12th Class Biology Chapter 25 MCQs with Answers

Welcome to the 12th Class Biology Chapter 25 MCQs Online Test. We are presenting you with top MCQ questions from the 12th Class Biology Chapter Ecosystem

We want to tell you that you can find all the 12th Class Biology Chapter 25 MCQs online tests on our website. These online tests are great for learning and as well as for scoring maximum marks in your Intermediate Exams. We are making these Class 12 Biology MCQs online tests for those who want full marks in their exams. Attempt all these Grade 12 Biology Online Multiple Choice Questions MCQs before going for the exam and it will be beneficial for you! These online tests contain all the important multiple choice questions in the important topics of the FSC Part 2 Biology Chapter 25 Ecosystem

12th Class Biology Chapter 25 MCQs with Answers

Youth For Pakistan has provided an excellent opportunity for the students of the 12th class to prepare their Biology Chapter 25 Ecosystem online with MCQs test.

This is a free platform for students to prepare for Biology Exams for Class 12 to get the best accomplishments in annual exams. 12th class Students can analyze themself by attempting this online test system as many times as they want until they find themself fully prepared.

MCQs Class 12 Biology with Answers

The purpose of these online MCQs tests is to help you evaluate your 12th Class Biology Chapter 25 MCQs. These Multiple Choice Questions (MCQs) will prepare you for your academic success in the 12th Class Exams. 12th Class Biology Chapters include Ch#15 Homeostasis, Ch#16 Support and Movement, Ch#17 Coordination and Control, Ch#18 Reproduction, Ch#19 Growth and Development, Ch#20 Chromosome and DNA, Ch#21 Cell Cycle, Ch#22 Variation and Genetics, Ch#23 Biotechnology, Ch#24 Evolution, Ch#25 Ecosystem, Ch#26 Some major Ecosystems and Ch#27 Man and his Environment

What is an Ecosystem?

Approximately 100,000 species of organisms called “fungi” are known and many more are estimated to be present. This group includes notorious pathogens such as disastrous rusts, smuts of wheat and com, and molds found growing on important crops and foodstuff. Delicacies such as mushrooms and morels, and other organisms of commercial use such as Penicillium – the source of the antibiotic penicillin, and the yeasts – used in bakeries and breweries are also members of this group. The ecological role of fungi as decomposers is paralleled only by bacteria.

12th Class Biology Chapter 25 MCQs: Ecosystem

1. The term niche was first proposed by choose which one is correct:

  • Ernst Haeckel
  • Hardy Weinberg
  • Charles Eton
  • Joseph Grinnell

2. One of the followings is not a biotic factor choose which one is correct:

  • Decomposer
  • Producer
  • Consumer
  • Lithosphere

3. The organisms which obtain their energy from the dead and decaying plants

and animals are called choose which one is correct:

  • Producers
  • Decomposers
  • Secondary consumers
  • Primary consumers

4. Dermatocarpon is an example of choose which one is correct:

  • Crustose lichen
  • Foliage lichen
  • Moss
  • Herbaceous plant

5. One of the followings is not the primary form of succession choose which one is correct:

  • Derosere
  • Crustose
  • Hydrosere
  • Xerosere

6. Fungi causing dandruff is an example of choose which one is correct:

  • Parasite
  • Endoparasite
  • Symbiosis
  • Ectoparasite

7. Lichens are an example of choose which one is correct:

  • Root nodule
  • Mutualism
  • Succession
  • Mycorrhiza

8. Nitrogen makes following percent of gases in atmosphere choose which one is correct:

  • 78%
  • 20%
  • 80%
  • 0.03%

9. Study of a single population relationship to its environment is called as choose which one is correct:

  • Synecology
  • Autecology
  • Ecology
  • Psychology

10. Major regional ecological community of plants and animals forms choose which one is correct:

  • Habitat
  • Niche
  • Biomes
  • Biosphere

11. While studying the community we come across following levels of

integration choose which one is correct:

  • Single level
  • Three level
  • Two level
  • Four level

12. “Owls prey on rabbits and mice”, this is an example of choose which one is correct:

  • Autecology
  • Community
  • Food web
  • Food chain

13. Lichens are dual organism composed of symbiotic association of choose which one is correct:

  • Algae with bacteria
  • Fungi with roots of higher plant
  • Algae with roots of higher plant
  • Algae with fungi

