Ecology and Environment MCQ Quiz - Objective Question with Answer for Ecology and Environment - Download Free PDF

The correct answer is Both Statement I and Statement II are true

Concept:

• Commensalism is a type of symbiotic relationship in which one species benefits while the other species is neither helped nor harmed. This relationship enhances the survival, growth, or reproduction of the commensal species without affecting the host species.
• Epiphytes are plants that grow on other plants for physical support. They are not parasitic and do not harm the host plant from which they derive support.

Examples of Commensalism:​

• Orchid growing on a mango tree: The orchid benefits by gaining physical support from the mango tree, which elevates it to a position where it can receive more sunlight. The mango tree is neither helped nor harmed.
• Barnacles growing on a whale: Barnacles attach themselves to the whale's skin, gaining mobility to different feeding areas and avoiding predators. The whale is unaffected by their presence.
• Cattle egrets foraging near grazing cattle: The cattle egrets benefit by feeding on insects stirred up by the movement of the grazing cattle. The cattle are unaffected by the presence of the egrets.
• Interaction between sea anemone that has stinging tentacles and the clown fish that lives among them.

The correct answer is Lama

Explanation:

• The term "Neotropical fauna" refers to the animal species that are native to the Neotropical realm, which includes South and Central America, the southern part of North America, and the Caribbean islands.This region is known for its rich biodiversity and is home to a wide variety of unique species of animals and plants.
• Llamas are domesticated animals that belong to the camelid family. They are native to the Andes mountains in South America and have been used for centuries by indigenous people for transportation and as a source of wool and meat.
• Since they are found in the Neotropical region, they are considered part of the Neotropical fauna. 

Other Options:

• Macropus: This refers to kangaroos, which are native to Australia. Australia is part of the Australasian realm, not the Neotropical realm.
• Zebra: Zebras are native to Africa and belong to the Afrotropical realm. They are not found in the Neotropical region.
• Rhinoceros: Rhinoceroses are primarily found in Africa and parts of Asia. They belong to the Afrotropical and Indomalayan realms, not the Neotropical realm.

The correct answer is The number of organisms of a species that can be supported in a given environment.

Explanation:

• Carrying capacity (K) refers to the maximum population size of a species that an ecosystem can support indefinitely without degrading its environment.
• It is determined by the availability of resources such as food, water, shelter, and the environmental conditions.
• Carrying capacity is not a fixed number; it can change over time due to factors like climate change, habitat destruction, or resource availability.
• When a population exceeds its carrying capacity, it can lead to resource depletion, environmental degradation, and a decrease in population size due to starvation, disease, or competition.
• Human activities, such as deforestation, pollution, and overexploitation of resources, can lower the carrying capacity of ecosystems.
• The carrying capacity is calculated by considering both biotic factors (like food availability and predation) and abiotic factors (like water, climate, and space).

Carrying capacity is an important factor in logistic growth patterns of populations.

Logistic growth is represented as: 

where,

• N = Population Density,
• K = Carrying Capacity,
•  = Intrinsic rate of natural increase
•  = Rate of change of population density.
• 'r' value denotes the difference between the per capita birth and death (b-d).
• The environmental resistance is represented in the equation as .

Concept:

• The ecosystem consists of all the biotic factors (plants, animals, and microorganisms) and the physical environment (abiotic factors) that they interact with..
• The interaction of the biotic and abiotic factors results in the physical structure of an ecosystem.
• The ecosystems of the world can be broadly divided into two:
  • Terrestrial ecosystems - Terrestrial ecosystems include forests, deserts, grasslands, etc.
  • Aquatic ecosystems - Wetlands, rivers, estuaries, etc. are some examples of aquatic ecosystems.

Important Points

• The components of an ecosystem are seen to function as a unit for its sustainability.

Components of Ecosystem -   ​

• Productivity - 
  • Primary production refers to the amount of biomass or organic matter that is produced per unit area over a time period by plants during photosynthesis.
  • The rate of biomass production is called productivity.
• Decomposition - 
  • It refers to the process by which decomposers break down complex organic matter into inorganic substances like carbon and water.
  • Due to decomposition, vital nutrients are made available to the primary producers.
• Energy flow - 
  • Sun is the major and only source of energy for all ecosystems. 
  • The energy from the sun is harnessed by autotrophs and used for the production of food.
  • The energy from the autotrophs is then passed on to consumers.
  • In an ecosystem, the flow of energy is unidirectional.
• Nutrient cycling - 
  • Nutrient cycles or biogeochemical cycles are defined as the natural pathways by which nutrient elements of an ecosystem are circulated.
  • Gaseous and sedimentary are the two types of nutrient cycles.

So the correct answer is option 3.

Key Points

• Sacred Groves are patches of forest or natural vegetation that are conserved by local communities due to religious and cultural practices.
• These groves often act as repositories of biodiversity, housing rare and endemic species of flora and fauna.
• Similar to biosphere reserves, Sacred Groves help in the conservation of ecosystems and promote sustainable interaction between humans and nature.
• They are often protected by traditional laws and serve as natural habitats for many species, supporting the idea of harmonious coexistence.

