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NEET Biology MCQ
Organisms And Population Mcq
Quiz 2
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Q.1
The total interacting animals and plants in any well defined area which as field or a pond is known as
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a) biosphere
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b) biome
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c) community
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d) ecosystem
Explanation
Biome refers to the community of plants and animals that occur naturally in an area, often sharing common characteristics specific to that area. a community is a group or association of populations of two or more different species occupying the same geographical area at the same time Answer:(b)
Q.2
Select the incorrect statement:
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a) An overwhelming majority of animals and all plants maintain a constant internal temperature.
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b) An orchid growing as an epiphyte on a mango branch is an example of commensalism.
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c) In brood parasitism, the parasitic bird lays its eggs in the nest of its host and lets the host to incubate them.
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d) Very small animals are rarely found in Polar Regions.
Explanation
Commensalism is the relationship where one organism is benefitted while the other is neither benefitted nor harmed. Orchid grows on mango tree to get proper light etc. and is benefitted but as it does not absorb nutrients from mango tree. Thus, the tree is neither harmed nor benefitted. Brood parasitism in birds is a fascinating example of parasitism in which the parasitic bird lays its eggs in the nest of its host and lets the host incubate them. Since small animals have a larger surface area relative to their volume, they tend to lose body heat very fast when it is cold outside; then they have to expend much energy to generate body heat through metabolism. This is the main reason why very small animals are rarely found in polar regions. Plants do not have such mechanisms to maintain internal temperatures. Option a is incorrect. Answer:(a)
Q.3
Natality is the characteristics of a population which means:
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a) The total number of individuals present per unit area at a given time.
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b) The increase in number of individuals in a population through reproduction under given environmental conditions.
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c) Loss of individuals due to death in a population through reproduction under the given environmental conditions.
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d) The movement of individuals into and out of population.
Explanation
Natality refers to the number of births during a given period in the population that are added to the initial density. Answer:(b)
Q.4
Choose the correct option for the given adaptations: (i) Biochemical adaptations are seen in organisms living in greater depths of the ocean to face crushing pressure. (ii) Allen’s rule explains mammals living in colder climates. (iii) Altitude sickness is caused because of body not getting enough oxygen due to low atmospheric pressure at high altitudes. (iv) Desert lizards lack behavioural means to manage their body temperature.
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a) (i), (ii) and (iii).
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b) (i), (ii) and (iv).
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c) (ii), (iii) and (iv).
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d) (i), (iii) and (iv).
Explanation
A large variety of marine invertebrates and fish live at great depths in the ocean where the pressure could be >100 times the normal atmospheric pressure that we experience. Organisms living in such extreme environments show a fascinating array of biochemical adaptations. (i) is correct. Mammals from colder climates generally have shorter ears and limbs to minimise heat loss. (This is called the Allen’s Rule.) (ii) is correct. Altitude sickness is because in the low atmospheric pressure of high altitudes, the body does not get enough oxygen. But, gradually you get acclimatised and stop experiencing altitude sickness. The body compensates low oxygen availability by increasing red blood cell production, decreasing the binding affinity of hemoglobin and by increasing breathing rate. (iii) is correct. Desert lizards lack the physiological ability that mammals have to deal with the high temperatures of their habitat, but manage to keep their body temperature fairly constant by behavioural means. (iv) is incorrect. Answer:(a)
Q.5
The type of benthic animals in aquatic environment is determined by:
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a) Presence of light.
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b) Sediment characters of soil.
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c) Water requirements.
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d) Levels of thermal tolerance.
Explanation
In the aquatic environment, the sediment-characteristics often determine the type of benthic animals that can thrive there. Answer:(b)
Q.6
Mac Arthur’s observation on closely related species of warblers is an excellent demonstration of how:
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a) Behavioural differences in foraging activities can avoid interspecific competition.
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b) Competitively inferior species will be eliminated eventually.
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c) The distribution range of one species expands in the absence of another.
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d) The fitness of one species is significantly lower in the presence of another species.
Explanation
Species facing competition might evolve mechanisms that promote co-existence rather than exclusion. One such mechanism is ‘resource partitioning’. If two species compete for the same resource, they could avoid competition by choosing, for instance, different times for feeding or different foraging patterns. MacArthur showed that five closely related species of warblers living on the same tree were able to avoid competition and co-exist due to behavioural differences in their foraging activities. Answer:(a)
Q.7
Which of the following condition will occur if the bass disappeared due to over fishing?
