To determine which row best describes the active transport of molecule [tex]\( X \)[/tex] through a cell membrane, let's break down the characteristics of active transport:
1. Direction of Movement: Active transport moves molecules against their concentration gradient. This means molecules are transported from an area of low concentration to an area of higher concentration.
2. Energy Requirement: Active transport requires energy, typically in the form of ATP, because it is moving molecules against the natural direction of diffusion.
Given this, we examine each row:
- Row (1):
- Movement Direction: high concentration [tex]\(\rightarrow\)[/tex] low concentration
- ATP: used
- Row (2):
- Movement Direction: high concentration [tex]\(\rightarrow\)[/tex] low concentration
- ATP: not used
- Row (3):
- Movement Direction: low concentration [tex]\(\rightarrow\)[/tex] higher concentration
- ATP: used
- Row (4):
- Movement Direction: low concentration [tex]\(\rightarrow\)[/tex] higher concentration
- ATP: not used
Explanation:
- For active transport, molecule [tex]\( X \)[/tex] must move from a low concentration to a higher concentration, which corresponds to rows 3 and 4.
- Additionally, active transport must use ATP, which corresponds to row 3.
Therefore, the correct answer is:
C. Row (3)
