Which organism can change its sex?

If the fossil of an organism is found in the deeper layers of the Earth,then we can predict that:

Who studied inheritance of traits in pea plants? Why did he select the pea plant? Which trait gets expressed in the first generation? In what ratio,traits with two contrasting characters get expressed in the second generation?

Which of the following statements is not true with respect to variation?

Which of the following statements is not true with respect to variation?

$A$ palaeontologist (a scientist who studies fossils) finds the fossil of an organism in a deeper layer of the Earth. What method will they use to estimate its age?