In the proton-proton cycle, the positron is
A) massless.
B) a spin conservation particle.
C) an anti-electron.
D) the chief means energy reaches the photosphere.
E) intermediate between the proton and neutron in mass.
Question 2
One of the best known craters on Earth is the Barringer Crater in Arizona. It was formed by:
A) a large volcanic eruption.
B) the same impact thought to have contributed to the extinction of the dinosaurs.
C) the impact of an asteroid whose mass was around 200,000 tons.
D) testing of nuclear bombs during the Cold War.
E) the impact of a comet whose mass was around 25 tons.
The sexual cycle of flowering plants involves alternation of sporophyte and gametophyte generations.
The life cycle of a flowering plant.
the four stages of the cell cycle
Reactions of the glyoxylate cycle
Simplified view of retrovirus life cycle
carbon cycle