A. <span>Exposure to an antigen
Exposure to viruses and antigens led to the foundation of modern vaccination. Vaccination introduces an antigenic material that helps the ability of the immune system to adapt a specific pathogen, therefore leading to a long-term immunity.</span>
Correct answer: True
The coral reefs are made up of thousands of tiny animals called as polyps. These are related to anemones and jellyfish. It possesses a sac-like a body and an opening which is encircled by the stinging tentacles called as cnidae.
They use calcium and carbonate ions which are derived from the seawater to in order to make a hard, cup-shaped skeleton. It protects the soft and delicate body of the polyp.
Hence, the correct answer would be true
the third answer is the correct answer.
Answer: The correct answer is- Chlorophyll a.
Chlorophyll is a green pigment that is found in the chloroplast of green plants and algae.
Chlorophyll a is considered as the primary pigment for photosynthesis as it is present in all photosynthetic eukaryotes.
In the first phase of photosynthesis (formation of food using carbon dioxide and water in the presence of sunlight), which is a light dependent phase, chlorophyll absorbs the solar energy and converts it into chemical energy in the form of ATP, and NADPH.
This energy is further utilized in the next phase (that is a light independent phase of photosynthesis) in formation of food (glucose) .
All the spheres are included in the biosphere
