Free Man and His Environment MCQs with Answers

31. Which of the following statements is true about Savannah?

• A. Dry season is very long and the temperature ranges more than 18 C throughout the year
• B. Its plants do not shed off their leaves
• C. The subsoil is permanently frozen
• D. Rainfall is up to 200 cm per year
• E. Rainfall exceeds evaporation

Explanation: The Savanna biome is part of a larger grassland biome and is mainly made up of flat grassland vegetation. There are two distinct seasons consisting of a wet and a dry season. The Savanna biome has an average temperature of 25oC. It goes as high as 30oC during the summer and as low as 20oC during the winter, annually.

32. Four words are shown below: Facultative obligate saprophytes parasites These words can be used in the basis of P Q R and S to complete the sentence below. Organisms that depend on living plants and animals for the nutritional requirements are known as.... P... Parasites, which depend on the nutrition entirely on other living organisms, are known as...Q... or total parasites and those which depend for these requirements partially on other living organisms are called...R...or partial parasite on the other hand the plants which depend on dead or rotten organic remains of plants and animals are called...S...

• A. Option A
• B. Option B
• C. Option C
• D. Option D

Explanation: Parasite is an organism that lives in or on an organism of another specie (its host) and benefits by deriving nutrients at the other's expense. An obligate parasite or holoparasite is a parasitic organism that can not complete its life-cycle without exploiting a suitable host. If an obligate parasite can not obtain a host, it will fail to reproduce. Saprotrophic nutrition or lysotrophic nutrition is a process of chemoheterotrophic extracellular digestion involved in the processing of decayed organic matter. It occurs in saprotrophs and is most often associated with fungi and soil bacteria. A facultative parasite is an organism that may resort to parasitic activity but does not absolutely rely on any host for completion of its life cycle. Examples of facultative parasitism occur among many species of fungi, such as family members of the genus Armillaria. So, Option b is the correct answer.

33. Flow of energy in an ecosystem is:

• A. Unidirectional
• B. Tridirectional
• C. Multidirectional
• D. Bidirectional

Explanation: The correct answer is "Unidirectional."Explanation of options:Unidirectional: This option means that the flow of energy in an ecosystem is one-way, meaning it moves from one trophic level to the next in a linear fashion. Energy enters the ecosystem through the primary producers (plants or photosynthetic organisms), is passed on to the primary consumers (herbivores), then to secondary consumers (carnivores or omnivores), and so on. Energy flow is unidirectional because energy is not recycled back to previous trophic levels.Tridirectional: This term is not commonly used in ecological contexts and doesn't accurately describe the flow of energy in an ecosystem. It implies that energy flows in three different directions, which is not the case.Multidirectional: Similar to "tridirectional," this term is not used to describe the flow of energy in an ecosystem. It suggests that energy flows in multiple directions simultaneously, which is not an accurate representation of energy flow.Bidirectional: This option implies that energy flows in two directions within an ecosystem. While there may be some instances where energy can move in more than one direction (e.g., through decomposition and detritus food chains), the overall flow of energy in an ecosystem is primarily unidirectional, as explained above.In summary, the flow of energy in an ecosystem is primarily unidirectional, moving from lower trophic levels to higher trophic levels.

34. Overgrazing results in:

• A. Totally barren lands
• B. Good pastured lands
• C. Salinity
• D. Rocky areas

Explanation: Overgrazing refers to the excessive grazing of an area by livestock, which leads to the depletion of vegetation and soil erosion. When the vegetation is gone, and the soil is eroded, the land can become totally barren and unsuitable for grazing or other uses.

35. In nitrogen fixation, nitrogen is converted to:

• A. Nitrate ions and ammonia
• B. Atomic nitrogen
• C. Urea
• D. All of these

Explanation: In nitrogen fixation, nitrogen is converted to Nitrate ions and ammonia. Nitrogen fixation is the process of converting atmospheric nitrogen gas (N2) into usable forms of nitrogen, such as nitrate ions (NO3-) and ammonia (NH3), by certain bacteria, such as Rhizobium, and lightning.

36. Which of the following trophic levels has the largest biomass in ecosystems?

• A. Decomposers
• B. Primary consumer
• C. Secondary consumer
• D. Producers
• E. Herbivores

Explanation: Option A: Decomposers break down dead organic matter and waste materials, playing a crucial role in nutrient recycling. However, their biomass is typically lower compared to other trophic levels. Option B: Primary consumers are herbivores that consume producers (plants) as their main food source. While they can have significant biomass, it is generally lower than that of producers. Option C: Secondary consumers are carnivores or omnivores that feed on primary consumers. Their biomass is even lower than that of primary consumers. Option D: Producers typically have the largest biomass in ecosystems. Producers, also known as autotrophs, are organisms that can convert energy from sunlight or inorganic compounds into organic matter through photosynthesis or chemosynthesis. They include plants, algae, and some bacteria. Since they can produce their own food, they form the base of the food chain and support the energy needs of other organisms in the ecosystem. As a result, the biomass of producers tends to be higher than that of other trophic levels. Option E: Herbivores specifically feed on plants and are primary consumers. While they can have substantial populations and biomass, it is typically lower than that of producers.

37. An area previously supporting life is made barren, the subsequent recolonization is called _.

• A. Climax community
• B. Pioneer succession
• C. Primary succession
• D. Secondary succession

Explanation: Secondary succession occurs when the primary ecosystem gets destroyed. For example, a climax community gets destroyed by fire. It gets recolonized after the destruction. A climax community is the final stage of succession, remaining relatively unchanged until destroyed by an event such as fire or human interference. Primary succession is an ecological succession that begins in essentially lifeless areas, such as regions in which there is no soil or where the soil is incapable of sustaining life The pioneer species are hardy species that are the first to colonize barren environments or previously biodiverse steady-state ecosystems that have been disrupted, such as by fire. Therefore, the correct answer is secondary succession.

38. The actual or preserved remains of the organisms that lived in the ancient past are called:

• A. Fossils
• B. Impression
• C. Ancient prints
• D. Ancient cast

Explanation: Fossils are the preserved remains, or traces of remains, of ancient organisms. An impression fossil is formed when the plant or animal decays completely but leaves behind an impression of itself.

39. Select the mismatched option:

• A. Rhodospirillum - Mycorrhiza
• B. Anabaena - Nitrogen fixer
• C. Rhizobium - Alfalfa
• D. Frankia - Alnus

Explanation: Rhodospirillum is a free-­living nitrogen-fixing bacteria. Mycorrhiza is the symbiotic association between fungi and roots of higher plants. The most common fungal partners of mycorrhiza are Glomus species.

40. Which of the following in sewage treatment removes suspended solids?

• A. Secondary treatment
• B. Primary treatment
• C. Sludge treatment
• D. Tertiary treatment

Explanation: Primary or physical treatment is the process of removal of small and large, floating and suspended solids from sewage through two processes of filtration and sedimentation.