Mix Examples- Ecosystem Questions in English

(A) The correct answer is $A$. In a detritus food chain,decomposers (saprotrophs) break down complex organic matter into simpler inorganic substances. Therefore,the statement that 'complex organic materials are formed from waste materials by decomposers' is incorrect,as the process involves the breakdown of complex organic matter into simpler forms,not the synthesis of complex materials from waste.

(B) In an ecosystem,the trophic level is determined by the organism's position in the food chain.
$1$. The primary producers (plants) occupy the first trophic level.
$2$. Primary consumers (herbivores) feed on producers and occupy the second trophic level.
$3$. Insects and worms that feed on plants are primary consumers.
$4$. Since the sparrow feeds on these insects and worms,it acts as a carnivore that consumes primary consumers,placing it at the third trophic level,which is defined as a secondary consumer.

(D) The correct answer is $D$. Pollution is not a functional unit of the ecosystem.
The major functional aspects (or components) of an ecosystem are:
$1$. Productivity
$2$. Decomposition
$3$. Energy flow
$4$. Nutrient cycling
Pollution is an external environmental issue caused by human activities and is not a natural functional process of an ecosystem.

(D) The correct matches are as follows:
$1$. Standing state refers to the amount of inorganic nutrients (like nitrogen,phosphorus,etc.) present in the soil at a given time $(1-q)$.
$2$. Pioneer species are the first organisms to colonize a previously bare area during ecological succession $(2-r)$.
$3$. Detritivores are organisms that break down detritus into smaller particles (e.g.,earthworms) $(3-s)$.
$4$. Standing crop refers to the total mass of living material (biomass) present in an ecosystem at a given time $(4-p)$.
Therefore,the correct combination is $1-q, 2-r, 3-s, 4-p$.

(D) The correct answer is $D$ (Frog).
In the given food chain,the plant acts as the primary producer.
The insect acts as the primary consumer (herbivore) that feeds on the plant.
The link '$M$' represents the secondary consumer,which feeds on the insect.
$A$ frog is a common secondary consumer that feeds on insects and is subsequently preyed upon by snakes (tertiary consumers).
Therefore,the frog fits perfectly as the link '$M$' in this food chain.

(B) trophic level is the position an organism occupies in a food chain.
$(1)$ Producers (plants) form the first trophic level.
$(2)$ Primary consumers (herbivores) eat producers and form the second trophic level.
$(3)$ Secondary consumers eat primary consumers and form the third trophic level.
When a sparrow eats seeds,it acts as a primary consumer (second trophic level).
When it eats insects (which are primary consumers),it acts as a secondary consumer (third trophic level).
Therefore,the sequence is Second - Third trophic level,which corresponds to the options provided as Secondary - Tertiary.