Plesiadapiforms
are organisms that may have been the first primates. This group of primates underwent an adaptive radiation which enable them to produce forms with very distinctive features including weird, multi-cusped incisors and a variety of very sepcialized lower premolars.
The first record of plesiadapiforms appeared just as the non-avian dinosaurs were about to be extinct 65 million years ago, near the inception of the Paleocene age. Some of these primates persisted well into the epoch of Eocene with the last of its species extincting around 37 million years ago.
Answer:
a mucus or a gelatinous sheath
Explanation:
Most species of cyanobacteria are enclosed in a gelatinous sheath which is made up of proteins.
Answer:
A presynaptic neuron knows when and how much of a certain neurotransmitter it has to release into the synapse by the frequency of the action potential.
Explanation:
Two nuerons connect to each other through synapse. When an action potential, or nerve impulse, arrives at the axon terminal, it activates voltage-gated calcium channels in the cell membrane, then the calcium which is present in hi highconcentration outside the neuron than inside, rushes into the cell. The Calcium then allows synaptic vesicles to fuse with the axon terminal membrane, releasing neurotransmitter into the synaptic cleft.
The nuerotransmitter than binds to the receptors at the post-synaptic cleft and causes the opening or closing of the channels, hence, depolarizing or hyperpolarizing the cells.This can produce a change in the membrane potential—voltage across the membrane of the receiving cell.
This is beneficial and is actually an adaptation of humans to climates with larger amounts of sunshine. The darker color of skin helps prevent damage such as sun burn.
Formation of island chains occurs when convergent boundaries interact and is denoted as option A.
<h3>What is Convergent boundary?</h3>
This refers to an area where two or more lithospheric plates collide in the earth.
When the y interact, island chains are formed which consists of sea with sparse islands around the area.
Read more about island chains here brainly.com/question/12433780
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