Name:______________________________
Chapter 4.2
Sexual reproduction and meiosis
Life Science
Pgs.
Sexual reproduction
During sexual reproduction __________ _____________ _______________, or an egg and a
sperm, come together.
Sperm are formed from ________________.
Eggs are from _________________.
Fertilization – the ___________________ of sperm and egg
Zygote – ___________________ that ____________________ after the sperm and egg
____________________.
Diploid cells
There are 2 types of cells – ________________ cells and ______________ cells.
A body cell in humans has _____________ chromosomes. These cells make up all the parts of an
organism.
If a cell has the _________________ of _______________________ that a body cell has it is
called a ___________________ cell.
Body cells in human have _________ chromosomes or 23 pairs.
Haploid cells
Sex cells ________ _______________ have _________________ of chromosomes. They are said
to be __________________ – they only have __________________- the number of
chromosomes that body cells have.
Human haploid cells have _____________ chromosomes.
Meiosis and sex cells
Meiosis – the process to _________________ ______________ cells.
Why is this an important process? If each parent pass on a _________________ cell – so in
human 46 chromosomes - the offspring would have _____________ the number of chromosomes –
____________________.
Animals ________ _______________ always __________________ if they have more
chromosomes than they should.
Meiosis makes sure that ____________________ have the _________________ number of
______________________.
Meiosis 1
In meiosis 1 ______________________ _______________________ and they follow mitosis
process. The end of meiosis 1 is we will have _____ cells with ___________________
chromosomes.
Meiosis II
The cells formed in meiosis 1 go on to further divide to end with ___________
___________________ cells.
Mistakes in meiosis
Mistakes in haploid cells can produce sex cells with ___________ ______________ or
_____________ ____________________ chromosomes. This will produce offspring that will
__________or not be able to grow normally.