Could earth's first atmosphere have supported the lives of humans and other living things of today?

What are some possible short and long term medical concerns for crew members on longer space exploration trips

Which statement about the immune system is false? a. lymphocytes reduce inflammation, b. b cells remember specific pathogens. c. most white blood cells kill bacteria d. white blood cells are made in lymph nodes.

Indicate the coat color and the proportion of offspring with that color for each of the following crosses of rabbits. assume all are homozygous. chinchilla x chinchilla 1/2 agouti, 1/2 chinchilla 3/4 agouti, 1/4 chinchilla all chinchilla