Monday, January 12, 2009
ECOLOGY homework
???WHY IS THERE A NEED FOR CONSERVATION???Conservation refers to the protection and preservation of resources on earth. It is necessary for humans to conserve as natural resources would then not be depleted by us. We should use it wisely.Example, when we enter a nature reserve(sungei buloh nature reserve), we must not pluck/remove anything that is once in there and take it away. This way, people from all over the world could enjoy the beauty of nature. Also, not only that, these natural resources that we're conserving may one day be useful to us as they may probably contain some medicinal values that might cure diseases or illness that have yet been answered.Most importantly, it won't affect the nature's balance and rich biodiversity of the earth.
ECOLOGY homework
???DISCUSS THE IMPACT OF HUMAN ACTIVITIES ON OUR ECOSYSTEM???
Human activities like deforestation, over-fishing and pollution destroys the ecosystem.By deforestating, humans are actually destroying habitats and maybe even sources of food for some animals and living things living in the forest. This will disrupt the ecological cycle. Once there is a lack of the producers(green plants)found in the forest after deforestating, the primary consumers that eats the green plants may die because of the lack of food. Also, those living things that are living in the forest, may lose their habitat and they may not survive outside shelter for long.(rick being eaten by predators.)On the otherhand, by over-fishing, it'll disturb the food chain and thus, same as above, it'll also cause some living creature to die as their food source(in this case is the fish) is being removed/lessened.Also, pollution will contaminate the surrounding atmosphere and it'll affect living creatures too. Example, if the water in the ocean is being contaminated and polluted, the lives of marine animals living in that ocean would probably be at risk.
ECOLOGY homework
???DESCRIBE THE CARBON CYCLE???
Carbon is a very important element as it makes up organic matter, which is a part of life. 
Carbon dioxide is released to the environment through 3 main processes:
- Respiration
- combustion
- decomposition.
Inorganic carbon dioxide in the atmosphere is converted by plants into simple carbohydrates, which are then used to produce more complex substances. Animals eat the plants and are then eaten by other animals. When these life forms die, they decay, breaking down into, among many other things, carbon dioxide, which returns to the atmosphere. Plants and animals also release carbon dioxide during respiration. Plants will help remove carbon dioxide in the air, it then makes use of it to photosynthesise and the whole cycle will repeat again. Also, fossil fuels which are burnt or combusted release carbon dioxide to the environment.
Sunday, January 11, 2009
ECOLOGY homework
???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 we go down the food chain. Hence, food chains are generally short, which means more energy is available to the final consumer because less energy is lost to the environment.
???WHAT HAPPENS TO MOST OF THE ENERGY IN THE ECOSYSTEM??
Energy is passed from one trophic level to another by feeding. The flow of energy through the ecosystem is non-cyclic. Some energy is released as heat to the environment as it flows through the ecosystem. This heat energy does not return to the same system/organisms that produced it. Hence, it cannot be recycled in the ecosystem. Dead organisms and waste matter contain trapped chemical energy which is used by decomposers for their needs. The rest of the energy is then lost as heat by the activity of decomposers.
Eventually, all the energy that enters the biotic part of the ecosystem is lost as heat energy.
......................................HEAT ENERGY.............................................
ECOLOGY homework
???WHAT ARE ECOLOGICAL PYRAMIDS?DESCRIBE THE DIFFERENT TYPES OF ECOLOGICAL PYRAMIDS.??? Ecological pyramids are used to compare the trophic levels in a food chain. The different types of ecological pyramids are:
- Pyramids of numbers
- Pyramids of biomass
- Pyramids of energy
In a pyramid of numbers, all the organisms at each trophic level are counted, regardless of their size and stage of development.
In a pyramid of biomass, it allows us to compare the mass of organisms present in each trophic level at a particular time. It is constructed based on the dry mass of organisms in each trophic level at any one time. This is called the standing mass of organisms.
In a pyramid of energy, the total energy in the various trophic levels of a food chain can be represented in the form of a pyramid. Unlike the pyramid of biomass, we need to determine the total energy content in each trophic level over a period of time(example: one year). This means that we have to take into consideration the rate at which organisms in each trophic level reproduce. The average energy content of each trophic level can then be calculated using special techniques. Knowing the energy content in each trophic level, we can construct a pyramid of energy. The pyramid of energy is thus constructed based on the total energy level in each trophic level over a certain period of time.
