Solution - P/R ratio refers to the Production/Respiration ratio . For climax communities P/R=1. Climax communities being stable utilize all the products. For Pioneer species P/R >1, to establish...
66. What is a biogeochemical cycle? What is the role of the reservoir in a biogeochemical cycle? Give an example of a sedimentary cycle with the reservoir located in earth’s crust.
Solution - The cyclic movement of nutrients from reservoirs to the plants and then back to the reservoir is called a biogeochemical cycle. This provides sufficient amount of nutrients to meet the...
65. The biodiversity increases when one moves from the pioneer to the climax stage. What could be the explanation?
Solution – this is so because during ecological succession, a stage is reached at which all the biotic species are in a state of fine balance among themselves and with the abiotic condition.
64. Give two examples of artificial or manmade ecosystems. List the salient features by which they differ from natural ecosystems
Solution – Two man-made ecosystems are - Crop fields and aquarium. The manmade ecosystem involves few organisms as compared to the natural ecosystem. In an artificial ecosystem, the maintenance will...
63. What will happen to an ecosystem if:
a. All producers are removed; b. All organisms of herbivore level are eliminated; and c. All top carnivore population is removed solution – If producers are removed then organisms are dead....
62. “The energy flow in the ecosystem follows the second law of thermodynamics.” Explain.
Solution - energy can neither be created nor be destroyed; it can only be transformed from one form to another form is the second law of thermodynamics . Energy flow in ecosystem from external...
61. Given below is a list of autotrophs and heterotrophs. With your knowledge about the food chain, establish various linkages between the organisms on the principle of ‘eating and being eaten’. What is this inter-linkage established known as? Algae, hydrilla, grasshopper, rat, squirrel, crow, maize plant, deer, rabbit, lizard, wolf, snake, peacock, phytoplankton, crustaceans, whale, tiger, lion, sparrow, duck, crane, cockroach, spider, toad, fish, leopard, elephant, goat, Nymphaea, Spirogyra.
Solution - t his linkage established is known as a food web . Primary Producer’s (Tropic level I): Algae, Hydrilla, a maize plant, Phytoplankton, Nymphaea, and Spirogyra. Primary Consumer (Tropic...
60. Write a short note on the pyramid of numbers and a pyramid of biomass
Solution – pyramid of number represents the number of individual organisms at each trophic level in an ecosystem. Pyramid of biomass indicates the quantity of organic matter present at each trophic...
59. What are the three types of ecological pyramids? What information is conveyed by each pyramid with regard to structure, function and energy in the ecosystem
Solution – three types of ecological pyramids are : Pyramid of numbers – denotes number of individual organisms at each trophic level in an ecosystem. It can be either upright or inverted pyramid...
58. Which of the following ecosystems will be more productive in terms of primary productivity? Justify your answer. A young forest, a natural old forest, a shallow polluted lake and alpine meadow
Solution - a young forest will be the most productive because primary productivity in an ecosystem depends upon the plant species in a given area and the rate of plant growth and the number of...
57. Justify the following statement in terms of ecosystem dynamics. “Nature tends to increase the gross primary productivity, while man tends to increase the net primary productivity”.
Solution - the rate of production of the organic matter during the photosynthesis in an ecosystem is the gross primary productivity (GPP ) . It follows the 10% law . Net primary productivity is...
56. A farmer harvests his crop and expresses his harvest in three different ways.
a. I have harvested 10 quintals of wheat. b. I have harvested 10 quintals of wheat today in one acre of land. c. I have harvested 10 quintals of wheat in one acre of land, 6 months after sowing. Do...
55. The rate of decomposition of detritus is affected by the abiotic factors like availability of oxygen, pH of the soil substratum, temperature etc. Discuss.
Solution - the process of decomposition is favoured by high temperature and high humidity . The growth of decomposer is reduced by the low pH . Thus the process of decomposition slows down .
54. Fill in the trophic levels (1, 2, 3 and 4) in the boxes provided in the figure.
Solution – 1) Producers 2) Primary consumers 3) Secondary consumers 4) Tertiary consumers (Topmost carnivore)
53. How do you distinguish between humification and mineralisation?
Solution - Humification: It is the formation of the amorphous topmost layer of soil called the humus. Mineralisation: it takes place when humus degrades to release inorganic nutrients.
51. What is an incomplete ecosystem? Explain with the help of a suitable example.
Solution – in an incomplete ecosystem either a biotic or abiotic factor is absent . For example a benthic zone in which the bottom part of the water body where light isn’t available.
50. Sometimes due to biotic/abiotic factor, the climax remains in a particular seral stage (pre-climax) without reaching climax. Do you agree with this statement? If yes give a suitable example.
Solution - abiotic and biotic factor affects the serial stage , and also the climax species form a pre-climax stage . . An example is seeds and vegetative propagules
49. Primary productivity varies from ecosystem to ecosystem. Explain?
Solution – primary productivity depends on the plant species and its capacity to carry out the photosynthesis . Thus it varies from ecosystem to ecosystem .
48. In relation to energy transfer in the ecosystem, explain the statement “10kg of deer’s meat is equivalent to 1 kg of lion’s flesh”.
Solution - Energy transfer in an ecosystem follows 10% rule (10% of energy is transferred to the next trophic level ) . So, if the lion eats 10 kg of deer meat then only 10% energy would be passed...
47. Poaching of the tiger is a burning issue in today’s world. What implication would this activity have on the functioning of the ecosystem of which the tigers are an integral part?
