The biological basis for assigning all human beings into a singe species is that there so many, even tons of living organisms living on earth. These organisms differ in their external and internal organs and so to differentiate them from them, they are being classified into kingdoms then classes then phylums then family.
This is (b.) False, because it was actually introduced in the 1930's.
<span>The elements that are found in a high proportion in Earth's crust are oxygen, aluminium, iron, calcium, potassium, sodium, and magnesium. But for your Option, I think it is B) Oxygen and Silicon. This is because Oxygen makes 46.6% while Silicon makes 27.7% of the Earth crust.</span>
A human has a total of 46 chromosomes (23 from daddy and 23 from mommy). :)
A sperm cell has 23 chromosomes and an egg cell that has 23 chromosomes. 23 + 23 equals 46. Sometimes (due to mutations), a person
may have less chromosomes than they need. This may cause some problems like Turner syndrome(treatment can help aid the situation but, it can't be cured).
Hope this helps you :)
Carbon dioxide is the compound in photosynthesis, I'm pretty sure
