Summary A level biology unit 4B

Fill in the gaps:
Normal body cells have the
_____ number (__) of ________.
This means each cell contains
____ of ___________ (a ___),
one from the ______ and one
from the _______.


4.1
4B ZQ

,• Normal body cells have the
diploid number (2n) of
chromosomes
• This means each cell
contains two of each
chromosome (a pair), one
from the biological mother
and one from the biological
father

,Fill in the gaps:
The _____ that make up each _____
are _____ and ________ (but they
could _____________). These pairs
of ________ are called _________.
Humans have _______ and so
__________ in total. Therefore, the
_______ for humans is ___.


4.1
4B ZQ

, • The chromosomes that make up
each pair are the same size and have
the same genes (but they could have
different versions of those genes
called alleles)
• These pairs of matching
chromosomes are called
homologous pairs
• Humans have 23 homologous pairs
and so 46 chromosomes in total
• Therefore, the diploid number for
humans is 46 chromosomes