A food web can be formed by more than one food chain, since the webs includes all possible interactions that can occur between individuals of different trophic levels.
Explanation:
Based on the scheme shown in the image
1. How many food chains make up the food web?
This food network is made up of three food chains
Plant → Bird → SnakePlant → Insect → Bird → SnakePlant → insect → Frog → Snake
Food webs often include several food chains, since they are due to the interaction between organisms at different trophic levels, which actually happens within an ecosystem.
2. Which organism is an herbivore?
In this case, both the insect and the bird are herbivorous organisms, since they feed of the producer, which is the plant.
3. Which organism is an autotroph?
The only autotrophic organism is the plant, since it is capable of manufacturing its nutrients from sunlight and inorganic matter.
4. Which organism is a third-order heterotroph? To what trophic level does that organism belong?
The third order heterotroph is the snake, since it feeds on other animals. The snake is a carnivore and can be a secondary or more commonly tertiary consumer, so it can be placed in the 3rd or 4th trophic level.
5. Which organism is an omnivore?
According to the scheme proposed, the bird is omnivorous, since it feeds on both plants and insects.
6. Which organisms belong to more than one food chain?
In this case, the plant, the insect, the bird and the snake are part of more than one food chain.
Plant → Bird → SnakePlant → Insect → Bird → SnakePlant → insect → Frog → Snake
7. Which organism belongs to more than one trophic level?
The bird can be located in both the second and third trophic level, being a primary consumer —when it feeds on plants— or secondary, when it feeds on insects.
8. What are decomposers? From which trophic levels are the organisms that decomposers feed on?
Decomposers are generally bacteria and fungi, organisms capable of degrading organic matter, thus enriching the soil. Decomposers can feed on any trophic level.
9. What does a pyramid of energy show about the amount of energy available at different trophic levels of a food chain?
As the ascent of the pyramid occurs —or at the upper trophic level— the amount of energy available decreases. This is because from one trophic level to another only 10% of the energy can be used. If a plant has 5000 Kcal available, the herbivore that consumes it can only use 500 Kcal.
10. Why do different trophic levels have different amounts of energy?
The main reason for the difference in energy in each trophic level is that energy is lost in each one of them, which the organisms use in their metabolism. A consequence of the metabolism is the loss of energy as heat, which is acquired by the environment.
