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Free download in PDF CBSE Class 12 Biology Short Questions & Answers. Here Gkseries provide Biology Solve Questions and Answers for CBSE Class 12 Students.
41
From his long term ecosystem experiments, David Tilman showed that
[A]
decreased diversity contributed to higher productivity
[B]
decreased diversity contributed to decreased productivity
[C]
increased diversity contributed to increased productivity
[D]
increased diversity contributed to decreased productivity
Answer: increased diversity contributed to increased productivity
42
Which of the following organisation is responsible for maintaining the Red Data Book?
[A]
IUCN
[B]
USDA
[C]
IDRI
[D]
All of these
43
Approximately how much of the solar energy that falls on the leaves of a plant is converted to chemical energy by photosynthesis? [NCERT Exemplar]
[A]
2-10%
[B]
50%
[C]
Less than 1%
[D]
30%
44
Which of the following ecosystems is most productive in terms of net primary production? [NCERT Exemplar]
[A]
Estuaries
[B]
Deserts
[C]
Tropical rain forests
[D]
Oceans
Answer: Tropical rain forests
45
The reservoir for the gaseous type of biogeochemical cycle exists in [NCERT Exemplar]
[A]
stratosphere
[B]
atmosphere
[C]
ionosphere
[D]
lithosphere
46
The sequence of communities of primary succession in water is
[A]
phytoplankton, rooted submerged hydrophytes, floating hydrophytes, reed swamp, sedges, meadow and trees.
[B]
free-floating hydrophytes, sedges, phytoplankton, rooted hydrophytes, grasses and trees.
[C]
phytoplankton, free-floating hydrophytes, rooted hydrophytes, sedges, grasses and trees.
[D]
phytoplankton, sedges, free-floating hydrophytes, rooted hydrophytes, grasses and trees.
Answer: phytoplankton, rooted submerged hydrophytes, floating hydrophytes, reed swamp, sedges, meadow and trees.
47
Which of the following statements is correct for secondary succession?
[A]
It is similar to primary succession, but has a relatively fast pace..
[B]
It follows primary succession.
[C]
It begins on a bare rock.
[D]
It occurs on a deforested area.
Answer: It is similar to primary succession, but has a relatively fast pace.
48
Which of the following is a pioneer species in xerarch succession?
[A]
Lichens
[B]
Sedges
[C]
Bryophytes
[D]
Phytoplanktons
49
The last stable community in succession that is in equilibrium with the environment, is called
[A]
climax community
[B]
pioneer community
[C]
serai community
[D]
None of these
50
In a pond ecosystem, the food chain starts with
[A]
Zooplanktons.
[B]
Small insects
[C]
Phytoplanktons
[D]
Small fishes
51
Which of the following represents the sedimentary type of nutrient cycle?
[A]
Nitrogen cycle
[B]
Carbon cycle
[C]
Phosphorus cycle.
[D]
Oxygen cycle
Answer: Phosphorus cycle.
52
What parameters are used for tiger census in our country’s national parks and sanctuaries? [NCERT Exemplar]
[A]
Pug marks and faecal pellets
[B]
Actual head counts
[C]
Pug marks only
[D]
Faecal pellets only
Answer: Pug marks and faecal pellets
53
Which of the following would necessarily decrease the density of a population in a given habitat? [NCERT Exemplar]
[A]
Mortality and emigration
[B]
Natality and immigration
[C]
Natality > mortality
[D]
Immigration > emigration
Answer: Mortality and emigration
54
A population has more young individuals compared to the older individuals. What would be the status of the population after some years? ]NCERT Exemplar]
[A]
It will increase
[B]
It will first decline and then stabilise
[C]
It will decline
[D]
It will stabilise
55
Amensalism is an association between two species where
[A]
one species is harmed and other is benefitted
[B]
one species is harmed and other is unaffected
[C]
one species is benefitted and other is unaffected
[D]
both the species are harmed.
Answer: one species is harmed and other is unaffected
56
Niche overlap indicates
[A]
mutualism between two species
[B]
active cooperation between two species
[C]
sharing of one or more resources between the two species
[D]
two different parasites on the same host.
Answer: sharing of one or more resources between the two species
57
The formula of exponential population growth curve, is
[A]
dN/dt = rN
[B]
rN/dN = dt
[C]
dt/dN rN
[D]
dN/rN = dt
58
Individuals of one kind, i.e., one species occupying a particular geographic area, at a given time form a/an
[A]
population
[B]
deme
[C]
community
[D]
biome
59
It natality is balanced by mortality in a population at a given time, there will be a/an
[A]
decrease in the population size
[B]
increase in the population size
[C]
zero population growth
[D]
population explosion
Answer: zero population growth
60
Mycorrhiza is an example of
[A]
mutualism
[B]
predation
[C]
endoparasitism
[D]
ectoparasitism
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