Answer:
Hydrogen bonding is caused by the tendency of some atoms in molecules to attract electrons more than their accompanying atom. This gives the molecule a permanent dipole moment – it makes it polar – so it acts like a magnet and attracts the opposite end of other polar molecules.
Answer: the first one
Explanation: the rest are very wasteful :)
Answer: Layer a is 500 million years old.
Explanation:
Trilobite is a member of the group of extinct arthropods found as fossils and they can be identified by the three-lobed as well as three segmented forms. These were the marine animals. These were appeared initially in the Cambrian Period. They used to live 542 million years ago so the fossils can be estimated to be aged of 500 above years old. These animals used to dominate in the sea area.
Answer:
IgM, IgA, IgE, IgD and IgG
Explanation:
IgM functions in the initial response to offence.
IgA is important for protection of mucus membranes such as in saliva, sweat, tears and gastric fluid.
IgE is active during allergic reactions and defense against infections.
IgD is found on the surface of lymphocytes and is activated upon contact with antigens.
IgG forms part of the secondary response to antigen and is also responsible for newborn protection.
