many plants are also dependent on sunlight to meet their photoperiodic requirement for flowering. The availability of light on land is closely linked with that of temperature since the sun is the source for both.

Question 34. What will happen if the predator is too efficient and over exploits its prey?
Answer: If a predator is too efficient and over-exploits its prey, then the prey might become extinct and following it, the predator will also become extinct for lack of food.

Question 35. Why it is difficult to draw sharp boundaries between ecosystems?
Answer: The different ecosystems do not have sharp boundaries between them. There are present transitional zones, between the adjacent ecosystems. These are called ecotones, these harbour some organisms from each of the adjacent ecosystems and some peculiar to themselves.

Question 36. In the following table of interspecific interactions, fill the blanks with ‘+’ sign for beneficient interaction, ‘-‘sign for detrimental and 0 for neutral interaction.

Answer:

Question 37. What is an ecosystem? How material and energy transformation occurs in an ecosystem?
Answer: An ecosystem is a structural and functional unit of the biosphere which consists of living organisms and their non-living environment.

Question 38. Differentiate between Autotrophs and Heterotrophs.
Answer:
Autotrophs:

1. Prepare their organic nutrients themselves.
2. Get inorganic materials from outside.
3. Obtain energy from sunlight or inorganic chemical reactions.
4. Usually add O₂ to the environment.
5. Are of 2 types : photoautotrophs and chemoautotrophs.
6. They are producer organisms.
7. Include plants, some protists and certain bacteria.

Heterotrophs:

1. Do not prepare organic nutrients themselves.
2. Get both organic and inorganic materials from outside.
3. Obtain energy from organic nutrients.
4. Add CO₂ to the environment.
5. Are of 2 types : phagotrophs and saprotrophs.
6. They are consumer organisms.
7. Include animals, many protists and bacteria and bacteria and fungi of decay.

Question 39. What are special consumers? Give a brief account?
Answer: Special consumers are organisms which have special mode of food intake. These may include parasites, double consumers, both producers and consumers and scavengers.

• Parasites like bacteria, protists and animals may be considered as secondary consumers or some higher order consumers.
• Double consumers like ants, bear, man. These are omnivores. They belong to more than one category for e.g. man is a primary consumer when vegetarian and a secondary consumer when non-vegetarian.
• Both producers and consumers, there are insectivores plants which are producers and secondary consumers.
• Scavengers or detrivores are animals which feed on decaying organic matter or dead organisms like earthworms, termites, vultures etc.

Question 40. What is the significance of decomposers?
Answer: The decomposers are bacteria and fungi who obtain their food from organic molecules of dead producers and consumers and their waste products. The decomposers play an important role of returning the chemical nutrients to the environment. They also make space for the new producers by consuming the dead and decaying matter, otherwise all the nutrients would remain locked in the dead remains of plants and animals and will not be available for recreation.

Question 41. Draw a scheme to show decomposition of detritus.
Answer: Dead remains of plants and animals are called detritus. The decomposition of detritus is a complex and enzymatic process, that involves step-wise degradation.

Question 42. With the help of a generalised scheme show how the biotic components of an ecosystem are related.
Answer:

Question 43. What is a food web? Give example.
Answer: Food web is a network of food chains which become interconnected at various trophic levels to form a number of feeding connections among different organisms of a biotic community. Food webs provide stability to the ecosystem.
For example food web in a pond.

Question 44. What is a food chain? Enlist its important characters.
Answer: The sequential inter-linking of organisms involving the transfer of food energy from the producers, through a series of organisms is known as a food chain. Its main characteristics are:

1. In food chain there occurs repeated eating and it involves nutritive interaction between the living organisms
2. It is always straight
3. It has undirectional flow of energy
4. It usually contains 4 to 5 trophic levels
5. Mostly 80 – 90% of energy is lost as heat.

Question 45. What is photosynthetic efficiency, net production efficiency, Assimilation efficiency and ecological efficiency?
Answer:
(1) Photosynthetic efficiency – It is the percentage ratio between gross primary productivity and incident total solar radiation. It generally varies from 1 to 5 percent.

