Class 10
Biology
Chapter 1
Plz Answer This Correctly
Because It Contains 10 Internal Assas ment Marks
Answers
1. Flow of Materials in Ecosystem is Cyclic but the Flow of Energy is Unidirectional?
The materials like water, carbon (as carbon dioxide) and nitrogen (as minerals) are taken up by the plants from soil, air and water bodies, etc., and made into food. This food is then passed on to the animals like herbivores and carnivores in a food chain.
After the death and decay of plants and animals, the materials like water, carbon and nitrogen present in their bodies are returned to soil, air and water, from where they were taken originally.
These materials can then be reused for the growth of new plants. In this way, the same materials are used again and again, the materials are not lost from the environment. So, the flow of materials like water, carbon and nitrogen, etc., in the ecosystem is said to be cyclic. This is not so in the case of energy.
The flow of energy in the ecosystem is unidirectional (or one-directional). The energy enters the plants (from the sun) through photosynthesis during the making of food. This energy is then passed on from one organism to another in a food chain.
Energy given out by the organisms as heat is lost to the environment, it does not return to be used by the plants again. This makes the flow of energy in ecosystem ‘unidirectional’. Thus, the flow of energy in the ecosystem is said to be unidirectional because the energy lost as heat from the living organisms of a food chain cannot be reused by plants in photosynthesis.
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2. According to 10% Law,
Plants have 20,000 J energy available.
Plants transferred their 10% energy to deer i.e.
20,000 * 10/100 = 2000 J
Deer received 2000 J energy from the plants and now it transfer 10% energy of itself to lion.
2000 ×10/100= 200 J
Hence, lion will have 200 J energy from deer.
hopefully its helped u dear :)