A or C
Just choose any of those!
A biologist .....they study living things only.
Answer:
This means that the two separate rocks were once part of one piece of rock. These layers got separated most probably by continental drift as a result of tectonic plate movements. An example of such a fossil is the Mesosaurus, a freshwater crocodile-like reptile, that is found in Southern Africa and Eastern South America continents- that means they were once one land mass.
The environment in these two separate layers would most likely be different. As the layers drift apart from each other , they drift across latitudes that are determinants of climate in a region. Therefore, even the organisms in these two rock layers will evolve differently (even though they will share a common ancestor) in adaptation to respective environments – this is called allopatric speciation.
Answer:
The correct answer would be calcium ion and cAMP.
Secondary messengers refers to the intracellular signaling molecules which pass the signals from the receptors located on the surface of the cell to the target molecule present within the cell.
The secondary messengers can be classified into three major class:
- Cyclic nucleotide for example cAMP (cyclic adenosine monophosphate), cGMP (cyclic guanosine monophosphate)
- DAG (diacylglycerol) and IP₃ (inositol triphosphate)
- Calcium ions (Ca⁺⁺)
Hence, from the given options, calcium ion and cAMP would make the correct choice.