(2) Net production efficiency – It is the percentage ratio between net primary productivity and gross primary productivity. It is around 50%.

Important efficiency measures for consumers include:
(1) Assimilation efficiency – It is the percentage ratio between food energy assimilated and food energy ingested at one trophic level.

(2) Ecological efficiency – It is the percentage ratio between energy in biomass production at one trophic level and energy in biomass production at previous trophic level. It is also called trophic level efficiency.

Question 46. Differentiate between Gaseous cycles and Sedimentary cycles.
Answer:

Gaseous Cycles	Sedimentary Cycles
1. Pertain to gases (C2, N2, O2).	1. Pertain to minerals (Ca, P, S, K, Mg.)
2. Have reservoir pool in air or water.	2. Have reservoir pool in rocks.
3. Occur quickly and take less time to complete.	3. Occur very slowly and take a long time to complete.
4. Are relatively perfect systems as the elements remain uniformly in circulation.	4. Are less perfect systems as the elements get locked in reservoir pool for long periods.

Question 47. Industries can cause rise and fall in the temperature of biosphere. How?
Answer: Industries add CO₂ and particulate matter to the air. The CO₂ acts as a greenhouse gas and increases the temperature of the air, whereas the particulate matter decreases the amount of sunlight reaching the earth and reduces the temperature on earth.

Question 48. Due to uncontrolled excessive hunting, the population of tigers in a forest becomes zero. Discuss the long-term effect of this situation on the population of deer in that forest.
Answer: In a forest ecosystem the food chain occurs like this:
Grass → Deer → Tiger
As a result of excessive hunting, the tiger population in a forest becomes zero. This will lead to an increase in the population of deer. Consequently, the amount of grass in the forest decreases. In long term, is such a situation exists it will be a decrease in deer population due to competition among deer for grass. Due to excessive grazing the forest may turn into a desert after a long time.

Question 49. Why soil is rich in nutrients in the tropical rain forests?
Answer: Soil in tropical rain forests is rich in minerals and humus because the high temperature and moisture are favourable for the decomposition of fallen leaves and dead organic matter by the decomposers.

Question 50. Define wild life. Write its significance in the maintenance of the environment.
Answer: The wild life refers to the naturally occurring species of animals and plants which are not domesticated or cultivated.

Significance:

• Wild life has links in food chains operating in nature. These food chains are extremely beneficial to us.
• Wild life maintains a balance in nature. For example, snakes control rodent population which destroy our crops.
• Wild life also performs the role of biological control. These help in the recycling of matter in nature.
• Green plants purify air, they gives us oxygen also maintain atmospheric temperature.
• Plants add water vapour by transpiration and influence rainfall.

Question 51. How is diversity at all levels generally conserved?
Answer: Diversity is recognised by gene pool, species and biotic community. The ecosystem changes due to the pollution, climate changes and exploitation etc. There is need to prevent further destruction or degradation of habitats. There are on site (in situ) and off site (ex situ) strategies of conservation. Protected areas like biosphere reserves should be maintained.

Question 52. What are threatened species? Name their 3 types in order of the danger of extinction they face.
Answer: Species likely to disappear sooner or later are threatened species. Their 3 types are:

1. Endangered species: These species are facing danger of imminent extinction, due to abundance of predators, pathogen or pullulans, very few in number or reduction in habitat.
2. Vulnerable species: Their abundant population is present but threatened to deplete in number due to some factors like DDT in bird population.
3. Rare species: These are naturally present in small populations, they have risks from predators/pathogen or environmental factors.

Question 53. What kind of threats to the biodiversity may lead to its loss?
Answer: Some important factors that lead to extinction of species and consequent loss of biodiversity are:

• habitat loss and fragmentation
• introduction of non-native species
• over exploitation
• soil, water and atmospheric pollution
• intensive agriculture
• forestry.