Solution - an imbalance in the natural ecosystem by poaching of the tigers .this results in removal of the predator species from the ecosystem and a rise in number of tiger’s prey is seen
46. Apart from plants and animals, microbes from a permanent biotic component in an ecosystem. While plants have been referred to as autotrophs and animals as heterotrophs, what are microbes referred to as? How do the microbes fulfil their energy requirements?
Solution - The Micro-organisms obtain their energy requirements from the organic matter which is obtained by dead and decaying animals and plants.
45. The flow of energy through various trophic levels in an ecosystem is unidirectional and non-cyclic. Explain.
Solution – the energy received from the sun can’t be passed to previous level . Hence the fklow of energy is unidirectional and non – cyclic
44. Human activities interfere with the carbon cycle. List any two such activities.
Solution – two human activities are : 1. Deforestation of trees: causes a rise in the carbon level by less production of oxygen and less consumption of carbon dioxide. 2. Rapidly burning of fossil...
43. What could be the reason for the faster rate of decomposition in the tropics?
Solution - in tropics, the soil will be rich in nutrients and there will be the presence of leaves and organic components which decomposes. This makes the rate of decomposition higher and faster.
41. The number of trophic levels in an ecosystem is limited. Comment.
Solution – the energy becomes zero after some trophic level . This is because of the 10% law , thus trophic succession stops and therefore, the number of trophic levels in an ecosystem are limited.
40. Organisms at a higher trophic level have less energy available. Comment.
Solution – this is because of 10 per cent law . It says that at each successive higher trophic level organisms transfers 10% of its energy . The remaining 90% is utilized for different metabolic...
39. What is common to the earthworm, mushroom, soil mites and dung beetle in an ecosystem?
Solution - All these organisms are detrivore, decomposing organisms which feed on dead remains of plants and animals.
37. Define self-sustainability.
Solution - the ability of an ecosystem to maintain itself is known as self – sustainability
36. Give any two examples of xerarch succession
Solution – examples of xerarch succession are Lithosphere - takes place on rocks Psammosere- takes place on the sandy habitat
35. Why are nutrient cycles in nature called biogeochemical cycles?
Solution - the biological cycle in the geo i.e. rocks, air etc. refers to the biogeochemical cycle . It involves the cycling of nutrients
34. Why is the rate of assimilation of energy at the herbivore level called secondary productivity?
Solution - As the consumers assimilate primary products synthesised by producers, it results in the formation of new organic mass. Therefore, the rate of production of organic matter by heterotrophs...
33. Why are oceans least productive?
Solution: Oceans are least productive because of the limited solar light and nutrients and have high saline water.
32. Is the common edible mushroom an autotroph or a heterotroph?
Solution - Common edible mushroom is heterotroph. It belongs to the kingdom fungi which does not synthesize their food.
31. What is the ultimate source of energy for the ecosystems?
Solution - ultimate source of energy for the ecosystem is the solar energy
30. Among bryophytes, lichens and fern which one is a pioneer species in a xeric succession?
Solution -Lichens are the pioneer species, because they are the first to invade the bare land.
29. Climax stage is achieved quickly in secondary succession as compared to primary succession. Why?
Solution - In primary succession, the process begins from a bare rock while in the secondary succession the soil is already left behind having nutrients and minerals in it .
28. In the North East region of India, during the process of jhum cultivation, forests are cleared by burning and left for regrowth after a year of cultivation. How would you explain the regrowth of forest in the ecological term?
Solution - The regrowth of the forest is called secondary succession.
27. Name any two organisms which can occupy more than one trophic level in an ecosystem
Solution: the two organisms which occupy more than one trophic level in an ecosystem are : human beings and sparrow
26. Justify the pitcher plant as a producer.
Solution - Pitchers plants have the green pigments known as chlorophyll and therefore, they are photosynthetic and can prepare food on their own. This makes them producers.
25. Name an omnivore which occurs in both grazing food chain and the decomposer food chain.
Solution - Cockroach is a very common example of an omnivore which is present in the grazing food chain .
24. Arrange the following as observed in vertical stratification of a forest: Grass, Shrubby plants, Teak, Amaranths
Solution - vertical stratification order of a forest is : Grass, Amaranths, Shrubby plants, Teak. The grass is the smallest in height while the highest in height are the teak trees
23. Under what conditions would a particular stage in the process of succession revert to an earlier stage?
Solution - a particular stage in the process of succession revert back to an earlier stage when there occurs a natural calamity like earthquakes, landslides, volcanic eruptions or human-induced...
22. What does the base tier of the ecological pyramid represent?
Solution - the producers in an ecosystem are represented by the - base tier of the ecological pyramid .
21. Name an organism found as a secondary carnivore in an aquatic ecosystem .
Solution - Catfish are a secondary carnivorous organism in an aquatic ecosystem.
20. Which of the following is an ecosystem service provided by a natural ecosystem ?
a. Cycling of nutrients b. Prevention of soil erosion c. Pollutant absorption and reduction of the threat of global warming d. All of the above Correct option – ( d ) Explanation – natural ecosystem...
19. Edaphic factor refers to:
a. Water b. Soil c. Relative humidity d. Altitude Correct option – ( b ) Explanation – edaphic factors are the soil properties that affect the diversity of organisms living in soil environment ....
