Task: Question Answering
Input (English): Context: If a plant gets hungry, it cannot walk to a local restaurant and buy a slice of pizza. So, how does a plant get the food it needs to survive? Plants are producers, which means they are able to make, or produce, their own food. They also produce the "food" for other organisms. Plants are also autotrophs. Autotrophs are the organisms that collect the energy from the sun and turn it into organic compounds. Using the energy from the sun, they produce complex organic compounds from simple inorganic molecules. So once again, how does a plant get the food it needs to survive? Through photosynthesis. Photosynthesis is the process plants use to make their own food from the suns energy, carbon dioxide, and water. During photosynthesis, carbon dioxide and water combine with solar energy to create glucose, a carbohydrate (C6 H12 O6 ), and oxygen. The process can be summarized as: in the presence of sunlight, carbon dioxide + water glucose + oxygen. Glucose, the main product of photosynthesis, is a sugar that acts as the "food" source for plants. The glucose is then converted into usable chemical energy, ATP, during cellular respiration. The oxygen formed during photosynthesis, which is necessary for animal life, is essentially a waste product of the photosynthesis process. Actually, almost all organisms obtain their energy from photosynthetic organisms. For example, if a bird eats a caterpillar, then the bird gets the energy that the caterpillar gets from the plants it eats. So the bird indirectly gets energy that began with the glucose formed through photosynthesis. Therefore, the process of photosynthesis is central to sustaining life on Earth. In eukaryotic organisms, photosynthesis occurs in chloroplasts. Only cells with chloroplastsplant cells and algal (protist) cellscan perform photosynthesis. Animal cells and fungal cells do not have chloroplasts and, therefore, cannot photosynthesize. That is why these organisms, as well as the non- photosynthetic protists, rely on other organisms to obtain their energy. These organisms are heterotrophs. The Photosynthesis Song explaining photosynthesis, can be heard at Click image to the left or use the URL below. URL: Why do leaves change color each fall? This MIT video demonstrates an experiment about the different pigments in leaves. See the video at . Click image to the left or use the URL below. URL: 
 Question: as almost all organisms on earth obtain their energy from photosynthetic organisms, it could be said that ultimately all energy comes from _________.
Output (English): the sun.