AP BIOLOGY

Detailed explanation-1: -Chemotaxis, the directed migration of cells in response to external chemical gradients is crucial for the survival of single-cell organisms, as it enables them to search for nutrients. Cells in multicellular organisms rely on gradient sensing and chemotaxis during development, and as part of the innate immune response.

Detailed explanation-2: -Chemotaxis is the directed motion of an organism toward environmental conditions it deems attractive and/or away from surroundings it finds repellent. Movement of flagellated bacteria such as Escherichia coli can be characterized as a sequence of smooth-swimming runs punctuated by intermittent tumbles.

Detailed explanation-3: -Chemotaxis (from chemo-+ taxis) is the movement of an organism or entity in response to a chemical stimulus. Somatic cells, bacteria, and other single-cell or multicellular organisms direct their movements according to certain chemicals in their environment.

Detailed explanation-4: -1.7 Chemotaxis. Chemotaxis is the movement of organisms in response to a nutrient source or chemical gradient. Cells with chemotatic capabilities can sense xenobiotic chemicals adsorbed to soil particles and swim toward them, thereby overcoming the mass-transfer limitations in the bioremediation process (Fig. 28.6).

Detailed explanation-5: -The same basic system mediates responses to a wide range of different chemicals including nutrients such as amino acids, peptides, and sugars (which are usually attractants) and toxic compounds such as phenol and acid (generally repellents).