18. The zone at the edge of a lake or ocean which is alternatively exposed to air and immersed in water is called:
a. Pelagic zone b. Benthic zone c. Lentic one d. Littoral zone Correct option –( c ) Explanation – lentic refers to standing water . So the zone at the edge of a lake or ocean which is alternatively...
17. Which of the following type of ecosystem is expected in an area where evaporation exceeds precipitation, and mean annual rainfall is below 100mm.
(a) Grassland (b) Shrubby forest (c) Desert (d) Mangrove Correct option – ( d ) Explanation – mangrove ecosystem is expected in an area where evaporation exceeds precipitation, and mean annual...
16. If the carbon atoms fixed by producers already have passed through three species, the trophic level of the last species would be.
a. scavenger b. tertiary producer c. tertiary consumer d. secondary consumer Correct option – ( c ) Explanation – if the carbon atoms fixed by producers already have passed through three species,...
15. The reservoir for the gaseous type of bio-geochemical cycle exists in
a. stratosphere b. atmosphere c. ionosphere d. lithosphere Correct option – ( b ) Explanation – the reservoir for the gaseous type of bio geochemical cycle exists in the atmosphere Hence correct...
14. The sequence of communities of primary succession in water is:
a. phytoplankton, sedges, free-floating hydrophytes, rooted hydrophytes, grasses and trees. b. phytoplankton, free-floating hydrophytes, rooted hydrophytes, sedges, grasses and trees. c....
13. Among the following biogeochemical cycles which one does not have losses due to respiration ?
a. Phosphorus b. Nitrogen c. Sulphur d. All of the above Correct option –( d ) Explanation – any natural pathway by which necessary elements of living matter are circulated is biogeochemical cycle ....
12. A climax community is in a state of:
a. non-equilibrium b. equilibrium c. disorder d. constant change. Correct option – ( b ) Explanation – climax community is an ecological community in which the composition of the species remains...
11. During the process of ecological succession the changes that take place in communities are:
a. Orderly and sequential b. Random c. Very quick d. Not influenced by the physical environment. Correct option – ( a ) Explanation – During the process of ecological succession the changes...
10. How much of the net primary productivity of a terrestrial ecosystem is eaten and digested by herbivores?
a. 1% b. 10% c. 40% d. 90% Correct option – ( b ) Explanation – according to 10% law , in a terrestrial ecosystem in energy transfer to next trophic level about ten percent of the energy in...
9. Among the following, where do you think the process of decomposition
would be the fastest? a. Tropical rain forest b. Antarctic c. Dry arid region d. Alpine region Correct option –( a ) Explanation – the high temperature and moisture is favourable for high microbial...
8. Approximately how much of the solar energy that falls on the leaves of a plant is converted to chemical energy by photosynthesis?
a. Less than 1% b. 2-10% c. 30% d. 50% Correct option – ( b ) Explanation – About 2 – 10% of solar energy is captured by the photosynthetic organisms for photosynthesis Hence correct answer is -...
7. Pyramid of numbers is:
a. Always upright b. Always inverted c. Ether upright or inverted d. Neither upright nor inverted. Correct option – ( c ) Explanation – pyramid of numbers shows the number of species per trophic...
6. Which of the following ecosystems is most productive in terms of net
primary production? a. Deserts b. Tropical rain forests c. Oceans d. Estuaries Correct option – ( b ) Explanation – tropical rain forest ecosystem is most productive in terms of net primary...
5. Which of the following is not a producer?
a. Spirogyra b. Agaricus c. Volvox d. Nostoc Correct option – ( b ) Explanation – Agaricus is a fungus , it is a achlorophyllus and not a producer . It has saprophytic mode of nutrition . Hence...
4. An inverted pyramid of biomass can be found in which the ecosystem?
a. Forest b. Marine c. Grassland d. Tundra Correct option –( b ) Explanation – the biomass of aquatic ecosystem is inverted . The biomass of primary producer is less than the zooplanktons , which is...
3. Productivity is the rate of production of biomass expressed in terms of:
i. (kcal m–3) yr–1 ii. g–2 yr–1 iii. g–1 yr–1 iv. (kcal m–2) yr–1 (a)ii, (b) iii, (c) ii and iv, (d) i and iii Correct option – ( c ) Explanation – the rate of synthesis of energy containing organic...
2. The process of mineralisation by microorganisms helps in the release of:
a. inorganic nutrients from humus b. both organic and inorganic nutrients from detritus c. organic nutrients from humus d. inorganic nutrients from detritus and formation of humus Correct option – (...
1. Decomposers like fungi and bacteria are:
i. autotrophs ii. heterotrophs iii. saprotrophs iv. chemo-autotrophs. Choose the correct answer: (a) i and iii, (b) i and iv (c) ii and iii, (d) i and ii Correct option – ( c ) Explanation –...
62. Give one example for each of the following:
i. Eurythermal plant species _______________ ii. A hot water spring organism _______________ iii. An organism seen in deep ocean trenches _______________ iv. An organism seen in compost pit...
61. Does light factor affect the distribution of organisms? Write a brief note giving suitable examples of either plants or animals
Solution - Yes, light factor affects the distribution of organisms. For photosynthesis light is an important factor . The small plants in the forests are usually overshadowed by tall, canopied tree
60. Which element is responsible for causing soil salinity? At what concentration does the soil become saline
Solution - Na+, K+, Ca2+, Mg2+ and Cl-. Are the elements responsible for making soil saline . When the salt concentration in water is 3 – 6 g/l then soil starts becoming saline .
59. Do you agree that regional and local variations exist within each biome?
Solution - Yes, regional and local variations exist within each biome.
