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NEET Biology MCQ
Organisms And The Environment Mcq
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Q.1
Halophytes are .... .... [Odisha 2004]
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a) Salt resistant
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b) Fire resistant
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c) Cold resistant
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d) Sand loving
Explanation
Halophytes are salt-tolerant plants that grow in waters with high salinity, such as in mangrove swamps, marshes, seashores and saline semi-deserts. Answer : (a)
Q.2
Ecology is study of relationship of .... ..... [A.I.I.M.S.2006]
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a) Members of a family
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b) Man and environment
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c) Organisms and environment
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d) Soil and water
Explanation
Ecology is a subject which studies the interactions among organisms and between the organism and its physical (abiotic) environment. Answer : (c)
Q.3
Association between sea anemone and hermit crab in gastropod shell is that of .... .... [A.M.U.2005]
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a) Symbiosis
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b) Commensalism
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c) Parasitism
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d) Amensalism
Explanation
Answer : (b)
Q.4
Which of the following is not an attribute of a population? [NEET 2020]
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a) Mortality
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b) Species interaction
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c) Sex ratio
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d) Natality
Explanation
Following are the different attributes of a population: (a) Birth and Death Rates (b) Sex Ratio (c) Age Distribution Population Density Answer : (b)
Q.5
In a species, the weight of newborn ranges from 2 to 5 kg. 97% of the newborn with an average weight between 3 to 3.3 kg survive whereas 99% of the infants born with weight from 2 to 2.5 kg or 4.5 to 5 kg die. Which type of selection process is taking place? ... [NEET 2019]
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a) Directional Selection
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b) Stabilizing Selection
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c) Disruptive Selection
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d) Cyclical Selection
Explanation
Stabilizing selection is any selective force or forces which push a population toward the average, or median trait. The given data shows stabilising selection as most of the newborn having average weight between 3 to 3.3 kg survive and babies with less and more weight have low survival rate. Directional selection occurs when individuals homozygous for one allele have a fitness greater than individuals with other genotypes and individuals homozygous Disruptive selection, also called diversifying selection, describes changes in population genetics in which extreme values for a trait are favored over intermediate values. Cyclical Selection occurs when populations of a certain species are exposed to several opposing selection pressures.In dry summers, individuals with a certain phenotype can have greater fitness, while individuals with a different phenotype have greater fitness in wet summers. Answer : (b)
Q.6
Pinus seed cannot germinate and established without fungal association. This is because : .... [NEET 2019]
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a) its embryo is immature.
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b) it has obligate association with mycorrhizae.
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c) it has very hard seed coat.
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d) its seeds contain inhibitors that present germination.
Explanation
Fungus associated with roots of Pinus increases minerals and water absorption for the plant by increasing surface area and in turn fungus gets food from plant. Therefore, mycorrhizal association is obligatory for Pinus seed germination Answer : (b)
Q.7
What triggers activation of protoxin to active Bt toxin of Bacillus thuringiensis in boll worm? [NEET 2019]
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a) Body temperature
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b) Moist surface of midgut
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c) Alkaline pH of gut
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d) Acidic pH of stomach
Explanation
microbial biocontrol agents that can be introduced in order to control butterfly caterpillars is the bacteria Bacillus thuringiensis (often written as Bt ). The pH of human stomach acid is about 2 while the pH of the insect gut is about 10. Bt toxin requires a high (basic) pH to be active, and must be activated by specific protein-cutting-proteins in the insect gut. The Bt toxin is comprised of a bunch of smaller proteins that work together by teaming up to form holes in the membranes of the cells that form the gut. Answer : (c)
Q.8
Which one of the following plants shows a very close relationship with a species of moth, where none of the two can complete its life cycle without the other ? [NEET 2018]
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a) Banana
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b) Yucca
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c) Hydrilla
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d) Viola
Explanation
Both Yucca plant and the moth cannot complete their life cycles without each other. The moth deposits its eggs in the locule of the ovary and the flower in turn gets pollinated by the moth. The larvae of the moth come out of the eggs as the seeds start developing. Answer : (b)
Q.9
Natality refers to [ NEET 2018]
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a) Number of individuals leaving the habitat
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b) Birth rate
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c) Death rate
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d) Number of individuals entering a habitat
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.10
Niche is ... .. [NEET 2018]
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a) the range of temperature that the organism needs to live
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b) the physical space where an organism lives
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c) all the biological factors in the organism’s environment
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d) the functional role played by the organism where it lives
Explanation
Each organism has an invariably defined range of conditions that it can tolerate, diversity in the resources it utilises and a distinct functional role in the ecological system, all these together comprise its niche. Answer : (d)
Q.11
Which one of the following population interactions is widely used in medical science for the production of antibiotics ?[ NEET 2018]
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a) Parasitism
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b) Mutualism
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c) Commensalism
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d) Amensalism
Explanation
Amensalism : An example of antibiosis is the interaction between Penicillium and bacteria. The mould Penicillium creates the secretion known as penicillin, which is extremely toxic to bacteria. This finding formed the basis for the first true antibiotic – called penicillin. Answer : (d)
Q.12
n a growing population of a country, .... [NEET 2018]
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a) reproductive and pre-reproductive individuals are equal in number.
