Question

question 12
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when does passive transport occur?
when nutrients are moving from an area of higher concentration to lower concentration.
when nutrients are moving from an area of lower concentration to higher concentration.
when fat molecules need to be transported to the liver.
when nutrients are too large to use active transport.

Explanation:

Passive transport is the movement of substances across a cell membrane without the use of energy. It occurs along the concentration gradient, i.e., from an area of higher concentration to an area of lower concentration. The second option describes active transport (movement against the concentration gradient, which requires energy). Transport of fat molecules to the liver involves other mechanisms (like lymphatic and then vascular transport, not passive transport definition - based). The last option is incorrect as passive transport is not defined by molecule size in that way (large molecules may use other mechanisms like endocytosis, but passive transport's key is concentration gradient, not size limiting active transport). So the correct option is the first one.

Answer:

A. When nutrients are moving from an area of higher concentration to lower concentration.