What caused the main ecological problem in Costa Rica between 1963 and 1983? When did Costa Rica establish a system of nature reserves and national parks?
What is Costa Rica strategy to correct the problem?

What is a photon? a. part of a ribosome b. a light particle c. a carbon dioxide molecule d. part of a chloroplast b.a light particle

What are antigens and antibodies? how are they involved in the body’s response to incompatible blood?

Nucleus has two lobes; contains granules of lysosomal enzymes; functions in attacking parasitic worms and plays complex roles in inflammatory diseases like allergies and asthma. what blood cells are described?