Answer:
B)attach specifically to host cell receptors
Explanation:
Viral spikes are one of the envelope proteins. These proteins are coded for by viral genes. Viral spikes project from the envelope surface. They are also called peplomers. One of the functions of these spikes is to specifically interact with the receptors present on the surface of the host cell to mediate the attachment of the virus to the host cell surface. Viral spikes and the host cell surface receptors are complementary to allow their specific binding. For example, the spike protein of the SARS-coronavirus bind specifically to the human host cell receptor ACE2.
Global warming, increase in co2 which melts land ice
Answer: Botulinum toxin
Toxins are non-living
biological and chemical agents produced by living microorganisms from animals
and plants that can cause harm to humans, plants and animals. An example of
toxin is botulinum toxin produced by the bacterium Clostridium, which is a
neurotoxic protein that prevents the release of the neurotransmitter
acetylcholine from axon endings at the neuromuscular junction and causes
flaccid paralysis.
Moreover, toxin are more
closely related to chemical warfare agents that can only affect those who are
exposed to the agent and that they are not considered as transmissible disease.