Basic unit of all living things.

Basic unit of all living things.

• A. Food chain
• B. Bacteria
• C. Alloy
• D. Cell

Answer: (D)

The main idea here is that the cell is the basic unit of life. It’s the smallest structure that can carry out all the processes that keep a living thing alive—metabolism, growth, responding to the environment, and reproduction. Some organisms are made of a single cell, like bacteria, which shows that life can exist at the cellular level. In multicellular organisms, many cells work together to form tissues and organs, but the cell itself remains the building block of life. The other options don’t fit as the basic unit of life. A food chain describes who eats whom and how energy moves through an ecosystem, not the smallest unit that can live. An alloy is a nonliving material, a mixture of metals. Bacteria are living and are example of cells themselves, but the statement points to the cell as the fundamental unit, not a specific organism.

The main idea here is that the cell is the basic unit of life. It’s the smallest structure that can carry out all the processes that keep a living thing alive—metabolism, growth, responding to the environment, and reproduction. Some organisms are made of a single cell, like bacteria, which shows that life can exist at the cellular level. In multicellular organisms, many cells work together to form tissues and organs, but the cell itself remains the building block of life.

The other options don’t fit as the basic unit of life. A food chain describes who eats whom and how energy moves through an ecosystem, not the smallest unit that can live. An alloy is a nonliving material, a mixture of metals. Bacteria are living and are example of cells themselves, but the statement points to the cell as the fundamental unit, not a specific organism.