Why is more than one reproductive isolation barrier needed to completely isolate a species?

If a set of instructions that determines all of the charactersitics of an organism is comparedto a book, and a chromosme is compared to chaper in the book, then what might be compared to a paragraph in the book?

My question says on my assignment. read the following scenarios and decide which of the properties of life are being described. the first one is. katherine stopped on the way to school to grab some donuts. 2. because a dog cannot sweat, it has to pant in order to stay cool. 3. an elephant trun had no bone but 4,000 muscles. i have no idea what i am supposed to anwer. i can't find the answer in my notes or book that i can understand anyway

Match the description of each organism to the appropriate category