Mix Examples - Our Environment Questions in English

(N/A) The two gases considered to be better alternatives to $CFCs$ (Chlorofluorocarbons) due to their lower ozone depletion potential are:
$(i)$ Hydrofluorocarbons $(HFCs)$: These compounds contain hydrogen,fluorine,and carbon. They do not contain chlorine,which is the primary element responsible for ozone destruction in $CFCs$.
$(ii)$ Perfluorocarbons $(PFCs)$: These are compounds consisting only of carbon and fluorine atoms. They are chemically inert and have a significantly lower impact on the ozone layer compared to $CFCs$.

(B) The ozone layer in the stratosphere acts as a shield by absorbing harmful ultraviolet $(UV)$ radiation from the sun.
Depletion of this layer allows these high-energy $UV$ rays to penetrate the Earth's atmosphere and reach the surface.
Exposure to these rays causes serious health hazards in human beings,such as skin cancer,cataracts,and damage to the immune system.

(B) Yes,there is an effect of heat and pressure on non-biodegradable materials.
Although they do not break down through microbial action,prolonged exposure to heat and pressure under the soil can cause physical and chemical degradation.
This process often leads to the leaching of toxic chemicals and additives present in these materials into the surrounding soil and groundwater.
Consequently,this results in soil pollution and potential contamination of the water table.

(B) According to the $10 \%$ Law of energy transfer in an ecosystem,only $10 \%$ of the energy available at one trophic level is transferred to the next trophic level.
The remaining $90 \%$ of the energy is lost to the environment.
This energy is primarily used by the organism for its own metabolic activities (such as respiration,movement,and growth) and is eventually released into the environment as heat.

(N/A) There is a need to dispose of waste in a proper manner because:
$(i)$ To stop pollution: Waste should be disposed of properly to prevent land and water pollution.
$(ii)$ To prevent diseases: If waste is disposed of improperly,it may cause diseases like cholera,dengue,typhoid,pneumonia,etc. To prevent such diseases,we need to dispose of waste in a proper way.

(N/A)

Food chain	Food web
$1$. It is a straight sequence of organisms which depicts 'who eats whom'.	$1$. It is a complex network of many food chains existing in an ecosystem.
$2$. Food chain does not have any cross linkages.	$2$. Food web has many cross linkages.

(B) The bodies of dead animals are acted upon by decomposers such as bacteria and fungi (saprophytes).
These organisms break down the complex organic matter of the dead bodies into simple inorganic nutrients.
These nutrients are released back into the soil,which acts as a nutrient pool.
Plants absorb these nutrients from the soil for their growth,thereby completing the nutrient cycle in the ecosystem.

(N/A) Harmful chemicals enter our bodies through the food chain. When these chemicals are sprayed in agricultural fields,they are often non-biodegradable,meaning they persist in the environment and may wash into water bodies. When human beings consume agricultural products or aquatic organisms such as fish or prawns,these chemicals are transferred and accumulate in their bodies at higher concentrations.
This phenomenon is called 'biological magnification' or 'biomagnification'.

(N/A) Kulhads have been discontinued in trains nowadays because:
$1$. They are made up of the top layer of soil,which is the most fertile layer. Excessive use of kulhads would deplete this fertile layer,which is essential for agriculture.
$2$. Kulhads are neither recyclable nor reusable; therefore,their use was discontinued to prevent environmental degradation and resource depletion.

(N/A) Devices like refrigerators and $ACs$ affect the environment in the following ways:
$1$. They release chlorofluorocarbons $(CFCs)$,which are among the most harmful greenhouse gases and are primarily responsible for ozone layer depletion.
$2$. They consume a significant amount of electricity,which leads to the increased burning of fossil fuels like coal and natural gas,thereby contributing to global warming and resource depletion.

(N/A) Differences between the Second Trophic Level and the Fourth Trophic Level:

Second Trophic Level	Fourth Trophic Level
$1$. The organisms of this trophic level are herbivores.	$1$. The organisms of this trophic level are carnivores.
$2$. They obtain more energy as they are closer to the producers. Example: $Deer, Rabbit, Grasshopper$.	$2$. They obtain less energy because they are further away from the producers. Example: $Snake, Peacock, Hawk$.

(N/A) If all lions are removed,the population of deer will increase significantly due to the lack of predators. This overpopulation will lead to overgrazing,causing a depletion of grass,which may eventually result in soil erosion.
$(b)$ If all deer are removed,the lions will lose their primary food source,leading to a decline in the lion population due to starvation. Conversely,the amount of grass will increase as there are no herbivores to consume it.