Important Points

• Biosphere reserves are designated areas that aim to conserve biodiversity while fostering sustainable development for local communities.
• They are recognized under UNESCO's "Man and Biosphere Program" and consist of three zones: core, buffer, and transition zones.
• Like Sacred Groves, biosphere reserves also emphasize the importance of protecting nature while maintaining cultural and social integrity.

The correct answer is i - b, ii - c, iii - d, iv - a.

Key Points

The trophic levels represent the hierarchical levels in an ecological food chain, indicating the position of organisms based on their feeding relationships. Here's the explanation for the correct match:

• First trophic level - phytoplankton:
  • The first trophic level typically consists of primary producers that convert sunlight into energy through photosynthesis.
  • Phytoplankton are microscopic plants that form the base of aquatic food chains.
• Second trophic level - zooplankton:
  • The second trophic level comprises primary consumers that feed on the primary producers.
  • Zooplankton, which includes tiny animals, consume phytoplankton, placing them at the second trophic level.
• Third trophic level - fishes:
  • The third trophic level involves secondary consumers that feed on primary consumers.
  • In aquatic ecosystems, fishes are often positioned at the third trophic level as they consume zooplankton or other smaller organisms.
• Fourth trophic level - human:
  • The fourth trophic level represents tertiary consumers, which are higher-order predators.
  • Humans, being omnivores or carnivores, are often placed at the fourth trophic level in food chains when they consume animals from lower trophic levels.​ 

The correct answer is Cow.

Key Points

• Food chain: 
  • A food chain shows the feeding relationship between different organisms in a particular environment and/or habitat.
  • A food chain shows how energy is passed from the sun to producers, from producers to consumers, and from consumers to decomposes such as fungi. 
  • They also show how animals depend on other organisms for food.
  • In a food chain of Grass > Cow > wolf > Tiger, the frog occupies the third trophic level as it eats insects and further becomes the food for the snake.
• Tropic level: 
  • Based on the source of their nutrition or food, organisms occupy a specific place in the food chain that is known as their trophic level.
  • Producers belong to the first trophic level, herbivores (primary consumers) to the second, and carnivores (secondary consumers) to the third. The important point to note is that the amount of energy decreases at successive trophic levels.
  • Primary producers are at the first tropic level - They produce food on their own with the help of photosynthesis. Ex- plants, trees.
  • Primary Consumers are herbivores animals, whose nutrition is directly based on plant products. Ex- Cow, deer, grasshoppers, small insects, etc.
  • Secondary consumers are carnivorous animals Like- small birds, wolfs, etc.
  • Tertiary Consumers are the top-level carnivore like men, lions, etc.
  • Only 10% of energy is transferred to higher levels from the previous one. So, the demand for food is more in higher levels.

Additional Information 

The correct answer is sulphur hexafluoride.Key Points

• Sulphur hexafluoride is a synthetic fluorinated gas with an extremely stable molecular structure, making it the most potent greenhouse gas ever found.
• It has a global warming potential of 23,500 times that of CO₂, meaning that it traps 23,500 times more heat in the atmosphere than CO₂.
• Sulphur hexafluoride is commonly used in electrical transmission and distribution equipment, as well as in the production of magnesium and aluminium.

Additional Information

• Hydrogen fluoride (option 1) is a highly corrosive gas used in the production of fluorine compounds, including sulphur hexafluoride.
• Sodium monofluorophosphate (option 2) is a salt commonly used in toothpaste to prevent tooth decay.
• Calcium fluoride (option 4) is a mineral found in teeth and bones and is also used in the production of aluminium.

The correct answer is Section 5 A.

Key Points

• The National Board for Wildlife (NBWL) -
  • It is constituted by the Central Government under Section 5 A of the Wildlife (Protection) Act, 1972 (WLPA). 
  • It may, at its discretion, constitute a Standing Committee under sub-section (1) of Section 5B.

Additional Information

• ​National Board for Wildlife (NBWL) -
  • It was formed in the year 2003 under the Wildlife (Protection) Act, of 1972.
  • It acts as the apex body in matters relating to forest ecology.
  • This body reviews matters relating to wildlife and construction or other projects around national parks and sanctuaries.
  • It is chaired by the Prime Minister.

Key Points

• Extinct species refer to those that have no living individual on Earth now.

• Extinction of a species can be caused by various natural and man-made reasons.

  • Invasion of non-native species - When new species are brought into their habitat from other external habitats.
  • Overexploitation of resources - When all the natural resources like food or water are exhausted due to overuse or over-crowding.
  • Pollution - Environmental pollution like air, water or soil pollution.
  • Global environment change - like global warming, rising of sea levels, etc.

