All questions of Daily Practice & Tests for NEET Exam

The first law, also known as Law of Conservation of Energy, states that energy cannot be created or destroyed in an isolated system. The third law of thermodynamics states that the entropy of a system approaches a constant value as the temperature approaches absolute zero.

Secondary productivity is the rate of formation of new organic matter by consumers. primary productivity depends on the producers inhabiting a particular area. Decomposers break down complex organic matter. Into inorganic substance like carbon dioxide water and nutrients. Parasitic species food on the body of other organisms.

An ecosystem includes all of the living things (plants, animals and organisms) in a given area, interacting with each other, and also with their non-living environments (weather, earth, sun, soil, climate, atmosphere). Ecosystems are the foundations of the Biosphere and they determine the health of the entire earth system.

**Explanation:**

Decomposition is the process by which organic matter breaks down into simpler substances, such as carbon dioxide, water, and minerals. It is a natural process that is essential for nutrient recycling in ecosystems.

Conditions that favor decomposition are important to understand because they can determine the rate at which organic matter decomposes and the types of organisms involved in the process.

The correct answer to the given question is option 'A', which states that high temperature and intermediate humidity favor decomposition. Let's understand why this is the case:

**1. High Temperature:**
- Decomposition is an enzymatic process, meaning it is facilitated by the action of enzymes produced by microorganisms, such as bacteria and fungi.
- Enzymatic reactions are generally more efficient at higher temperatures because they increase the rate of biochemical reactions.
- High temperatures accelerate the metabolic activity of decomposer organisms, leading to faster decomposition rates.

**2. Intermediate Humidity:**
- Decomposer organisms require a certain level of moisture to carry out their metabolic processes effectively.
- If the humidity is too high, the excessive moisture can create an anaerobic environment (lack of oxygen) that is unfavorable for many decomposer organisms.
- If the humidity is too low, the lack of moisture restricts the activity of decomposer organisms.
- Intermediate humidity provides the ideal conditions for decomposer organisms to thrive and efficiently decompose organic matter.

**Conclusion:**
In conclusion, the correct answer to the given question is option 'A' (high temperature and intermediate humidity) because these conditions provide the ideal environment for the activity of decomposer organisms, leading to faster and more efficient decomposition of organic matter.

Yes it is cryopreservation, done at minus 196 degree Celsius

 The important steps in the process of decomposition are fragmentation, leaching, catabolism, humification and mineralisation.

Microorganisms like bacteria etc decompose organic matter.

The correct answer is option 'D' i.e., retention of water and prevention of soil erosion.

Explanation:
Forests are essential for the survival of life on earth. They are responsible for various ecological, environmental, and social benefits. Forests play a crucial role in controlling drought by retaining water and preventing soil erosion. Let's discuss how forests control drought through water retention and soil erosion prevention:

Retention of water:

Forests help in retaining water in the following ways:

1. Watershed: Forests act as a water catchment area and function as a natural watershed. They store and release water gradually, reducing the risk of floods and droughts.

2. Groundwater recharge: Forests help in recharging groundwater by allowing rainwater to seep into the soil, thus replenishing underground water resources.

3. Transpiration: Trees in the forest transpire water, which helps in the formation of clouds and precipitation, leading to increased rainfall.

Prevention of soil erosion:

Forests help in preventing soil erosion in the following ways:

1. Root systems: Trees in the forest have deep root systems that hold the soil in place and prevent it from eroding.

2. Canopy cover: The canopy cover of trees in the forest acts as a barrier, reducing the impact of raindrops on the soil surface and preventing soil erosion.

3. Organic matter: Forests are rich in organic matter, which helps in improving soil structure, reducing soil erosion, and retaining water.

Conclusion:

Forests play a crucial role in controlling drought by retaining water and preventing soil erosion. Therefore, it is important to conserve and protect forests to ensure a sustainable future for all.

Biosphere is one of the layers surrounding the earth along with the lithosphere(land) ,hydrosphere(water),atmosphere (air).

The correct answer is option D, Net primary productivity and secondary productivity, respectively.

Explanation:
- Net primary productivity (NPP) is the biomass available for consumption to heterotrophs after the autotrophs have utilized some of the organic matter for their own metabolism through respiration.
- Secondary productivity is the rate of formation of new organic matter by consumers (heterotrophs) that eat the autotrophs or other heterotrophs.
- Gross primary productivity (GPP) is the total amount of organic matter produced by autotrophs through photosynthesis, including the organic matter used for their own respiration.
- Gross secondary productivity is the total amount of organic matter assimilated by consumers, including the organic matter lost through excretion and egestion.

Therefore, the correct answer is option D, as NPP and secondary productivity are the two parameters that indicate the amount of organic matter available for consumption to higher trophic levels in an ecosystem.

