AIIMS 2006
- Exam
- AIIMS
- Year
- 2006
- Subject
- Botany
- Chapter
- Ecosystem
AIIMS 2006 · Botany · Ecosystem
Assertion : In tropical rain forests, O-horizon and A-horizon of...
Assertion : In tropical rain forests, O-horizon and A-horizon of soil profile are shallow and nutrient-poor.
Reason : Excessive growth of micro-organisms in the soil depletes its organic content.
Options
- AIf both assertion and reason are true and reason is the correct explanation of the assertion
- BIf both assertion and reason are true but reason is not the correct explanation of the assertion
- CIf assertion is true, but reason is false
- DBoth assertion and reason are false statements.
Correct answer
B. If both assertion and reason are true but reason is not the correct explanation of the assertion
Step-by-step solution
A cross section of well developed soil shows more or less distinct layers called horizons. Ohorizon is the topmost layer of soil and A-horizon comes below O horizon. In the topmost layer, vegetation grows and various biological activities takes place. Tropical rain forests are found in tropical zone of the world and are characterized by very high temperature and abundance of rainfall. Soil in these area are red latosols and are exceedingly thick. Leaching of minerals from the top soil occurs rapidly but cycling of nutrients also occur here. The laterite soils are generally infertile because of intensive leaching and not due to growth of micro-organism.