Habitat loss is the primary reason because if habitat is destroyed, then species would be destroyed (e.g. burning of forest, cutting of trees etc.) Pollution may eliminate some species. Eutrophication in lakes reduces biodiversity. Introduction of exotic species hinder the development of natural species, e.g. exotic fish Nile perch, water hyacinth and Lantana camara.

Question 54. What do you understand by conservation of wildlife? What are its main objectives?
Answer: Wise use and preservation of natural resources is called ‘conservation of wild life. Its main objectives are:

• To ensure utilization of species and ecosystems – All the endangered species of plants and animals should be preserved. National Parks and Sanctuaries should be set up for wildlife. Wildlife should be protected in zoological gardens.
• Preservation of species diversity – If a particular species migrates from one area to another, arrangements should be made to set up that species in the other area.
• Maintenance of life supporting systems – Unique ecosystem should be protected. National protection programmes should be linked with international programmes.

Question 55. Give two main cases of extinction of species by human intervention.
Answer: Two main causes of extinction of a species are:
(i) By destroying their natural habitat. Many wild areas are being converted to human settlements, harbour, dams, reservoirs, croplands, mining sites etc. Environmental pollution and deforestation also results in the destruction of habitat, e.g., Habitat of largest flying bird (California Condor) of today has been affected by human cleanliness. Minor disturbances in the routes of migratory animals also affect them, i.e., some dams are blocking spawning.

(ii) Indiscriminate killing of the organism. Due to some properties of particular organisms, e.g., Rhinoceros is hunted for its horn, snakes are killed because of their venom and skin; Tigers, Lions, Leopards are killed on a large scale skin; Tigers, Lions, Leopards are killed on a large scale because of their skin and demand of some plants because of its medicinal ornamental property.

Question 56. Broadly classify the extinction process.
Answer: Extinction of species – The extinction of species is a natural process. Species have disappeared and new ones have evolved to take their place over. There are three types of extinction processes:

• Natural extinction – When there is change in environment conditions, certain species disappear and others, (which are more adapted to changed conditions) take their place. This loss of species that occurred in the geological past at a very slow rate is known as natural (background extinction.)
• Mass extinction – There have been several periods in the earth’s geological history when large number of species became extinct due to catastrophes.
• Anthropogenic extinction – More number of species is disappearing from the face of the earth due to human activities. Man-made mass extinction represents a very severe depletion of biodiversity.

World Conservation Monitoring Centre has recorded that 533 animal (mostly vertebrates) and 384 plant species (mostly flowering plants) have become extinct since the year 1600. The current rate of extinction is 1000 to 10000 times higher than the background rate of extinction.

Question 57. Describe the role of wild life in modern agriculture.
Answer: Many new improved varieties of crops and useful animals have been derived from their wild relatives by genetic modifications. The wild forms serve as a reserve gene pool which may be tapped for improving disease resistance, pest resistance, cold tolerance and drought tolerance etc.

Question 58. Why there is legal lapse as far as wildlife conservation is concerned?
Answer: The existing laws are adequate to protect our wildlife. The failure of enforcement of these laws of protection of wildlife is one of the reasons for the depletion and extinction of wildlife.

Question 59. Write a note on extinction.
Answer: Extinction is the disappearance of a species from earth when its last surviving member dies. It is of three types:

• Natural extinction, is the slow replacement of existing species with better adapted species.
• Mass extinction is extinction of large number of species due to catastrophe, for e.g. extinction of dinosaurs.
• Anthropogenic extinction is extinction of species: due to human activities.

Question 60. What are the main causes of extinction of species?
Answer: The main causes of extinction of species are as follows:

• Hunting for commercial purposes and as a sport.
• Destruction of habitats due to deforestation, establishment of new human settlements, polluted water bodies, roads, dams building etc.
• Exotic species produce ecological imbalance due to removal of biological control.
• Pollution-environmental pollution has degraded many important habitats, resulting in decrease in life.
• Deforestation reduces the area of free movement of wild animals and reduces their reproductive capacity.

