Consider the following statements concerning food chains
1.Removal of 80% tigers from an area resulted in greatly increased growth of vegetation
2.Removal of most of the carnivores resulted in an increased population of deers
3.The length of food chains is generally limited to 3-4 trophic levels due to energy loss
4.The length of food chains may vary from 2 to 8 trophic levels Which two of the above statements are correct?
The slow rate of decomposition of fallen logs in nature is due to their:
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Solution
The slow rate of decomposition of fallen logs in nature is due to their low cellulose content. It plays an essential part in abscission in plants, while microbial cellulases enable the digestion of plant material by herbivores.
About 70% of total global carbon is found in:
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Solution
About 70% of total global carbon is found in oceans.This oceanic reservoir regulates the amount of carbon dioxide in the atmosphere. Atmosphere contains only about one percent of total global carbon.
A lake near a village suffered heavy mortality of fishes within a few days. Consider the following reasons for this:
1.Lots of urea and phosphate fertilizer were used in the crops in the vicinity
2.The area was sprayed with DDT by an aircraft
3.The lake water turned green and stinky
4.Phytoplankton populations in the lake declined initially thereby greatly reducing photosynthesis.Which two of the above were the main causes of fish mortality in the lake?
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Solution
Lots of urea and phosphate fertilizer were used in the crops in the vicinity and the lake water turned green and stinky.Due to this, lake near a village suffered heavy mortality of fishes within a few days.
Which one of the following ecosystem types has the highest annual net primary productivity?
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Solution
They are found in the equatorial regions rainfall exceeds 140 cm. The warm humid climate supports broad leaved evergreen plants. Productivity is very high (12000 k.cal/m2/ year). The vegetation show stratification into two or more well defined layers.
Which one of the following is not used for construction of ecological pyramids?
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Solution
Fresh weight is not used for the construction of ecological pyramids because the total fresh weight does not change into energy. Hence we can say that fresh weight is not continuous in the tropic levels.
More than 70% of world’s freshwater is contained in:
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Solution
Three fourth surface of earth is covered by oceans which contain 97.5% of total water. It is marine water with about 3.5% salt content only 2.5% is fresh water which occurs on land. Most of this water (1.97%) occurs as frozen icecaps and glaciers, 0.5%fresh water occurs as groundwater. Rivers and lakes contain 0.02%, soil 0.01% while atmosphere possesses 0.001% of water as vapours.
An ecosystem which can be easily damaged but can recover after some time if damaging effect stops will be having:
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Solution
An ecosystem having low stability can be easily damaged. An ecosystem having high resilience will take less time to recover.
Which of the following is expected to have the highest value(gm/m2/yr) in a grassland ecosystem?
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Solution
Grasslands will have highest value of gross production.Net production is obtained after subtracting the respiratory utilization from gross production. Secondary and tertiary production is related with secondary and tertiary consumers respectively.
Bamboo plant is growing in a fir forest then what will be the trophic level of it?
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Solution
First trophic level is occupied by producers. Second trophic level is occupied by primary consumers. Third trophic level is occupied by the secondary consumers.