Answer to Question 1
D
Answer to Question 2
The first stages are similar to those of a low-mass star, except that they happen over much shorter time periods. While on the main sequence, the star fuses hydrogen by the CNO cycle and remains at this stage only for several million years. In addition to helium fusion, high-mass stars also undergo alpha-capture, which creates heavier elements by fusing a helium nucleus with an existing atom. After helium is used up in the core, the core contracts while helium and hydrogen fusion continue in outer shells. The core contracts until carbon ignition occurs, and the star moves left again on the H-R diagram while carbon fusion occurs in the core. The process continues for stars of still higher mass, zigzagging across the H-R diagram as heavier elements are fused in the core and used up as fuel. Each fusion stage requires less time until iron is finally produced in the core. Iron cannot be fused to produce energy, so the core collapses and pressures increase so that electrons and protons are converted to neutrons. A high quantity of neutrinos is released, which may help force the outer layers violently outward in an explosion called a supernova. Elements heavier than iron are created, the outer layers move away from the core at great velocities, and only a neutron star or black hole is left as a remnant.
Testing the reducing atmosphere hypothesis for the origin of life - the Miller and Urey experiment.
Two main types of nerve cells.
Origin of T cells, B cells, RBCs, WBCs, and platelets.
Glacial deposits overlain by marine carbonates formed in very warm water
Main lymph nodes of the leg
Calculate the pH of a solution formed by mixing 120.0 mL of 0.30 M HClO with 1180.0 mL of 0.20 ...