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b) reproductive individuals are less than the post-reproductive individuals.
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c) pre-reproductive individuals are more than the reproductive individuals.
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d) pre-reproductive individuals are less than the reproductive individuals.
Explanation
Growing population pyramids depict populations that have a larger percentage of people in pre-reproductive individuals. Pre-reproductive individuals are greater than reproductive individuals. Answer : (c)
Q.13
Which plant is found in mangrove zone? ..... ..... [R.P.M.T.2006]
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a) Rhizophora
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b) Acacia
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c) Pinus
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d) Tectona grandis
Explanation
Rhizophora is a genus of tropical mangrove trees, sometimes collectively called true mangroves. Answer : (a)
Q.14
Mark the odd one .... .... [Har.P.M.T.2001]
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a) Pistia
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b) Hydrilla
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c) Vallisneria
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d) Casuarina
Explanation
Pistia is a genus of aquatic plants in the arum family, Araceae. hydrilla, (Hydrilla verticillata), submerged aquatic plant that is the sole member of the genus Hydrilla in the frog's-bit family (Hydrocharitaceae). Vallisneria is a genus of freshwater aquatic plant, commonly called eelgrass, tape grass or vallis. Casuarina is an evergreen tree growing to 6–35 m (20–115 ft) tall. Answer : (d)
Q.15
Assertion: Age sex structure of human population in countries like France and Germany gives a steep pyramid. Reason: In countries like Sudan and India, the population is increasing at a rapid rate. A.I.I.M.S. 2005
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a) Both Assertion and Reason are true and Reason is the correct explanation of Assertion
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b) The Assertion and Reason are true but Reason is not correct explanation of Assertion
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c) Assertion is true but, Reason is false
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d) Assertion is false but, Reason is true
Explanation
A population pyramid is also called an age-gender-pyramid. In developing countries like India and Sudan, the population pyramid has a wide base and narrow top, i.e., population is expanding at greater rate. Rectangular shape pyramids are often characteristic of developed nations like France and Germany, where birth rates are low and overall quality of life is high. The slope of the pramid is very steep, almost vertical. Answer : (b)
Q.16
Match the columns of size with soil particles .... .... [Guj.C.E.T.2007]
a. 0.2 - 2.00 mm
(i) silt
b. less than 0.002 mm
(ii) clay
c. 0.02 - 0.2 mm
(iii) coarse sand particles
d. 0.002 - 0.02 mm
(iv) fine sand particles
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a) a - iv, b - i, c - iii, d - ii
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b) a - iii, b - ii, c - iv, d - i
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c) a - ii, b - iii, c - iv, d - i
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d) None of the above
Explanation
Particle size
Soil type
less than 0.002 mm
clay
0.002 - 0.02 mm
silt
0.02 - 0.2 mm
fine sand particles
0.2 - 2.00 mm
coarse sand particles
Answer:(b)
Q.17
Avicennia, Rhizophora and Atriplex are .... .... [Odisha 2005]
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a) Xerophytes
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b) Halophytes
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c) Hydrophytes
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d) Mesophytes
Explanation
Avicennia are called black mangrove. Rhizophora is a genus of tropical mangrove trees, sometimes collectively called true mangroves. Atriplex is a plant genus of 250–300 species, known by the common names of saltbush. The genus is quite variable and widely distributed. It includes many desert and seashore plants and halophytes. All the three genuses grow in high salinity, hence halophyte. Halophytes are salt-tolerant plants that grow in waters with high salinity, such as in mangrove swamps, marshes, seashores and saline semi-deserts Answer : (b)
Q.18
Xerophytes posses .... .... [R.P.M.T.1998]
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a) Sunken stomata
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b) Deep roots
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c) Thick cuticle
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d) All the above
Explanation
Xerophyte, any plant adapted to life in a dry or physiologically dry habitat. Many desert plants have a thick cuticle on their leaf surfaces and have their stomata arranged in deep pits (sunken) to minimise water loss through transpiration. Xerophytes such as cacti are capable of withstanding extended periods of dry conditions as they have deep-spreading roots and capacity to store water. Answer : (d)
Q.19
Reduction in vascular tissue, mechanical tissue and cuticle are characteristic of .... .... [C.B.S.E.2009]
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a) Mesophytes
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b) Hydrophytes
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c) Xerophytes
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d) Epiphytes
Explanation
Hydrophytes are aquatic plants that are especially suited for living in aquatic environments. Characteristics are as follows: Floating leaves: the leaves are thin, flat and have large air spaces inside to give them buoyancy. This keeps them close to the surface of the water where there is more light for photosynthesis Thin waterproof waxy cuticle: it is very thin as there is little need to prevent water loss. Stomata located on the upper surface of the leaves: this allows for gas exchange to occur with the air instead of the water. Reduced root system: only small roots are required as they can also extract nutrients from the surrounding water through their tissues. Reduced veins in the leaves: the xylem is significantly reduced as there is no need to transport water throughout the plant Answer : (b)
Q.20
Abyssal zone in ocean has .... .... [B.H.U.1992]
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a) No sunlight but contains consumers and decomposers
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b) No sunlight but contains producers
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c) No sunlight but contains living beings
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d) Sunlight as well as producers
Explanation
