Ecology and Evolution — DU B. Sc. Life Science (Botany) Previous Year Question Papers

4. All parts of a question must be answered together. 5. Draw diagrams wherever required 1. (a) Define the following (any five): (ii) Density-dependent factors (iii) Neo-endemism (v) Ecological pyramid (b) State True/False for the following statements (any five) (i) Liebig's Law of the Minimum states that growth is controlled by the most abundant factor. (ii) Type I survivorship curve shows high mortality in early life. (iii) Biomes are defined mainly by climatic conditions rather than species composition. (iv) Nitrogen cycle includes a gaseous phase, whereas phosphorus cycle does not. (v) Artificial selection mimics natural selection but is controlled by humans. (vi) Paleo-endemics are recently evolved species. (c) Match the following: (i) Horizon A (A) Study of plant distribution (ii) Dispersion (B) Geographical isolation (iii) Niche (C) Distribution pattern (iv) Allopatric speciation (D) Functional role (v) Phytogeography (E) Mineral layer of soil 2. With the help of well labelled diagrams, explain any three of the following (i) Thermal stratification in water bodies (ii) Levels of ecological organization (iv) Phosphorus cycle (any three) (5x3=15) 3. Differentiate between the following (i) Ecosystem and Biome (ii) Mutualism and Commensalism (iii) Autogenic and Allogenic succession (iv) Endemic and Cosmopolitan species 4. (a) Describe natality and mortality and their ecological significance. (b) Describe ecological succession and its stages. (c) Describe modes of speciation with examples. 5. (a) Discuss the role of geographical and climatic factors in plant distribution. (b) Describe Darwinism and natural selection with examples.