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ลำดับตอนที่ #6 : Sciman - 2 (15/9/59)

Class Work 2

(Section 427)

Group 7

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Present to

Teacher Khin Saw Mon

Review Questions (Chapter 5)

1.  How is an organism’s niche different from its habits?

Niche is the role a species plays in a community such as feeding relationships, space, and what the organism needs to survive in the environment. It includes how a species uses and affects its environment.

Habitat is the place where an organism lives out its life. Different species of organisms may appear to have the same habitat but each has a different niche so that they can survive in that habitat.

For example, the scarlet tanager lives in a deciduous forest habitat. Its niche, in part, is gleaning insects from the canopy foliage.

2.  What roles do producers, consumers, and decomposers fulfill in an ecosystem?

Producer – Converts simple inorganic molecules into organic molecules by the process of photosynthesis, such as trees, flowers, grasses, ferns, mosses, algae.

Consumer – Use organic matter as a source of food, such as animals, fungi, bacteria.

Decomposer – Return organic material to inorganic material or you can call ‘recycling of atom’, such as fungi, bacteria, some insects and worms.

3.  How is the concept of trophic levels related to energy flow in an ecosystem?

Each ecosystems are sustained by a flow of energy through them. The main source of the energy, sunlight or solar radiation, enters the ecosystem when it is absorbed by producers. And when the producers are eaten, the energy stored in the molecules of producers is transferred to other organisms.

Trophic level is each step in the flow of energy through an ecosystem.

Producers, such as plants, are the first trophic level. Herbivores, such as cows, are the second. Carnivores that eat herbivores are the third. Carnivores that eat carnivores are the fourth trophic level. For Omnivores, parasites, and scavengers are in different trophic level depending on the time when they eating.

For example, if we eat steak, we are at the third trophic level but if we eat cabbage, we are at the second trophic level.

4.  Describe a food chain and food web.

All living things need to give them the energy to grow and move. A food chain shows how each living thing gets its food. It shows who is eating who. The arrow means “is eaten by”.

Grass ---->	Grasshopper ---->	Toad ---->	Snake ---->	Hawk

Grass is eaten by Grasshopper is eaten by Toad is eaten by Snake is eaten by Hawk

Food web consists of many food chains and shows the many different paths plants and animals are connected. For example, A hawk might also eat a mouse, a squirrel, a frog or some other animal. The snake may eat a beetle or some other animal. And so on for all the other animals in the food chain.

5.  Describe how each of the following is involved in the carbon cycle: carbon dioxide, producer, organic compounds, consumer, respiration, and decomposer.

- Carbon dioxide enters the atmosphere from respiration and combustion.

- Carbon dioxide is absorbed by producers to make an organic compounds through the process of photosynthesis.

- Animals feed on the plant, which is consumer, passing the carbon compounds along the food chain. Most of the carbon they consume is emitted as carbon dioxide formed during respiration. The animals and plants eventually die.

- The dead organisms are eaten by decomposers and the carbon in their bodies is returned to the atmosphere as carbon dioxide.

6.  Describe how each of the following is involved in the nitrogen cycle: atmospheric nitrogen, nitrogen-fixing bacteria, nitrifying bacteria, denitrifying bacteria, producer, protein, consumer, and decomposer.

- Because atmospheric nitrogen is not usable by plants, the primary way which plants can use to obtain nitrogen compounds is with the help of bacteria that live in the soil.

- Nitrogen-fixing bacteria is the bacteria which live in soil. They can change the nitrogen gas that enters the soil into ammonia that plants can use.

- Producer use ammonia to create proteins, DNA, and others.

- The nitrogen is passed through the food chain by consumers and then released into the soil by decomposer bacteria when they die.

- Decomposer break down protein in dead organic to ammonia.

- Nitrifying bacteria can convert ammonia to nitrate so plants can use it.

- Finally, Denitrifying bacteria change nitrate or other nitrogen-containing compounds to nitrogen gas and release it to the atmosphere.

Second presentation