Important Points

• Dodo was a flightless bird that lived on the island of Mauritius.
• It nested on the ground and were more vulnerable.
• It did not have any natural predator in its habitat, so it was not afraid of humans.
• When Portuguese and Dutch sailors landed on this island, the birds were discovered for the first time.
• They started killing these birds for its flesh.
• The sailors used them for food because they were easy source for fresh meat.
• The bird population started decreasing because of this.
• As human settlements increased, the bird's natural habitat was also lost.
• This led to the ultimate extinction of the bird.
• The last Dodo was killed in 1681.

Additional Information

• Some other animals that went extinct due to overexploitation are:
  • Quagga from South Africa
  • Stellar's Sea Cow from Russia
  • Thylacine from Australia

The correct answer is 10%.Key Points

• The term "trophic level transfer efficiency" is the average amount of organic matter that is transferred from one trophic level to the next.
• This value is usually around 10%, meaning that only 10% of the organic matter from one level is transferred to the next level.
• Because energy is lost as metabolic heat when animals from one trophic level are consumed by species from the next, energy declines as it goes up the trophic levels.

Additional Information

• The food chain is a straight line made up of creatures in which energy and nutrients are passed from one to the next.
• When one creature eats another, this happens. 
• The decomposer organism comes at the end of the chain, having started with the producer organism. 

The correct answer is Low level ozone (or tropospheric ozone) is an atmospheric pollutant.

Key Points

• "Low-level ozone (or tropospheric ozone) is an atmospheric pollutant", this statement is true.
  • Tropospheric ozone is a short-lived climate pollutant with an atmospheric lifetime of hours to weeks.
  • It does not have any direct emissions sources, rather it is a secondary gas formed by the interaction of sunlight with hydrocarbons.
  • The conversion of Ozone to oxygen is an exothermic reaction.
  • It means when ozone gets converted into oxygen, heat is released.​

Additional Information

• Ozone (O3) is a triatomic molecule consisting of three oxygen atoms. 
• It is an oxygen allotrope.
• It has three electron groups around the central oxygen, and so has the trigonal planar electron geometry.
• It has one double bond and one single bond in its Lewis structure.

The correct answer is option 1 that is organic matter.

Concept:

• The concentration of hydrogen ions in the soil solution is measured by soil pH, which also serves as a gauge for the acidity or alkalinity of the soil.
• Some plants do best in neutral (pH 7) soil, while others do better in slightly acidic (pH 7) or slightly alkaline (pH > 7) soil.
• The ability of a plant to absorb nutrients can be hampered when the pH of the soil is too severe (either too acidic or too basic), which can have a detrimental effect on growth and productivity.
• Many minerals, including iron, manganese, and phosphorus, become less accessible for plant absorption in strongly alkaline or basic soils (pH significantly more than 7).

Explanation:

• The pH of the soil can be lowered (making it less alkaline) and overall soil health can be improved by adding organic matter, such as compost or well-rotted manure.
• These additives improve the activity of the soil's producing organic acid-producing organisms, which can aid in balancing the soil's alkalinity.
• Note that adding materials like quicklime or calamine solution would actually increase the soil's alkalinity, making it more basic rather than less. These choices would therefore not be suitable.
• It is typically advised that soil be tested to ascertain its current pH and nutrient levels before to making any modifications. This can assist in determining which adjustments, if any, would be most helpful.

Hence,the correct option is organic matter.

The correct answer is 10%.

Key Points

• About 10% of the energy available at one trophic level is transferred to the next level in an ecological pyramid.
• This principle is known as the 10% law, or the Lindeman rule.
• The remaining 90% of the energy is lost as heat due to the organisms' metabolic processes, such as respiration, movement, and maintaining body temperature.
• A breakdown of the energy flow in an ecological pyramid:
  • Producers (base of the pyramid): Capture energy from sunlight or inorganic chemicals (chemosynthesis) and convert it into organic matter (biomass) through photosynthesis or chemosynthesis.
  • Primary consumers (herbivores): Eat producers and transfer about 10% of the energy they consume to their own biomass.
  • Secondary consumers (carnivores): Eat primary consumers and transfer about 10% of the energy they consume to their own biomass.
  • Tertiary consumers (apex predators): Eat secondary consumers and transfer about 10% of the energy they consume to their own biomass.

Concept:

• An ecological pyramid is a pictorial representation of the relationship between different organisms in an ecosystem.
• It is of three types: Pyramid of the number, Pyramid of biomass, and Pyramid of energy.
• The base of each pyramid represents the producers or the first trophic level while the apex represents the tertiary or top-level consumer.

Explanation:

The Limitations of an ecological pyramid are:

• It does not take into account the same species belonging to two or more trophic levels.
• It assumes a simple food chain, something that almost never exists in nature; it does not accommodate a food web.
• The saprophytes are not given any place in ecological pyramids even though they play a vital role in the ecosystem.
• Thereby, the correct option is ''all of them''

Important Points

• The pyramid of biomass in the sea or pond is generally inverted because the biomass of fishes far exceeds that of phytoplankton.  

• The pyramid of energy is always upright, can never be inverted, because when energy flows from a particular trophic level to the next trophic level, some energy is always lost as heat at each step.