Bihar Board 12th Biology Objective Answers Chapter 14 Ecosystem

Bihar Board 12th Biology Objective Questions and Answers

Bihar Board 12th Biology Objective Answers Chapter 14 Ecosystem

Question 1.
Term ‘ecosystem’ was coined by
(a) Odum
(b) Tansley
(c) Lindeman
(d) Elton.
Answer:
(b) Tansley

Question 2.
Which of the following pairs is not correct ?
(a) E. Haeckel – Coined the term ‘Ecology’
(b) Tansley – Coined the term ‘Ecosystem’
(c) R. Mishra – Father of Indian Ecology
(d) None of these
Answer:
(d) None of these

Question 3.
Vertical distribution of different species occupying different levels in dense vegetation is called
(a) stratification
(b) species composition
(c) standing crop
(d) trophic structure
Answer:
(a) stratification

Question 4.
Which one of the following aspects is not a component of functional unit of ecosystem ?
(a) Productivity
(b) Decomposition
(c) Energy flow
(d) Ecological pyramids
Answer:
(d) Ecological pyramids

Question 5.
The movement of energy from lower to higher trophic level is
(a) always unidirectional
(b) sometimes unidirectional
(c) always bidirectional
(d) undeterminable.
Answer:
(a) always unidirectional

Question 6.
The rate of conversion of light energy into chemical energy of organic molecules in an ecosystem is
(a) net primary productivity
(b) gross primary productivity
(c) secondary productivity
(d) gross secondary productivity.
Answer:
(b) gross primary productivity

Question 7.
The biomass available for consumption by the herbivores and the decomposers is called
(a) net primary productivity
(b) secondary productivity
(c) standing crop
(d) gross primary productivity
Answer:
(a) net primary productivity

Question 8.
________ is the rate of production of organic matter by
consumers.
(a) Primary productivity
(b) Secondary productivity
(c) Net primary productivity
(d) Gross primary productivity
Answer:
(b) Secondary productivity

Question 9.
The rate of formation of new organic matter by rabbit in a g rassland, is called
(a) net productivity
(b) secondary productivity
(c) net primary productivity
(d) gross primary productivity
Answer:
(b) secondary productivity

Question 10.
Primary productivity depends upon
(a) light and temperature
(b) water and nutrients
(c) photosynthetic capacity of producers
(d) all of these.
Answer:
(d) all of these.

Question 11.
The annual net primary productivity of the whole biosphere is approximately.
(a) 150 billion tons
(b) 160 billion tons
(c) 170 billion tons
(d) 180 billion tons.
Answer:
(c) 170 billion tons

Question 12.
Which one of the following exhibits least productivity ?
(a) Salty marshes
(b) Grasslands
(c) Open oceans
(d) Coral reefs
Answer:
(c) Open oceans

Question 13.
Which one of the following is the most productive ecosystem ?
(a) Temperate forest
(b) Grassland
(c) Desert
(d) Tropical rainforest
Answer:
(d) Tropical rainforest

Question 14.
During the process of decomposition
(a) CO₂ is consumed and O₂ is released
(b) O₂ is consumed and CO₂ is released
(c) CO₂ is consumed and H₂O is released
(d) none of these.
Answer:
(b) O₂ is consumed and CO₂ is released

Question 15.
Rate of decomposition depends upon
(a) chemical composition of detritus
(b) temperature
(c) soil moisture and soil pH
(d) all of these.
Answer:
(d) all of these.

Question 16.
Decomposers are also called as
(a) transducers
(b) reducers
(c) micro-consumers
(d) both (b) and (c).
Answer:
(d) both (b) and (c).

Question 17.
The ultimate energy source of all ecosystems is
(a) producers
(b) organic molecules
(c) carbohydrate
(d) solar radiation.
Answer:
(d) solar radiation.

