<span>Because the bases can be arranged in many different combinations</span>
Explanation:
Pancreas functions as both endocrine and exocrine gland. Hence, called as dual function gland or a mixed gland. Exocrine part of pancreas secretes digestive enzymes while, its endocrine part (islets of Langerhans) produce two hormones, i.e. insulin and glucagon.
<span>Botulinum toxin does not bind to receptors presemt at the axon terminal in order to enter the neuron. It is a neurotoxin protein produced by Clostridium botulinum which is a bacterium. It prevents the release of neurotransmitter from axon endings that results to flaccid paralysis.</span>
<span>a. an element is a substance that cannot be broken down</span>
