It became clear in the 1970's
Passive transport<span> is a movement of </span>biochemicals<span> and other </span>atomic<span> or </span>molecular<span> substances across </span>cell membranes through <span>concentration gradients</span><span> without need of </span>energy<span> input. Unlike </span>active transport<span>, it does not require an input of cellular energy because it is instead driven by the tendency of the system to grow in </span>entropy<span>. The rate of passive transport depends on the </span>permeability<span> of the cell membrane, which, in turn, depends on the organization and characteristics of the membrane </span>lipids<span> and </span>proteins<span>. The four main kinds of passive transport are simple </span>diffusion<span>, </span>facilitated diffusion<span>, </span>filtration<span>, and </span>osmosis.
Answer:
In prophase, the nucleolus disappears and chromosomes condense and become visible. In prometaphase, kinetochores appear at the centromeres and mitotic spindle microtubules attach to kinetochores. In metaphase, chromosomes are lined up and each sister chromatid is attached to a spindle fiber.
Explanation:
