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Ecology @ 8:37 PM
8) What happens to most of the energy in the ecosystem?
As energy flows through the ecosystem, some of it is lost to the environment at heat. Heat energy cannot be recycled. Hence, energy has to be constantly supplied to the ecosystem. In an ecosystem, energy does not flow in a cycle. Energy is non-cyclic(linear).
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Ecology @ 5:28 AM
7) Why are short food chains better?
Short food chains are better as they are more efficient in energy transfer. Since energy is lost at each trophic level, less and less energy is available for the organism at the next level as the food chain goes on. Hence, a shorter food chain means more energy is avaliable for the final consumer because less energy is lost to the environment.
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Ecology @ 9:05 PM
6) What are ecological pyramids? Describe the different types of ecological pyramids.
Ecological pyramids can be used to compare trophic levels in a food chain.The three ecological pyramids:
1) Pyramid of numbers
2) Pyramid of biomass
3) Pyramid of energy
1) Pyramid of numbers
The pyramid of numbers allows us to compare the number of organisms present in each tropic level at a present time.
There are also pyramids of numbers which are inverted. It occurs when:
-Organisms on one trophic level are parasitic on organisms on another trophic level.
-Many small organisms of one trophic level feed on a large organism of another trophic level.
2) Pyramid of biomassA pyramid of biomass allows us to compare the mass of organisms present in each trophic level at a particular time.
An ecological pyramid of biomass shows the relationship between biomass and trophic level by quantifying the amount of biomass present at each trophic level at any one time. This is called the standing mass of organisms.
The pyramid of biomass is more accurate than the pyramid of numbers, as the pyramid of numbers may be inverted in some cases while the pyramid of biomass, is based on standard mass. Thus, most of the time it will be broad at the bottom and narrow at the top.
The biomass pyramid may also be 'inverted' which happens when the producer has a very fast rate of reproduction which is fast enough the replace the organisms eaten by the primary consumers.
3) Pyramid of energy
The energy in the various trophic levels of a food chain can be represented in the form of a pyramid. It is known as the pyramid of energy.
The pyramid of energy is constructed based on the total energy level in each trophic level over a certain period of time. A huge amount of energy is lost to the environment as food is transferred from one trophic level to the next. Energy may be lost to the environment in a few ways:
-as heat during respiration at every trophic level
-in uneaten body parts
-through undigested matter egested by consumers
-through waste products excreted by consumers, for example, urea.
Heat energy is wasted as it cannot be recycled in any way in the ecosystem.
Loss of energy occurs as the food chain continues. The total energy at the first trophic level is the highest while the energy at the lowest trophic level is the lowest. Hence, a pyramid of energy is always broad at the bottom and narrow on top. About 90% of the energy is lost during energy transfer from one trophic level to another. The greatest amount of energy lost is during the transfer of energy from producer to primary consumer.
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Ecology @ 8:49 PM
5) What is the relationship between predator and prey? Two predators with the same prey?
A predator is an organism that kills and feeds on other organisms. The organisms that are eaten are called the prey.
An increase in the population size of the prey means that more food is available for the predator. Therfore, an increase in population of the predator will be observed. This causes a decrease in the population of the prey, which in turn results in a decreased population of predators as there is less food available. This cycle then repeats itself.
A graph of changes in the population of predators and prey over time:
If there are two predators with the same prey, the population of the predator would be small as there is less food available to both predators. This will cause a jump in the population of the prey as population of both predators are small. The population of the predators would increase as there is more food available, thus causing a decrease in pupulation of prey. This cycle repeats itself.
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Ecology @ 6:24 PM
4) How do energy and nutrients flow through an ecosystem? Give an example of a food chain and a food web.
The living organisms in any ecosystem are made up of producers, consumers and decomposers. Energy and nutrients are transferred from producers to consumers to decomposers through feeding. Most ecosystems depend on energy from the sun through photosynthesis. The energy the flows through the food chain to the primary consumers which are also known as herbivores. And then on to secondary and tertiary consumers. The energy is gradually used up as it pass through the ecosystem.Inorganic nutrients, need not be supplied from outside the ecosystem. They are obtained from the abiotic environment and flow through the ecosystem in a cycle. Thus in a 'balanced' ecosystem, nutrients are continually recycled and are not lost.
The general form of a food chain:
PRODUCER->PRIMARY CONSUMER->SECONDARY CONSUMER->TERTIARY CONSUMER
In a community, food chains are interlinked to form a food web.
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Ecology @ 6:06 PM
3) Are organisms interdependant? Why?
Yes, organisms are inderdependant. This is because the life of each organism depends on and is influenced by the other organisms which are surrounding it. Therfore, we say that organisms are interdependant.
Organisms are interdependant because a change in one population affects other populations of the commmunity. E.g: If the population of small crabs living in the mud of the mangrove community decreases, the population of mudskippers may also decrease because there is less food for the mudskippers. Its is also possible that mudskippers may look for another food source. E.g: insects and small worms. Thus, the population of insects and small worms may decrease.
This biological balance or equilibrium is like a web- breaking a single strand will affect the entire
system.
An example of a marine ecosystem
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Ecology @ 6:41 PM
2) How do the physical features of the surroundings affect organisms? What are these physical factors? How do organisms adapt to these physical factors.
Since animals rely directly or indirectly on plants for food, the animals living in the region are determined by the plants growing there.
The organisms found in a region are usually adapted to the physical features of the environment.
The physical factors include:
1)Light intensity
2)Temperature
3)Water availability
4)Oxygen content
5)Salt concentration of soil or water
6)pH of soil or water
Example:
1) Light intensity
Green plants exist only where there is an adequate supply of sunlight. Certain plants have developed adaptations to block off excessive light. For example, some plants have a dense covering of hairs on the leaf epidermis or a layer of thick-walled cells called the hypodermis just beneath the epidermis. These adaptations protect the plant by screening off excessive heat and reducing the rate of transpiration. (Loss of water vapour from the aerial parts of the plant)
2) Temperature
Plants such as the cactus are adapted to survive in a hot environment as they can store water in their storage organs, the leaves have a very small surface area to reduce water loss.
3) Water availability
Some plants known as xerophytes are adapted t survive long droughts. Xerophytes may have some of these adaptations:
-They reduce the rate of transpiration by shedding their young leaves or by developing leaves reduced to spines.
-Their stems become fleshy, storingup much water.
-The green stems take over the function of photosynthesis from the leaves.
4) Oxygen content
Fish living in water of low oxygen content are usually air-breathers. They can come to the surface of the water to gulp for air.
5) Salinity
Saltwater fishes have a waterproof coat consisting of closely-fitting scales covered by a slimy mucous material which reduces the rate of water loss.
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Ecology @ 12:32 AM
Ecology
1)What comprises of ecology?
Ecology is the study of the distribution, life and the interactions between organisms and their natural environment.
Ecology comprises of a population, habitat, community and ecosystem. They are the parts of the Earth where life can be found. In ecology, there are small organizations and big organizations. The order of the organizations is: Population>Community>Ecosystem.
