Answer:
Cell surface receptors (membrane receptors, transmembrane receptors) are receptors that are embedded in the plasma membrane of cells. They act in cell signaling by receiving (binding to) extracellular molecules. They are specialized integral membrane proteins that allow communication between the cell and the extracellular space.
Explanation:
Answer:
Sistemas orgánicos
Explanation:
Aunque cada órgano del cuerpo realiza sus funciones específicas, los órganos también funcionan juntos por grupos, a los que se denomina sistemas orgánicos (ver Principales sistemas orgánicos). Los médicos clasifican las enfermedades y sus propias especialidades médicas de acuerdo a los diferentes sistemas orgánicos.
Answer:
sporopollenin
While the exine is composed of sporopollenin, a complex and highly resistant biopolymer containing fatty acids, phenylpropanoids, phenolics and carotenoids, the intine is largely composed of pectin and cellulose.
Explanation:
<u>Answer:</u>
Cyanobacteria start producing pure oxygen around 200 million years ago.
<u>Explanation:</u>
Many scientists believed that Earth did not have any oxygen. Cyanobacteria or the blue green algae are the microbes which produced oxygen for the first time with the help of photosynthesis. This was around 4.5 billion years ago: after Hadean eon.
They were very simple, but they produced oxygen in the early earth’s atmosphere. So, they brought evolution on earth. This “blue-green algae” exists in salt water, rocks and soils and play a major role in maintaining the ecosystem.