Question 61. List some special Wild Life Projects in India.
Answer:

• Gir Lion sanctuary Project: It has started since 1972 by Gujarat and Central Government to save Asiatic Lion.
• Project Tiger: This programme has started on 1, 1973 by Central Government.
• Project Hangul: This project was launched by IUCN, WWF and Government of Jammu and Kashmir in 1970 for Kashmir Stag or hangul.
• Himalayan Musk Deer Project: This a joint effort of Gujarat and Central Government to save Musk deer. It was started in 1972.
• Crocodile Breeding Project: It was started in 1975 by Central Government and UNDP to save gharial and mugger.

Question 62. What do you mean by conservation of biodiversity? What are its objectives?
Answer: Conservation may be defined as a technique of deriving maximum advantage from the biosphere without in any may degrading it. Conservation of biodiversity has three main objectives:

• To maintain essential ecological processes and life supporting systems like air, water and soil.
• To preserve the diversity of species and the range of genetic material of world’s organisms.
• To ensure a continuous use of species, and ecosystems which will support the rural communities and urban industries.

Question 63. What is species richness? How is it related to species diversity?
Answer: Species richness is the nuclear of species per unit area. With the increase in area, species richness also increases because of availability of natural resources. Number of individuals of different species will give an idea about evenness or equitability of species.

Species diversity is the product of species richness and species evenness.

Question 64. What are the factors responsible for loss of biodiversity?
Answer: Various factors responsible for loss of biodiversity are natural, mass extinction and anthropogenic or due human activities. Human activities have accelerated extinction of species by hunting, destroying habitats, fragmentation, introduction of new species in ecosystem, environmental pollution, construction of buildings, highways, industries, over-exploitation of rare species and due to ignorance.

Question 65. How can biodiversity be conserved?
Answer: For conservation, main steps include, protection of wildlife in natural and artificial habitats, preference should be given to threatened species during conservation programmes, emphasis on preserving ecosystem rather than a single species, protection of critical habitats like breeding habitats, feeding habitat etc., stopping animal trade of rare species, making international agreements to protect the migratory animals, setting up of National parks and Sanctuaries to protect animals.

Combining national efforts with international effort and active public participation for various in their natural habitat. Biodiversity in not homogeneously distributed over time and space. It differs from place to place.

Question 66. How do you define biodiversity? Explain its significance in the present context
Answer: Biodiversity is the totality of genes, species and ecosystem of a region. Depending upon the environmental conditions and species tolerance, biodiversity differs from place to place.

Significance: Human race depends on biodiversity for food source, breeding improved varieties, drugs and medicines, for aesthetic and cultural values and for maintaining the ecological balance.

Human beings are destroying biologically rich and unique habitats for their own interests. Due to increasing population, consumption of resources and pollution human beings are destroying the delicate balance of biosphere, this is affecting biological diversity and causing extinction of species. Biodiversity loss is one of world’s most concerned crisis. It is essential to conserve biodiversity.

Question 67. What is species diversity?
Answer: SPecies are distinct units of diversity, each one is playing a unique role in the ecosystem. Species diversity is the variety of species within a region. It can be measured in terms of species richness, which is the number of species per unit area. So greater the species richness, greater is the species diversity. The number of species increases with the area of the site.

Question 68. What is the major cause for atmospheric pollution in metro cities? How can this pollution be reduced?
Answer: Automobiles are a major cause of atmospheric pollution in metro cities. The pollution can be reduced by proper maintenance of automobiles along with use of lead-free petrol or diesel.

Question 69. Name the three divisions of diversity.
Answer: Biodiversity may be divided into three types: genetic diversity, species diversity and community or ecological diversity. Genetic diversity is related to the variations of genes within a species. The variations may be present in same genes, in entire genes or in chromosomal structures. Species diversity is the variety of species within a region. It depends on species richness and species evenness. Species richness is the number of species per unit area.

Community or ecological or ecosystem diversity is the different types of habitats or ecosystems. It contains diverse number of niches, trophic levels and various ecological processes which support energy flow, food webs and nutrient recycling.