14. A short food chain of two or three links supports a community choose which one is correct:

  • Less efficiently
  • Efficiently
  • Inefficiently
  • More efficiently

15. Following percent of total energy from the sun is trapped by the producers in

an ecosystem choose which one is correct:

  • 1.0%
  • 90%
  • 10%
  • 99%

16. All the food chains and food webs begin with choose which one is correct:

  • Decomposers
  • Producers
  • Consumers
  • Tertiary consumers

17. One of the followings do not feed on grasses choose which one is correct:

  • Cow
  • Goat
  • Tiger
  • Rabbit

18. As energy is transferred from one trophic level to next following percent of

energy is lost choose which one is correct:

  • 70 80%
  • 60 70%
  • 90 95%
  • 80 90%

19. The legume plants, pea and bean are the hosts choose which one is correct:

  • To symbiont virus
  • To symbiont bacteria
  • To symbiont algae
  • To symbiont mosses

20. The branch of biology which deals with the study of relationship between

organism and their environment choose which one is correct:

  • Biology
  • Ecology
  • Morphology
  • Physiology

21. Joseph Grinnel choose which one is correct:

  • Niche
  • Single population
  • Producer
  • Consumer

22. Ecology choose which one is correct:

  • Oikos
  • Producer
  • Niche
  • Consumer

23. Autecology choose which one is correct:

  • Producer
  • Niche
  • Consumer
  • Single population

24. Biotic component choose which one is correct:

  • Single population
  • Water
  • Niche
  • Producer

25. Abiotic component choose which one is correct:

  • Pioneers
  • Lithosphere
  • Rabbit and mice
  • Catter pillar

26. Eagle choose which one is correct:

  • Pioneers
  • Lithosphere
  • Rabbit and mice
  • Catter pillar

27. Insects choose which one is correct:

  • Rabbit and mice
  • Blue bird
  • Lithosphere
  • Catter pillar

28. Owl choose which one is correct:

  • Rabbit and mice
  • Pioneers
  • Lithosphere
  • Catter pillar

29. Pond choose which one is correct:

  • Hydrosere
  • Derosere
  • Flower
  • Permellia

30. Dry soi choose which one is correct:

  • Flower
  • Derosere
  • Xerosere
  • Hydrosere

31. Foliage lichen choose which one is correct:

  • Xerosere
  • Permellia
  • Hydrosere
  • Flower

32. Dry habitat choose which one is correct:

  • Xerosere
  • Hydrosere
  • Flower
  • Permellia

33. Root nodules choose which one is correct:

  • Insects and flowering plants
  • Fungi symbiont
  • Legume plants
  • Biomass

34. Mycorrhiza choose which one is correct:

  • Biomass
  • Fungi symbiont
  • Legume plants
  • Insects and flowering plants

35. Mutualism choose which one is correct:

  • Biomass
  • Insects and flowering plants
  • Legume plants
  • Fungi symbiont

36. Net primary production choose which one is correct:

  • Fungi symbiont
  • Mosquito
  • Biomass
  • Legume plants

37. Many individuals of the same species living together in a defined area form choose which one is correct:

  • Community
  • Genus
  • Population
  • Ecosystem

38. Biological communities change because choose which one is correct:

  • Each stage modifies the environment and adapts for a later stage
  • The soil is depleted and food gives out
  • Old species move out and new species move in
  • Old species evolve into new species

39. When two different species overlap in the same biological niche, they are choose which one is correct:

  • Unaffected by one another
  • Dependent on one another
  • In co-operation with one another
  • In competition with one another

40. Consider the following list of factors choose which one is correct:

I. Dispersal II. Rainfall

III. Mineral deposits IV. Competition

V. Temperature

Which of the factors listed above are most significant in determining the fact

that belts of vegetation at successively higher altitudes often correspond to

those at successively higher latitudes?

  • III and V
  • II and IV
  • II and V
  • I and V

41. Which of the followings is characteristic of parasitism?

  • One organism kills and consumes another
  • Two organisms live together and neither is harmed
  • Two organisms feed side by side from the same food
  • Two organisms nourish each other; both benefit

42. Which of the following terms best describes the inter-relationship between

nitrogen-fixing bacteria and the clover in whose roots they live?