Most ecological pyramids are pyramid-shaped, but there are important exceptions. Example:
- tree--->aphid--->protozoa
In this case, the pyramid of numbers is inverted. The bottom of the pyramid is represented by only one tree. Many aphids are parasitic on the tree and many protozoa are parasitic on the aphids.
However, the pyramid of biomass remains broad and narrow at the apex. This is because one tree has a comparatively large biomass to support the other populations.
- Pyramids of biomass for rapidly reproducing organisms are also not pyramid-shaped. Since the pyramid of biomass is based on standing mass, it does not take into account the rate of reproduction of organisms. This is a disadvantage when considering organisms that reproduce rapidly.
phytoplankton--->zooplankton--->small fish--->large fish
Phytoplankton are microscopic plant-like organisms that can make food by photosynthesis. Zooplankton are microscopic primary consumers that feed on phytoplankton. For the food chain above, the pyramid may look like
The pyramid gives the impression that the biomass of phytoplankton is smaller than that of zooplankton, which is impossible. What happens is that the rate of reproductionof phytoplankton is fast enough to replace the organisms that were eaten by zooplankton.
Labels: pictures from www.learner.org/workshops/sheddinglight/highlights/highlights6.html
Tuesday, January 6, 2009
ECOLOGY homework
???WHAT IS THE RELATIONSHIP BETWEEN A PREDATOR AND A PREY?TWO PREDATORS WITH THE SAME PREY????
An animal that feeds on another animal is a predator. An animal that is eaten by another animal is the prey. For example, snakes eat chickens, so, snakes are predators of chicke
ns. Chickens are the p
rey of snakes.
A picture of the snake(predator)and the chicken(prey)...
An increase in the population of the prey would result in the increase of the population of the predator as it would mean more food for them. Subsequently, the population of prey would decrease, which in turn results in an inevitable decrease in the predator as less food is available. The decrease in number of predator then allows an increase in number of the prey. This cycle of the predator-prey relationship repeats over time.
If there is two predator with the same prey, the population of the prey would then be decreased approximately twice as fast as when there is just one predator.
Labels: pictures from www.flickr.com
Monday, January 5, 2009
ECOLOGY homework
???HOW DO ENERGY AND NUTRIENTS FLOW THROUGH AN ECOSYSTEM?GIVE AN EXAMPLE OF A FOOD CHAIN, AND FOOD WEB.???The living organisms in any ecosystem are made up of producers, consumers and decomposers. This is how energy and nutrients flow through an ecosystem:
- The producers(mainly green plants)convert light energy (sun)into chemical energy and store it as food during photosynthesis. Besides green plants, algae and certain bacteria can also photosynthesise and are producers. Producers are the only organism that can manufacture/produce complex organic food from inorganic raw materials.
- Consumers(all animals)obtain their energy by feeding on other organisms. Plant-eaters(herbivores)feed directly from plants. Hence, they are known as primary consumers. Meat-eaters(carnivores)feed on other animals. Carnivores that feed on herbivores are know as secondary consumers those that feed on other carnivores are tertiary consumers
.
- picture of herivores(rabbit) and carnivores(lion).
3. Decomposers(fungi, bacteria, earthworms)obtain energy by breaking down dead organisms, faeces and excretory products. When the dead organisms and waste matter are broken down, the materials locked up in them are released. Thus, carbon and nitrogen compounds return to the physical environment and are used again by green plants.
Therefore, the energy and nutrients flow through an ecosystem starting from the producers(green plants)to the consumers(animals)and eventually to the decomposers(fungi, bacteria, earthworms)to break down waste matter which in turn could be used by the green plants and this will continue all over again.
An example of a food chain and food web is below:
green plant--->earthworms--->chicken--->snake
Feeding relationships between organisms in an ecosystem can be represented using food chains. Each arrow means "is eaten by."
green plant----->earthworms----->chicken----->snake means green plant is eaten by earthworms, earthworms is eaten by chicken and the chicken is eaten by snake.
Each stage in a food chain is known as a trophic level. It generally doesn't have more than 4 levels.
Many food chains could be interlinked together to form a food web. In a food web, there may be 2 or more food chains.
Labels: pictures from www.flickr.com and www.wildlifetrust.org.uk
Human activities like deforestation, over-fishing and pollution destroys the ecosystem.
ns. Chickens are the p
rey of snakes. 
.