Ecosystem Ecology MCQ Quiz in বাংলা - Objective Question with Answer for Ecosystem Ecology - বিনামূল্যে ডাউনলোড করুন [PDF]

The correct answer is Option 3 i.e. A - Asia, B - Europe, C - South America, D - Africa

Explanation-

• Africa had the highest net loss of forest area in 2010–2020, with a loss of 3.94 million hectares per year, followed by South America with 2.60 million hectares per year (Figure).
• Since 1990, Africa has reported an increase in the rate of net loss, while South America’s losses have decreased substantially, more than halving Since 2010 relative to the previous decade.
• Asia showed the highest net gain in forest area in the period 2010–2020, followed by Oceania and Europe.
• Both Europe and Asia reported a net forest gain for each ten-year period since 1990, although both regions show a substantial reduction in the rate of gain since 2010.

The correct answer is All the lions in a reserve forest.

Explanation-

An "ecological population" refers to a group of individuals of a single species that live in the same geographic area at the same time, and can interbreed. Therefore, the correct answer according to the definition is: All the lions in a reserve forest

• This represents a population of the same species (lions) living in the same geographic area (a reserve forest).
• The other options include different species or individuals living in different habitats, and thus don't represent an ecological population according to the definition

 Key Points 1. A pitcher plant and a trapped fly in it: Here we are looking at two different species – a plant (pitcher plant) and an animal (fly). One is a predator and the other is the prey. This represents a interaction within a community, but not a population.

2. All animals that live near each other in a national park: Here, there are multiple species of animals living in the same area (the national park). This could represent a community or an ecosystem, as it involves multiple interbreeding populations, but it is not a single population by ecological definition.

3.The leeches and flatworms that live in a forest: In this case, we are looking at more than one species - the leeches and the flatworms. They might live in the same forest, but they represent two distinct populations, not one.

4.All the lions in a reserve forest: This represents a group of the same species (lions) living in the same geographical area (reserve forest) which can potentially interbreed with each other. It refers to a population in the context of ecology. Thus, option 4 is the correct answer.

The Correct Answer is: Sugar cane

Explanation:

The energy conversion efficiency of a plant or ecosystem refers to its ability to convert solar energy into chemical energy through photosynthesis. Among the given options, sugar cane has the highest energy conversion efficiency due to its highly efficient C4 photosynthetic pathway.

1. Sugar Cane (C4 Plant):

   • Sugar cane has a C4 photosynthesis mechanism, which is highly efficient in capturing carbon dioxide and minimizing photorespiration.
   • It has a photosynthetic efficiency of up to 7-8%, which is higher than most plants.
   • This makes it the most productive crop in terms of biomass and energy yield per unit area.

2. Tropical Forest Plantation:

   • Tropical forests are very productive ecosystems due to abundant sunlight and water.
   • However, their photosynthetic efficiency is lower than that of C4 plants like sugar cane because most plants in tropical forests use the C3 pathway, which is less efficient in hot conditions.

3. Cornfield:

   • Corn (maize) is another C4 plant, but its energy conversion efficiency is lower than that of sugar cane.
   • Corn allocates more energy to structures like roots and stems, whereas sugar cane stores more energy in its stalks.

4. Open Sea:

   • Open seas have the lowest energy conversion efficiency due to:
     • Limited light penetration.
     • Sparse phytoplankton, which are the primary producers.
   • Productivity is much lower compared to terrestrial plants and ecosystems.

The correct answer is Local extinction of a species caused by demographic stochasticity

Explanation:

An ecological community consists of various species living in the same area, interacting with each other and their environment. Attributes of ecological communities include species diversity, interactions (like predation, and competition), food web stability, and patterns of species abundance. These attributes help define the structure, function, and resilience of the community.

1. Local extinction of a species caused by demographic stochasticity: This refers to random fluctuations in population size due to birth and death rates, which can cause species extinction. It is a characteristic of population dynamics, not necessarily a core attribute of ecological communities as a whole. Thus, this option is NOT an attribute of ecological communities.
2. Logseries species abundance distributions: This is a pattern of how species are distributed by abundance in a community. It is commonly used to describe species richness and diversity, making it a community attribute.
3. Stability of a food web in the face of disturbance: This refers to how resilient or stable an ecological community's food web is when subjected to environmental disturbances. Stability is a crucial community-level attribute.
4. The limits to similarity of competing species: This concept refers to the extent to which competing species can coexist without one outcompeting the other, known as niche differentiation. It is a feature of community structure and interspecies interactions.

Key Points 

• Local extinction of a species due to demographic stochasticity pertains more to population dynamics than ecological communities as a whole.
• Species abundance distributions (like logseries) are patterns that describe community structure.
• Food web stability is an important attribute related to the resilience of ecological communities.
• Niche differentiation and competition are attributes of species interactions within communities.

