So that means if one chromosome is composed of one DNA molecule and there are 46 chromosomes therefore 46 DNA molecules are present in each DNA. Right?

I am referring to DNA molecule (entire chain of polypnucleotide) or you can say how many chains of deoxy ribonucleic acid are found in each cell?

So you mean human cell have 46 DNA strands which are coiled to form chromosomes?

I want to know that how scientists determined function of organ for example it is said that hypothalamus of brain is responsible for controlling blood pressure, homeostasis, body temperature, hunger , thirst etc but how did they know this?

OK I will check.

But in my textbook both nutation and circumnutation are classified under nastic movements (directional) and on the other side are nastic movements(non directional) which are induced . I am preparing for entrance test of medical college.