- Need energy to carry out life processes
- Are composed of one or more cells (the cell theory)
- Evolve and share an evolutionary history
- Respond to their environment
- Grow, reproduce themselves, and pass on information to their offspring in the form of
genes - Maintain a stable internal environment (homeostasis)
Figure 2.1: Life on Earth is very diverse, yet all these forms of life share some characteristics.
Forms of life include: A) Bacteria, B) Algae, C) Fungi, D) Plants, and E) Animals. ( 13 )
Living Things Maintain Stable Internal Conditions
All living things have some ability to maintain a stable internal environment. The inside of
an organism is separate and different from the outside world. Maintaining that separation
and difference is known ashomeostasis. For example, many animals work hard to keep
their temperature within a certain range. If the animal gets too hot or too cold, it will die.
As a result, many animals have evolved behaviors that regulate their internal temperature.
A lizard may stretch out on a sunny rock to increase its internal temperature, and a bird
may fluff its feathers to stay warm (Figure2.2).