Answer:
In cellular biology, active transport is the movement of molecules across a cell membrane from a region of lower concentration to a region of higher concentration—against the concentration gradient.
Explanation:
I hope I helped
For radioactive materials with short half-lives, you use a very sensitive calibrated detector to measure how many counts per second it is producing. Then using the exact same set up you do the same at a latter time. You use the two readings and the time between them to determine the half-life. You don’t have to wait exactly a half-life, you can do the math with any significant time difference. Also, you don’t need to know the absolute radioactivity, as long as the set up is the same you only need to know fraction by which it changed.
For radioactive materials with long half-lives that won’t work. Instead you approach the problem differently. You precisely measure the mass of a very pure sample of the radioactive material. You can use that to calculate the number of atoms in the sample. Then you put the sample in a counter that is calibrated to determine the absolute number of disintegrations happening in a given time. Now you know how many of them are disintegrating every second. You use the following equations:
Decays per Second = (Number of Atoms) x (Decay Constant)
Half-life = (Natural Log of 2) / (Decay Constant)
And you can calculate the half-life
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The correct answer is: d. it contains many light-sensing columns called ommatidia
Ommatidia are units that form compound eyes of arthropods such as insects, crustaceans and millipedes (these are invertebrates) and make them very sensitive to motion. Ommatidia are composed of photoreceptor cells (visual detection) surrounded by support cells and pigment cells.
The eyes of vertebrates are more complex showing that progressive improvements in the structure of the eye occurred during the evolution.
Hydrolase
This is because it catalyzes a hydrolysis reaction.
