Oral polio vaccine is highly effective and inexpensive (about US$0.10 per dose, or US$0.30 per child and its availability has bolstered efforts to eradicate polio. A study carried out in an isolated Eskimo village showed that antibodies produced from subclinical wild virus infection persisted for at least 40 years. Because the immune response to oral polio vaccine is very similar to natural polio infection, it is expected that oral polio vaccination provides similar lifelong immunity to the virus.
Contact immunity to polio can occur when attenuated poliovirus derived from the oral polio vaccine is excreted, and infects and indirectly vaccinates unvaccinated individuals.
B. Density has been decreased Or D.
Stellar evolution is the process by which a star undergoes a sequence of radical changes during its lifetime. Depending on the mass of the star, this lifetime ranges from only a few million years (for the most massive) to trillions of years (for the less massive), considerably more than the age of the universe. ^
Small, relatively cold, low mass red dwarfs burn hydrogen slowly and will burn for hundreds of billions of years
Massive hot supergiants will live for just a few million years.
A mid-sized star like the Sun will remain on the main sequence for about 10 billion years. Hope tis helps!!
(D) Both perform photosynthesis is the observation that led researchers to propose that chloroplasts evolved from cyanobacteria.
Chloroplasts is the area where photosynthesis takes place. It is a green organelle in a plant cell. Pigments called the chloros in a chlorophyll are needed for the photosynthesis.
Cyanobacteria or blue-gree algae contains a blue photosynthetic pigment and a chlorophyll for photosynthesis.
Answer:
The ligand has only one receptor that it is able to bind to
Explanation:
The shape of the ligand and its corresponding receptor allow there to be specificity. For example, receptors for ligand A would be found on the target immune system cells and not on cardiac muscle cells or skin epithelial cells. Therfore, even though the cardiac muscle cells or the skin epithelial cells would be exposed to ligand A, they would not be able to bind to it and therefore could not react because of the specificity of the receptor of ligand A at that moment
