Differentiate between body cells and gametes: Compare autosomes and sex chromosomes:
Compare the two cycles of division in meiosis:
Describe how haploid cells develop into gametes:
Explain how crossing over during meiosis increases genetic diversity:
Compare mitosis and meiosis:

the nitrogen cycle provides nitrogen to the ecosystem from the atmosphere, ground and oceans. nitrogen is an important component of complex molecules such as amino acids and nucleotides, which lead to the creation of proteins and dna, the building blocks of all life. plants absorb nitrogen in the form of ammonium, nitrate ion and, on rare occasions, as amino acids. animals receive nitrogen necessary for biological processes from feeding on living or dead organic matter.

label a:   the core

label b : the chromosphere

label c : the photosphere

label d: the corona