The Correct Answer is:  P - ii; Q - iii; R - i

Explanation:

The correct matching of mating systems with their corresponding ecological conditions is as follows:

• P: Resource defense polygyny: The ecological condition is Resource is abundant and occurs in clumps (ii). In resource defense polygyny, males defend territories rich in resources that attract females.
• Q: Lek Mating: The ecological condition is Resource is limited and occurrence is unpredictable (iii). In lek mating, males aggregate and display in specific locations (leks) to attract females, often when resources are scarce or unpredictable.
• R: Monogamy: The ecological condition is Resource is abundant and occurs all over the habitat (i). Monogamy often occurs when resources are evenly distributed, supporting pairs to form and raise offspring together.

Therefore, the correct option is:

2) P - ii; Q - iii; R - i

Key Points

• Resource defense polygyny: Males defend resource-rich territories that attract multiple females.
• Lek mating: Males display in small territories (leks) to attract females, typical when resources are unpredictable.
• Monogamy: Males and females pair up to mate, often seen when resources are evenly distributed and abundant across the habitat.
• Ecological correlation: Understanding these mating systems helps in studying animal behavior and reproductive strategies in different environments.
• Behavioral Adaptations: Adaptations in males, such as aggressive defense of territories in polygyny and elaborate displays in lek mating, are driven by ecological conditions and female distribution.
• Reproductive Success: Each mating system is optimized to maximize male and female reproductive success based on prevailing ecological conditions.
• Species Examples: Understanding which species exhibit these mating systems can help in studying their ecology and behavior. For example, many antelope species exhibit resource defense polygyny, while some birds like the sage grouse exhibit lek mating.
• Implications for Conservation: Knowledge of mating systems and their ecological links can inform conservation strategies, particularly in managing habitats and ensuring the availability of critical resources.
• Mating System Variability: Some species may exhibit flexibility in their mating systems based on changes in ecological conditions, highlighting the importance of adaptive strategies in evolutionary biology.

The correct answer is Littoral zone

Explanation:

• Littoral Zone: This zone refers to the part of a sea, lake, or ocean that is close to the shore. It is characterized by being alternately exposed to air and immersed in water due to tidal movements or the changing levels of the water body. It is a critical habitat for many species due to the abundant light, and it supports a diverse range of organisms.
• Pelagic Zone: Incorrect because this term describes the open ocean waters that are not close to the bottom or the shore. It is typically divided into different layers depending on depth, such as the epipelagic, mesopelagic, and bathypelagic zones. It is known for its pelagic organisms like jellyfish, tuna, and many species of sharks.
• Benthic Zone: Incorrect as this refers to the ecological region at the lowest level of a body of water such as an ocean or a lake, including the sediment surface and some sub-surface layers. Organisms living in this zone are called benthos and include microorganisms as well as larger forms like crabs and seaweeds.
• Lentic Zone: The term "lentic" actually refers to still or standing waters, like lakes and ponds, as opposed to "lotic" which refers to flowing water systems like rivers and streams. It doesn't specifically describe a zone that is alternately exposed and submerged.

The correct answer is Option 2 i.e. A and B.

Explanation-

• Assimilation efficiency depends on the quality of the food source and the physiology of the consumer.Unassimilated food returns as feces.
• Carnivores have higher assimilation efficiency (about 80 percent) than do terrestrial herbivores (5 to 20 percent).Thus statement A is correct.
• Production Efficiency = Net production/assimilation.Invertebrates are better than vertebrates at this, and cold blooded species do better than warm blooded species.
• Vertebrates spend a huge amount of energy obtaining food, and the basal metabolic rate of warm blooded organisms uses a lot of energy.Hence statement C is incorrect.

Key Points 

Assimilation efficiency of carnivores is higher than herbivores (A):

• Carnivores generally have a higher assimilation efficiency compared to herbivores. This is because animal tissues are often more easily digestible and have higher energy content than plant tissues, which may contain complex carbohydrates and structural components that are harder to digest.

Consumption efficiency of aquatic herbivores is higher than terrestrial herbivores (B):

•  Aquatic herbivores often have a higher consumption efficiency compared to terrestrial herbivores. This is attributed to the fact that aquatic plants are generally softer and more digestible than many terrestrial plants. The accessibility and quality of plant material contribute to higher consumption efficiency in aquatic ecosystems.

Vertebrates have higher production efficiencies than invertebrates.(C)

• Vertebrates, including mammals, birds, and fish, often have lower production efficiencies due to various factors. Vertebrates invest a significant amount of energy in maintaining a constant internal body temperature (endothermy), which requires a high metabolic rate. This high metabolic rate results in more energy being used for maintenance processes, leaving less energy available for growth and reproduction.

Trophic-level transfer efficiency is higher in terrestrial food chains than in marine(D)

• Trophic-level transfer efficiency refers to the percentage of energy that is transferred from one trophic level to the next in a food chain. In general, marine ecosystems often have higher transfer efficiencies compared to terrestrial ecosystems.

Conclusion- So,the correct statement is Statement A and B.

The correct answer is Option 2 i.e.Individual performing the altruistic act and the recipient

Explanation-

The probability that the altruist and the recipient share a gene is called the coefficient of relatedness (r).