  • Mutualism
  • Commensalism
  • Predation
  • Parasitism

43. The progressive series of changes that eventually produce a climax

community on wheat was once a bare rocky island is an example of choose which one is correct:

  • Primary succession
  • Speciation
  • Secondary succession
  • Evolution

44. Some water, a small amount of soil, a few green aquatic plants and a fish

were placed in a large bottle. The bottle was scaled to prevent the exchange

of gases and other materials between its contents and the outside. The bottle

was placed in a window to receive light during the daytime. Is carbon dioxide

produced by the plants?

  • Yes, but it is produced only at night when the plants can no longer carry on photosynthesis
  • No, it is a waste product of animals only
  • No, plants take in only the waste products exhaled by animals
  • No, plants only produce oxygen

45. During the growth of a tomato plant from a seed, it increases considerably in biomass. Which of the following materials, obtained from the environment,

are necessary for the growth and increase in biomass?

  • Carbon dioxide, oxygen and nitrogen
  • Water, nitrate and methane
  • Water, carbon dioxide and mineral salts
  • Mineral salts, carbon dioxide and oxygen

46. Nitrogen gas returns to the atmosphere by the action of choose which one is correct:

  • Nitrogen fixing bacteria
  • Denitrifying bacteria
  • Nitrifying bacteria
  • Nitrate fertilizers

47. A molecule of nitrogen which you have just breathed in may have been part

of a plant that lived thousands of years ago, or part of a dinosaur that lived

millions of years ago. This illustrates the principle that choose which one is correct:

  • Dead organisms may be fossilized
  • Molecules of cytoplasm may be replaced by inorganic salts
  • Nitrogen does not combine readily with other elements
  • Decay bacteria cycle elements

48. The sequence of energy flow through a food chain is choose which one is correct:

  • Producers-higher order consumers-primary consumers
  • Higher order consumers-primary consumers-producers
  • Primary consumers-higher order consumers-producers
  • Producers-primary consumers-higher order consumers

49. In a terrestrial ecosystem, the trophic level that would contain the largest

biomass would be the choose which one is correct:

  • Producers
  • Primary consumers
  • Secondary consumers
  • Highest order consumers

50. A carrot plant is exposed to carbon dioxide containing radioactive carbon for 24 hours. After this exposure, the carrot roots are found to have accumulated

radioactivity. These carrots are then fed to a rabbit. One week later, the

rabbit’s tissue is tested for radioactivity and is found to have a higher than

normal background count. Which biogeochemical cycle is apparent from this

study?

  • Oxygen
  • Mineral
  • Carbon
  • Nitrogen

51. The rate of growth of a natural population choose which one is correct:

  • Always reaches the carrying capacity of the ecosystem
  • is limited by the carrying capacity of the ecosystem
  • When graphed, always has a positive slope
  • Exceeds the death rate and rate of emigration

52. In the past decade, which of the followings has not been a major cause of the increase in the world’s population?

  • Longer life span
  • Lower infant mortality
  • Increase in birth rate
  • Improved sanitation

53. Which of the followings is not a problem with ground water?

  • Slow movement
  • Increasing use rate
  • Pollution
  • Government ownership

54. Problems with ground water include slow movement, increasing use rate,

and increasing rate of pollution. The term “detritivore” includes choose which one is correct:

  • Decomposers
  • Primary consumers
  • Secondary consumers
  • Autotrophs

55. The category “detritivore” includes decomposers as well as scavengers. In a salt marsh, the meiofauna choose which one is correct:

  • Are represented by crabs and lobsters
  • Include fish
  • Are very small animals that live between the sand grains
  • Are the algae

56. Net primary productivity is the gross primary productivity less choose which one is correct:

  • that which is consumed by herbivores
  • that which is consumed by the producers in metabolism
  • Secondary productivity
  • Loss due to mortality

57. Net productivity is the gross productivity less that which is consumed by the producers in metabolism. Which of the followings does not contribute to the species diversity of the tropics?

