The study of tree rings is called dendrochronology. Trees produce a single growth ring each year and by studying the size and composition of each ring scientists can get information about the age of the tree, available nutrients in the area, and general climatic conditions. A relatively small ring may indicate a year when there was very little rainfall and a larger ring indicates favourable conditions for plant growth.
Ice cores hold information on past global volcanic activity and past atmospheric conditions. Tiny bubbles in the ice cores give information on the concentration of gases in the atmosphere. Ice core data plays a key role in linking the increase in carbon dioxide concentrations to present day global warming.
Most of the downsides of recombinant DNA technology are ethical in nature. Some people feel that recombinant DNA technology goes against the laws of nature, or against their religious beliefs, due to how much control this technology gives humans over the most basic buildings blocks of life.
Other ethical concerns also exist. Some people worry that if companies can pay scientists to patent, buy and sell genetic material, then genetic material could become an expensive commodity. Such a system might lead to people having their genetic information stolen and used without permission. It may sound odd, but such cases have already happened. In 1951, a scientist used unique cells stolen from a woman named Henrietta Lacks to create an important cell line (the HeLa cell line) which is still used in medical research today. Her family did not know about her involuntary donation until after her death, and never received compensation, but others have profited from the use of HeLa cells.
Many people worry about the safety of modifying food and medicines using recombinant DNA technology. Although genetically modified foods seem safe in multiple studies, it is easy to see why such fears exist.
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Answer:
a. Type O blood - No A or B antigens on RBCs-Anti-A antibodies in plasma-Anti-B antibodies in plasma
b. Type A blood - A antigen on RBCs- Anti-B antibodies in plasma
c. Type B blood - B antigen on RBCs- Anti-A antibodies in plasma
d. Type AB blood - A antigen on RBCs- B antigen on RBCs- Neither anti-A or anti-B in plasma
Explanation:
ABO blood grouping system represents multiple allelism which was discovered in humans by Karl Landsteiner. The blood group is determined by the presence or absence of A & B antigens and antibodies.
The 4 blood groups which exist in ABO system are O, A, B and AB. Also, allele A and B are co-dominant i.e. if they both will exist on the surface of an RBC then both will be equally expressed which implies that there will be no dominant or recessive allele.
Type O blood group has H antigen on the surface of RBC and has both the antibodies i.e. antibody A and B. The absence of antigens A and B makes it a universal donor.
Type A blood group has A antigen on RBC and has antibody B in the plasma.
Type B blood group has B antigen on RBC and has antibody A in the plasma.
Type AB blood group has both the antigens i.e. antigen A and B on RBC and does not have any antibody in the plasma which makes it a universal acceptor.