Role of Decomposers in Pond Ecosystem
In a pond ecosystem, the decomposition of dead organic matter is crucial for nutrient recycling. This process is primarily facilitated by fungi and bacteria, making them the key decomposers in such environments.
Importance of Decomposers
Decomposers play several vital roles in maintaining the health of the ecosystem:

• Breaking Down Organic Matter: Fungi and bacteria break down dead plants and animals, recycling essential nutrients back into the ecosystem.
• Nutrient Release: As these organisms decompose organic materials, they release nutrients like nitrogen, phosphorus, and potassium, which are essential for the growth of aquatic plants.
• Soil and Water Quality: The decomposition process helps improve soil quality and can enhance water clarity by reducing organic waste.
• Energy Flow: Decomposers are integral to the energy flow in the ecosystem. By breaking down dead matter, they convert it into forms that can be utilized by primary producers like phytoplankton.

Comparison with Other Organisms
While phytoplankton and algae are primary producers that convert sunlight into energy, and zooplankton are consumers that feed on these producers, they do not play significant roles in decomposition:

• Phytoplankton: Primarily photosynthetic and contribute to oxygen production.
• Zooplankton: Heterotrophic and consume phytoplankton, but do not decompose dead matter.
• Algae: Also producers that depend on sunlight and nutrients but are not involved in decomposition.

Conclusion
In summary, fungi and bacteria are essential for decomposition in pond ecosystems, enabling nutrient recycling and supporting overall ecological balance.

Understanding Nutrient Cycling
Nutrient cycling is essential for maintaining ecosystem health and can be categorized into two main types: gaseous cycles and sedimentary cycles.
Assertion (A): Nutrient Cycling Types
- Nutrient cycling encompasses both gaseous and sedimentary cycles.
- These cycles are crucial for ecosystem health as they facilitate the movement of essential nutrients.
Reason (R): Reservoirs of Nutrient Cycles
- The gaseous cycle primarily relies on the atmosphere as its reservoir.
- The sedimentary cycle is dependent on the Earth’s crust for its reservoirs.
Evaluating the Assertion and Reason
- Both Assertion (A) and Reason (R) are true statements.
- However, the Reason (R) does not serve as the correct explanation for the Assertion (A).
Why Option B is Correct?
- While it is accurate that nutrient cycling involves both gaseous and sedimentary cycles, the explanation provided in Reason (R) does not directly clarify why these cycles are important for ecosystem health.
- The reason only describes the reservoirs of the cycles but fails to connect this information to the overall significance of nutrient cycling in supporting life and maintaining ecosystem balance.
Conclusion
Thus, the answer is option 'B': both Assertion and Reason are true, but Reason is not the correct explanation of Assertion. Understanding the distinction between these cycles and their roles enhances our comprehension of ecosystem dynamics.

In an aquatic ecosystem, the grazing food chain (GFC) is the major pathway for energy flow, whereas the detritus food chain plays a smaller role compared to terrestrial ecosystems.

Zooplankton are primary consumers in aquatic ecosystems, feeding directly on phytoplankton, the producers in the food chain.

The percentage of photosynthetically active radiation (PAR) in the incident solar radiation is less than 50%. PAR refers to the portion of sunlight that is within the wavelength range of 400 to 700 nanometers, which is the range most effectively used by plants for photosynthesis.

Here is a detailed explanation:

1. Definition of PAR:
- PAR is the range of light wavelengths that are absorbed by chlorophyll and other pigments in plants, enabling them to carry out photosynthesis.
- PAR is typically measured in micromoles per square meter per second (µmol/m²/s).

2. Components of solar radiation:
- Solar radiation is composed of various wavelengths, including ultraviolet (UV), visible, and infrared (IR) light.
- Only a small portion of solar radiation falls within the PAR range.

3. Wavelengths of PAR:
- The PAR range is defined as 400 to 700 nanometers (nm), which corresponds to the visible light spectrum.
- Within this range, different wavelengths of light have varying effects on plant growth and development.

4. Importance of PAR for photosynthesis:
- Photosynthesis is the process by which plants convert light energy into chemical energy, using water and carbon dioxide to produce glucose and oxygen.
- Chlorophyll, the primary pigment in plants, absorbs light most efficiently in the blue (400-500 nm) and red (600-700 nm) regions of the spectrum.
- Therefore, light within the PAR range is crucial for driving photosynthesis.

5. Percentage of PAR in incident solar radiation:
- While the exact percentage of PAR in incident solar radiation varies depending on factors such as atmospheric conditions and time of day, it is generally accepted to be less than 50%.
- This means that more than half of the solar radiation that reaches the Earth's surface falls outside the PAR range.

6. Utilization of non-PAR wavelengths:
- Plants can also utilize certain wavelengths of light outside the PAR range, such as UV and IR light, for various physiological processes.
- UV light, for example, can stimulate the production of protective compounds in plants, while IR light can affect plant growth and development.

In conclusion, the percentage of photosynthetically active radiation (PAR) in the incident solar radiation is less than 50%. This indicates that a significant portion of solar radiation falls outside the PAR range, highlighting the importance of considering the entire spectrum of light when studying plant responses to sunlight.

