Q: What percentage of all species that ever lived on earth have gone extinct? Choices: - 25% - 50% - 93 % - 99% A:
99%

Q: Metabolism is controlled by regulation of what? Choices: - sequence activity - nucleus activity - cell activity - enzyme activity A:
enzyme activity

Q: Q: When a warm air mass becomes trapped between two cold air masses, what type of front occurs? Choices: - storm front - obscured front - stationary front - occluded front A:
A: occluded front

Question: Q: Living things need to take in nutrients so that they can grow and create what? Choices: - protein - plasma - hydrogen - energy A:
Answer: energy

*Question*
Q: An atom can be classified as a particular element based solely on its what? Choices: - light number - spectrum - ability - atomic number A:
**Answer**
atomic number

(Q).
Q: Which group of species is defined as having moist skin without scales? Choices: - fish - mammals - reptiles - amphibians A:
(A).
amphibians