  • Predictability
  • Predation
  • Spatial homogeneity
  • High productivity

58. What is happening to the amount of carbon dioxide in the atmosphere?

  • It is increasing
  • It is decreasing
  • It is holding steady
  • It is fluctuating wildly

59. The major reservoir for phosphorus is choose which one is correct:

  • Aquaifers
  • Soil and rocks
  • The atmosphere
  • the sun

60. The accumulation of herbivore biomass in an ecosystem is an example of choose which one is correct:

  • Biogeochemical cycles
  • Transpiration
  • Net primary productivity
  • Gross primary productivity

61. The process of converting nitrate to nitrogen gas and nitrous oxide is called choose which one is correct:

  • Nitrogen fixation
  • Ammonification
  • Denitrification
  • Eutrophication

62. Which of the followings is a secondary consumer?

  • A carnivore
  • A herbivore
  • A plant
  • All of the above

63. Which of the following pyramids can never be inverted in a natural ecosystem?

  • Pyramid of numbers
  • Pyramid of energy
  • Pyramid of biomass
  • All can be inverted

64. On an average, for a crop plant to produce one kilogram of food it requires

how many kilograms of water?

  • 1
  • 10
  • 100
  • 1000

65. Which of the followings contains a lot of carbon?

  • Fossil fuels
  • the oceans
  • Peal
  • All of the above contain a lot of carbon

66. On an annual basis, approximately what percentage of all the CO2 in the

atmosphere is fixed by photosynthesis?

  • 100%
  • 70%
  • 36%
  • 10%

67. Which of the following organisms is a primary consumer?

  • An autotroph
  • A horse parasite
  • An oak tree parasite
  • A wolf

68. Of the fresh water in the United States, 96% consists of choose which one is correct:

  • Streams and rivers
  • Lakes and ponds
  • Groundwater
  • Swimming pools

69. The earth is an open system with respect to choose which one is correct:

  • Organisms
  • Chemicals
  • Energy
  • All of the above

70. Which of the following chemicals enters living organisms primarily from the atmosphere rather than from rocks or soil?

  • Calcium
  • Sulfur
  • Sodium
  • Carbon

71. Carbon dioxide makes up approximately what percentage of the atmosphere?

  • 0.03%
  • 0.47%
  • 21.0%
  • 78.0%

72. What type of organism carries out nitrogen fixation?

  • Bacteria
  • Fungi
  • Protists
  • All of the above

73. Which of the following communities is the most productive?

  • Temperate forests
  • Tropical forests
  • Savannas
  • Wetlands

74. Goats depend on autotrophs for the production of choose which one is correct:

  • O2
  • Glucose
  • Both of the above
  • None of the above

75. The total amount of energy that is converted to organic compounds in a

given area per unit of time is called the choose which one is correct:

  • Biomass
  • Transpiration
  • Net primary productivity
  • Gross primary productivity

76. What percentage of sun’s available energy do the plants capture, while the

other trophic levels captures approximately choose which one is correct:

  • 1%, 10%
  • 10%, 60%
  • 10%, 1%
  • 60%, 10%

77. Which trophic level is incorrectly defined?

  • Carnivores secondary or tertiary consumer
  • Decomposers microbial heterotrophs
  • Herbivores primary consumer
  • Omnivores molds, yeasts and mushrooms

78. Carnivores represent what trophic level?

  • Producers
  • Primary consumers
  • Secondary consumers
  • Decomposers

79. The amount of energy actually incorporated into the biomass of phototrophs is choose which one is correct:

  • Gross primary productivity
  • Net primary productivity
  • Standing crop biomass
  • Transpiration

80. What is true of turnover rates of chemicals in ecosystems?

  • Turnover is faster in summer than in winter
  • Residence time is usually of the order of years for terrestrial ecosystems
  • Residence time in lakes during the summer is only a few minutes
  • All of these are true statements

81. The hydrologic cycle is driven primarily by choose which one is correct:

  • Evapotranspiration from plants
  • Rainfall
  • Snowmelt
  • Percolation of water through the soil

82. The conversion of atmospheric free nitrogen gas to ammonia occurs through the activities of certain bacteria and cyanobacteria choose which one is correct:

  • Nitrogen fixation
  • Denitrification
  • Nitrification
  • Oxidation

83. Which one of the followings would be a detritivore?

  • A snake
  • A mouse
  • A bacterium
  • A deer

84. Organisms in trophic level 3 are choose which one is correct:

  • Detritivores
  • Herbivores
  • Carnivores
  • Producers

85. Which of the followings are producers?

  • Termites
  • Bacteria
  • Algae
  • Grasshoppers

86. Which of the following levels of organization is arranged in the correct

sequence starting from most to least inclusive?

