Which statement is true about the increase in an organism's mass?

The statement that the movement of atoms from outside to inside can contribute to mass increase is true because an organism's mass is influenced by the materials it takes in from its environment. This process is often evident in how organisms consume food, absorb nutrients, and take in water and gases. When these external substances are integrated into the body — forming new molecules and contributing to cellular structures — they directly lead to an increase in mass.

For example, a plant acquires carbon dioxide from the air and water from the soil, which it uses for photosynthesis to produce glucose and build biomass. Similarly, animals consume food that is metabolized to create new tissues, leading to growth. This movement of atoms and molecules into the organism is essential for growth and development, supporting the assertion that mass can indeed increase through these external contributions.

This understanding highlights the continuous exchange between organisms and their environment, emphasizing that mass increase is not solely reliant on internal processes or stored energy.