Ecosystem: MCQ Test

21. Except for deep sea hydro-thermal ecosystems, what is the primary source of energy for all ecosystems on Earth?

• Chemical energy from rocks
• Geothermal energy
• Solar energy
• Decomposition of organic matter

22. What percentage of incident solar radiation is Photosynthetically Active Radiation (PAR)?

• Less than 10%
• Less than 50%
• More than 75%
• Approximately 100%

23. Green plants capture a small amount of PAR to sustain the entire living world. What percentage of PAR do plants typically capture?

• Less than 1%
• 2-10%
• 10-20%
• 50-70%

24. The flow of energy in an ecosystem is characterized as:

• Bidirectional
• Cyclical
• Unidirectional
• Varies greatly depending on the season

25. In a terrestrial ecosystem, which organisms are primarily classified as producers?

• Fungi and bacteria
• Herbaceous and woody plants
• Insects and birds
• Earthworms and molluscs

26. If an animal feeds on producers, such as plants, it is classified as a:

• Secondary consumer
• Primary consumer
• Tertiary consumer
• Decomposer

27. Which of the following common herbivores are mentioned for a terrestrial ecosystem?

• Molluscs
• Phytoplankton
• Insects, birds, and mammals
• Fungi and bacteria

28. The detritus food chain (DFC) begins with:

• Live green plants
• Sunlight
• Dead organic matter
• Primary consumers

29. Organisms of the detritus food chain, mainly fungi and bacteria, are also known as:

• Autotrophs
• Producers
• Saprotrophs
• Carnivores

30. In which type of ecosystem is the Grazing Food Chain (GFC) generally the major conduit for energy flow?

• Terrestrial ecosystems
• Desert ecosystems
• Aquatic ecosystems
• Forest ecosystems

31. Organisms occupy a specific place in the food chain based on their feeding relationship, known as their:

• Habitat
• Niche
• Trophic level
• Population density

32. Which trophic level do herbivores belong to in an ecosystem?

• First trophic level
• Second trophic level
• Third trophic level
• Fourth trophic level

33. The amount of energy in an ecosystem generally ____________ at successive trophic levels.

• Increases
• Stays the same
• Decreases
• Fluctuates unpredictably

34. The mass of living material at a particular trophic level at a given time is called the:

• Biomass productivity
• Standing crop
• Net primary production
• Gross primary production

35. According to the 10 percent law, what proportion of energy is typically transferred from one trophic level to the next higher trophic level?

• All of it (100%)
• Half of it (50%)
• One-tenth of it (10%)
• One hundredth of it (1%)

36. In ecological pyramids, the apex represents the:

• Producers or first trophic level
• Primary consumers
• Tertiary or top level consumer
• Decomposers

37. Which type of ecological pyramid is always upright and can never be inverted?

• Pyramid of number
• Pyramid of biomass
• Pyramid of energy
• Both pyramid of number and biomass

38. In most ecosystems, what is the general shape of pyramids of number, energy, and biomass?

• Inverted
• Spindle-shaped
• Upright
• Variable

39. The pyramid of biomass in the sea is generally inverted. This is primarily because:

• Energy transfer is highly inefficient in aquatic environments.
• The biomass of fishes far exceeds that of phytoplankton.
• Aquatic producers have a very long lifespan.
• There are fewer trophic levels in aquatic food chains.

40. A major limitation of ecological pyramids is that they do not account for which of the following?

• The basic structure of an ecosystem.
• Energy flow between trophic levels.
• The same species belonging to two or more trophic levels.
• The total number of organisms at each trophic level.