(N/A) According to the $10\%$ law of energy transfer, only about $10\%$ of the energy available at one trophic level is transferred to the next higher trophic level.
Because so little energy is available for the next level of consumers, food chains generally consist of only three or four steps.
The loss of energy at each step is so significant that very little usable energy remains after four trophic levels to support a fifth level.

(B) $food \text{ } chain$ is a linear sequence of organisms through which energy is transferred.
However, in nature, organisms rarely feed on only one type of organism.
Most organisms feed on multiple types of organisms from lower trophic levels, creating a complex, interconnected network of feeding relationships.
This interconnected network of multiple food chains is known as a $food \text{ } web$.

(C) In an ecosystem, energy enters from the sun and is captured by producers (plants) through photosynthesis.
As energy moves from one trophic level to the next (e.g., from producers to primary consumers, then to secondary consumers), a significant portion of energy is lost as heat at each step, according to the $10\%$ law.
Because energy cannot be recycled or reused by the producers once it is lost as heat, the flow of energy is strictly unidirectional, moving from the sun to producers and then to higher trophic levels.

(D) Disposable plastic plates are made of synthetic polymers that are non-biodegradable.
This means they cannot be broken down by microorganisms into simpler,harmless substances in the environment.
As a result,they accumulate in the environment,leading to pollution and posing a threat to ecosystems and wildlife.
Therefore,the correct option is $D$.

(A) The depletion of the ozone layer is primarily caused by the release of chlorofluorocarbons $(CFCs)$ into the atmosphere.
These compounds are used in refrigerators,air conditioners,and aerosol sprays.
When $CFCs$ reach the stratosphere,they are broken down by ultraviolet radiation,releasing chlorine atoms.
These chlorine atoms act as catalysts in the destruction of ozone $(O_3)$ molecules,converting them into oxygen $(O_2)$,which leads to the thinning of the ozone layer.

(B) Organisms that synthesize carbohydrates (food) from inorganic compounds like $CO_2$ and $H_2O$ using radiant energy (sunlight) are known as producers or autotrophs.
These organisms,primarily green plants,algae,and some bacteria,form the first trophic level in an ecosystem by converting solar energy into chemical energy.

(C) According to the $10 \%$ Law proposed by Lindeman,only about $10 \%$ of the energy entering a particular trophic level of organisms is available for transfer to the next higher trophic level.
This energy is stored in the biomass of the organisms in the form of chemical energy (organic compounds like carbohydrates,proteins,and fats).
The remaining $90 \%$ of the energy is lost to the environment as heat during metabolic processes or used for the organism's own life activities.

(D) In the given food chain,Grass $\rightarrow$ Deer $\rightarrow$ Tiger,the deer acts as the primary consumer and the tiger acts as the secondary consumer.
If the deer is removed from this food chain,the tiger will lose its primary source of food,leading to a decrease in the tiger population due to starvation.
Simultaneously,since the deer (which consumes grass) is no longer present to graze,the grass population will increase due to the lack of predation.
Therefore,the correct consequence is that the population of tiger decreases and the population of grass increases.

(A) Decomposers are organisms,such as bacteria and fungi,that break down dead and decaying organic matter.
During this process,they decompose complex organic substances into simpler inorganic substances (like minerals,carbon dioxide,and water) that can be reused by producers in the ecosystem.
Therefore,they play a crucial role in nutrient cycling by converting organic material into inorganic forms.

(B) In a food chain,the trophic levels are organized as follows:
$1$. The first trophic level $(T_1)$ is occupied by producers (plants),which synthesize their own food.
$2$. The second trophic level $(T_2)$ is occupied by primary consumers (herbivores),which feed on producers.
$3$. The third trophic level $(T_3)$ is occupied by secondary consumers (carnivores),which feed on herbivores.
Therefore,the third trophic level is always occupied by carnivores.

(C) An ecosystem is a structural and functional unit of nature where living organisms interact among themselves and also with the surrounding physical environment.
It consists of two main components:
$1$. Biotic components: These include all living organisms such as plants,animals,and microorganisms.
$2$. Abiotic components: These include non-living physical factors such as sunlight,temperature,water,soil,and air.
Therefore,an ecosystem includes both living organisms and non-living objects.

(D) The number of trophic levels in a food chain is limited by the $10\%$ law of energy transfer.
According to this law,only about $10\%$ of the energy available at one trophic level is transferred to the next higher trophic level.
The remaining $90\%$ of energy is lost as heat to the environment or used for metabolic activities by the organisms.
Due to this significant loss of energy at each step,there is very little energy left to support a higher trophic level after $3$ to $4$ transfers.
Therefore,the decrease in energy at higher trophic levels acts as a limiting factor for the length of a food chain.

