Ecology Test - 2

Weathering breaks down and loosens the surface minerals of rock so they can be transported away by agents of erosion such as water, wind and ice. There are two types of weathering: mechanical and chemical. Mechanical weathering is the disintegration of rock into smaller and smaller fragments and chemical weathering is the weakening and subsequent disintegration of rock by chemical reactions. These reactions include oxidation, hydrolysis, and carbonation.

The atmosphere contains many gases, most in small amounts, including some pollutants and greenhouse gases. The most abundant gas in the atmosphere is nitrogen, with oxygen second. Argon, an inert gas, is the third most abundant gas in the atmosphere.

Desert soil is mostly sandy soil (90–95%) found in low-rainfall regions. It has a low content of nitrogen and organic matter with very high calcium carbonate and phosphate, thus making it infertile.

This soil is susceptible to wind erosion and supports a low density of population.

The driest soils, in deserts, have very little organic matter because there is not enough water to support a large or diverse plant community. Desert soils are nutrient poor because of the low organic matter and because the lack of water slows the weathering process that can release nutrients from soil minerals.

The troposphere is the lowest layer of Earth's atmosphere, and is also where nearly all weather conditions take place. It contains approximately 75% of the atmosphere's mass and 99% of the total mass of water vapor and aerosols.

Green plants make there own food.

Similarly, autotrophs means organisms which make their own food. (Auto means on own).

Some plant species are parasitic, meaning they get their nutrients from other sources. So, parasitic plants are heterotrophic.

Therefore, any plant with green leaves is classified as an autotroph.

So, from above given information it is clear that option 1 is correct answer here.

The process by which green plants make their own food from carbon-dioxide and water in the presence of sunlight and chlorophyll is called photosynthesis.

During this process oxygen gas is released.

Decomposers decompose the dead animals at the end of the food web.

Biomass can be defined as the weight of living matter (usually measured in dry weight per unit area). In most ecosystems, the amount of biomass found in each trophic level decreases progressively as one moves from the beginning to the end of the grazing food chain. Plants are the original source of fixed organic energy in the ecosystems. Only the primary consumers or herbivores directly feed on the primary producers, and thereby they have greatest biomass.

An ecosystem is a community of living organisms in conjunction with the nonliving components of their environment (things like air, water and mineral soil), interacting as a system.These biotic and abiotic components are regarded as linked together through nutrient cycles and energy flows.