Question

carbon 14 degrades to form nitrogen and has a half life of 5730 years. as a single millenium (1000 years) passes, in a bone (which contains carbon isotopes in the proportions normally found on earth), what should happen to the amount of carbon 14 relative to the amount of nitrogen over that time?
it will increase as the amount of nitrogen also rises
it will decrease as the amount of nitrogen rises
it will decrease as the amount of nitrogen decreases
both will remain the same
40 multiple choice 10 points
which of the following is a mammal?
echidna
cow
kangaroo
all of the above
41 multiple choice 10 points
during which period did most of the major animal phyla (phylums, such as chordata, arthropoda, etc) develop?

Explanation:

First Question (Carbon - 14 Degradation)

Carbon - 14 undergoes radioactive decay to form nitrogen. As time passes (here, 1000 years), the amount of Carbon - 14 decreases because it is decaying, and the amount of nitrogen increases as a product of this decay. So we analyze each option:

• Option 1: Carbon - 14 doesn't increase as it's decaying, so this is wrong.
• Option 2: Carbon - 14 decreases (due to decay) and nitrogen increases (as a decay product), so this is correct.
• Option 3: Nitrogen should increase, not decrease, so this is wrong.
• Option 4: Both can't remain the same as decay is occurring, so this is wrong.

• Echidna: It is a monotreme mammal (lays eggs but has mammalian characteristics like milk production).
• Cow: It is a placental mammal, has fur (or hair), gives live birth, and produces milk.
• Kangaroo: It is a marsupial mammal, gives birth to underdeveloped young that develop in a pouch and produces milk.

So all of these are mammals.

Answer:

It will decrease as the amount of nitrogen rises

Second Question (Which is a mammal)