Question 18.
Percentage of photosynthetically active radiation (PAR) in the incident solar radiation is
(a) 1 – 5%
(b) 2 – 10%
(c) less than 50%
(d) approx. 100%
Answer:
(c) less than 50%

Question 19.
Percentage of photosynthetically active radiation (PAR) that is captured by plants in synthesis of organic matter is
(a) 50 – 70%
(b) 30 – 40%
(c) 80 – 100%
(d) 2 – 10%
Answer:
(d) 2 – 10%

Question 20.
Select the incorrect food chain.
(a) Grass → Grasshopper → Frog → Snake → Eagle
(b) Phytoplanktons → Zooplanktons → Small fish → Large fish
(c) Diatoms → Zooplanktons → Small fish
(d) Grass → Frog → Vulture
Answer:
(d) Grass → Frog → Vulture

Question 21.
If 10 joules of energy is available at the producer level, then amount of energy present at the level of secondary consumers is
(a) 10 J
(b) 1J
(c) 0.1 J
(d) 0.01 J.
Answer:
(c) 0.1 J

Question 22.
The energy and biomass relationship between the organisms at different trophic levels can better expressed by
(a) food chain
(b) food web
(c) ecological pyramids
(d) energy cycle
Answer:
(c) ecological pyramids

Question 23.
Which one of the following animals may occupy more than one trophic levels in the same ecosystem at the same time ?
(a) Sparrow
(b) Lion
(c) Goat
(d) Frog
Answer:
(a) Sparrow

Question 24.
Organisms which are associated with first as well as third trophic level are
(a) macrophytes
(b) phytoplanktons
(c) chemoautotrophs
(d) insectivorous plants.
Answer:
(d) insectivorous plants.

Question 25.
Mr. X is eating curd/yoghurt. For this food intake in a food chain he should be considered as occupying
(a) First trophic level
(b) second trophic level
(c) third trophic level
(d) fourth trophic level
Answer:
(c) third trophic level

Question 26.
Primary succession occurs on
(a) area destroyed due to forest fire
(b) newly formed river delta
(c) harvested crop field
(d) all of these.
Answer:
(b) newly formed river delta

Question 27.
Successions that occur on soils or areas which have recently lost their community are referred to as
(a) primary successions
(b) secondary successions
(c) lithoseres
(d) priseres.
Answer:
(b) secondary successions

Question 28.
Which one of the following statements is correct for secondary succession ?
(a) It begins on a bare rock.
(b) It occurs on a deforested site.
(c) It follows primary succession.
(d) It is similar to primary succession except that primary succession has a relatively fast pace.
Answer:
(b) It occurs on a deforested site.

Question 29.
The rate of secondary succession is faster than primary succession because
(a) soil or sediment is already present
(b) water is available in large quantity
(c) climax community is already present
(d) pH of soil is favourable.
Answer:
(d) pH of soil is favourable.

Question 30.
As the succession proceeds number and types of __________ change.
(a) vegetation
(b) animals
(c) vegetation and animals
(d) vegetation, animals and decomposers
Answer:
(d) vegetation, animals and decomposers

Question 31.
Which of the following is considered as pioneer community in xerarch ?
(a) Annual herbs
(b) Perennial herbs
(c) Shrubs
(d) Lichens
Answer:
(d) Lichens

Question 32.
Correct sequence of stages of succession on a bare rock is
(a) Lichens → Mosses → Grasses → Shrubs → Trees
(b) Trees → Shrubs → Lichens → Mosses → Grasses
(c) Mosses → Shrubs → Trees → Lichens → Grasses
(d) Mosses → Lichens → Grasses → Shrubs → Trees.
Answer:
(a) Lichens → Mosses → Grasses → Shrubs → Trees

Question 33.
In lithosere, foliose lichens make the conditions favourable for the growth of
(a) crustose lichens
(b) mosses
(c) annual grasses
(d) perennial grasses.
Answer:
(b) mosses

Question 34.
The correct sequence of plants in a hydrosere is
(a) Volvox → Hydrilla → Pistia → Scirpus→ Carex → Quercus
(b) Pistia → Volvox → Scirpus → Hydrilla → Quercus → Carex
(c) Quercus → Carex → Volvox → Hydrilla → Pistia → Scirpus
(d) Quercus → Carex → Scirpus → Pistia → Hydrilla → Volvox.
Answer:
(a) Volvox → Hydrilla → Pistia → Scirpus→ Carex → Quercus

Question 35.
The second stage of hydrosere is occupied by plants like
(a) Azolla
(b) Typha
(c) Carex
(d) Vallisneria.
Answer:
(d) Vallisneria.

