Option 1 states that diffusion of ions and small molecules across the cell membrane requires energy. This is correct. Diffusion is the movement of particles from an area of higher concentration to an area of lower concentration, and it does not require energy. However, in the case of ions and small molecules, which are charged particles, they cannot passively diffuse across the cell membrane. They require specific transport proteins called ion channels or transporter proteins to facilitate their movement. The binding and movement of these ions and small molecules across the membrane against the concentration gradient, from an area of lower concentration to an area of higher concentration, is known as active transport and it does require energy.

Option 2 states that active transport of ions and small molecules across the cell membrane against the concentration gradient requires energy. This is correct. Active transport involves the movement of particles against their concentration gradient, typically from an area of lower concentration to an area of higher concentration, and it requires energy in the form of ATP (adenosine triphosphate) to power the transport proteins.

Option 3 states that cells conserve energy and no energy is required for the transport of ions and small molecules against the concentration gradient. This statement is incorrect. As mentioned earlier, active transport against the concentration gradient requires energy.