The Food Chain and Energy
XX. Put the following vocabulary words. in the correct blank spaces in the following text.
Autotrophy, heterotrophy, consumer, decomposer, omnivore, bacteria, herbivore, producer, carnivore.
The food chain begins with green plants because they are able to use the sun's energy, along with carbon dioxide and water, to make food through photosynthesis. _______ — the plants that form the bottom, or base, of the food chain—are also called _______ because they can make their own food.
The higher levels are all _______, which are animals that cannot produce their own food. Instead, they must obtain energy from other living organisms or from the dead remains of plants and animals. These animals are also called _______, which can be divided into four categories.
_______ are animals that eat only plants. The second level of the food chain is made up of _______, which feed on _______. The top _______ in a food chain feeds on other _______. Animals that eat both plants and animals are called _______. Therefore, they can be found at any level above herbivores in a food chain. Finally, _______ are tiny organisms such as _______ that break down dead plant and animal matter. This process releases chemicals that the _______ can use again.
Thus, energy and matter is cycled through the ecosystem.
XXI. We learned earlier that the sun is the main source of energy for an ecosystem. In order to understand how an ecosystem works, we must understand the biotic component of an ecosystem, and how energy and materials move through it.
On this picture, draw an arrow to the place where the primary source of energy is used first. Look at the picture and complete the following paragraph, using the vocabulary words.
The first arrow goes from the sun to green plants, which are called _______, or ________. The second arrow goes from green plants to the rabbit. This animal is called a _________ because it feeds on green plants. The next arrow should go from this rabbit to the _______. This animal is called a ________ because it feeds on ________. An arrow should go from the plants and animals that will die to the ________. These tiny organisms are called _________.
XXII. Read and translate the text.
Water travels through out the earth through the hydrological cycle. As the sun radiates energy to the earth, the water on the earth, such as that in lakes, rivers, and oceans, evaporates. Evaporation is the process by which water changes from a liquid to a gas. Trees and plants absorb water from the soil, and this water also evaporates through their leaves. As the gas rises in the atmosphere, it cools and changes back to a liquid form through the process of condensation. As a result of condensation clouds form. Within the clouds, the droplets of water grow and eventually return to the earth as some form of precipitation, either rain or snow. Some of the water returnes to the sea in streams and rivers through runoff.
Write each of the following words in the appropriate arrow drawn in the diagram: Evaporation, condensation, absorption, precipitation, runoff.