Fig.: Interrelationship in Biodiversity.

Question 70. Write a short note on Ex-situ conservation.
Answer: Ex-situ conservation – This approach of conservation of endangered species includes the protection of a group of typical ecosystem f by a network of protected areas. Artificial conditions for individuals of a species are maintained under human supervision. Cultivation of rare plants and rearing of threatened animals is done in botanical and zoological gardens and are preserved in seed banks (plants) or genetic banks (animals).

Question 71. Explain in brief electrostatic precipitator.
Answer: The electrostatic precipitator can remove 99 percent particulate matter present in the exhaust from a thermal power plant. The precipitator has electrode wires that are maintained of several thousand volts, which produce corona that releases electrons. These electrons attach to dust particles giving them a net negative charge. The collecting plates are grounded and attract the charged dust particles. The velocity of air between the plates must be low enough be allow dust to fall. A scrubber inside the precipitator removes gases like sulphur dioxide. In a scrubber, the exhaust is passed through a spray of water or lime.

Question 72. What laws should be enforced to protect ourselves from noise pollution?
Answer: Stringent following of laws laid down in relation to noise like delimitation of horn-free zones around hospitals and schools, permissible sound-levels of crackers and of loudspeakers, timings after which loudspeakers cannot be played, etc. need to be enforced to protect oursevles from noise pollution.

Question 73. What are the effects of discharge of sewage into a river?
Answer: When sewage is discharged into a river, micro-organisms involved in biodegradation of organic matter in the receiving water bodies consume a lot of oxygen, and thus, there is a sharp decline in dissolved oxygen downstream from the point of sewage discharge. This cause mortality of fish and other aquatic creatures.

Question 74. What are the effects of the presence of large amount of nutrients in water?
Answer: Presence of large amount of nutrients in water causes excessive growth of planktonic algae, called algal bloom which imparts a distant colour to the water bodies. Algal blooms cause deterioration of the water quality and fish mortality. Some algal bloom are also extremely toxic to human beings and animals.

Question 75. Why are plants of water hyacinth called the world’s most problematic aquatic weed?
Answer: Plants of water hyacinth are called the most problematic aquatic weed because these plant grow abundantly in eutrophic water bodies, and lead to an imbalance in the ecosystem of the water bodies.

Question 76. What are the effect of disposal of sewage from homes and hospitals directly into water bodies?
Answer: Sewage of homes and hospitals contain many undesirable pathogenic micro-organisms, and if disposed directly into water can causfe outbreak of serious diseases, such as, dysentery, typhoid, jaundice, cholera etc.

Question 77. What are the components of water from industries like petroleum, paper manufacturing, metal extraction and processing and chemical manufacturing?
Answer: Waste water of the above industries contain toxic substances and a variety of organic compounds.

Question 78. What is cultural or accelerated eutrophication?
Answer: Pollutants from man’s activities like effluent from industries and homes can radically accelerate the ageing process of water bodies. This phenomenon is called cultural or accelerated eutrophication.

Question 79. What are sanitary landfills?
Answer: Sanitary landfills are open pits. The wastes are dumped in a depression or trench after compaction, and covered with dirt every day.

Question 80. What is reforestation?
Answer: Reforestation is the process of restoring a forest that once existed but was removed at some point of time in the past. In a deforested area, reforestation may occur naturally. Reforestation can be speeded by planting trees with due to consideration to biodiversity that earlier existed in that area.

Question 81. What are the effects of wastewater of thermal power plants if disposed directly into water bodies?
Answer: Thermal wastewater if disposed directly into water bodies eliminates or reduces the number of organisms sensitive to high temperature, and may exchange the growth of plant and fish in extremely cold areas but, only after causing damage to the indigenous flora and fauna.

Question 82. What are municipal solid wastes?
Answer: Municipal solid wastes are waste from homes, offices, stores, schools, hospitals, etc. That are collected and disposed by the municipality. These wastes generally comprise paper, food wastes, plastics, glass, metals, rubber, leather, textile, etc.

