Krebs and colleagues identified the intermediates in a series of experiments where they took short chain acids known to be in the cell and added them to enzyme extracts from eukaryotic sources. How would they know if a given acid was an intermediate?

vascular tissue transports materials from the environment into the plant.

as resources become scarce because of population growth, the growth decreases after few years due to lack of resources and food.

the answer is; comparing the frequency of collisions with and without the device

this makes the anti-collision system an independent variable and the collisions a dependent variable. if there are fewer collisions with an anti-collision system that without, then it can be stated that the system is a success. essentially, collisions under an anti-collision system are compared with the frequency of collisions by cars with the human drivers.

the level of progesterone is low at the pre-ovulatory phase of the cycle but it gradually increases and the levels are high at the luteal phase. if pregnancy occurs, the level of progesterone will be high throughout the pregnancy.

if egg is fertilized and the mother gets pregnant, progesterone starts preparing the uterus for the implantation. it starts building up the lining of uterus and make it hostile of the period of pregnancy.