Most animals use more than one species as food. Therefore, the term food web is a better description of food relationship than the term food chain. A food web is a complex feeding systems that contains several food chains. For example, mice, rabbits and deer eat plants. Owls eat meat and rabbits. Mountain lion eats rabbits and deer. These five species are parts of food chains that together form a food web.
The first link in a food chain is always a green plant. Only organisms with chlorophyll, such as green plants, can make food. For example, the first link in the aquatic chains is algae. Most algae are microscopic green plants that produce food by photosynthesis. In photosynthesis, energy from sunlight converts carbon dioxide and water to sugar. Tiny fish in lakes, streams and oceans eat algae. In turn, these tiny fishes are eaten by larger fish. These larger fish are eaten by still larger fish. The food supply for fish is made by algae.This food is then passed through the food chains as one animal eats another.
Organisms may be divided into three groups based on how they obtain food. These groups are producer, decomposer and consumer. Organisms containing chlorophyll are producers. Thus, green plants are producers. Animals that eat other animals and plants are consumers. Microbes, one-celled organisms that cause the decay of the dead animals and plants are decomposers. Since, decomposers cannot make their own food, they are also consumers.
This same Passage is used for the next three (Examples 1 to 6)questions as well.
* These Questions are taken from the section of TOEFL Reading Comprehension of previous year's original Question Paper.
The difficult words in this passage are web (network), aquatic (water living), algae (tiny plants which grow in water) and photosynthesis (process by which plant leaves produce food in the presence of sunlight).
Which of the following would most likely be the first link in a food chain?
The first sentence of the paragraph 2 says that the first link in the food chain is always a green plant. Among the choices in this question, grass is the only instance of a green plant. So, (D) is the answer.