Select the initial source or sources of carbon dioxide in earth's atmosphere

a.) volcanoes
b.) respiration
c.) meteoroids
d.) photosynthesis
e.) buring fossil fuels

Name the following: (a) category of pathogen that causes diseases, like common cold and mumps. (b) the microorganism that requires a host to produce.

Each pair of clay balls represents two planetesimals. if each planetesimal is composed of the same material and is separated he the same distance, which pair experiences the frayed gravitational attraction?

Which best describes meiosis? a. it produces cells that are identical to the original cell b. it is responsible for the replacement of damaged skin cells c. it is responsible for growth of the organism d. it produces male and female sex cells