Question 83. What steps should be taken by human beings to solve environment issues?
Answer: All waste that is generated by us should be categorised into three types:

1. bio-degradable
2. recyclable
3. non-biodegradable.

The biodegradable materials should be put into deep pits in the ground and be left for natural breakdown. Only the non-biodegradable waste should be disposed off. The need to reduce our garbage generation should be a prime goal.

Question 84. What is organic farming?
Answer: Organic farming is a cyclical, zero-waste procedure, where waste products from one process are cycled in as nutrients for other processes. This allows the maximum utilisation of resource and increases the efficiency of production.

Question 85. What has led to the enchancement of ozone degradation? How?
Answer: Chlorofluorocarbons (CFCs) has led to the degradation of the ozone layer. CFCs discharged in the lower part of atmosphere move upward and reach stratosphere. In stratosphere, UV rays acts on them releasing Cl atoms.

Cl degrades ozone releasing molecular oxygen, with these atoms acting mearly as catalysts. Cl atoms are not consumed in the reaction. Thus CFCs are added to the stratosphere which have permanent and continuing affects on ozone levels.

Question 86. What are the effects of waterlogging?
Answer: Irrigation without proper drainage of water leads to waterlogging in the soil besides affecting the crops, waterlogging draws salt to the surface of the soil. The salt is then deposited as a thin crust on the land surface or starts collecting at the roots of the plants. This increased salt content is inimical to the growth of crops and is extremely damaging to agriculture.

Question 87. How does deforestation occur?
Answer: Deforestation occurs due to various human activities. These are as follows:

• Conversion of forest to agricultural land so as to feed the growing human population.
• Trees are used for timber, firewood, cattle ranching and for several other purposes.
• Slash and burn agriculture also called Jhum cultivation in northeastern state of India, has also contributed to deforestation.

Question 88. Write chromosomal abnormalities in Klinefelter’s Syndrome and Turner’s Syndrome.
Answer: In Klinefelter’s syndrome are more sex chromosome present. In such syndrome the chromosomes are 47 (44A + xxy). This is trisomy condition.

In Turner’s syndrome there is one sex-chromosome is less. This is monosomy condition. The chromosomes are 45 (44A + xo). Such is sterile female.

Question 89. What is polygenic trait?
Answer: This is a condition in which one character is controlled by more an one pair genes. When a character is controlled by more than a pair of g genes then such inheritance is called polygenic inheritance. For example the 5 sun of human is controlled by more than two pair genes.

Question 90. Name the technique used to separate DNA fragments in the laboratory.
Answer: In laboratory the DNA fragments are separated by Agarose Gel electrophoresis.

Question 91. Discuss about advantages of asexual reproduction.
Answer: Advantages of asexual reproduction are

• Single parent is required
• Genetically identical offsprings produced
• Helps in dispersal of species
• Rapid reproduction.

Question 92. What is interferon?
Answer: Interferon is secreted from microbes infected cell. Interferon enters into nearby cells and made resistance against microbes. After enterance into healthy cells promote proteins synthesis agaist microbes. It gives temporary immunity.

Question 93. How did Louis Pasteur discredited the theory of spontaneous generation?
Answer: Louis Pasteur discredited the theory of spontaneous generation by not plugging the sterilized sugar solution. He observed the livings entered into sugar solution and reproduce. Thus he proved the new organism developed when microbes entered into sugar solution.

Question 94. Give a schematic representation of gene therapy.
Answer:

Fig.: An example of gene therapy. A patient of SCID starts developing immune response after receiving a normal functional gene.

Question 95. What are steroids?
Answer: Steroids are complex crystallisable lipids of high molecular might, with a core structure of one 5-carbon ring and three 6-carbon rings. They are present in plants as well as in animals. Several micro-organisms like fungi, bacteria, actinomycetes, leasts, protozoan and algae transform naturally available steroids into chemotherapeutically important steroids.

Cholesterol is an important steroid in animals and humans. It acts as starting point for the synthesis of many steroid hormones like male sex hormonetestosterone, and female sex hormones-progesterone and oestrogen.

