Adisease breaks out among sheep in california. a scientist takes blood from the sheep and grows a previously unknown organism. that organism is then injected into a healthy sheep. the healthy sheep becomes sick with the same symptoms as the original sheep and dies. that sheep's blood is then cultured, and the original organism is isolated. this applies the principles of
a) spontaneous generationb) koch's postulatesc) epidemiologyd) vaccination

The correct answer is b) Koch's postulates

Explanation:

Koch has given some postulates which determine whether a particular bacteria is a cause of a particular disease or not. The Koch postulates are as follows :

1. In every disease bacteria(microbe) is present.

2. This bacteria can be isolated from the host and can be grown in a pure culture.

3. This pure culture of bacteria if injected in a healthy host then it will cause that specific disease in the healthy host.

4. The bacteria can be recovered from the host again.

Therefore in the given question, Koch principles are applied.

c) 50% there are four chromosomes. after crossing over, 2 of the four have been changed. that means any gamete has a 2 in 4 chance or 50% chance of receiving the mutated chromosome.