Science Olympiad Test: Our Environment- 2 - Class 10 MCQ

Sapro is a combining form used like a prefix meaning “rotten.” It is used in some scientific terms, especially in biology. Sapro comes from the Greek saprós, meaning “rotten, putrid.”

Biotic factors include all living organisms present in the environment. It includes plants, animals and microorganisms. 

Unidirectional flow of energy and cycling of nutrients are the two most basic characteristics of all ecosystems. In most of the natural ecosystems energy comes from the sun, it is trapped by producers and then passed on to successive trophic levels in the form of food. Thus, along the food chain, there is a loss of energy and only 10 percent of the energy available at each trophic level is passed on to the next trophic level.

As large carnivores are at the upper trophic levels, they get the minimum energy through the food chain, according to the 10 percent law.

Terrestrial habitats are ones that are found on land. Desert, forest and grasslands are all terrestrial habitats.

• The living components of an ecosystem are arranged in a hierarchical order with respect to food dependency. In a food chain, the organisms present in first trophic level are producers which synthesise food for themselves as well as all the other organisms.
• At the second trophic level, are present herbivores which consume producers and at the third trophic level are present carnivores which consume herbivores for their nutrition supply.

Thus, the correct answer is option B.

CFCs are used as refrigerants in refrigerators and AC. CFCs discharged in the lower part of atmosphere move upward and reach the stratosphere. In the stratosphere, UV rays act on them releasing Cl atoms. Cl reduces the ozone and releases molecular oxygen, Cl atoms are not consumed in the reaction. Hence, whatever CFCs are added to the stratosphere, they have permanent and continuing effects on ozone levels. This has resulted in the formation of a large area of thinned ozone layer, commonly called as the ozone hole.

As we know at each level 10 kJ of energy is lost so if 3 kJ is present at the fourth level then 3000kJ of energy is present at the producer level.

So the correct option is 3000kJ.

Fungi is a micro-consumer. They feed by breaking down complex organic compounds of dead and decaying matter.

• Food web is an interconnected network of many food chains. An organism occupies more than one trophic level in a food chain. It feeds on different organisms of lower trophic levels and may be eaten by other organisms of higher trophic levels.
• An ecological pyramid is the diagrammatic representation of the relationship between numbers, biomass and energy content of producers and consumers in an ecosystem.
• The ecosystem is the community of organisms which interact with each other and with their surroundings or environment.
• A food chain is a series of organisms which eat one and get eaten by others.

So, the correct answer is 'Food web'.

Aquatic, marine, and wetlands constitute the non-terrestrial ecosystems, while the major terrestrial ecosystems include desert, forest, grassland, mountain and polar.

Putrefying bacteria decompose dead organisms and hence act as decomposers in an ecosystem.

The energy transferred to the lion is 0.1J.
According to the 10 percent law of energy, during the transfer of energy from one trophic level to the next trophic level, only about ten percent of the energy of the previous trophic level is made available to the next trophic level, remaining energy is lost as heat to the environment. Producers belong to the first trophic level, primary consumer to the second and secondary consumer to the third trophic level.
If 10 joules of energy is available at the producer level then according to the 10 percent law of energy only 10 percent of 10 J will be transferred to the primary consumer level which is 1 J.
The energy transferred to the secondary consumer level will be 10 percent of the energy available at the primary consumer level which is 10 % of 1 joule.
So energy available at the secondary consumer level will be 0.1 J.

Oxygen is converted into ozone by ultraviolet radiations.

The initial organism of a food chain is the producer, which produces food through photosynthesis.