Answer:
The modern evolutionary synthesis defines evolution as the change over time in this genetic variation. The frequency of one particular allele will become more or less prevalent relative to other forms of that gene.
Explanation:
A substantial part of the phenotypic variation in a population is caused by genotypic variation.
After the macrophage fails the Helper T Cell stimulates the B cells (create antibodies) if pathogen is extracellular and Cytotoxic T Cells (killer T cells, release perforin) if pathogen is intracellular. Once the pathogen is killed the B Cells create Memory B Cells and the Killer T Cells create memory T Cells.
<span>Hope that's helpful.</span>
Jeremy is sitting quietly when the muscles in his left leg begin to “twitch.” This activation of movement in his voluntary muscles is most likely due to the release of the neurotransmitter Acetylcholine .
The primary function of acetylcholine is to carry signals from motor neurons to the body's skeletal muscles.
Answer:
Stimuli must be sensed in order to respond.
Explanation:
Classical conditioning can be defined as a learning process which typically involves repeatedly pairing two stimuli: conditioned stimulus and unconditioned stimulus.
Simply stated, it is a learning procedure that helps us to understand when a neutral stimulus is paired with a conditioned response.
An example is the process of salivating in response to the aroma of a meal being prepared in the kitchen.
Also, operant conditioning can be defined as an associative learning process which involves reinforcing the strength of a behavior.
Stimulus in biology can be defined as an obvious change in either the chemical or physical structure of an organism' environment (either external or internal). Thus, all living organisms (both animals and plants) respond to changes in their environment and consequently, an appropriate response or reaction is made. Also, stimulus arising from within the organism is known as internal stimulus while those from its environment are known as the external stimulus.
In organisms, the specialized cells that detect stimulus are generally known as sensory receptors while a group of these receptors is referred to as sense organ.
Hence, the senses are necessary for behavior because stimuli must be sensed in order to respond.
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