Answer:
17. Producers, also known as autotrophs, make their own food. They make up the first level of every food chain. Autotrophs are usually plants or one-celled organisms. Nearly all autotrophs use a process called photosynthesis to create “food” (a nutrient called glucose) from sunlight, carbon dioxide, and water.
18.Primary consumers: cows, rabbits, tadpoles, ants, zooplankton, mice. Secondary consumers: frogs, small fish, krill, spiders. Tertiary consumers: snakes, raccoons, foxes, fish.