58. While living in and on the host species, the animal parasite has evolved certain adaptations. Describe these adaptations with examples
Solution – the adaptations include : loss of unnecessary sense organs . presence of adhesive organs or suckers to cling on to the host , loss of digestive system and High reproductive capacity
57. In an aquarium, two herbivorous species of fish are living together and feeding on phytoplankton. As per the Gause’s Principle, one of the species is to be eliminated in due course of time, but both are surviving well in the aquarium. Give possible reasons.
Solution - According to Gause’s principle , no two species can live in the same niche and hence one of them need to be eliminated . But in the given condition two herbivorous species are living...
56. Discuss the various types of positive interactions between species.
Solution - POSITIVE POPULATION INTERACTIONSSpecies A + +Species B + 0Nature of interaction Mutualism Commensalism
55. A population of Paramecium caudatum was grown in a culture medium. After 5 days the culture medium became overcrowded with Paramecium and had depleted nutrients. What will happen to the population and what type of growth curve will the population attain? Draw the growth curve.
Solution - It shows a population growing in a habitat having limited resources. Sigmoid type of growth curve would be obtained
54. Comment on the growth curve given below
Solution - The above graph indicates a population growing in a habitat with limited resources. The graph represents an initial lag phase. After that, a rise in population takes place known as...
53. The following diagrams are the age pyramids of different populations. Comment on the status of these populations
Solution - Figure ‘A’ is a pyramid-shaped figure. This structure has a larger base than the mid and the top. Status: This shape indicates the population would grow rapidly. Figure ‘B’ is an inverted...
52. An individual and population have certain characteristics. Name these attributes with definitions.
Solution – A) A population has birth rate and death rate , whereas an individual has birth and death. B) The population density is referred as the individual per unit area and density changes...
50. Observe the set of 4 figures A, B, C and D and, answer the following questions
i. Which one of the figures shows mutualism? ii. What kind of association is shown in D? iii. Name the organisms and the association in C. iv. What role is the insect performing in B? Solution – i)...
49. Fill in the blanks
Species ASpecies BType of interactionExample+ + +– + …A……….………B……….. …………C…….. Commensalism……D…… ………E… ……F……. Solution: A = 0 B = Parasitism C = Mutualism D = Commensalism E = Cuscuta D = Lichen E =...
48. Give one example for each of the following types.
a) Migratory animal b) Camouflaged animal c) Predator animal d) Biological control agent e) Phytophagous animal f) Chemical defence agent Solution: a) Migratory animal – Siberian crane, salmon,...
47. List any four characters that are employed in the human population census
Solution – four characters employed in the human population census are : Natality and mortality Sex ratio Population density Age distribution
46. Define ‘zero population growth rate’. Draw an age pyramid for the same.
Solution - a condition wherein the population neither grows nor declines is termed as zero population growth .
45. What is a tree line?
Solution - an altitude beyond which no tree is seen and beyond the tree line, only shrubs and herbs are found is termed as tree line.
44. Give the scientific names of any two microorganisms inhabiting the human intestine.
Solution - Escherichia coli and Lactobacillus. Are the two scientific names microorganisms inhabiting the human intestine
43. Lianas are vascular plants rooted in the ground and maintain erectness of their stem by making use of other trees for support. They do not maintain a direct relationship with those trees. Discuss the type of association the lianas have with the trees.
Solution - The association in which one is Lianas and other is trees is commensalism . In such type of association one species is benefitted and the other is neither benefitted nor harmed . The...
8. What are recombinant DNA vaccines? Give two examples of such vaccines. Discuss their advantages.
Solution: A recombinant vaccination is one that is made using recombinant DNA technology, which involves introducing DNA encoding an antigen that promotes an immune response into bacterial or...
7. What is the Pulse Polio Programme of Government of India? What is OPV? Why is it that India is yet to eradicate Polio?
Solution: Since 1995, the Government of India has been working to eradicate polio in India through the Pulse Polio Programme. All children under the age of five are inoculated orally against the...
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.
Solution; Drugs are chemical molecules that have psychological and physiological impacts on your body, however overdosing can have the following negative consequences: 1. When taken in excess, it...
5. What are the methods of cancer detection? Describe the common approaches for the treatment of cancer.
Solution: Gene mutations can cause unregulated and fast cell division, resulting in a mass or tumour. Cancer is the name for this tumour. Methods of cancer detection: 1. Bone marrow biopsy 2....
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.
Solution: 1. If a person is addicted, he or she will adopt a selfish attitude and may deny his or her family's demands in order to satisfy their own. 2. Reduced attention to personal and...
3. Why do some adolescents start taking drugs? How can this be avoided?
Solution: Adolescents begin using drugs because they have physiological and psychological effects on our bodies. There are several factors that contribute to addiction.: 1. Peer pressure 2. Feeling...
2. Compare the lifestyle of people living in urban areas with those of rural areas and briefly describe how lifestyle affects their health.
Solution: Rural areaUrban areaLack of health facilities Poor sanitation Poor living condition Unavailability of water, electricity etc.Health facilities are present Better sanitation facilities...
1. Represent schematically the life cycle of a malarial parasite.
Solution:
23. If there are two pathogenic viruses, one with DNA and other with RNA, which would mutate faster? And Why?
Solution; If two dangerous viruses exist, one with DNA and the other with RNA, the one with RNA will mutate quicker because RNA is a single-stranded structure that is very unstable and can mutate...
