ECOLOGY (UNIT 4)

Autotrophs

Autotrophs

Organisms that convert carbon dioxide into carbohydrates and other carbon compounds.

Carbon dioxide absorption

The process by which autotrophs absorb carbon dioxide from the atmosphere.

Reduction of carbon dioxide concentration

The contribution of autotrophs in reducing the concentration of carbon dioxide in the atmosphere.

Carbonic acid

A compound formed when carbon dioxide combines with water, which can dissociate into hydrogen ions and hydrogen carbonate ions.

pH reduction

The decrease in pH of water due to the formation of carbonic acid and dissociation into ions, making it more acidic.

Diffusion of carbon dioxide

The movement of carbon dioxide from the atmosphere or water into autotrophs.

Concentration gradient

The difference in concentration of carbon dioxide between the interior of autotroph cells and the surrounding environment.

Stomata

Openings on the underside of leaves in land plants through which carbon dioxide diffuses.

Methane production

The generation of methane in anaerobic environments as a waste product.

Methanogenic archaeans

Anaerobic prokaryotes responsible for the production of methane in various environments.

Methane oxidation

The process by which methane is converted to carbon dioxide and water in the atmosphere.

Peat formation

The accumulation of undecomposed organic matter in waterlogged soils, resulting in the formation of peat.

Oil and gas formation

The transformation of partially decomposed organic matter into oil and gas through compression and heating.

Crude oil and natural gas

Complex mixtures of liquid carbon compounds or gases generated from the incomplete decomposition of organic matter.

Combustion

The process of burning biomass and fossilized organic matter, resulting in the production of carbon dioxide.

Species

Groups of organisms that can potentially interbreed to produce fertile offspring.

Reproductive isolation

When members of a species are isolated in separate populations and cannot interbreed.

Population

Organisms of the same species living in the same area at the same time.

Same species

Two populations that could potentially interbreed, even if they inhabit different areas.

Different species

Two populations that cannot interbreed and produce fertile offspring.

Heterotrophs

Species that obtain their carbon compounds from other organisms.

Consumers

Heterotrophs that feed on living organisms by ingestion.

Trophic groups

Consumers divided into groups based on the organisms they consume.

Detritivores

Heterotrophs that obtain organic nutrients from detritus by internal digestion.

Saprotrophs

Heterotrophs that obtain organic nutrients from dead organic matter by external digestion.

Decomposers

Bacteria and fungi that function as saprotrophs and break down dead organic matter.

Community

Populations of different species living together and interacting with each other.

Ecosystem

Formed by a community's interactions with the abiotic environment.

Inorganic nutrients

Elements needed by autotrophs and heterotrophs obtained from the abiotic environment.

Nutrient cycling

Continuous recycling of inorganic nutrients in ecosystems.

Sustainability

Ability of an ecosystem to continue indefinitely.

Three requirements for sustainability

Nutrient availability, detoxification of waste products, and energy availability.

Sunlight

The primary source of energy in most ecosystems, which is harnessed through photosynthesis by autotrophs.

Photosynthesis

The process by which autotrophs use chlorophyll and photosynthetic pigments to absorb sunlight and convert it into chemical energy in the form of carbohydrates, lipids, and other carbon compounds.

Cellular Respiration

The process by which living organisms release the energy stored in carbon compounds through the oxidation of carbohydrates and lipids, producing ATP.

Food Chain

A sequence of organisms in which each organism feeds on the previous one, representing the flow of energy from producers to consumers.

Heat

The form of energy that is lost from living organisms and ecosystems, resulting from the inefficiency of energy transformations.

Biomass

The total mass of a group of organisms, including their cells, tissues, and carbon compounds they contain.

Energy Losses

The diminishing energy available to successive trophic levels due to energy loss through respiration, indigestible material, and egestion in feces.

Limiting Factors to number of trophic levels

Factors such as energy losses and biomass decrease that restrict the number of trophic levels in an ecosystem.

Greenhouse Effect

The phenomenon in which greenhouse gases trap heat in the Earth's atmosphere, leading to a warmer climate.

Major Greenhouse Gases

Carbon dioxide (CO2) and water vapor are the most significant greenhouse gases that contribute to the greenhouse effect.

Carbon Dioxide (CO2)

A greenhouse gas released by cell respiration and the combustion of biomass/fossil fuels. It is removed from the atmosphere through photosynthesis and dissolving in oceans.

Water Vapor (H2O)

A greenhouse gas formed by evaporation and transpiration. It is removed from the atmosphere through rainfall and snow.

Role of Water Vapor

Water vapor retains heat post-condensation in cloud droplets and absorbs and radiates heat energy to the Earth's surface.

Methane (CH4)

The third most significant greenhouse gas emitted from marshes, waterlogged habitats, landfills, fossil fuel extraction, and melting polar ice.

Nitrous Oxide (N2O)

Another significant greenhouse gas released naturally by bacteria, as well as from agriculture and vehicle exhausts.

Abundant Gases in Earth's Atmosphere

Oxygen and nitrogen are the two most abundant gases in the atmosphere and are not greenhouse gases as they do not absorb longer-wave radiation.

Determinants of GHG Warming Impact

The warming impact of a greenhouse gas is determined by its ability to absorb long-wave radiation and its concentration in the atmosphere.

Concentration and Impact

The concentration of a greenhouse gas is influenced by its rate of release into the atmosphere and its average duration in the atmosphere.

Earth's Surface Energy Absorption and Emission

The Earth's surface absorbs short-wave energy from the sun and re-emits it at longer wavelengths, primarily in the infrared range.

Solar Radiation Absorption

25-30% of short-wavelength solar radiation passing through the atmosphere is absorbed before reaching the Earth's surface, primarily by ozone.

Re-emitted Earth's Surface Radiation

Between 70% and 85% of longer-wavelength radiation emitted by the Earth's surface is absorbed by greenhouse gases in the atmosphere.

Greenhouse Gas Effect and Global Warming

The re-emitted energy by greenhouse gases contributes to global warming by directing some of it back toward the Earth's surface.

Selective Energy Absorption

Greenhouse gases selectively absorb energy in specific wavebands, contributing to the greenhouse effect.

Greenhouse Gas Impact on Climate

Changes in the concentration of greenhouse gases in the atmosphere can influence their contribution to the greenhouse effect and lead to shifts in global temperatures.

Ice Core Analysis

Drilling ice cores in Antarctica allows the extraction and analysis of air bubbles trapped in the ice, providing information about historical carbon dioxide levels and global temperatures.

Correlation and Causation

While correlation does not directly prove causation, the correlation between higher carbon dioxide levels and warmer periods aligns with the understanding that carbon dioxide is a greenhouse gas.

Enhanced Greenhouse Effect and Warming

The presence of greenhouse gases contributes to a warmer Earth surface, with mean temperatures estimated to be 32°C higher than they would be without greenhouse gases.

Industrial Revolution Impact

The industrial revolution, starting in the late 18th century, led to increased carbon dioxide emissions due to the widespread use of coal, oil, and natural gas for energy production.

Recent Increases in Atmospheric Carbon Dioxide

The recent increase in atmospheric carbon dioxide concentrations, nearing 400 ppm, is unprecedented within the past 800,000 years and is largely attributed to the burning of fossil fuels.