4 topics with concise reviews: definitions, key facts, and class questions.
The biosphere is Earth's global ecosystem, where living matter is inextricably linked with inanimate nature. In this section, we analyze the classic doctrine of the biosphere by V.I. Vernadsky, its boundaries, composition, and planetary functions.
The material is strictly structured and includes four key topics. You will study the structure of Earth's envelopes (lithosphere, hydrosphere, and atmosphere), trace the patterns of the evolution of the biosphere up to its transition into the noosphere, and examine in detail the mechanisms of biogeochemical cycles—nitrogen, carbon, oxygen, and phosphorus.
At colloquia and biology exams, students are most often tripped up on the functions of living matter (concentrational, redox) and asked to reproduce biogeochemical cycle diagrams from memory. Pay special attention to the role of bacteria in the nitrogen cycle—this is a favorite question of professors.
What is the difference between Lamarck's and Vernadsky's contributions to the doctrine of the biosphere?
J.B. Lamarck in 1802 merely proposed the term "biosphere" itself and noted the influence of life on geology. V.I. Vernadsky, however, in the 1920s created a cohesive scientific doctrine, describing the biosphere in detail as a system and introducing the concept of "living matter".
What is the main difference between the continental lithosphere and the oceanic lithosphere?
In the lithosphere beneath the World Ocean, the granitic layer is absent. It consists of only two layers: an upper sedimentary layer and a lower basaltic layer.
Why did Earth's primordial atmosphere lose its reducing properties?
This occurred due to the photochemical splitting of water, as a result of which hydrogen ions permanently left the atmosphere, shifting the balance toward oxidation.
What is the main difference between abiogenic and biogeochemical cycles?
Abiogenic geochemical cycles proceed without the slightest participation of living organisms, as was the case before the appearance of life (e.g., the oxidation of volcanic gases and their precipitation). Biogeochemical cycles, conversely, are inextricably linked with the vital activity of organisms and involve the direct exchange of substances between the biota and the environment.
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Assignments and quizzes after every topic — just like in a colloquium