22. What are lifestyle diseases? How are they caused? Name any two such diseases.
Solution: Lifestyle diseases are illnesses brought on by a person's way of life, or his daily habits and routine. They are brought on by poor eating habits, a lack of physical activity, and a lack...
21. For an organ transplant, it is an advantage to have an identical twin. Why?
Solution: Because the blood group and tissue match is easy in identical twins, the risks of graft rejection are lower.
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?
Solution: This uncommon hypersensitive reaction is an allergy that develops as a result of being exposed to allergens. Such reactions are caused by mast cells. This can be avoided by taking...
19. What is cancer? How is a cancer cell different from the normal cell? How do normal cells attain cancerous nature?
Solution: Gene mutations can cause unregulated and fast cell division, resulting in a mass or tumour. Cancer is the name for this tumour. A cancer cell is a highly invasive metastasis that spreads...
18. What is the basic principle of vaccination? How do vaccines prevent microbial infections? Name the organism from which the hepatitis B Vaccine is produced.
Solution: The technique of injecting a weak or inactive pathogen of a specific disease into an individual's body is known as vaccination. This causes the body to respond by producing antibodies from...
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.
Solution: 1. The air and noise pollution levels in cities are extremely high. Pollutants are released by factories and other sectors, causing allergies. 2. It weakens children's immunity and makes...
16. From which plant cannabinoids are obtained? Name any two cannabinoids. Which part of the body is affected by consuming these substances?
Solution: Cannabinoids are chemical compounds that primarily operate on the brain's cannabinoid receptor. It's made from Cannabis Sativa's inflorescence. Marijuana, Ganja, and Charas are examples of...
15. Diseases like dysentery, cholera, typhoid etc., are more common in overcrowded human settlements. Why?
Solution: In the case of open excretion, the water mixes with the infected excreta, and the contaminated water spreads the disease further.
14. Drugs and alcohol give short-term ‘high’ and long-term ‘damages’, Discuss.
Solution: Alcohol and narcotics can irritate the stomach lining, causing nausea, vomiting, and other stomach problems, as well as being a CNS depressant.
13. What is secondary metabolism?
Solution; It's a word for metabolic pathways and tiny molecule products that aren't necessary for survival. Secondary metabolites, such as antibiotics and pigments, are created by bacteria, fungus,...
12. Why cannabinoids are banned in sports and games?
Solution: These substances are prohibited in sports because they are known to improve performance while also harming the player's health in the long run.
11. Many secondary metabolites of plants have medicinal properties. It is their misuse that creates problems. Justify the statement with an example.
Solution: This is due to the fact that they could be narcotics such as opium, heroin, LSD, and other chemical compounds that operate on brain receptors and enable a person to relax, improve...
10. Give the full form of CT and MRI. How are they different from each other? Where are they used?
Solution: CT: Computed Tomography MRI: Magnetic Resonance Imaging CT uses X-ray and is an invasive technique. MRI uses a magnetic field and radiofrequency pulses and non-invasive technique.
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 the consumption of these drugs. Solution: a. It...
8. The following table shows certain diseases, their causative organisms and symptoms. Fill the gaps.
Solution:
7. “Maintenance of personal and public hygiene is necessary for prevention and control of many infectious diseases”. Justify the statement by giving suitable examples.
Solution: Personal and public cleanliness must be maintained for the prevention and control of many infectious diseases because if hygiene is not maintained, germs will thrive and spread readily....
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 the virus called retrovirus? c. Can the infected cell survive while viruses are being replicated and released? Solution: 1) Block 1: Viral DNA is produced by reverse...
5. Explain any three preventive measures to control microbial infections.
Solution: 1. Overcrowded places should be avoided 2. Preventive vaccination could be done 3. Hygiene should be maintained
4. “Prevention is better than cure”. Comment.
Solution: It is always preferable to prevent than than cure. When a disease enters a person's body, it causes severe complications and agony. So, if we take precautions, it will always be beneficial...
3. Do you consider passive smoking is more dangerous than active smoking? Why?
Solution: Passive smoking, often known as second-hand smoke, refers to inhaling smoke that has been produced by someone else. It's just as bad as active smoking, and it can lead to lung cancer and...
2. Differentiate between a benign tumour and malignant tumour.
Solution: A benign tumour is a slow-growing, non-cancerous type of tumour. A malignant tumour is one that is cancerous and rapidly expanding.
1. Differentiate between active immunity and passive immunity.
Solution: Active immunity refers to the body's direct immunological reaction to an antigen, whereas passive immunity refers to the transfer of lymphocytes from an already vaccinated person to an...
16. If a patient is advised Anti Retroviral Therapy, which infection is he suffering from? Name the causative organism.
Solution: If a patient is prescribed antiretroviral therapy, he or she has Acquired Immune Deficiency Syndrome (AIDS). A virus known as HIV (Human Immunodeficiency Virus) is the causal organism.
15. What does the term `memory’ of the Immune system mean?
Solution: The immune system's memory refers to the body's ability to recall an antigen, recognise it from a previous encounter, and mount an immunological reaction against it.
14. Why is an antibody molecule represented as H2L2?
Solution: It has two light chains (L2) and two heavy chains (H2) hence the representation H2L2.
13. Lymph nodes are secondary lymphoid organs. Explain the role of lymph nodes in our immune response.
Solution: The lymph node's primary role is to cleanse the lymph (a clear liquid derived from plasma) that transports infections and other foreign material (such as cancer cells) carried by the lymph...