(A) According to the $10\%$ law of energy transfer in an ecosystem,only $10\%$ of the energy available at one trophic level is transferred to the next higher trophic level.
In the given food chain: Grass (Producer,$T_1$) $\rightarrow$ Grasshopper $(T_2)$ $\rightarrow$ Frog $(T_3)$ $\rightarrow$ Snake $(T_4)$ $\rightarrow$ Hawk $(T_5)$.
The fourth trophic level $(T_4)$ is the Snake.
Given: Energy at $T_4 = 5 \, kJ$.
To find the energy at the producer level $(T_1)$,we move backwards by multiplying by $10$ for each step:
Energy at $T_3 = 5 \times 10 = 50 \, kJ$.
Energy at $T_2 = 50 \times 10 = 500 \, kJ$.
Energy at $T_1$ (Producer) $= 500 \times 10 = 5000 \, kJ$.
Therefore,the energy available at the producer level is $5000 \, kJ$.

(B) Biomagnification is the process where the concentration of non-biodegradable substances,such as pesticides (e.g.,$DDT$),increases at each successive trophic level in a food chain.
This occurs because these substances cannot be broken down by organisms and are stored in their tissues,leading to higher concentrations as they move up the food chain from producers to top consumers.

(C) An ecosystem is a community of living organisms in conjunction with the non-living components of their environment, interacting as a system.
Artificial ecosystems are those created and maintained by human beings.
$A$ $crop$ $field$ is an example of an artificial ecosystem because it is created and managed by humans for agricultural purposes.
In contrast, ponds, lakes, and forests are examples of natural ecosystems as they occur and function without human intervention.

(A) In an ecological pyramid,the base represents the first trophic level $(T_1)$,which consists of producers (plants).
According to the $10\%$ law of energy transfer,energy decreases as we move up the trophic levels. Therefore,the maximum energy is available at the base,which is $T_1$.
Similarly,in a typical pyramid of numbers,the number of organisms is highest at the producer level $(T_1)$ and decreases as we move towards the higher trophic levels $(T_2, T_3, T_4)$.
Thus,both maximum energy and the maximum number of organisms are present at the $T_1$ trophic level.

(B) The statement is $False$.
Food chains vary significantly in length and complexity depending on the ecosystem.
Some food chains may consist of only two or three trophic levels (e.g., grass $\rightarrow$ deer $\rightarrow$ lion), while others can be much longer and more complex, involving many interconnected organisms in a food web.
Energy loss at each trophic level (as per the $10\%$ law) limits the length of food chains, but the specific structure and complexity are determined by the biodiversity and environmental conditions of the habitat.

(B) The flow of energy in an ecosystem is always unidirectional or one-way.
Energy enters the ecosystem from the sun and is captured by producers (plants) through photosynthesis.
It then moves from producers to consumers (herbivores,carnivores,etc.) and is eventually lost as heat at each trophic level.
Energy is never recycled back to the sun or to the previous trophic level,which is why the flow is unidirectional.

(B) The statement is False. In a food chain,energy flow is unidirectional,but organic matter (nutrients) follows a cyclic path. Organic matter is recycled through the ecosystem by decomposers,which break down dead organic material and return nutrients to the soil,where they are again taken up by producers.

(B) The statement is False. According to the $10 \%$ Law of energy transfer in an ecosystem,only about $10 \%$ of the energy available at one trophic level is transferred to the next trophic level as organic matter. The remaining $90 \%$ is lost to the environment as heat or used by the organism for its own metabolic processes.

(B) The statement is False.
Green plants (producers) capture only about $1 \%$ of the energy of sunlight that falls on their leaves and convert it into food energy through the process of photosynthesis.
The $10 \%$ law of energy transfer,proposed by Lindeman,states that only $10 \%$ of the energy available at one trophic level is transferred to the next higher trophic level.

(A) In an ecosystem, energy flows from producers to consumers. According to the $10\%$ law of energy transfer, only about $10\%$ of the energy is transferred from one trophic level to the next. Due to this significant loss of energy, the number of organisms that can be supported decreases as we move up the food chain. Therefore, the base of the pyramid (producers) typically contains the highest number of individuals, while the top trophic levels (apex predators) contain the fewest.

(A) Biological magnification (or biomagnification) refers to the increase in the concentration of toxic substances,such as pesticides or heavy metals,at successive trophic levels in a food chain.
Since humans are often at the top of the food chain,these harmful chemicals accumulate in our bodies in higher concentrations compared to other organisms,making the statement True.

(A) According to the $10 \%$ Law proposed by Lindeman in $1942$,only about $10 \%$ of the energy entering a particular trophic level of organisms is stored as biomass and is available for transfer to the next higher trophic level.
Most of the energy is lost as heat to the environment during metabolic activities like respiration,movement,and digestion.
Therefore,the statement is True.

(A) Biodegradable waste refers to organic materials that can be broken down by microorganisms like bacteria and fungi into simpler substances.
Vegetables and fruit are organic materials derived from plants,which easily decompose in the environment.
Glass,plastic,and metal are non-biodegradable materials because they cannot be broken down by biological processes and persist in the environment for a long time.

(D) Non-biodegradable wastes are those substances that cannot be broken down into simpler,harmless substances by the action of microorganisms (like bacteria or fungi).
Polythene is a synthetic polymer (plastic) that does not decompose naturally in the environment.
In contrast,fruits,vegetables,and paper are biodegradable as they are organic materials that can be decomposed by biological processes.

(A) An ecosystem is defined as a functional unit of nature where living organisms interact among themselves and also with the surrounding physical environment.
It consists of two main components: biotic components (all living organisms like producers,consumers,and decomposers) and abiotic components (physical surroundings like sunlight,temperature,water,soil,etc.).
Therefore,an ecosystem is an interacting system made up of organisms and their physical surroundings.

(C) An ecosystem is defined as the structural and functional unit of the environment.
It consists of a community of living organisms (biotic components) interacting with the non-living (abiotic) components of their environment.
Through these interactions,energy flow and nutrient cycling occur,which maintain the stability of the environment.

(B) In an ecosystem,consumers are classified based on their food source.
$1$. Primary consumers (First order consumers) are organisms that feed directly on producers (plants).
$2$. Since plants are producers,organisms that eat plants are known as herbivores.
$3$. Therefore,first order consumers are herbivores.

(C) Omnivores are organisms that have the ability to obtain energy and nutrients from materials originating from both plant and animal sources.
They are primary,secondary,or tertiary consumers in a food chain.
Examples include humans,bears,and crows.
Therefore,the correct option is $C$.

(A) Edaphic factors refer to the physical and chemical properties of the soil,such as soil texture,pH,mineral content,and water-holding capacity.
These factors are non-living components of an ecosystem.
In ecology,non-living components are classified as abiotic components.
Therefore,edaphic factors are included in abiotic components.

(B) Chlorine atoms act as catalysts in the depletion of the ozone layer.
One atom of chlorine can destroy approximately $1,00,000$ molecules of ozone $(O_3)$ through a chain reaction process.
In this process,the chlorine atom is not consumed but continues to react with ozone molecules repeatedly.
Therefore,the correct option is $B$.

(C) Chlorofluorocarbons $(CFCs)$ are synthetic compounds used in refrigerators,air conditioners,and aerosol sprays.
When $CFCs$ reach the upper atmosphere,they are broken down by ultraviolet radiation,releasing chlorine atoms.
These chlorine atoms act as catalysts in the destruction of ozone $(O_3)$ molecules.
It is estimated that $CFCs$ are responsible for approximately $80\%$ of the total depletion of the ozone layer.

(A) An ecosystem consists of biotic components (biological community) and abiotic components (physical factors like sunlight,temperature,water,soil,etc.) that interact with each other to form a functional unit.
Therefore,the correct term for this system is an ecosystem.

(B) An ecosystem consists of two main components: Abiotic and Biotic components.
$1$. Abiotic components include non-living factors like sunlight,temperature,water,and soil.
$2$. Biotic components include all living organisms within the ecosystem.
$3$. Producers (plants),consumers (animals),and decomposers (bacteria and fungi) are all living organisms,therefore they are classified as Biotic components.

(D) freshwater ecosystem consists of water bodies with low salt concentrations,such as rivers,lakes,and ponds. $A$ sea is a marine ecosystem characterized by high salt concentrations. Therefore,the sea is not a freshwater ecosystem.

(B) In an ecosystem,components are broadly classified into two categories: $1.$ Abiotic components (non-living) and $2.$ Biotic components (living).
- Soil,Light,and Temperature are all abiotic components of the environment.
- Decomposers are biotic components (living organisms like bacteria and fungi) that break down organic matter.
- Therefore,Decomposers is the odd one out.

(D) Producers are organisms that can produce their own food through photosynthesis,such as plants,algae,and some bacteria.
In the given options,humans,deer,and snakes are consumers (heterotrophs) that depend on other organisms for food.
Algae are photosynthetic organisms that produce their own food,thus they are classified as producers.