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

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 \(\dfrac{dN}{dt} = rN\left(\dfrac{K-N}{K}\right)\)dN/dt=rN(K−N)K" id="MathJax-Element-10-Frame" role="presentation" style=" position: relative;" tabindex="0">dN/dt=rN(K−N)K" id="MathJax-Element-23-Frame" role="presentation" style=" position: relative;" tabindex="0">dN/dt=rN(K−N)KdN/dt=rN(K−N)K" id="MathJax-Element-21-Frame" role="presentation" style="position: relative;" tabindex="0">[Math Processing Error]dN/dt=rN(K−N)K" id="MathJax-Element-55-Frame" role="presentation" style=" position: relative;" tabindex="0">dN/dt=rN(K−N)KdN/dt=rN(K−N)K" id="MathJax-Element-77-Frame" role="presentation" style=" position: relative;" tabindex="0">dN/dt=rN(K−N)KdN/dt=rN(K−N)K" id="MathJax-Element-2-Frame" role="presentation" style="position: relative;" tabindex="0">dN/dt=rN(K−N)KdN/dt=rN(K−N)K dN/dt=rN(K−N)K

Explanation:

Verhulst-Pearl logistic growth, also simply known as logistic growth, is a model of population growth that describes how a population grows more slowly as it approaches its carrying capacity. 

A population growing in a habitat with limited resources show initially a lag phase, followed by phases of acceleration and deceleration and finally an asymptote, when the population density reaches the carrying capacity.

A plot of N in relation to time (t) results in a sigmoid curve. This type of population growth is called Verhulst-Pearl Logistic Growth.

• Ideally if the resources in a habitat are unlimited, the population shows exponential growth pattern.
• But resources are not available to any species population in unlimited amount. Thus, the species compete for the available resources to survive.
• This competition for the limited resources restricts the exponential or unlimited growth of any population.
• Any given habitat can only provide resources to support a maximum possible number, beyond which it further growth of population is not possible. This is known as the carrying capacity (K) for a particular species in a habitat.

Logistic growth is represented as: \({dN \over dt} = rN({K-N\over K})\)

where,

• N = Population Density at time t
• K = Carrying Capacity,
• \(r \) = Intrinsic rate of natural increase
• \(dN \over dt\) = 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 \(({K-N\over K})\).

The correct answer is Statement I is correct but Statement II is incorrect

Concept:

• An ecosystem is a functional unit of nature where living organisms interact with each other and their physical environment to form a self-sustaining system.
• The functional aspects of an ecosystem refer to the processes and interactions that maintain the ecosystem's structure and dynamics. These processes include energy flow, decomposition, and nutrient cycling, which are critical for the functioning and sustainability of ecosystems.
• The flow of energy in an ecosystem is unidirectional, starting from the sun to producers (plants), then to consumers (animals), and finally to decomposers (fungi and bacteria).
• The Second Law of Thermodynamics states that energy transformations are never 100% efficient, and some energy is always lost as heat during these processes. Ecosystems are not exempt from this law and adhere to it.

Explanation:

Statement I (Correct):

• Energy flow in an ecosystem is unidirectional. It originates from the sun, is captured by producers (plants) during photosynthesis, and then moves to consumers (herbivores, carnivores, and omnivores) and decomposers.
• Producers convert solar energy into chemical energy (e.g., glucose), which is then transferred to consumers when they eat plants or other consumers. Decomposers break down dead matter, releasing nutrients back into the environment but do not reverse the flow of energy.
• This unidirectional flow ensures energy is consistently passed through trophic levels but is never recycled back to the sun, adhering to the principle of energy flow in ecosystems.

Statement II (Incorrect):

• The Second Law of Thermodynamics applies to ecosystems. This law states that energy transformations lead to an increase in entropy (disorder), and some energy is always lost as heat during these processes.
• Ecosystems are not exempt from the Second Law of thermodynamics. They need a constant supply of energy to synthesise the molecules they require, to counteract the universal tendency toward increasing disorderliness.
• For example, when energy moves through trophic levels, a significant portion is lost as heat during respiration or metabolic activities. Only about 10% of the energy is transferred to the next trophic level, following the "10% law."

The correct answer is A-III, B-I, C-II, D-IV

Explanation:

• A. The Evil Quartet - III. Causes of biodiversity losses:
  • The "Evil Quartet" refers to four major causes of biodiversity loss: habitat destruction, overexploitation, invasive species, and co-extinctions.
  • These factors collectively threaten the survival of various species and ecosystems globally.
• B. Ex situ conservation - I. Cryopreservation:
  • Ex situ conservation involves conserving biodiversity outside their natural habitats, such as in seed banks, botanical gardens, or through cryopreservation.
  • Cryopreservation is a technique used for freezing and storing genetic material (like seeds or embryos) at very low temperatures for future use.
• C. Lantana camara - II. Alien species invasion:
  • Lantana camara is an invasive alien species that disrupts native ecosystems by competing with native flora and causing ecological imbalances.
  • Alien species invasions are a major contributor to biodiversity loss and ecosystem degradation.
  • The environmental damage caused and threat posed to our native species by invasive weed species like carrot grass (Parthenium), Lantana and water hyacinth (Eicchornia).
• D. Dodo - IV. Extinction:
  • The Dodo is an example of a species that has gone extinct due to human activities such as hunting and habitat destruction.
  • Extinction is the complete loss of a species, often driven by factors like overexploitation, invasive species, and habitat destruction.

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

Concept:

• Fig trees (genus Ficus) and fig wasps exhibit a fascinating mutualistic relationship that has evolved over millions of years. This relationship is a classic example of co-evolution.
• The fig fruit is technically a syconium, which is an enclosed structure containing numerous tiny flowers inside. Fig wasps play a crucial role in pollinating these flowers.
• Fig wasps enter the syconium to lay their eggs, and in the process, they help pollinate the fig flowers. The fig tree provides a habitat for the wasps to complete their life cycle, while the wasps ensure the tree's reproduction through pollination.
• The presence of wasp remnants inside the fig fruit does not make it non-vegetarian, as the remnants are naturally decomposed and absorbed into the fruit during its development.

Explanation:

Statement I: "Fig fruit is a non-vegetarian fruit as it has enclosed fig wasps in it" is incorrect because:

• Fig fruits are considered vegetarian as they are plant-based, and any wasp remnants are naturally decomposed during fruit development.
• The presence of wasps is part of a natural ecological process and does not change the classification of the fruit as vegetarian.

Statement II: "Fig wasp and fig tree exhibit a mutual relationship as fig wasp completes its life cycle in fig fruit and fig fruit gets pollinated by fig wasp" is incorrect because:

• A part of the life cycle of the wasp is completed in fig fruit. (not complete)
• Fig wasps lay their eggs inside the fig fruit, and their larvae develop there.
• Fig species can be pollinated only by its ‘partner’ wasp species and no other species.
• The female wasp uses the fruit not only as an oviposition (egg-laying) site but uses the developing seeds within the fruit for nourishing its larvae.
• The wasp pollinates the fig inflorescence while searching for suitable egg-laying sites.
• In return for the favour of pollination, the fig offers the wasp some of its developing seeds, as food for the developing wasp larvae.

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.