12. The harmful allele of sickle cell anaemia has not been eliminated from the human population. Such afflicted people derive some other benefit. Discuss.
Solution: Sickle cell anemia's damaging allele has not been eradicated from the human population. People who are afflicted in this way gain another advantage. Malaria will be less likely as a result...
11. Why is it that during changing weather, one is advised to avoid closed, crowded and air-conditioned places like cinema halls etc.?
Solution: The bacteria are active and numerous at this period. As a result, the person is more susceptible to viral infections.
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.
Solution: 1 It causes anxiousness. 2. Having difficulty concentrating and thinking clearly. 3. Headache and nausea. 4. Mood swings are also observed.
9. In the figure, the structure of an antibody molecule is shown. Name the parts A, B and C.
Show A, B and C in the diagram. Solution: Site A is the constant region for heavy chain. Site B is the constant region for the light chain. Site C is the variable region of light and heavy...
8. What are interferons? How do interferons check infection of new cells?
Solution: Interferons are a collection of natural proteins produced by the host cell in response to the presence of viruses, tumour cells, parasites, and other pathogens. Interferons stop viruses...
7. Why is the mother’s milk considered the most appropriate food for a newborn infant?
Solution: Because colostrum, a rich yellowish fluid that contains antibodies that stimulate the immune system, is generated in the first days of life, mother's milk is considered the best diet for a...
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?
Solution: The following are some of our body's preventive barriers: 1. Lysozyme present in saliva 2. The mucous coating on the epithelium lining of the gut. 3. The parietal cells in the stomach...
5. What would happen to the immune system, if thymus gland is removed from the body of a person?
Solution: T-lymphocytes would be unable to mature if the thymus gland was removed from a person's body.
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. Viruscoldb. SalmonellaTyphoidc. MicrosporumFilariasisd. Plasmodiummalaria Solution: The option ‘c' is wrongly matched in the above question option. Filariasis is a parasitic infection caused by...
3. Where are B-cells and T-cells formed? How do they differ from each other?
Solution: The bone marrow is where B-cells are made. They go through a maturation process in the bone marrow as well. Immunity is provided by B cells, which detect antigens on pathogens, whereas...
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 the body are affected by the pathogen? Solution: a. The patient is suffering from Acquired...
1. Certain pathogens are tissue/organ-specific. Justify the statement with suitable examples
Solution: Pathogens are organisms that cause disease. Pathogens that affect only one tissue or organ are known as tissue/organ-specific pathogens. Salmonella typhi infects just the small intestine.
23. A person with sickle cell anaemia is
a. more prone to malaria b. more prone to typhoid c. less prone to malaria d. less prone to typhoid Solution: Option (c) is the answer.
22. Which of the following is not the causal organism for ringworm?
a. Microsporum b. Trichophyton c. Epidermophyton d. Microsporum Solution: Option (d) is the answer.
21. Haemozoin is a:
a. precursor of haemoglobin b. the toxin released from Streptococcus infected cells c. the toxin released from Plasmodium-infected cells d. the toxin released from Haemophilus infected cells...
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 Solution: Option (c) is the answer.
19. Which of the following is not a lymphoid tissue?
a. Spleen b. Tonsils c. Pancreas d. Thymus Solution: Option (c) is the answer.
18. Antivenom against snake poison contains:
a. Antigens b. Antigen-antibody complexes c. Antibodies d. Enzymes Solution: Option (c) is the answer.
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. Curamin d. Catechin Solution: Option (a) is the answer
16. Antibodies present in colostrum which protect the newborn from certain
diseases are of a. IgG type b. Ig A type c. Ig D type d. Ig E type Solution: Option (b) is the answer.
15. Transplantation of tissues/organs to save certain patients often fails
due to the 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...
14. The substance produced by a cell in a viral infection that can protect other
cells from further infection are: a. serotonin b. colostrum c. interferon d. histamine Solution: Option (c) is the answer.
13. ‘Smack’ is a drug obtained from the:
a. latex of Papaver somniferum b. leaves of Cannabis sativa c. flowers of Dhatura d. fruits of Erythroxylum coca Solution: Option (a) is the answer.
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 person d. Sexual contact with infected persons Solution: Option (c) is the...
11. Which of the following is the reason(s) for Rheumatoid arthritis? Choose
the correct option. i. The ability to differentiate pathogens or foreign molecules from self cells increases. ii. The body attacks self cells iii. More antibodies are produced in the body iv. The...
10. When a 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...
9. In malignant tumours, the cells proliferate, grow rapidly and move to
other parts of the body to form new tumours. This stage of the disease is called: a. metagenesis b. metastasis c. teratogenesis d. mitosis Solution: Option (b) is the answer.
8. Cancer-causing genes are called:
a. structural genes b. expressed genes c. oncogenes d. regulatory genes Solution: Option (c) is the answer.
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...
6. The disease chikungunya is transmitted by:
a. house fly b. Aedes mosquito c. cockroach d. female Anopheles Solution: Option (b) is the answer.
5. The sporozoites that cause infection when a female Anopheles mosquito
bites a person, are formed in: a. liver of the person b. RBCs of mosquito c. salivary glands of mosquito d. gut of mosquito Solution: Option (d) is the answer.
4. Diseases are broadly grouped into infectious and non-infectious diseases.
In the list given below, identify infectious diseases. i. Cancer ii. Influenza iii. Allergy iv. Smallpox (a) i and ii (b) ii and iii (c) iii and iv (d)ii and iv Solution: Option (d) is the...