Question 96. Give some examples of genetically modified organisms.
Answer:

• Bacterium Rhizobium meliloti is used as biofertilizer.
• Bacterium Pseudomonas accumulates heavy metals (Cu, Pb) from environment and fix them into compounds (CuSO₄, PbSO₄). This is called bioremediation.
• Fungus Fuichoderma helps in biocontrol against pests and plant diseases.
• Fungus Penicillium (Genetically modified) are producing antibiotic penicillium in high amounts, than the natural strains.
• Bacteria are used for the synthesis of various enzymes like cellulose and vitamins like human growth hormone.
• Bacillus thuringiensisis used as insecticide.

Question 97. Give example to support how genetic engineering can help in improving the process of photosynthesis.
Answer: Photosynthesis can be improved by controlling the enzymes which play important role during the process of photosynthesis. For example, RUBISCO enzyme.
Ribulose 1, 5-bisphosphate (RUBISCO) is an important enzyme of photosynthesis which can act both on CO₂ and O₂. Under certain condition, in light, the enzyme RUBISCO oxygenates Ribulose bisphosphate and inhibits carboxylation as a result of which 25% of the fixed CO₂ is photorespired as CO₂.

It is now possible to isolate the RUBISCO gene, modify it accordingly and reinsert into plants to minimise the loss due to photorespiration. One such gene controlling RUBISCO enzyme has been transferred from pea plant to tobacco plant to increase photosynthetic process and high leaf yield.

Question 98. What is biopatent? What are the flaws of US patent law?
Answer: Biopatent is government protection to an inventor of a biological material, securing to him for a specific time, (usually 20 years) the exclusive right to manufacture, use and sell its products.

US patent law does not recognise technologies and methods which are used in other countries as ‘prior art’, if this knowledge is new for US.

Question 99. What is biopiracy?
Answer: Biopiracy is the theft or robbery of biological and genetic resources indigenous to a country. The process of biopiracy involves collection of biological samples without permission and commercial scale production of the product for benefits. Biopiracy is widespread in developing countries which have diverse ecosystems and posses abundant bio resources.

Some multinational corporations benefit greatly from biopiracy activities. These do not pay any financial compensation to the countries where biological material originated. It robs us of our right to utilize our own resources.

Question 100. Enlist some pharmaceutical products, produced by genetic engineering techniques.
Answer:
(i) Hormones – Mammalian hormones are the first products prepared in bacteria by recombinant DNA technology, human insulin and human growth hormone are some examples.

(ii) Immunomoduiations – (a) These are antisense nucleic acid, which bind to the mRNA of viruses and inactivate them and (b) genetically engineered proteins which block the surface receptors on cell membrance so that the pathogenic antigens can’t bind the membranes, (c) vaccines are produced which are pure and more effective.

(iii) Interferons – Interferons are proteins produced by infected cells to limit cell to cell spread of viruses in the body. Interferons can be produced in large amounts by recombinant DNA technology.

Question 101. Define a patent.
Answer: A patent is an official document giving the holder of the patent, sole rights to make, use or sell an invention and prevent others from limitating it. A patent can be granted for an invention, an improvement in an invention, process of generating a product or testing and for a concept or design.

Question 102. Write two symptoms of AIDS.
Answer: The two symptoms of AIDS are as follows:

1. The weight of body decreases gradually due to AIDS
2. The body is always maintaining fever.

Question 103. Write a short notes on:
(a) Production of human growth hormone by E. Coli
(b) Animals as organ donors for humans
(c) Plant Variety Protection and Farmer’s Right Act.
Answer:
(a) Production of human growth hormone by E. Coli – Human growth hormone (HGH) is very useful to children born with hypopituitarism which is a form of dwarfism caused by under secretion of HGH by anterior pituitary gland. It also helps in heating of injuries. The gene for HGM M is introduced in the plasmid of bacterium E. Coli. This recombinant E. Coli bacterium secretes Human growth hormone which is used for treating hypopituitarism.