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a) The algae population would increase.
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b) The frogs and sunfish would disappear.
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c) The minnow population would increase and the sunfish population would decrease.
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d) The frog and sunfish populations would increase.
Explanation
If bass disappears, then there is no predator for frogs and sunfishes. Hence their population will increase. Answer:(d)
Q.8
carrying capacity of a population is determined by ... ...(BHU 2001)
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a) Birth rate
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b) Death rate
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c) limiting resources
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d) Reproductive ability
Explanation
Carrying capacity can be defined as a species' average population size in a particular habitat. The species population size is limited by environmental factors like adequate food, shelter, water, and mates. If these needs are not met, the population will decrease until the resource rebounds. Answer:(c)
Q.9
Organism with very high intrinsic growth rates have
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a) Long generation times
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b) Short generation times
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c) No courtship behaviour
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d) No carrying capacities
Explanation
The intrinsic rate of increase is inversely related to generation time t. Therefore, organisms with very high intrinsic growth rates have short generation time. Answer:(b)
Q.10
In order to find out VITAL INDEX in Rampur Village, following information was gathered Death Rate = 1/x Birth Rate = z Average population = 1/y What is the Vital Index ?
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a) xyz × 100
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b) z/xy =100
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c) xy/z × 100
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d) 100/xyz
Explanation
birth rate is (number of births) x 1000 / estimated population at mid-year. Death rate is (number of death) x 1000 / estimated population at mid-year. The vital index is the ratio between natality or number of births and mortality or the number of deaths in a given time duration. Answer:(a)
Q.11
If ‘+’ sign is assigned to beneficial interaction ’-‘ sign to detrimental and ‘0’ sign to neutral interaction, then the population interaction represented by ‘+’ ‘-‘ refers to
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a) mutualism
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b) amensalism
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c) commensalism
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d) parasitism
Explanation
Species A
Species B
Name of interaction
+
+
Mutualism
-
-
Competition
+
-
Predation
+
-
Parasitism
+
0
Commensalism
-
0
Amensalism
Interspecific interactions arise from the interaction of populations of two different species. They could be beneficial, detrimental or neutral (neither harm nor benefit) to one of the species or both. Assigning a ‘+’ sign for beneficial interaction, ‘-’ sign for detrimental and 0 for neutral interaction. Answer:(d)
Q.12
The given age pyramid represents a
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a) Fast expanding population
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b) Slowly expanding population
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c) Stable population
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d) Declining population
Explanation
Stationary population pyramids are those that show a somewhat equal proportion of the population in each age group. There is not a decrease or increase in population; it is stable. Answer:(c)
Q.13
In a tide pool, 15 species of invertebrates were reduced to 8 after one species was removed. The removed species may be a
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a) Parasite
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b) Mutualist
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c) Top predator
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d) Herbivore
Explanation
Top predators play an important role in maintaining the balance and biodiversity of an ecosystem. If the top predator is removed from the delicate balance of any particular ecosystem, there may be disastrous effects for the other plants and animals that inhabit the environment. Answer:(c)
Q.14
Which of the following is correct for r-selected species?
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a) Large number of progeny with small size
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b) Large number of progeny with large size
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c) Small number of progeny with small size
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d) Small number of progeny with large size
Explanation
R-selected species are those that produce a large number of offspring and contribute few resources to each individual offspring. They often offer little to no parental care, have high offspring mortality, short life spans, and small body sizes. Answer:(a)
Q.15
Just as a person moving from Delhi to Shimla to escape the heat for the duration of hot summer, thousands of migratory birds from Siberia and other extremely cold Northern regions move to
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a) Western Ghat
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b) Meghalaya
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c) Corbett National Park
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d) Keolado National Park
Explanation
Many animals, particularly birds, during winter undertake long-distance migrations to more hospitable areas. Every winter the famous Keolado National Park (Bharatpur) in Rajasthan host thousands of migratory birds coming from Siberia and other extremely cold northern regions Answer:(d)
Q.16
Consider the following four statements (A-D) about certain desert animals such as kangaroo rat a) they have dark colour and high rate of reproduction and excrete solid urine b) they do not drink water, breathe at slow rate to conserve water and have their body covered with thick hairs c) they feed on dry seeds and do not require drinking water d) they excrete very concentrated urine and do not use water to regulate body temperature Which two of the above statements for such animals are true?
