Drag the terms on the left to complete the sentences on the right. active transport less concentrated more concentrated passive transport when molecules move down their concentration gradient, they move from where they are to where they are . diffusion across a biological membrane is called .

When molecules move down their concentration gradient, they move from where they are MORE CONCENTRATED to where they are LESS CONCENTRATED.

Diffusion across a biological membrane is called PASSIVE TRANSPORT.

Explanation:

Substances are transported by active or passive mechanisms. Active transport makes use of energy to move the substances against their concentration gradients while passive transport is driven by the concentration gradient of the substance itself. Passive transport moves the substances from the region of their higher concentration to that of their lower concentration, that is, down the concentration gradients.

Diffusion is the movement of substances down their concentration gradient. Substances are diffused across the cell membranes down the concentration gradients. This movement does not use energy and hence, is passive transport.  

the abdomen (less formally called the belly, stomach, tummy or midriff) constitutes the part of the body between the thorax (chest) and pelvis, in humans and in other vertebrates. the region occupied by the abdomen is termed the abdominal cavity. the stomach secretes acid and enzymes that digest food. ridges of muscle tissue called rugae line the stomach. the stomach muscles contract periodically, churning food to enhance digestion. the pyloric sphincter is a muscular valve that opens to allow food to pass from the stomach to the small intestine.