Ecology & Environment – Population Ecology, Ecosystems & Energy Flow, Biodiversity & Conservation, Environmental Issues Quiz - ICSE Class 12 Biology

Free practice quiz: Ecology & Environment – Population Ecology, Ecosystems & Energy Flow, Biodiversity & Conservation, Environmental Issues (ICSE Class 12 Biology). 52 multiple-choice questions with answers and explanations. Play online, no sign-up needed.

Sample questions

1. In a logistic growth model, what is the carrying capacity (K) most accurately defined as?

   1. The maximum population size that can be sustained indefinitely by the environment's resources.
   2. The initial growth rate of a population.
   3. The point where birth rate equals death rate.
   4. The theoretical maximum population size achievable without resource limitation.
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   Answer: A. The maximum population size that can be sustained indefinitely by the environment's resources.

   The carrying capacity (K) in logistic growth represents the upper limit of the population size that an environment can support over a prolonged period due to limited resources like food, water, and shelter. While option C describes a state of zero growth, K is the specific population size that achieves this equilibrium sustainably.

2. Which biogeochemical cycle is most significantly impacted by the burning of fossil fuels, contributing to global warming?

   1. Nitrogen Cycle
   2. Phosphorus Cycle
   3. Carbon Cycle
   4. Water Cycle
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   Answer: C. Carbon Cycle

   The burning of fossil fuels releases large amounts of carbon dioxide (CO2) into the atmosphere, which is a major greenhouse gas. This disrupts the natural carbon cycle, leading to an increase in atmospheric CO2 concentrations and contributing to global warming.

3. The concept of 'ecological footprint' is a measure of:

   1. The area of land needed to support a population's resource consumption and waste assimilation.
   2. The impact of a single species on its ecosystem's carrying capacity.
   3. The biodiversity richness within a specific geographical region.
   4. The efficiency of energy transfer between trophic levels.
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   Answer: A. The area of land needed to support a population's resource consumption and waste assimilation.

   The ecological footprint is a metric that quantifies the demand placed on the planet's ecosystems by human activities. It measures the amount of biologically productive land and water area needed to produce the resources a population consumes and to absorb the waste it generates.

4. The 'dilution effect' in disease ecology refers to the phenomenon where:

   1. Increased host density leads to more rapid disease transmission.
   2. Higher biodiversity can reduce the prevalence of certain infectious diseases.
   3. Pathogens become less virulent in larger populations.
   4. The concentration of a pathogen decreases with distance from the source.
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   Answer: B. Higher biodiversity can reduce the prevalence of certain infectious diseases.

   The dilution effect suggests that in biodiverse ecosystems, the presence of many different host species, some of which may not be competent or efficient reservoirs for a particular pathogen, can dilute the impact of transmission on the species that are competent reservoirs, thereby reducing the overall risk of infection for those species and potentially for humans.

5. In an energy pyramid, what is the fundamental reason why the biomass and energy content decrease sharply at each successive trophic level?

   1. All organisms at higher trophic levels are larger.
   2. Energy is lost as heat during metabolic processes (second law of thermodynamics).
   3. Primary producers are less abundant than consumers.
   4. Predation efficiency increases at higher trophic levels.
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   Answer: B. Energy is lost as heat during metabolic processes (second law of thermodynamics).

   The second law of thermodynamics states that in any energy transfer, some energy is lost as heat. In ecosystems, organisms use energy for their own life processes (respiration, movement, reproduction). Therefore, only a fraction of the energy consumed is converted into biomass at the next trophic level, leading to the pyramid structure.

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