Section 2.1 – A Matter of Life and Death
Questions 1 to 4 from page 42
1. What is a closed system?
A closed system is one in which recycling is continuous, with nothing entering or leaving. The
Earth is an example of a closed ecosystem. An aquarium is a closed system.
2. By what process do nutrients in the body of a dead mouse become part of the abiotic
environment?
When a mouse dies, the materials in the mouse are broken down by decomposers. In the process
of decomposition, nutrients in the body of the dead mouse return to the environment as abiotic
components.
3. How might the elements in a living plant become part of the body of a living bear?
Chemical energy is stored in parts of a plant (root, stem, or leaf). This chemical energy is
transferred to the bear when it eats this part of the plant. The energy is then used for building
cells in the bear’s body tissues.
4. Describe one way in which a waste product from a living toad is used by a plant.
A living toad releases carbon dioxide, which plants need to carry out photosynthesis, and wastes
from the food it eats, containing nutrients such as nitrogen and phosphorous, which plants need
to grow.