(b) Animals as organ donors for humans – Successful operations were carried out so far, to donate organs from live person or deceased person. These include organs like heart, intestine, kidneys, lungs, pancreas, grafts like bones, corneas, heart valves, skin grafts, tendon etc. Most of times all the donor were human beings. Scientists are working out ways to develop some healthy tissues inside animals which may serve the same function if implanted in human body, but there are risks of severe allergies and autoimmune response.

(c) Plant Variety Protection and Farmer’s Right Act – Grants plant breeders the right on new varieties of seeds. The Farmer’s Rights Act has granted the farmers the right to save, use, sow, re-sow, exchange, share or sell his farm product including seeds.

Question 104. Explain the following terms in one or two sentences intellectual property rights, humulin and bio-fortified foods.
Answer: Intellectual property rights – Intellectual Property Rights (IPRs) are rights to make, use and sell a new product or technology for a period of 20 years to the inventor. These are granted in the form of patents, trademarks and copyrights.

Humulin – Humulin is the commercial name given to human insulin by an American firm Eli Lily. These insulins are manufactured by genetic engineering using fermentation of appropriate recombinant E. Coli clones.

Bio-fortified foods – With the help of genetic engineering techniques biotechnologists, have developed plants which are rich in nutritional content. These are potato with increased starch content upto 20 – 40%, Tomato with delayed ripening, golden rice which is rich in vitamin A.

Question 105. Explain why scientists have failed to produce vaccines against AIDS.
Answer: AIDS spread through HIV virus. It is a retrovirus with RNA as genome. Chances of mutation are very high in RNA. The virus every time mutates in its reverse transcription and replication cycle. Most HIV particles produced in an infected person differ in surface receptors at least slightly from those on the original infecting virus.

Question 106. What is cancer? What are three main types of cancer?
Answer: Cancer is characterized by uncontrolled growth and division of certain body tissues thus forming a tumour. Such cells are called neoplastic cells. Cancer cells do not undergo differentiation and have high invasiveness. Depending on the basis of location cancerous tumours are of three types

1. Carcinomas – Cancer which are located in epithelial tissues e.g. breast, stomach, lung, skin and pancreas cancer.
2. Sarcomas – Cancer of connective tissue and muscular tissue derived from mesoderm e.g. bone, lymph nodes and muscle cancer.
3. Leukaemia or Blood cancers – It affects children below 15 years. WBC count in blood increases due to increased formation of WBCs in bone marrow, which decreases erythropoiesis and RBCs count.

Question 107. What is meant by reservoirs of infection.
Answer: Reservoirs of infection are those sites which are occupied by pathogens, when they are not inside the human body. There are different for different pathogens. They are of following type:

• Carriers or vectors – Those living organisms which spread the pathogens form an infected person to healthy person. Themselves they do not suffer from the disease, e.g. for plasmodium (pathogen) the carrier host is female Anopheles mosquito.
• Soil is the reservoir of infection of Clostridium tetani (tetanus bacteria).
• Air is reservoir of bacterial cysts of tuberculosis and diphtheria and many others.
• Food and water – They serve reservoir for cholera, typhoid, polio, Entamoeba histolytica etc.

Question 108. Write down the effects of Nicotine on human body?
Answer: Nicotine stimulates passage of nerve impulses, causes muscles to relax and causes the release of adrenalin, increases both blood pressure and rate of heart beat. The increased blood pressure caused by smoking leads to increased risk of heart diseases.

Question 109. Briefly write the functions of macrophages.
Answer: Macrophages have following functions:

• Defence – Wandering macrophages dispose of microbes in the connective tissue. They are known as histiocytes. Fixed macrophages destroy microbes in the blood and lymph.
• Scavenging – Macrophages also dispose of dead tissue cells and noncellular foreign matter.
• Antigen display – Macrophages carry the antigens on their surface and display them to lymphocytes.
• Many macrophages may fuse to form a large multinucleated giant cell to capture a big size foreign body.