Abyssal zone, portion of the ocean deeper than about 2,000 m (6,600 feet) and shallower than about 6,000 m (20,000 feet). The abyssal zone has no sunlight and extreme temperatures near freezing. It also has incredible pressure, up to 600 times that of the surface. The life that is found in the Abyssal Zone includes chemosynthetic bacteria, tubeworms, and small fish that are dark in color or transparent. Answer : (a)
Q.21
July 11 is .... .... [A.I.I.M.S. 2008]
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a) No tobacco day
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b) World population day
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c) World environment day
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d) World health day
Explanation
World Population Day is an annual event, observed on July 11 every year, which seeks to raise awareness of global population issues. Answer : (b)
Q.22
A fertile agricultural soil appears deep colored at the surface as compared to soil one meter down. The reason for color of top soil is .... .... [C.B.S.E.1992]
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a) More moisture
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b) Rich in organic matter
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c) Rich in iron, calcium and magnesium
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d) Recent formation
Explanation
Dark brown or black color in soil indicates that the soil has a high organic matter content Answer : (b)
Q.23
A parasite living within tissue of host is .... .... [A.F.M.C. 1996]
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a) Epiphyte
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b) Endophyte
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c) Ectophyte
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d) None of above
Explanation
Endophytes are microorganisms (bacteria or fungi or actinomycetes) that dwell within robust plant tissues by having a symbiotic association. Answer : (b)
Q.24
Peak concentration of ozone occurs in the atmosphere above a highest of .... .... [Kerala 2000]
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a) 10 KM
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b) 15 KM
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c) 20 KM
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d) 25 KM
Explanation
Ozone primarily occurs in the stratosphere though some ozone, approximately 10% of the total amount, exists in the troposphere. The maximum ozone concentration is between 20 and 25 kilometers (about 12 to 15 miles) above the surface. Answer:(d)
Q.25
In succession, the structural complexity .... .... [Har.P.M.T. 2005]
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a) Drastically increases
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b) Remains constant
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c) Slowly increase
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d) Does not increase
Explanation
Ecological succession is the gradual process by which ecosystems change and develop over time. Succession develops through increasing complexity until it becomes stable or self-perpetuating as a climax community where the ecosystem is balanced and there is less risk of any interfering event or change to the environment. Answer:(c)
Q.26
Population where pre--reproductive animals occur in large number is .... .... [E.A.M.C.E.T. 2005]
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a) Declining
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b) Stable
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c) Fluctuating
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d) Growing
Explanation
Population where pre-reproductive animals occur in large number is expanding or growing population. Answer : (d)
Q.27
Which is not true for species? .... .... [C.B.S.E.2005]
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a) Members of species can interbreed
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b) Each species is reproductively isolated from every other species
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c) Gene flow does not occur between populations of a species
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d) Variations occur among members of a species
Explanation
Species are the major subdivision of a genus or subgenus, regarded as the basic category of biological classification, composed of related individuals that resemble one another, are able to breed among themselves, but are not able to breed with members of another species. Gene flow is the transfer of genetic material from one population to another. Gene flow can take place between two populations of the same species through migration, and is mediated by reproduction and vertical gene transfer from parent to offspring. Answer : (c)
Q.28
Homeostasis is .... .... [C.B.S.E.1991]
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a) Tendency of biological systems to change with change in environment
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b) Tendency of biological systems to resist change
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c) Disturbance of self regulatory system and natural controls
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d) Biotic materials used in homeopathic medicines
Explanation
Homeostasis is any self-regulating process by which an organism tends to maintain stability while adjusting to conditions that are best for its survival. Ideally, the organism should try to maintain the constancy of its internal environment despite varying external environmental conditions that tend to upset its homeostasis. Answer : (b)
Q.29
Volume and surface area of deer 1,50,000 cm3 and 19,000 cm3 and of a squirrel is 625 cm3 and 530 cm3 . The area available for heat loss per cm3 of squirrel will be approx. .... .... [A.M.U. 2010]
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a) Seven times more than deer
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b) Eleven times more than deer
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c) Three times more than deer
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d) Eleven times more than deer
Explanation
Heat ∝ Area/Volume Deer: H1 = 19,000/1,50,000 Squirrel : H2 = 625/530 H2 / H1 = 7 Answer : (a)
Q.30
Which one is partially submerged and fixed in mud .... .... [R.P.M.T.1996]
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a) Marsilea
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b) Cyperus
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c) Eichhornia
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d) Typha
Explanation
Typha are aquatic or semi-aquatic, rhizomatous, herbaceous perennial plants. Typha is a rooted emergent. Roots are in soil shoots or leaves are partly outside and partly inside the water. Answer : (d)
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