PLEASE HELP The tryptophan operon in some bacteria is a repressible operon. Which of the following statements correctly describes this operon?

It is activated only when glucose is present in the growth medium.
It is deactivated whenever tryptophan is added to the growth medium.
It is activated only when tryptophan is present in the growth medium.
It is permanently active.

Which plains area lies in both the united states and canada? altiplano central canadian shield coastal plains great plains

Consider the motion of the balloon and its air contents in terms of momentum. in step 1 above, the total momentum of the balloon and its contents was zero. recall that momentum = mv. both the balloon and the air inside it had a velocity of zero and therefore the total momentum was zero. now think about what happened when the air escaped from the balloon. a certain mass of air accelerated in one direction. in order to keep the total momentum of the system zero, the balloon itself (which has mass) had to accelerate in the opposite direction. use this scenario to you explain why the soda can rotates when the water squirts out of the escape holes. what was your hypothesis concerning the water-filled can? according to your data, do you think your hypothesis was correct? (be sure to refer to your data when answering this question.) summarize any difficulties or problems you had in performing the experiment that might have affected the results. describe how you might change the procedure to avoid these problems. give at least one more example of newton's third law in everyday life.

What is the term for the two sets of chromatids formed in the parent cell a. haploid b. diploid c. gamete d. tetrad