Catabolism - Breakdown of Detritus by Microbial Enzymes

Catabolism is the breakdown of complex organic matter into simpler compounds by the action of microbial enzymes. In the process of catabolism, detritus is decomposed and transformed into various forms that are readily available for use by other living organisms. This process is important for the maintenance of the ecosystem as it cycles nutrients and energy from dead organic matter back into the living world.

Mechanism of Catabolism

The process of catabolism involves the following steps:

1. Fragmentation: The detritus is fragmented into smaller particles by the action of physical and chemical forces.

2. Leaching: The soluble compounds are leached out of the detritus and are transported to other parts of the ecosystem.

3. Mineralization: The remaining organic matter is decomposed by the action of microbial enzymes into simpler forms such as carbon dioxide, water, and inorganic nutrients like nitrogen and phosphorus.

4. Catabolism: The simpler compounds are further broken down into energy and essential nutrients by the action of microbial enzymes.

Significance of Catabolism

Catabolism plays a crucial role in the cycling of nutrients and energy in the ecosystem. The breakdown of detritus by microbial enzymes releases essential nutrients like nitrogen and phosphorus into the soil, which can be taken up by plants for growth. The energy released during catabolism is also utilized by other living organisms in the ecosystem, thereby sustaining the food web. In addition, catabolism also helps in the removal of waste materials from the ecosystem.

Conclusion

Catabolism is a complex process that involves the breakdown of detritus into simpler forms by the action of microbial enzymes. This process is essential for the cycling of nutrients and energy in the ecosystem and helps in sustaining the food web. The significance of catabolism in the maintenance of the ecosystem cannot be overemphasized as it plays a crucial role in the removal of waste materials and the release of essential nutrients into the environment.

Understanding Ecological Pyramids
Ecological pyramids visually represent the relationships between different levels of an ecosystem, typically illustrating the distribution of energy, biomass, or the number of organisms.
Pyramid of Biomass in Aquatic Systems
- In aquatic ecosystems, such as seas, the pyramid of biomass is often inverted.
- This occurs because the biomass of primary producers (like phytoplankton) is much lower than that of primary consumers (like small fish) due to rapid turnover rates.
- Phytoplankton grow and reproduce quickly, creating a situation where a large biomass of consumers can exist despite the producers' smaller overall mass.
Comparative Analysis of Other Options
- Pyramid of Numbers in Grassland: Typically, this pyramid is upright, as numerous primary producers (plants) support fewer herbivores and even fewer carnivores.
- Pyramid of Energy: This pyramid is always upright as energy decreases from producers to consumers. Energy transfer inefficiencies ensure that each trophic level has less energy than the one below.
- Pyramid of Biomass in a Forest: Generally upright as well, with a larger biomass of trees (producers) supporting a smaller biomass of herbivores and carnivores.
Conclusion
The inverted pyramid of biomass in aquatic environments underscores the unique dynamics of these ecosystems, where a small base of primary producers supports a large and diverse range of consumers. Understanding these differences is crucial for ecological studies and conservation efforts.

In the pond ecosystem, there is a unidirectional movement of energy towards higher trophic levels, starting from autotrophs to heterotrophs, and energy is eventually dissipated as heat.

Nutrient availability is the key limiting factor for productivity in aquatic ecosystems, as plants and phytoplankton require nutrients for growth.

Understanding the Inverted Pyramid of Biomass
In aquatic ecosystems, the pyramid of biomass is often inverted, which is distinct from the typical structure seen in terrestrial ecosystems. Here’s why:
1. Definition of Biomass Pyramid
- The biomass pyramid represents the total mass of living organisms at each trophic level.
- In a typical terrestrial ecosystem, it decreases as you move from producers to top consumers.
2. Aquatic Ecosystems Characteristics
- In aquatic environments, producers such as phytoplankton have a low biomass compared to the organisms that feed on them, like zooplankton and small fish.
- The rapid reproduction and turnover rates of phytoplankton lead to a situation where the total weight of consumers can exceed that of the producers.
3. Reasons for Inversion
- High Reproduction Rates: Phytoplankton reproduce quickly, but their biomass is low at any given time.
- Efficiency of Energy Transfer: In aquatic systems, energy transfer from producers to consumers is highly efficient, allowing a larger biomass of consumers.
- Size Difference: Small primary producers can support larger consumers, leading to an inverted biomass pyramid.
4. Implications
- This structure challenges the traditional understanding of food webs and energy flow.
- It highlights the unique dynamics of aquatic ecosystems where even small organisms can support a diverse and larger community of consumers.
In conclusion, the pyramid of biomass is inverted in aquatic ecosystems due to the high productivity and turnover of phytoplankton, resulting in greater biomass of consumers compared to producers.

Primary productivity refers to the rate of biomass or organic matter production by autotrophic organisms (like plants) through photosynthesis.