Question 36.
An ecosystem which can be easily damaged but can recover after some time if damaging effect stops, will be having
(a) low stability and high resilience
(b) high stability and low resilience
(c) low stability and low resilience
(d) high stability and high resilience.
Answer:
(a) low stability and high resilience

Question 37.
Which one of the following is not a gaseous biogeochemical cycle in ecosystem ?
(a) Water cycle
(b) phosphorus cycle
(c) Nitrogen cycle
(d) Carbon cycle
Answer:
(b) phosphorus cycle

Question 38.
The function of reservoir pool is to meet with the deficit of nutrient that occurs due to
(a) imbalance in rate of efflux and influx of nutrients
(b) only efflux of nutrients
(c) ceased nutrient cycle
(d) none of these.
Answer:
(a) imbalance in rate of efflux and influx of nutrients

Question 39.
About 71 % of total global carbon is found in
(a) Oceans
(b) Forests
(c) grasslands
(d) agroecosystems.
Answer:
(a) Oceans

Question 40.
What percentage of total global carbon is atmospheric carbon ?
(a) 0.03%
(b) 1%
(c) 10%
(d) 30%
Answer:
(b) 1%

Question 41.
Which of the following processes does not contribute to the C02 pool in the atmosphere ?
(a) Respiration by producers
(b) photosynthesis by producers
(c) Respiration by consumers
(d) Decomposition by decomposers
Answer:
(b) photosynthesis by producers

Question 42.
Major source of sulphur is
(a) oceans
(b) land
(c) rocks
(d) lakes.
Answer:
(c) rocks

Question 43.
The ecosystem services include
(a) maintenance of biodiversity
(b) pollination of crop
(c) spiritual, cultural and aesthetic values
(d) all of these.
Answer:
(d) all of these.

Question 44.
Out of the total proposed cost of various ecosystem services, cost of climate regulations and habitat for wildlife are
(a) 50%
(b) 10%
(c) 6%
(d) 25%
Answer:
(c) 6%

Question 45.
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.
Answer:
(a) inorganic nutrients from humus

Question 46.
An inverted pyramid of biomass can be found in which ecosystem ?
(a) Forest
(b) Marine
(c) Grassland
(d) Tundra
Answer:
(b) Marine

Question 47.
Which of the following is not a producer ?
(a) Spirogyra
(b) Agaricus
(c) Volvox
(d) Nostoc
Answer:
(b) Agaricus

Question 48.
Which of the following ecosystems is most productive in terms of net primary production ?
(a) Deserts
(b) Tropical rainforests
(c) Oceans
(d) Estuaries
Answer:
(b) Tropical rainforests

Question 49.
Among the following, where do you think the process of decomposition would be the fastest ?
(a) Tropical rainforest
(b) Antarctic
(c) Dry arid region
(d) Alpine region
Answer:
(a) Tropical rainforest

Question 50.
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.
Answer:
(a) orderly and sequential

Question 51.
Climax community is in a state of
(a) non-equilibrium
(b) equilibrium
(c) disorder
(d) constant change.
Answer:
(b) equilibrium

Question 52.
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
Answer:
(d) All of the above

Question 53.
The reservoir for the gaseous type of biogeochemical cycle exists in
(a) stratosphere
(b) atmosphere
(c) ionosphere
(d) lithosphere.
Answer:
(b) atmosphere

Question 54.
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 zone
(d) littoral zone.
Answer:
(d) littoral zone.

Question 55.
Edaphic factor refers to
(a) water
(b) soil
(c) relative humidity
(d) altitude.
Answer:
(b) soil