Our environment Flashcards
What does the ecosystem constitute of?
All organisms such as plants, animals, microorganisms and human beings as well as the physical surroundings interact with each other and maintain a balance in nature. All the interacting organisms in an area together with the non-living constituents of the environment form an ecosystem. Thus, an ecosystem consists of biotic components comprising living organisms and abiotic components comprising physical factors like temperature, rainfall, wind, soil and minerals
types of ecosystems
. Other types of ecosystems are forests, ponds and lakes. These are natural ecosystems while gardens and crop-fields are human- made (artificial) ecosystems.
organisms can be grouped as
organisms can be grouped as producers, consumers and decomposers according to the manner in which they obtain their sustenance from the environment.
How do organisms use photosyntheses?
-organisms can make organic compounds like sugar and starch from inorganic substances using the radiant energy of the Sun in the presence of chlorophyll.
-All green plants and certain bacteria which can produce food by photosynthesis come under this category and are called the producers.
How do organisms use photosyntheses?
-organisms can make organic compounds like sugar and starch from inorganic substances using the radiant energy of the Sun in the presence of chlorophyll.
-All green plants and certain bacteria which can produce food by photosynthesis come under this category and are called the producers.
What is the role of decomposers in the ecosystem?
The microorganisms, comprising bacteria and fungi, break-down the dead remains and waste products of organisms. These microorganisms are the decomposers as they break-down the complex organic substances into simple inorganic substances that go into the soil and are used up once more by the plants.
What are trophic levels? Give an example of a food chain and state the différent trophic levels in it.
Each step or level of the food chain forms a trophic level. The autotrophs or the producers are at the first trophic level. They fix up the solar energy and make it available for heterotrophs or the consumers. The herbivores or the primary consumers come at the second, small carnivores or the secondary consumers at the third and larger carnivores or the tertiary consumers form the fourth trophic level
Importance of food/ energy.
the food we eat acts as a fuel to provide us energy to do work. Thus the interactions among various components of the environment involves flow of energy from one component of the system to another. As we have studied, the autotrophs capture the energy present in sunlight and convert it into chemical energy. This energy supports all the activities of the living world. From autotrophs, the energy goes to the heterotrophs and decomposers.
when one form of energy is changed to another, some energy is lost to the environment in forms which cannot be used again.
The flow of energy between various components of the environment has been extensively studied and it has been found that –
- The green plants in the terrestrial ecosystem capture about
1% of the energy of sunlight that falls on their leaves and convert it into food energy
When green plants are eaten by primary consumers, a great deal of energy is lost as heat to the environment, some amount goes into digestion and in doing work and the rest goes towards growth and reproduction. An average of 10% of the food eaten is turned into its own body and made available for the next level of consumers.
Therefore, 10% can be taken as the average value for the amount of organic matter that is present at each step and reaches the next level of consumers.
Since so little energy is available for the next level of consumers, food chains generally consist of only three or four steps. The loss of energy at each step is so great that very little usable energy remains after four trophic levels.
There are generally a greater number of individuals at the lower trophic levels of an ecosystem, the greatest number is of the producers.
The length and complexity of food chains vary greatly. Each organism is generally eaten by two or more other kinds of organisms which in turn are eaten by several other organisms. So instead of a straight line food chain, the relationship can be shown as a series of branching lines called a food web (Fig. 15.3).
Describe the energy flow diagram
From the energy flow diagram , two things become clear. Firstly, the flow of energy is unidirectional. The energy that is captured by the autotrophs does not revert back to the solar input and the energy which passes to the herbivores does not come back to autotrophs. As it moves progressively through the various trophic levels it is no longer available to the previous level. Secondly, the energy available at each trophic level gets diminished progressively due to loss of energy at each level.
How does water get polluted and it’s effects?
- how water gets polluted. One of the reasons is the use of several pesticides and other chemicals to protect our crops from diseases and pests. These chemicals are either washed down into the soil or into the water bodies.
- From the soil, these are absorbed by the plants along with water and minerals, and from the water bodies these are taken up by aquatic plants and animals. This is one of the ways in which they enter the food chain. As these chemicals are not degradable, these get accumulated progressively at each trophic level.
- As human beings occupy the top level in any food chain, the maximum concentration of these chemicals get accumulated in our bodies. This phenomenon is known as biological magnification. This is the reason why our food grains such as wheat and rice, vegetables and fruits, and even meat, contain varying amounts of pesticide residues. They cannot always be removed by washing or other means.
Describe the ozone layer
- Ozone (O3
) is a molecule formed by three atoms of oxygen. While O2, which we normally refer to as oxygen, is essential for all aerobic forms of
life. Ozone, is a deadly poison. - However, at the higher levels of the
atmosphere, ozone performs an essential function. It shields the surface
of the earth from ultraviolet (UV) radiation from the Sun. This radiation is highly damaging to organisms, for example, it is known to cause skin
cancer in human beings. - Ozone at the higher levels of the atmosphere is a product of UV radiation acting on oxygen (O2 ) molecule. The higher energy UV radiations split apart some moleculer oxygen (O2 ) into free oxygen (O) atoms
What has led to the decline of the ozone
The amount of ozone in the atmosphere began to drop sharply in
the 1980s. This decrease has been linked to synthetic chemicals like
chlorofluorocarbons (CFCs) which are used as refrigerants and in fire
extinguishers. In 1987, the United Nations Environment Programme
(UNEP) succeeded in forging an agreement to freeze CFC production at
1986 levels. It is now mandatory for all the manufacturing companies
to make CFC-free refrigerators throughout the world.
why
the same enzyme does not break-down everything we eat?
Enzymes are
specific in their action, specific enzymes are needed for the break-down of a particular substance. That is why we will not get any energy if we
try to eat coal!
Because of this, many human-made materials like plastics
will not be broken down by the action of bacteria or other saprophytes.
These materials will be acted upon by physical processes like heat and
pressure, but under the ambient conditions found in our environment,
these persist for a long time
What are biodegradable substances?
Substances that are broken down by biological processes are said
to be biodegradable.
