The concentration of molecules or ions in a particular area as compared to another area is referred to as the concentration

Concentration gradient

Explanation:

When the concentration of molecules and ions is compared to the concentration of ions and molecules in another area, the difference in the concentration will be called the concentration gradient.

The concentration gradient is the factor which determines the rate and direction of the molecules and ions in the environment which could be physical or biological.  

Thus, concentration gradient is the correct answer.

one is through turgidity. this occurs before ground tissue ( collenchyma

and sclerenchyma cells) become well

developed to give structural support to the plant as it grows bigger. the xylem

tissue (composed of rigid tissue) of the young

plant render this support and also maintaining osmotic turgidity of the surrounding

plant cells.

answer: the correct option is d. enzyme

lactase and carbonic anhydrase are the examples of enzymes.

lactase is an enzyme, which is present in the small intestine of mammals. it in the digestion of the disaccharide, lactose ( milk sugar) by converting it into two monosachharide, which are glucose and galactose.

carbonic anhydrase is present in the red blood cells. this enzyme plays significant role in the transport of co₂. it in the conversion of co₂ and h₂o into carbonic acid, which is then dissociated into bicarbonate ions and hydrogen ions.