Sunday, 10 January 2016

Frequently Asked Ecology Interview Questions and Answers

61. What are fossil fuels?
Fossil fuels, like oil, gas, and coal, form when organic material is preserved from the complete action of decomposers, generally buried deep and under pressure during millions of years. Under such conditions, the organic material transforms into hydrocarbon fuels.
Fossil fuels are natural reservatory of carbon. When oxygen is present, these fuels can be burned and carbon dioxide and carbon monoxide are released to the atmosphere.

62. What is the most abundant form under which nitrogen is found in nature?
The most abundant nitrogen-containing molecule found in nature is molecular nitrogen (N2). The air is 80% constituted of molecular nitrogen.

63. What is the nitrogen cycle?
The nitrogen cycle represents the circulation and recycling of the chemical element nitrogen in nature.
The nitrogen cycle depends on the action of some specialized bacteria. Bacteria of the soil called nitrogen-fixing bacteria present in plant roots absorb molecular nitrogen from the air and liberate nitrogen under the form of ammonia. The decomposition of organic material also produces ammonia. In the soil and roots (mainly of leguminous), a first group of chemosynthetic bacteria called nitrifying bacteria, the nitrosomonas, produces energy consuming ammonia and releasing nitrite (NO2). The second group of nitrifying bacteria, the nitrobacteria, uses nitrite in chemosynthesis releasing nitrate (NO3). In the form of nitrate, nitrogen is then incorporated by the plants to be used as constituent of proteins and nucleic acids and the element then follows along the food chain. Nitrogen returns to the atmosphere by the action of denitrifying bacteria that use nitrogen-containing compounds from the soil and release nitrogen gas (molecular nitrogen).
Image Diversity: the nitrogen cycle

64. Why is leguminous crop rotation used in agriculture?
Leguminous crop rotation and other crop rotations are used in agriculture because in these plants many bacteria important for the nitrogen cycle live. The leguminous crop rotation (or conjointly with the main crop) helps the soil to become rich in nitrates that then are absorbed by the plants.
Green manure, the covering of the soil with grass and leguminous, is a way to improve the fixation of nitrogen and it is an option to avoid chemical fertilizers.

65. What is biodiversity?
Biological diversity is the variety of species of living beings of an ecosystem. In ecosystems, more biodiverse, like tropical forests, a great variety of plants, microorganisms, and animals live; in ecosystems less biodiverse, like deserts, there are less variety of living beings.
Image Diversity: variety of life on Earth

66. How does biological diversity relate to the characteristics of the abiotic factors of an ecosystem?
The availability of abiotic factors, like light, moisture, mineral salts, heat and carbon dioxide, conditions more or less biodiversity of an ecosystem. Photosynthesis depends on water and light, and plants need mineral salts, carbon dioxide, and adequate temperature for their cells to work. In environments where these factors are not restrictive, the synthesis of organic material (by photosynthesis) is maximum, plants and algae can reproduce easier, the population of these beings increases, potential ecological niches multiply and new species emerge. The large mass of producers makes viable the appearing of a diversity of consumers of several orders. In environments with restrictive abiotic factors, like deserts, the producers exist in little number and less diversity, a feature that thus extends to consumers and conditions fewer ecological niches to be explored.

67. How does the vegetal stratification of an ecosystem influence the biological diversity?
The vegetal stratification of an ecosystem, like the strata of the Amazon Rainforest, creates vertical layers with peculiar abiotic and biotic factors, dividing the ecosystem into several different environments. Therefore, in the superior layer near the crowns of big trees, the exposition to light, rain, and wind is greater but moisture is lower comparing to the inferior layers. As one goes down the strata, the penetration of light diminishes and moisture increases. Regarding the biotic factors, communities of each stratum present composition, features, food habits, and reproduction strategies, etc., also different. Such variations in the abiotic and biotic factors make the selective pressure upon the living beings also diversified, there are more ecological niches to be explored and more varied beings emerge during the evolutionary process.

68. Despite having a great biodiversity why, is the Amazon Rainforest under risk of desertification?
The natural soil of the Amazon Rainforest is not too fertile but it is enriched by the vegetal covering made of leaves and branches that fall from the trees. Deforestation reduces this enrichment. In deforestation zones, the rain falls directly on the ground causing erosion, "washing" large areas (leaching) and contributing to make the soil even less fertile. Besides that, the deforestation disallows the recycling of essential nutrients for plants, like nitrogen. In this manner, those regions and their neighboring regions undergo desertification.
Image Diversity: Amazon Rainforest

69. How can a great biological diversity protect an ecosystem from environmental damages? Why are less biodiverse ecosystems under the risk of suffering deep biological harms if submitted to even small changes?
In ecosystems with more biodiversity, the food webs and ecological interactions among living beings are more complex and diverse. In these ecosystems, environmental changes can easier be compensated by the multiplicity of available resources, foods, and survival options.
In ecosystems with less biodiversity, the individuals are more dependent on some beings that serve them as food and they interact with a small number of different species. In these ecosystems, generally, abiotic factors are restrictive and the species are more specialized to such conditions and more sensitive to environmental changes. Even small environmental harms can cause big disturbances in the equilibrium of the ecosystem.

70. Is monoculture a system that contributes to great biological diversity of an ecosystem?
Monoculture means that in a large area a single crop (only one species of plant) is cultivated. Therefore, monoculture does not contribute to the formation of a community with great variety of species in the area. Since there is only a single type of producer the types of consumers that can live in the area are also restricted.

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