Which body system dose the immune system rely on to provide the first line of defense against pathogenes?
a) integumentary system
b) nervous system
c) circulitory system
d) endocrine system

Why is it important to reduce the number of chromosomes in half when forming gametes for sexual reproduction?

Which represents the cross between parent plants if one is heterozygous for yellow-colored pods and the other is homozygous for green-colored pods? yy  ´    ´    ´    ´  yy

Which is the correct order in the scientific process? ask a question ® form a hypothesis ® make an observation ask a question ® make an observation ® form a hypothesis make an observation ® form a hypothesis ® ask a question make an observation ® ask a question ® form a hypothesis