In psychologist Robert Rescorla's classical conditioning experiment, one group of rats experienced a tone just before each of 20 shocks. A second group of rats experienced the same number of tone-shock pairings plus an additional 20 shocks with no tone. Rescorla found that the rats in the first group showed a much stronger conditioned fear response than the rats in the second group. How did Rescorla explain this finding

The answer is given below.

Explanation:

Rescorla explain this finding by stating that the tone experienced by the group of rats just before each of 20 shocks was a reliable predictor of the shock for the first group.

The psychologist Robert Rescorla stated in his famous classical conditioning experiment that  2 stimuli does not produce the same level and kind of conditioning.  Conditioning works in a better way, if the conditioned stimulus will act as a reliable signal that projects the appearance of an unconditioned stimulus.

answer:

the water molecules are transferred from the roots to the stem or top parts of the tall tree because of important properties of water which are adhesion, cohesion and capillary action. cohesion is the property of water molecules keeps water molecules in a combined state by sharing of bonds between them at the atomic level. adhesion allows the interaction of water molecules with other substances or substrate. adhesion will cause the attachment of water molecules to the wall of the vessel (xylem) of the plant. capillary action occurs when the adhesive force to the vessel wall is stronger than the cohesive force between water molecules. capillary action mimics the transfer of water from a tube or pipe. in this way water utilizes its property to transfer water from down to top level of the plant.  

the three components of a nucleotide are the nitrogenous base, the phosphate group and the five-carbon sugar.