Problem: Living things need non-living matter as well as energy. What do you think matter is used for? One thing is to build bodies. They also need it to carry out the processes of life. Any non-living matter that living things need is called a nutrient. Carbon and nitrogen are examples of nutrients. Unlike energy, matter is recycled in ecosystems. You can see how in Figure 3.11. Decomposers release nutrients when they break down dead organisms. The nutrients are taken up by plants through their roots. The nutrients pass to primary consumers when they eat the plants. The nutrients pass to higher level consumers when they eat lower level consumers. When living things die, the cycle repeats.

Question: "Can you name something that matter is used for?"

Answer: "Building bodies"
Answer: yes

Problem: Plants also detect the daily cycle of light and darkness. Do you know how plants respond to these changes? Some plants open their leaves during the day. It is during these hours the plant can collect sunlight. At night, the plant closes its leaves to prevent water loss. Many plants respond to the change in the length of the day. As days grow shorter, some plants respond by going dormant. Dormant is when a plant suspends its growth. It does this in order to survive. Shorter days signal the coming of winter. Winter in most areas means extreme cold. It is also very dry in the winter months. As winter approaches, some plants respond by their leaves changing color. After the change in color, they fall off. This dormancy period helps trees. It allows them to survive the cold and dry winter. Plants only want to grow when conditions are right.

Question: "How do plants respond as the length of the day changes?"

Answer: "They don't respond at all"
Answer: no

Problem: As food is pushed along, it undergoes digestion. Digestion is the process of breaking down food into nutrients. There are two types of digestion: mechanical digestion and chemical digestion. Mechanical digestion occurs when large chunks are turned into smaller chucks. Perhaps not surprisingly, this happens when you chew your food. Once you swallow the food, your stomach also does some of this work. Chemical digestion occurs when food is broken down into useful nutrients. This is a chemical process that begins as you start to chew your food. The saliva in your mouth starts this process. Once you swallow, the acid in your stomach further breaks down food. From the stomach, the foods moves into the small intestine. In the small intestines, another set of chemicals goes to work. Are you surprised? Your small intestine, and not your stomach, does most of the work!

Question: "At what point does chemical digestion start?"

Answer: "When you chew the food"
Answer:
no