  • Community, ecosystem, individual, population
  • Individual, population, community, ecosystem
  • Ecosystem, community, population, individual
  • Individual, community, population, ecosystem

87. Species transplant experiments are one way of determining choose which one is correct:

  • the distribution of a species in a specified area
  • the abundance of a species in a specified area
  • if dispersal is a key factor in limiting distribution
  • the strength of interspecific interactions in an area

88. If a meteor impact or volcanic eruption injected a lot of dust into the

atmosphere and reduced sunlight reaching Earth’s surface by 70% for one

year, all of the following communities would be greatly affected except a choose which one is correct:

  • Forest community
  • Deep-sea vent community
  • Oligotrophic lake community
  • Eutrophic lake community

89. A population is correctly defined as having which of the following characteristics?

I. Inhabiting the same general area

II. Individuals belonging to the same species

III. Possessing a constant and uniform density and dispersion

  • I only
  • III only
  • I and II only
  • II and III only

90. To measure the population density of monarch butterflies occupying a

particular park, 100 butterflies are captured, marked with a small dot on a

wing, and then released. The next day, another 100 butterflies are captured,

including the recapture of 20 marked butterflies. One would correctly

estimate the population to be choose which one is correct:

  • 20
  • 100
  • 200
  • 500

91. The pattern of dispersion for a certain species of kelp is clumped. The

pattern of dispersion for a certain species of snail that lives only on this kelp

would likely be choose which one is correct:

  • Clumped
  • Demographic
  • Random
  • Uniform

92. Natural selection has led to the evolution of diverse natural history strategies. Which of the following characteristics do these different natural history strategies have in common?

  • Maximum lifetime reproductive success
  • Many offspring per reproductive episode
  • Relatively large offspring
  • Multiple reproductive episodes per lifetime

93. Carrying capacity (K) choose which one is correct:

  • Differs among species, but dos not vary within a given species
  • is calculated as the product of intrinsic growth rate (r) and population size (N)
  • Remains constant in all environments
  • is often determined by resource limitation

94. All of the statements regarding models of logistic population growth are

correct except choose which one is correct:

  • Population growth rate slows as N approaches K
  • Density-independent factors limit population growth
  • Density-dependent factors limit population growth
  • Intraspecific interactions limit population growth

95. In which of the following habitats would you expect to find the largest

number of K-selected individuals?

  • a recently abandoned field in Ohio
  • a newly emergent volcanic island
  • South Florida after a hurricane
  • the rain forests of Brazil

96. All of the following can contribute to density-dependent regulation of

population except choose which one is correct:

  • Intraspecific competition for nutrients
  • Interspecific competition for space
  • Annual temperature increases
  • Herbivory

97. Which of the following statements is most consistent with the interactive

hypothesis?

  • Communities lack discrete geographic boundaries
  • Species are distributed independently of other species
  • The community functions as an integrated unit
  • The composition of plant species seems to change on a continuum

98. All of the followings act to increase species diversity except choose which one is correct:

  • Keystone predators
  • Competitive exclusion
  • Migration of populations
  • Moderate disturbances

99. Two barnacles, Balanus and Chthamalus, can both survive on the lower

rocks just above the low tide line on the Scottish coast, but only Balanus

actually does so, with Chthamalus living in a higher zone. Which of the

followings is the most likely cause of this niche separation?

  • Primary succession
  • Mutualism
  • Competitive exclusion
  • Predation of Chthamalus by Balanus

100. Resource partitioning would be most likely to occur between choose which one is correct:

  • Sympatric populations of a predator and its prey
  • Sympatric populations of a flowering plant and its specialized insect pollinator
  • Allopatric populations of the same animal species
  • Sympatric populations of species with similar ecological niches

101. Which of the followings is an example of Batesian mimicry?

  • A snapping turtle that uses its tongue to mimic a worm, thus attracting fish
  • A butterfly that resembles a leaf
  • A nonvenomous snake that looks like a venomous snake
  • A fawn with fur coloring that camouflages it in the forest environment

102. Evidence shows that some grasses benefit from being grazed. Which of the following terms would best describe this plant-herbivore interaction?

  • Predation
  • Mutualism
  • Competition
  • Parasitism

Leave a Comment