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a) C and D
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b) B and C
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c) C and A
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d) A and B
Explanation
In the absence of an external source of water, the kangaroo rat in North American deserts is capable of meeting all its water requirements through its internal fat oxidation (in which water is a by product). It also has the ability to concentrate its urine so that minimal volume of water is used to remove excretory products. The kangaroo rat is almost perfectly adapted to life in the desert. They can survive without ever drinking any water, getting needed moisture from their seed diet. Answer:(a)
Q.17
The population dynamics of a species is basically regulated by
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a) climate
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b) food supply
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c) competition between and within the species
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d) all of the above
Explanation
The size of a population for any species is not a static parameter. It keeps changing with time, depending on various factors including food availability, predation pressure and adverse weather Answer:(d)
Q.18
Which one of the following do not correctly represents an organism and its ecological niche?
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a) Vallisneria and Pond
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b) Desert locust (Scistocerca) and desert
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c) Plant lice (aphids) and leaf
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d) Vultures and dense forest
Explanation
The desert locust (Schistocerca gregaria) are found primarily in the deserts and dry areas of northern and eastern Africa, Arabia, and southwest Asia. Aphids can be found on bushes, shrubs, trees, the leaves of vegetables, and the leaves of ornamental plants. Vulture inhabits relatively open areas which provide scattered forests or shrublands. Option (d) is correct answer. Answer:(d)
Q.19
Sinking of zooplankton during the day and rising to the surface at night is an example of
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a) circinal rhythm
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b) circadian rhythm
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c) tidal rhythm
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d) None of these
Explanation
Circadian rhythms are physical, mental, and behavioral changes that follow a 24-hour cycle. zooplankton migrate to deep waters during the day to avoid predation and come up to the surface at night to feed. Answer:(b)
Q.20
When all the starfish were removed from an enclosed intertidal area, more than 10 species of invertebrates became extinct within a year. This experiment explains:
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a) Biological control method.
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b) Predator is too efficient and overexploits its prey.
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c) Predator helps in maintaining species diversity.
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d) Energy transfer.
Explanation
Predators also help in maintaining species diversity in a community, by reducing the intensity of competition among competing prey species. In the rocky intertidal communities of the American Pacific Coast the starfish Pisaster is an important predator. In a field experiment, when all the starfish were removed from an enclosed intertidal area, more than 10 species of invertebrates became extinct within a year, because of interspecific competition. Answer:(c)
Q.21
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 to be eliminated in due course of time. But both are surviving well in the aquarium. Give possible reasons: (i) Predator free environment. (ii) Resources (food, protection, space) are not limited. (iii) Limited resource. (iv) Competitive release. (v) Resource partitioning
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a) Only (i), (iii) and (v).
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b) Only (i) and (ii) and (v).
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c) Only (i), (ii) and (iv).
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d) Only (ii), (iv) and (v).
Explanation
Gause’s ‘Competitive Exclusion Principle’ may be true if resources are limiting, but not otherwise. Since both species are exisiting it meand resources might not be limited. Species facing competition might evolve mechanisms that promote co-existence rather than exclusion. One such mechanism is ‘resource partitioning. Distribution is wide beacuse there is no predator or competition release. Answer:(b)
Q.22
Assertion: With increase in population size, environmental resistance tend to increases. Reason: This is nature’s way to check the expression of biotic potential.
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a) Both Assertion and Reason are true and Reason is the correct explanation of Assertion.
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b) Both Assertion and Reason are true but Reason is NOT the correct explanation of Assertion.
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c) Assertion is true but Reason is false.
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d) Both Assertion and Reason are false.
Explanation
The inherent maximum capacity of an organism to reproduce or increase in number is termed biotic potential. Nature keeps a check on the expression of biotic potential. With increase in population size, the environmental resistance tends to increase. Answer:(a)
Q.23
What is true for the following statements ? Statement X : Marine fishes have chlorine secretory cells.while riverine fishes have chlorine cells. Statement Y : Compared to marine water, fluid present in fish is hypotonic while reverine water is hypertonic compared to fluid present in fish.