3. The clinical test that is used for the diagnosis of typhoid is:
a. ELISA b. ESR c. PCR d. Widal Solution: Option (d) is the answer.
2. The organisms which cause diseases in plants and animals are called:
a. Pathogens b. Vectors c. Insects d. WormsSolution: Option (a) is the answer.
1. The term ‘Health’ is defined in many ways. The most accurate definition
of 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...
7. Had Darwin been aware of Mendel’s work, would he be able to explain the origin of variations? Discuss.
Solution: The theory of natural selection is credited to Darwin. The source of these differences was unknown to Darwin. He was familiar with Mendel's work. Darwin could have explained the origin of...
6. We are told that evolution is a continuing phenomenon for all living things. Are humans also evolving? Justify your answer.
Solution: Evolution is a constantly changing process. This implies that it occurs on a regular basis. Humans are also involved in this process. Some examples of the phenomena are available. 1. The...
5. Two organisms occupying a particular geographical area (say desert) show similar adaptive strategies. Taking examples, describe the phenomenon.
Solution: Convergent evolution occurs when two animals share the same habitat. They are able to adapt to their surroundings, which is beneficial to them. Take, for example, drought-resistant desert...
3. You have studied the story of Pepper moths in England. Had the industries been removed, what impact could it have on the moth population? Discuss.
Solution: Because of growing pollution in the post-industrial period, the lichens did not survive, resulting in the storey of Pepper moths in England. The trunks of the trees were darkened by soot....
2. Explain divergent evolution in detail. What is the driving force behind it?
Solution: In divergent evolution, two species share common ancestors but develop distinct features as a result of environmental changes to which they slowly adapt, resulting in the emergence of new...
1. Name the law that states that the sum of allelic frequencies in a population remains constant. What are the five factors that influence these values?
Solution: The Hardy-Weinberg principle asserts that the sum of allelic frequencies in a population remains constant. He represented it using the algebraic equation (p+q)2 = p2 + 2pq +...
12. “Migration may enhance or blur the effects of selection”. Comment.
Solution: Migration either expands the gene pool of alleles that are being selected for, or it blurs the effects of selection by replenishing alleles that were naturally selected against.
11. Enumerate three most characteristic criteria for designating a Mendelian population.
Solution: i. The population must be large enough. ii. It should be capable of ensuring the free flow of genetic elements through sexual reproduction. iii. There should be negligible or nil migration...
10. When we say “survival of the fittest”, does it mean that
a. those which are fit only survive, or b. those that survive are called fit? Comment. Solution: The phrase "survival of the fittest" refers to the fact that those who survive are physically fit....
9. How do you express the meaning of words like race, breed, cultivars or variety?
Solution: Race – Race is a classification system that divides people into several groupings or populations. Breed - A breed is a group of domestic animals or plants that have the same look,...
8. Gene flow occurs through generations. Gene flow can occur across language barriers in humans. If we have a technique of measuring specific allele frequencies in a different population of the world, can we not predict human migratory patterns in pre-history and history? Do you agree or disagree? Explain your answer.
Solution: Yes, there is intergenerational gene flow. We can forecast human migratory patterns in prehistory and history by researching certain gene frequencies in different populations around the...
7. State and explain any three factors affecting allele frequency in populations.
Solution: 1. Gene migration or gene flow – Gene migration, also known as gene flow, is the movement of alleles into and out of a gene pool. 2. Genetic drift – Genetic drift refers to the...
6. Comment on the statement that “evolution and natural selections are result or consequence of some other processes but themselves are not processed”.
Solution: All of these changes are the outcome of evolution, which may be seen as a process. When it comes to life, however, we say that evolution is a result of natural selection. Evolution is...
5. The evolutionary story of moths in England during industrialisation reveals, that ‘evolution is reversible’. Clarify this statement.
Solution: White-winged moths were seen in greater numbers on trees than dark-winged or melanized moths. However, as a result of industrialisation, there were more dark-winged moths in the same area,...
4. While creation and presence of variation are directionless, natural selection is directional as it is in the context of adaptation. Comment.
Solution: Natural selection is directed in the sense that it leads to just one path, which is the selection of better-adapted individuals.
3. Why is nascent oxygen supported to be toxic to aerobic life forms?
Solution: Nascent oxygen is a highly reactive chemical that acts as a constant oxidizer. It can easily react with a variety of compounds found in aerobic living forms, such as DNA and proteins.
2. The scientists believe that evolution is gradual. But extinction, part of evolutionary story, is ‘sudden’ and ‘abrupt’ and also group-specific. Comment whether a natural disaster can be the cause for the extinction of species.
Solution: A natural event such as an earthquake can result in the extinction of species. During the End Permian, the third mass extinction occurred. Following a tremendous outpouring of volcanic...
1. Louis Pasteur’s experiments, if you recall, proved that life can arise from only pre-existing life. Can we correct this as life evolves from pre-existent life or otherwise we will never answer the question as to how the first forms of life arose? Comment.
Solution: So we can rectify Louis Pasteur's assertion, Oparin of Russia and Haldane of England hypothesised that the first form of life could have emerged from pre-existing non-living organic...
15. Among Ramapithecus, Australopithecines and Homo habilis – who probably did not eat meat?
Solution: Among Ramapithecus, Australopithecines and Homo habilis – Homo habilis did not eat meat.