The rule states that a social behaviour will be favoured by natural selection if and only if rb > c,

where ‘b’ is the effect of the behaviour on the reproductive success of others, ‘c’ is the effect on one’s own reproductive success, and ‘r’ is the coefficient of relatedness, which measures the statistical association between the genes of the actor who performs the behaviour and the genes of the recipient affected by it.

Key Points

• Hamilton's rule is a concept in evolutionary biology formulated by William D. Hamilton.
• It explains the conditions under which natural selection would favor the evolution of altruistic behavior. The rule is often stated as follows: rb > c.
• Hamilton's rule suggests that natural selection will favor altruistic behaviors if the genetic relatedness between the individual performing the altruistic act and the individual benefiting from the act (r) multiplied by the additional reproductive success gained by the recipient (B) exceeds the reproductive cost to the individual performing the altruistic act (C).
• This rule helps explain the evolution of behaviors that may appear altruistic, such as helping relatives or members of the same social group, by considering the inclusive fitness gained through shared genetic relatedness.

The correct answer is Option 4 i.e.lower predation intensity in the tropics allows survival of more prey species.

Explanation-

The competition hypothesis is based on the idea that competition is the most important factor of evolution in the tropics, whereas natural selection at higher latitudes is controlled mainly by physical factors such as drought and cold (Dobzhansky 1950).

Such catastrophic mortality factors are said to be rare in the tropics and thus competition for resources becomes keener and niches become smaller, resulting in a greater opportunity for new species to evolve. The predation hypothesis contradicts the competition hypothesis. It claims that there are more predators and/or parasites in the tropics and that these hold down individual prey populations enough to lower the level of competition between and among them. The lowered level of competition then allows the addition and co-existence of new intermediate prey type, which in turn support new predators in the system.

Key Points Predation Dynamics: The tropics often experience higher predation intensity rather than lower. Various predators, including insects, mammals, and birds, contribute to a complex web of interactions.
Biotic Interactions:Tropical ecosystems are characterized by intricate biotic interactions, including predation, herbivory, and competition. The high diversity is often attributed to the interplay of these factors.
Climate Stability:Tropical regions do experience relatively stable climatic conditions, which is an accurate point mentioned in Option 1. However, this stability is not necessarily linked to lower predation; instead, it supports a more continuous and diverse range of ecological niches.
Biological Competition: Greater biological competition in the tropics leading to narrower niches (Option 3) is a recognized phenomenon. The intense competition can result in specialized adaptations and coexistence of numerous species.
Spatial Heterogeneity: Option 2 correctly states that tropical regions have high spatial heterogeneity. The variety of habitats, microclimates, and ecological niches contribute to increased species diversity.
Survival Strategies: Prey species in the tropics often evolve various survival strategies, such as mimicry, camouflage, or defensive mechanisms, to cope with the diverse range of predators.
Conclusion- In summary, the correction to the initial statement in Option 4 is that tropical regions typically experience higher predation intensity, and this contributes to the intricate biodiversity observed in these areas.

The correct answer is Option 2 i.e.Open Oceans> Tropical rain forests> Northern coniferous forests> Estuaries

Explanation-

Key PointsNet Primary Production (NPP) is a key ecological concept that measures the amount of energy captured by primary producers (usually plants) through photosynthesis minus the energy lost due to cellular respiration. NPP quantifies the amount of energy that is available for consumption by herbivores and, subsequently, higher trophic levels in an ecosystem. Here's a detailed explanation of the components and significance of NPP:

Components of NPP:

• Gross Primary Production (GPP):-GPP represents the total amount of solar energy captured by plants through photosynthesis. It is the initial energy fixed by plants from sunlight.
• Respiration (R):Respiration is the process through which organisms release energy by breaking down organic compounds. In the context of NPP, it refers to the energy used by plants for their own metabolic processes.
• Net Primary Production (NPP): NPP is the net gain of energy that remains after deducting the energy used by plants for respiration (R) from the total energy fixed during photosynthesis (GPP). It is the energy available for consumption by herbivores and other trophic levels.

        NPP = GPP - R

Significance of NPP:

• Energy Flow Through Ecosystems: NPP is a crucial metric for understanding the flow of energy through ecosystems. It represents the energy available to support the growth and reproduction of plants and, subsequently, herbivores and carnivores.
• Biomass Production: NPP is closely related to the growth of plant biomass. High NPP indicates a high rate of biomass production, which is essential for sustaining animal populations.
• Ecosystem Health: Monitoring changes in NPP over time can provide insights into the health and productivity of ecosystems. Changes in climate, land use, or disturbances can impact NPP and, consequently, the overall ecosystem functioning.
• Carbon Sequestration: Plants absorb carbon dioxide during photosynthesis, and a portion of the fixed carbon is stored in plant biomass. Therefore, NPP is a key factor in understanding the role of ecosystems in carbon sequestration and climate regulation.
• Resource Availability: NPP influences the availability of resources in an ecosystem. High NPP ecosystems tend to have more resources available for organisms, supporting a greater diversity of species.