A bacterium synthesizes DNA from each replication fork at a rate of 1000 nucleotides per second. This bacterium completely replicates its circular chromosome by theta replication in 30 min. How many base pairs does the chromosome contain

180,000 nucleotide pairs = 180 kilobase pair (kbp) =  0.18 Megabase pairs (Mbp)

Explanation:  

Synthesis rate = 1,000 nucleotides (nts) x second

1 minute = 60 seconds  

30 minutes = 60 x 30 = 1,800 seconds

>> 1,800 seconds x 1,000 nuleotides per second = 180,000 nts  

A typical bacterial genome contains approximately 5 Mbps of DNA that conforms a circular chromosome localized in the cytoplasm. In consequence, in this case the bacterial genome is small (0.18 Mbp).

i think it would be b. tissue because an organ system is a group of organs that work together to perform one or more functions. each does a particular job in the body, and is made up of certain tissues.

when you breathe in, or inhale, your diaphragm contracts (tightens) and moves downward. this increases the space in your chest cavity, into which your lungs expand. the intercostal muscles between your ribs also enlarge the chest cavity. they contract to pull your rib cage both upward and outward when you inhale.