H-Dev Mod 2

• cells duplicates itself 
• cell divides once
• forming two cells 
• vs
• cell duplicates its chromosomes
• cell divides twice 
• forming four cells
• (cell division occurs to form eggs and sperm)

XY  (23 pair) 

XX  (23 pair)

males Y chromosome is smaller than a females X chromosome

• Identical develop from a single fertilized egg
• more conduct problems
• more similar genetically

• fraternal twins develop from separate eggs
• less conduct problems
• less similar genetically

consist of observable characteristics 

• height
• weight
• hair color

is a form of intellectual disability caused by the presence of an extra copy of chromosome 21

genetic disorder that impairs the functioning of the body's red blood cells

brain functioning technique

the inability to conceive a child after 12 months of regular intercourse without contraception

correlation exists when the natural parents who are genetically related to the child, provide rearing environment for the child

states that development reflects an ongoing, bidirectional interchange between heredity and the environment