Free Ecosystems MCQs with Answers

61. "The open water zone away from shore to the depth of affective light penetration and occupied by phylopplankion Iike green algae euglena etc." which of the following regions of fresh water has all these properties?

• A. Littoral
• B. Limnetic
• C. Profundal
• D. Both "a" and "b"

Explanation: It is the open water zone away from the shore and it extends up to the effective light penetration level. The limnetic zone is well-lighted (like the littoral zone) and is dominated by plankton, both phytoplankton and zooplankton. Plankton are small organisms that play a crucial role in the food chain.

62. Swelling of dead bodies in water is due to:

• A. Osmosis
• B. Diffusion
• C. Expansion
• D. Decomposition

Explanation: The swelling of dead bodies in water is primarily due to the process of decomposition. When a body is submerged in water, bacteria and other microorganisms begin to break down the tissues, releasing gases such as methane, hydrogen, and nitrogen. As the gases accumulate, they can cause the body to bloat and swell.

63. A study of communities in relation to environment is called:

• A. Social ecology
• B. Synecology
• C. Autoecology
• D. Heteroecology

Explanation: Synecology (or community ecology) refers to the study of groups of organisms in relation to their environment.

64. Bacteria living in the gut form the association of:

• A. Mutualism
• B. Predation
• C. Parasitism
• D. Commensalism

Explanation: The human gut microbiome includes trillions of commensal bacteria that offer substantial benefits to the host, including aiding digestion, promoting the development of the immune system, and occupying niches that would otherwise be available to pathogens

65. Identify the mismatch pair in the following:

• A. Cyanobacteria - primary producer
• B. Grasshopper - primary producer
• C. Fungi - Decomposer
• D. Zooplankton - secondary consumer

Explanation: Zooplankton is a primary consumer NOT a secondary consumer.

66. The first stage in development of Xerosere is appearance of:

• A. Foliose lichens
• B. Crustose lichens
• C. Fruticose lichens
• D. Climax stage

Explanation: Due to great exposure to the sun and extreme deficiency of water, the first pioneers in the bare rock area are a few simple organisms. The most successful of such organisms is crustose lichens.

67. What is the direction of energy flow in an ecosystem:

• A. Always unidirectional
• B. Always bidirectional
• C. In any direction
• D. Always down directional

Explanation: In an ecosystem, energy flows in a unidirectional manner, primarily from producers (such as plants) to consumers (such as herbivores, carnivores, and omnivores). This flow occurs through feeding interactions in a food chain or food web.Producers capture energy from sunlight through photosynthesis and convert it into chemical energy. This energy is then passed on to consumers as they eat the producers. Energy is gradually lost as heat at each trophic level, making it a one-way flow. Therefore, option a is correct.

68. The rate at which the new individuals are added to a population in a unit time is:

• A. Density
• B. Natality
• C. Mortality
• D. Dispersion

Explanation: Natality refers to the rate at which new individuals are added to a population in a unit of time. It is also known as birth rate. Natality is an important factor in determining population growth. Therefore, option b is correct.

69. In succession lithoseres takes place on:

• A. Sand
• B. Water
• C. Forest floor
• D. Bare rocks

Explanation: Lithosere is a specific type of ecological succession that occurs on bare rocks. It involves the colonization of plant species on a substrate of rock or stone. Over time, through the action of pioneer species and their interactions with the environment, soil gradually forms, allowing for more complex plant communities to establish. Therefore, option d is correct.