E C O L O G Y

FANTASY LIFE.

Tuesday, December 30, 2008

8)What happens to most of the energy in the ecosystem?

Energy flow in an ecosystem is non-cyclic. Energy is lost to the environment as heat, which cannot be recycled in the ecosystem. Hence, energy must be constantly supplied to the ecosystem. In any ecosystem, the ultimate source of energy is the sun. Light energy is then absorbed by chlorophyll in producers and then converted to chemical energy during photosynthesis. Energy is then passed from one trophic level to another through feeding. Dead organisms and egested and excreted materials contain trapped chemical energy. The energy is then released by activity of decomposers, some energy is used by the decomposers while the rest of the energy is lost as heat. Eventually, all the energy that enters the biotic part of the ecosystem is lost as heat energy and living organisms are unable to use heat energy to do work.

Labels: Energy

-------------------final fantasy--------------- ; {11:58 PM}
_________________________________________________________

7)Why are short food chains better??

Since about 90% of the energy is lost when it is transferred to the next trophic level, a shorter food chain means more energy is avaliable to the final consumer as less energy is lost to the environment.For e.g, we will recieve more energy if we feeds directly on crop plants rather than eating a cattle that feed on crop plants. Therefore, a shorter food chain is more efficient than long food chain.

Labels: Food chains

-------------------final fantasy--------------- ; {11:41 PM}
_________________________________________________________

6)What are ecological pyramids? Describe the different types of ecological pyramids.

An ecological pyramid is a graphical representation designed to show the biomass or productivity at each trophic level in a ecosystem.
*Each stage in a food chain is known as a trophic level.

The picture above shows an ecological pyramid

There are two types of ecological pyramid, the Pyramid of biomass and the Pyramid of energy(pyramid of productivity).

Pyramid of biomass
An ecological pyramid of biomass shows the relationship between biomass and trophic level. It is constructed based on the dry mass of organisms in each trophic level at any one time. Lets take this food chain as an example.
Grass-->Rabbit-->Snake-->Hawk
All the grass together have a larger biomass than the rabbits, all the rabbits together have a larger biomass than the snake, all the snakes together have a larger biomass than the hawks. Hence, the pyramid of biomass for this food chain will be broad at base and narrow towards the top.

Pyramid of energy
An ecological pyramid of energy shows the production or turnover of biomass at each trophic level. It is constructed base on the total energy level in each trophic level over a certain period of time,for e.g, 1 year.
More and more energy is lost as it goes down a food chain.Almost 90% of the energy is lost when it is transferred from one trophic level to another. The total energy level is the highest at the first trophic level and lowest at the last trophic level. Hence, the pyramid of energy is always broad at base and narrow towards the top.

Labels: Ecological pyramids

-------------------final fantasy--------------- ; {10:47 PM}
_________________________________________________________

5)What is the relationship between a predator and a prey? Two predators with the same prey?

A predator is an organisms that feeds on other organisms which is the prey

In the picture above, the spider is the predator while the fly is the prey.

An increase in population of prey would means more food for the predator, thus causing the population of predator to increase. However, this causes the population of prey to decrease, which in turn results in a decrease in the predator population due to the lack of food. As the population of predatore decreases, the population of prey would increase again and so on..

A prey-predator graph

If they are two predators feeding on the same prey. Both predators will be competing against each other for food. This causes the population of prey to decrease. Overtime both population of predator would decrease if they do not look for other scoure of food and the population of prey would increase when there are lesser predators.

Labels: Predator-prey relationship

-------------------final fantasy--------------- ; {10:19 PM}
_________________________________________________________

Monday, December 29, 2008

4)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, comsumers and decomposers. Almost all ecosystems run on energy captured from the sun by primary producers via photosynthesis. This energy then flows through the food chains to primary consumers (herbivores who eat and digest the plants), and on to secondary and tertiary consumers (either carnivores or omnivores). Energy is lost when it is used by the organisms to do work, or lost as heat.

Photosynthetic plants fix carbon from carbon dioxide and nitrogen from atmospheric nitrogen or nitrates present in the soil to produce amino acids.Much of the carbon and nitrogen contained in ecosystems is created by such plants, and is then consumed. Nutrients are usually returned to the ecosystem via decomposition. The entire movement of chemicals in an ecosystem is termed a biogeochemical cycle.

