Ecosystems. Abdulhafez Selim, MD, PhD. Ecosystem. Physical environment. Ecosystem. Organisms. +. =. Earth. The organisms living in a particular area, together with the physical environment with which they interact, constitute an ecosystem.
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Abdulhafez Selim, MD, PhD
with which they interact, constitute an ecosystem.
More energy received at
equator than at poles
At equator, warm raising air produces a belt of
low pressure and winds.
Air circulation around the globe would be simple (and the weather boring) if the Earth did not rotate and the rotation was not tilted relative to the Sun.Please click to enlarge!
Poleward-moving currents are warm, and equatorward-moving currents are cold.
Surface ocean currents are driven by global winds and play an important role in
redistributing heat around the globe.
Description: Map showing the seven major ocean currents
Photosynthesis is a process in which green plants use energy from the sun to
transform water, carbon dioxide, and
minerals into oxygen and organic
compounds. It is one example of how
people and plants are dependent
on each other in sustaining life
Before 1977, scientists believed that all forms of life ultimately depended on
the Sun for energy.
A few deep-sea and cave ecosystems are powered by chemosynthesis rather
Chemosynthesis is the biological conversion of 1-carbon molecules
(usually carbon dioxide or methane) and nutrients into organic matter using
the oxidation of inorganic molecules (e.g. hydrogen gas, hydrogen sulfide) or
methane as a source of energy, rather than sunlight, as in photosynthesis.
Crops need many things for good growth and maximum productivity- light, carbon dioxide, nutrients, water and a sufficiently long period without frost. What is often forgotten is that another requirement for growth and development of crops is needed - heat. Each crop is very specific as to its heat requirements. the most rapid growth and development takes place at 2 l' C (70' F). The growth rate decreases with the increase in temperature and finally stops at 30 C (86' F).
on primary production and on the efficiency of transfer of energy
from one trophic level to another
Who eats whom in a ecosystem can be diagrammed as a food web.
Primary production in oceans is highest
adjacent to continents,
where nutrient-rich waters rise to the
Layers of the AtmosphereThe atmosphere is divided into five main
layers plus the ionosphere.
It extends over 430 miles (700 km) into the sky.
The two lowest layers of Earth's atmosphere differ
from each other in their circulation patterns,
the amount of moisture they contain,
and the amount of ultraviolet radiation they receive.
Temperate-zone lakes turn over
twice each year as water cools and warms.
The cycle of water-the hydrological cycle-is driven by evaporation of water;
most of it from ocean surfaces.
Atmospheric carbon dioxide is the immediate source of carbon for
earthly organisms, but only a small part of Earth's carbon is in the atmosphere.
Although nitrogen makes up 78 percent of Earth's atmosphere, nitrogen can be
converted into biologically useful forms only by a few species of bacteria and
The most striking example of a local effect of altered bio-geochemical cycles is
A great lake - Gin-clear water!Oligotrophic
Acid rain is a term for precipitation that is polluted by acids, which have a pH below 7.0