A research assistant in a lab conditions dogs to salivate to the sound of a bell. During conditioning, the assistant rings a bell and then presents the animal with food. After conditioning the dog to salivate to the bell, the bell is the stimulus and the food is the stimulus. A) unconditioned; neutral
B) neutral; conditionedC) unconditioned; conditioned D) conditioned; unconditioned

Answer is option D (conditioned; unconditioned).

Explanation:

Classical conditioning or Pavlovian conditioning is a learning process through association in which two stimuli are connected together to produce a new learned response in an organism. It has three stages: before conditioning, during conditioning, and after conditioning.

Ian Pavlov, a Russian physiologist conducted some studies in dogs and observed that the dogs began to salivate at the taste and the sight of food, which is a reflexive reaction (no learning is involved). He had done some controlled experiments to train the dogs to salivate in response to stimuli such as a touch on the leg, the sound of a bell, a light, etc that had nothing to do with food and learned that an animal or an individual has two types of responses to its stimulus: unlearned or unconditioned responses and learned or conditioned responses.

When a research assistant in a lab presents food to a dog before conditioning, it salivates but does not produce a response to the ringing of the bell alone. Here, the food is an unconditioned stimulus (a stimulus that produces a reflexive response), salivation is an unconditioned response ( a natural, unlearned reaction to a given stimulus) and the bell is a neutral stimulus (a stimulus that does not naturally produce a response).

During conditioning, the research assistant rings a bell (neutral stimulus) and then gives food (unconditioned stimulus) to the dog immediately. The repeated process of ringing a bell and then presenting the dog with food began to elicit salivation from the dog. Thus after conditioning, the dogs began to salivate to the ringing of the bell alone in anticipation of food. The bell (neutral stimulus) became the conditioned stimulus (a stimulus that produces a response after repeatedly being paired with an unconditioned stimulus) and the behavior caused by the conditioned stimulus-i.e., salivation became the conditioned response.

only about ten percent of the energy at one trophic level is passed on to organisms at the next trophic level. the remainder of the energy is used in life processes or lost as heat.

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.