A biogeochemical cycle is a pathway by which a chemical element or molecule moves through both biotic and abiotic compartments of Earth

Feeding relationships between organisms in an ecosystem are represented by food chains. A food chain always begins with a producer!

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.

Labels: The ecosystem

-------------------final fantasy--------------- ; {11:35 PM}
_________________________________________________________

3)Are organisms interdependent. Why?

Yup.Organisms are interdependent. The life of each organism depends on and is influenced by other organisms around it. A change in one population affects the other populations of the community. E.g, if the population of small crabs living in mud of a mangrove community decreases, the population of mudskippers will also decrease as there is lesser food for them. Alternatively, the mudskippers may feed on small insects or worms to get food, thus decreasing the population of insects and worms. This biological balance is like a web where breaking a single strand will affect the rest.

Labels: Interdependent

-------------------final fantasy--------------- ; {11:20 PM}
_________________________________________________________

2)How do the physical features of the suroundings affect organisms? What are these physical factors? How do organisms adapt to these physical factors?

The six physical features include
~Light intensity
~Temperature
~Water
~Oxygen content
~Salt concentration of soil or water
~pH of soil or water

These physical features determine the types of plant that are found in the region. Since plants directly or indirectly supply food for animals, the animals are determined by the plants that grow in the region

Now i am going to explain how these physical features affect organisms and how do organisms adapt to them

1)Light intensity
Green plants exist only where there is an adequate supply of sunlight. Some plants, like climbing plants, develop adaptations to reach the light. In the case of climbing plants, they twine around a support to pull themselves higher. Certain plants have developed adaptations to screen off excessive light, for example, some plants have dense covering of hairs on the leaf epidermis or a layer of thick-walled cells.These adaptations allow the plant to screen of excessive light and reducing the rate of transpiration.

2)Temperature
Temperature affects the rate of reaction of enzymes. Temperature that are too high or low would kill an organism.Many plants are adapted to changing seasons. Such plants are able to survive through a hot and cold season by storing food in underground storage organs, shedding leaves to reduce water loss or forming seeds that are resistant to heat, cold or drought.

3)Water
Without water, most organism cannot survive long. Hence, amount of water avaliable is one of the major factors that affects the number of plants and animals in a region. Some organisms are adapted to survive under conditions where water is limited. For e.g, camels can drink more than 100 litres of water and survive for many days without water. Some plants , known as xerophytes, are adapted to survive drought by
~shedding young leaves or developing leaves reduced to spines
~Fleshy stems, storing up much water
~Green stems taking cover the function of photosynthesis

Cacti are xerophytes

On the other hand, plants living in water or every wet places such as the mangrove plants adapt by having special breathing roots project above the mud surface. These breathing roots have pores for gaseous exchange.

4)Oxygen content
Most organisms require oxygen for respiration, thus unable to survive in environments of low oxygen content. However some possess adaptations such as mangrove plants having breathing roots, fish living in water of low oxygen content are air-breathers where they come to the surface to gulp air.

5)Salt concentration of water
Animals living in seawater tend to lose water by osmosis as seawater has a higher salt concentration.Saltwater fishes have a waterproof coat consisting of closely-fitting scales covered by slimy mucous material to reduce the rate of water loss. Cytoplasm of celss of freshwater organisms usually has a higher salt concentration than surrounding water so water tend to enter the organism by osmosis.

6)pH of water
Aquatic organisms are sensitive to the pH of the water and may die if there are drastic or sudden changes in pH.

Labels: Physical factors

-------------------final fantasy--------------- ; {10:26 PM}
_________________________________________________________

Sunday, December 21, 2008

Ecology is the study of the distribution and abundance of life and the interactions between organisms and their natural environment.

Ecology comprises of a habitat, population, community and ecosystem.

Populations --> Communities --> Ecosystems
These parts are linked together as groups of organisms interact with one another and the environment to form levels of organisation that get bigger and more complex

Labels: Ecology

-------------------final fantasy--------------- ; {12:54 AM}
_________________________________________________________

Jin Hao
Queenstown

;

Biology Assignment
soulesspuppy@hotmail.com
4A

LINKS

Keng Kiat | Valerie |

Credits

Info and images are taken from wikipedia. Please do not remove credits.view my other blogskins. This blogskin is made by Devil regina

Past fantasy

December 2008
January 2009

Forum

TAGBAORD CODE GOES HERE