Question

(16] Question 3 uestions that follow. Figure 1 Food web 3.1.1 3.1.2 3.1.3 Explain what a food web is. Distinguish between autotrophs and heterotrophs. Name two groups that are absolutely essential to the functioning of an ecosystem and explain why. Name three groups of heterotrophs and explain the difference among them. Explain why only 10% of energy is passed along to the next level in the food chain. Identify the type of symbiotic relationship illustrated in diagrams A-C below: 3.2 3.3 3.4 (2)

Answer 1

3.1.1. Answer: A food web is a model that shows the complex network of feeding relationships and the flow of energy within and sometimes beyond an ecosystem. these are more complex models of ecosystems than the food chain. many organisms, especially generalists, play multiple roles in an ecosystem and thus are connected to many different levels.

3.1.2.

Autotroph	Heterotroph
Produces their own food and energy by some special process. these are primary level in a food chain either photoautotroph or chemoautotroph example: plant, algae and some bacteria are the examples.	Can't produce their own food and energy so depend on others in an ecosystem. are at secondary, tertiary or quaternary levels in a food chain are photoheterotroph or chemoheterotroph Herbivores, omnivore, carnivores are the examples.

3.1.3 Producers and decomposers are absolutely essential to the functioning of an ecosystem.

Producers: the trophic level that supports all others consisting of autotrophs. so 2nd tropic level and others can live.

Decomposers: breakdown of organic materials to inorganic ones so that nutrient cycle can take place.

3.2 herbivore are animals that eat pants exclusively.

carnivore are animals that eat other animals.

detritivores are the organisms that feed on dead and decay material.

3.3 In a food chain only around 10 percent of the energy is passed on to the next trophic level. The rest of the energy loss out of the food chain in a number of ways:

• it is used as heat energy
• it is used for life processes (movement)
• faeces and remains are passed to decomposers

Less energy is transferred at each level of the food chain so the biomass gets smaller. As a result, there are usually fewer than five trophic levels in food chains.

3.4

A- mutualism

B- parasitism (only one get benefits)

C- predation