Today's atmosphere on Earth is made up of nitrogen, oxygen, carbon dioxide, and water. According to all models, which of these was largely absent 3.8 billion years ago?
A) nitrogen
B) carbon dioxide
C) oxygen
D) water
Answer: C
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The vascular bundles in eudicot stems separate the ground tissue into two zones. Which sequence correctly describes the arrangement of those zones from the outside to the center?
a. epidermis ? vascular bundle ? pith ? cortex b. pith ? vascular bundle ? cortex ? epidermis c. epidermis ? cortex ? vascular bundle ? pith d. epidermis ? vascular bundle ? cortex ? pith e. cortex ? epidermis ? vascular bundle ? pith
The endoplasmic reticulum
A. functions in internal transport of macromolecules. B. carries on cellular respiration. C. is the site of photosynthesis. D. is dispersed nuclear material of DNA and protein.
The slow build-up of differences in the genes between populations is ______.
a) vicariance b) genetic divergence c) dispersal d) genetic equilibrium
Ebola hemorrhagic fever is caused by which type of virus?
A. filovirus B. rhabdovirus C. paramyxovirus D. rubulavirus E. pneumovirus