Which of the following is a trace element required only in small amounts by most living things?

Carbohydrates,the most abundant biomolecules on Earth,are produced by:

The energy transformation in the nervous system is:

Choose the correct option.
$x$ - More than $70$ percent of all the species recorded are animals.
$y$ - The number of algae species in the world is more than the combined total of the species of fishes,amphibians,reptiles,and mammals.
$z$ - India is one of the $15$ mega diversity countries of the world.

Bones of birds are:

Which of the following is produced only by plants?