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a) X=True ; Y= True
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b) X=True; Y= False
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c) X=False; Y= False
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d) X=False; Y= True
Explanation
chloride secretory cell: Any of the cells in the gills of marine bony fish that remove chloride from the blood and secrete it into the sea, thereby maintaining the osmotic composition of the body. In marine teleost fish, by expending energy to power the enzyme Na+/K+-ATPase and in coordination with other protein transporters, ionocytes pump excessive sodium and chloride ions against the concentration gradient into the ocean. Conversely, freshwater teleost ionocytes use this low intracellular environment to attain sodium and chloride ions into the organism, and also against the concentration gradient. Answer:(a)
Q.24
Association of a sea-anemone with hermit crab living in a gastropod shell is an example of
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a) mutualism
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b) commensalism
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c) symbiosis
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d) parasitism
Explanation
Hermit crabs and sea anemones share an unusual and intimate underwater relationship. Young hermit crabs will often pick up a young sea anemone to attach to their shell and they become partners for life. They even grow at roughly the same rate. Commensalism means one organism benefits and the other organism isn't harmed by the partnership. Neither the hermit crab nor the sea anemone is negatively affected by their symbiotic and commensalistic relationship. The hermit crab gains protection from predators by its relationship with the sea anemone.. . Answer:(b)
Q.25
From the following statements: (i) Many fishes thrive in Antarctic water where temperature is always below zero. (ii) Microbes can survive in hot springs where temperature exceeds 100°C. (iii) Many fishes can survive even at a depth where pressure exceeds 100 atm. (iv) Desert lizards have marvellous physiological ability to survive scorching heat of desert. (v) Many desert plants have a thick cuticle on their leaf surfaces and have their stomata arranged in surface to minimise water loss.
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a) All are correct.
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b) Only (i), (ii), (iii) and (iv) are correct.
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c) Only (i), (ii), (iii) and (v) are correct.
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d) Only (i), (ii) and (iii) are correct.
Explanation
Desert lizards lack the physiological ability that mammals have to deal with the high temperatures of their habitat, but manage to keep their body temperature fairly constant by behavioural means. Statement (iv) is incorrect. Rest of the statements are correct. Answer:(c)
Q.26
iche of an organism consists of: (i) Range of tolerance and functional role. (ii) Resource it utilises only. (iii) Small living area within the habitat. (iv) Large living area and the functional role. (v) Adaptation and the large living area.
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a) (i), (ii), (iii) and (v) are correct.
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b) (i), (ii) and (iii) are correct.
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c) (i), (iii) and (v) are correct.
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d) (i), (iii) and (iv) are correct.
Explanation
In ecology, a niche is the match of a species to a specific environmental condition. It describes how an organism or population responds to the distribution of resources and competitors (for example, by growing when resources are abundant, and when predators, parasites and pathogens are scarce) and how it in turn alters those same factors (for example, limiting access to resources by other organisms, acting as a food source for predators and a consumer of prey). Answer:(b)
Q.27
A stage of suspended development in many zooplanktons under unfavourable conditions:
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a) Suspension.
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b) Diapause.
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c) Conformers.
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d) Adaptation.
Explanation
Under unfavourable conditions many zooplankton species in lakes and ponds are known to enter diapause, a stage of suspended development Answer:(b)
Q.28
Population density refers to:
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a) Number of women per thousand men.
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b) Number of individuals per square kilometer at any given time
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c) Number of men per thousand women
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d) Number of men died in a year
Explanation
Population density is a measurement of population per unit area, or exceptionally unit volume; it is a quantity of type number density. Answer:(b)
Q.29
In snakes realised (actual) natality is less than potential natality; because.....
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a) all the eggs are not incubated
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b) enviornmental boomrang (resistance)
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c) Though eggs are incubated they donot reach upto adult stage.
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d) All of these.
Explanation
Potenetial natality is mere estimation of birth. There are lot of factors which decreases the actual birth rate. In this case, they are: 1) Incubation period of egg in snakes is 45 to 60 days. It is possible that all egg are not completely incubated. or incubated egg did not reach adult stage. 2) Another reason can be Enviromental boomerang or ecological backlash. The unexpected and detrimental consequences of an environmental modification is known as ecologial backlash. Answer:(d)
Q.30
Which is appropriate for the following statement ? Statement X : Pacific salmon fish reproduces only once in its life time. Statement Y : In a reproductive season it lays 280,000,000 eggs.
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a) X=True; Y=True
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b) X=False; Y= False
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c) X=True; Y= False
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d) X=False; Y= True
Explanation
Each year mature salmon make the long journey back to their natal river to reproduce, just once. Each female salmon can have between 1,500 and 10,000 eggs. Only a few (0 to 10) of these eggs will survive to be adult salmon. X= true and Y= false. Answer:(c)
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