The true end of any food chain is Decomposers. The organism that breaks down the dead and decaying matter and carries out the decomposition process by an organism is called a Decomposer.
32. The second trophic level in a lake is
Phytoplankton
Zooplanktons
Fishes
Benthos
Answer.2. Zooplanktons
Explanation:
A lake ecosystem is an aquatic food chain. It consists of different trophic levels. The first trophic level is phytoplankton. They produce their own food.
Zooplankton is the primary consumer in aquatic food chains. They feed upon phytoplankton. They are present in the second trophic level. Hence, the second most important trophic level in a lake is zooplankton.
Zooplankton is small, aquatic microorganisms in the water column that include crustaceans, rotifers, open water insect larvae, and aquatic mites.
33. Which of the following can act as a pioneer species in a xerarch succession?
Lichens
Humans
Herbs
Animals
Answer.1. Lichens
Explanation:
The species that invade a bare area are called pioneer species. In primary succession in xerarch, these are usually lichens that are able to secrete acids to dissolve rock, helping in weathering and soil formation.
34. Energy flow in an ecosystem is
Bidirectional
Unidirectional
Multidirectional
All rounds
Answer.2. Unidirectional
Explanation:
Energy flow is the flow of energy through living things within an ecosystem. Energy flow in an ecosystem is always unidirectional, i.e. it always flows from producers to consumers.
All living organisms can be organized into producers and consumers, and those producers and consumers can further be organized into a food chain. Each of the levels within the food chain is a trophic level.
35. Which of the following is an example of a man-made ecosystem?
Tissue culture
Herbarium
Aquarium
Forest
Answer.3. Aquarium
Explanation:
The aquarium is the artificial aquatic ecosystem made by man which contains plants, fishes, and other organisms which serve as a source of food.
An ecosystem, which is created and maintained by human beings, is called an artificial or man-made ecosystem. Some examples of man-made ecosystems are aquariums, gardens, agriculture, apiary, poultry, piggery, etc.
36. Pyramid of energy in a pond ecosystem is always
Inverted
Upright
Linear
Irregular
Answer.2. Upright
Explanation:
The energy flow in an ecosystem is from the producer level to the consumer level. At each trophic level, 80 to 90% of energy is lost. Hence, the amount of energy decreases from the producer level to the consumer level.
Pyramid of energy 1s is always upright because, during the flow of energy from one trophic level to the next one, there always occurs a loss of energy.
37. If in a population, natality is balanced by mortality, then there will be
Decrease in population growth
Increase in population growth
Zero population growth
Overpopulation
Answer.3. Zero population growth
Explanation:
Natality is defined as the number of birth of organisms in a population of a specific area with the passage of time. Mortality is defined as the number of deaths of organisms in a population of a specific area with the passage of time.
If in a population, natality is balanced by mortality then there will be zero population growth.
38. In a pyramid of numbers in grassland ecosystems, the largest population is that of
Herbivores
Primary consumers
Secondary consumer
Producers
Answer.4. Producers
Explanation:
In grassland, a large number of grass or herbs support a lesser number of grasshoppers, the grasshoppers support a fewer number of frogs, and the frogs to still smaller number of snakes, the latter support very few peacocks or falcons.
The maximum number of individuals occurs at the producers level. They support a small number of herbivores. The herbivores, in turn, support a fewer number of primary carnivores and so on. Top carnivores are very few in number.
39. Which of these belong to the category of primary consumers in the grazing food chain?
snakes and frogs
Insects and cattle
Eagle and snakes
Cow and rabbit
Answer.4. Cow and rabbit
Explanation:
Primary consumers are organisms that eat producers. They are also called herbivores or plant-eaters. Any plant-eating animal is a primary consumer. Fish that eat algae are also primary consumers. E.g., Goat, Deer, Cow, and rabbit.
40. The pyramid of energy is always upright for any ecosystem, this situation indicates that
Herbivores have better energy conversion efficiency than carnivores
Producers have the lowest energy conversion efficiency
Carnivores have a better energy conversion efficacy than herbivores
Energy conversion efficiency is same at all trophic levels
Answer.1. Herbivores have better energy conversion efficiency than carnivores
Explanation:
The pyramid of energy represents the amount of energy at each trophic level.
Transfer of energy from producers to primary consumers, or from plants to herbivores, also involves energy ‘wastage’. It is estimated that for every 100g of plant material available, only about 10g ends up as new herbivore biomass. This represents a conversion efficiency of 10%.
Similar losses of energy occur between subsequent trophic levels Carnivores are more efficient at energy conversion. Some are able to achieve as much as 20%. That is, 20% of the herbivore biomass eaten ends up as carnivore biomass. This is because they are able to digest high-protein diets more efficiently. It is this loss of energy at each trophic level that gives ecological pyramids their characteristic shape.
Thus, the correct answer is ‘Herbivores have a better energy conversion efficiency than carnivores.’
41. Which of the ecological pyramid is always upright?
Pyramid of numbers
Pyramid of biomass
Pyramid of energy
All of the above
Answer.3. Pyramid of energy
Explanation:
Pyramid of energy 1s is always upright because, during the flow of energy from one trophic level to the next one, there always occurs a loss of energy.
42. Which one of the following is not a gaseous biogeochemical cycle?
Nitrogen cycle
Carbon cycle
Sulfur cycle
Phosphorus cycle
Answer.4. Phosphorus cycle
Explanation:
Gaseous cycles are a type of biogeochemical cycle in which the reservoir is the air or the oceans (via evaporation). Such cycles include those of nitrogen, oxygen, carbon, and water.
The phosphorus cycle is a sedimentary cycle. The phosphorus cycle is the biogeochemical cycle that describes the movement of phosphorus through the lithosphere, hydrosphere, and biosphere.
43. Deserts, grasslands, forests and tundra regions are the examples of
Biomes
Biogeographically regions
Ecosystems
Biospheres
Answer.3. Ecosystems
Explanation:
An ecosystem is a geographic area where plants, animals, and other organisms, as well as weather and landscape, work together to form a bubble of life. Deserts, grasslands, forests, and tundra regions are examples of Ecosystems.
Ecosystems contain biotic or living, parts, as well as abiotic factors, or nonliving parts. Biotic factors include plants, animals, and other organisms.
44. The upright pyramid of numbers is absent in
Lake
Pond
Grasslands
Forests
Answer.4. Forests
Explanation:
A pyramid of numbers is a graphical representation that shows the number of organisms at each trophic level.
In forests, a single tree can support a large number of birds thus base showing producers in a pyramid of numbers will be narrower than the next slab showing primary consumers. Hence an upright pyramid of numbers is not formed in a forest ecosystem.
45. The final stable community in ecological succession is
Climax
Pioneer
Sere
Carnivores
Answer.1. Climax
Explanation:
A climax community is the final stage of succession, remaining relatively unchanged until destroyed by an event such as fire or human interference.