14. By what Latin name was the first hominid known?
Solution: Homo habilis is the Latin name for the first known hominid.
13. Who among the Dryopithecus and Ramapithecus was more man-like?
Solution: With the same length arms and legs, Ramapithecus was more man-like, while Dryopithecus was more ape-like.
12. What is the founder effect?
Solution: The Founder Effect is a phenomenon that occurs when a small group of organisms gets isolated from a larger population and becomes genetically distinct enough from the original population...
11. Among the five factors that are known to affect Hardy-Weinberg equilibrium, three factors are gene flow, genetic drift and genetic recombination. What are the other two factors?
Solution: Natural selection and mutation are the other two factors.
10. In a certain population, the frequency of three genotypes is as follows:
GenotypeBBBbbbFrequency22%62%16% What is the likely frequency of B and b alleles? Solution: Frequency of B allele = all of BB + 1/2 of Bb = 22 + 31 = 53% Frequency of b allele = all of bb + 1/2 of...
9. When we talk of functional macromolecules (e.g. proteins as enzymes, hormones, receptors, antibodies etc), towards what are they evolving?
Solution: The evolution of functional macromolecules is leading to the formation of a complex organism.
8. How do we compute the age of a rock?
Solution: Natural radioactive decay of specific elements can be used to calculate the age of a rock.
7. What is the most important pre-condition for adaptive radiation?
Solution: A geographic barrier or an isolated habitat is the most significant pre-condition for adaptive radiation.
6. How do we compute the age of a fossil?
Solution: Radioactive dating can be used to determine the age of a fossil. Using established decay rates, a comparison is made between naturally existing radioactive isotopes and the decay product.
5. Give an example of convergent evolution and identify the features towards which they are converging.
Solution: Convergent evolution refers to the presence of wings in birds and butterflies, which are designed for flight. Analogous structures are formed by convergence evolution.
4. How do we compute the age of a living tree?
Solution: The age of a living tree is determined by counting the number of rings in the trunk or comparing the diameter of the trunk with the tree's average growth factor.
3. What are we referring to when we say ‘simple organisms’ or ‘complex organisms’?
Solution: The terms "simple organisms" and "complex organisms" refer to primitive and advanced organisms, respectively.
2. Did aquatic life forms get fossilised? If yes where do we come across such fossils?
Solution: Yes, Many aquatic life forms did, in fact, become fossilised. Sea creature fossils are found in mountains rather than deep-sea deposits.
1. What were the characteristics of life forms that had been fossilised?
Solution: i. Early fossils were primitive life forms that subsequently developed into more complex forms. ii. The hard body surface of fossilized organisms allowed them to be kept and...
18. Variations during mutations of meiotic recombinations are:
a. random and directionless b. random and directional c. small and directional d. random, small and directional Solution: Option (a) is the answer.
17. In 1953 S. L. Miller created primitive earth conditions in the laboratory
and gave experimental evidence for the origin of the first form of life from preexisting non-living organic molecules. The primitive earth conditions created include: a. low temperature, volcanic...
16. Match the scientists listed under column ‘I’ with ideas listed column ‘II’.
Column I A. Darwin B. Oparin C. Lamarck D. WagnerColumn II i. abiogenesis ii. use and disuse of organs iii. continental drift theory iv. evolution by natural selection a. A-i; B-iv; C-ii; D-iii b....
15. Which of the following is an example for link species?
a. Lobe fish b. Dodo bird c. Seaweed d. ChimpanzeeSolution: Option (a) is the answer.
14. The most accepted line of descent in human evolution is:
a. Australopithecus → Ramapithecus → Homo sapiens → Homo habilis b. Homo erectus → Homo habilis → Homo sapiens c. Ramapithecus → Homo habilis → Homo erectus → Homo sapiens d. Australopithecus →...
13. Which type of selection explains industrial melanism observed in the moth,
Boston Bulgaria: a. Stabilising b. Directional c. Disruptive d. Artificial Solution: Option (b) is the answer
12. For the MN-blood group system, the frequencies of M and N alleles are
0.7 and 0.3, respectively. The expected frequency of MN-blood group bearing organisms is likely to be a. 42% b. 49% c. 9% d. 58% Solution: Option (a) is the answer.
11. Fossils are generally found in:
a. Sedimentary rocks b. Igneous rocks c. Metamorphic rocks d. Any type of rock Solution: Option (a) is the answer.
10. Viviparity is considered to be more evolved because:
a. the young ones are left on their b. the young ones are protected by a thick shell c. the young ones are protected inside the mother’s body and are looked after they are born leading to more...
9. Evolution of life shows that life forms had a trend of moving from:
a. land to water b. dryland to wetland c. freshwater to seawater d. water to land Solution: Option (d) is the answer.
8. The appearance of antibiotic-resistant bacteria is an example of:
a. adaptive radiation b. transduction c. pre-existing variation in the population d. divergent evolution Solution: Option (c) is the answer.
7. (p+q)2 = p2 + 2pq + q2 = 1 represents an equation used in:
a. population genetics b. mendelian genetics c. biometrics d. molecular genetics Solution: Option (a) is the answer.
6. Analogous organs arise due to:
a. divergent evolution b. artificial selection c. genetic drift d. convergent evolution Solution: Option (d) is the answer.
5. The bones of forelimbs of whale, bat, cheetah and man are similar in
structure, because: a. one organism has given rise to another b. they share a common ancestor c. they perform the same function d. the have biochemical similarities Solution: Option (b) is the...