If a water molecule passes through the outer membrane of a chloroplast, how many more membranes will it have to move through to be in the stroma?

To determine how many more membranes a water molecule must cross to enter the stroma after passing through the outer membrane of a chloroplast, it's important to understand the structure of the chloroplast. A chloroplast is surrounded by two membranes: an outer membrane and an inner membrane.

Once a water molecule passes through the outer membrane, it encounters the inner membrane next. After crossing the inner membrane, it will enter the stroma, which is the fluid-filled space surrounding the thylakoids inside the chloroplast, where many of the biochemical processes of photosynthesis occur.

Thus, the water molecule only needs to move through one additional membrane, the inner membrane, to reach the stroma. This makes the total number of membranes to cross from the outer to the stroma just one. Hence, the correct number of membranes the water molecule must traverse after the outer membrane is accurately one.