4-2 Sexual Reproduction and Meiosis Part I
Name _________________________
Define the terms:
Sexual Reproduction: ______________________________________________________________________
Sperm: __________________________________________________________________________________
Egg: ____________________________________________________________________________________
Fertilization: ______________________________________________________________________________
Zygote: __________________________________________________________________________________
Haploid: _________________________________________________________________________________
Diploid: _________________________________________________________________________________
Meiosis: _________________________________________________________________________________
The joining of a sperm cell and an egg cell is called (1)_____________________. The new diploid cell formed
when the egg and sperm combine is called a (2)___________________. Since the zygote is diploid the egg and
sperm must have been (3)_______________. In humans, body cells like brain, skin and bone etc. are diploid
having (4)_______ chromosomes, but the egg and sperm must be haploid having (5)______. Since the egg and
how many ?
how many ?
sperm cells are haploid while the other cells in the body are diploid, a special process (different than mitosis) is
needed to produce them called (6)_____________. This process happens in 8 phases unlike mitosis which
happens in only 4 phases. At the very beginning of meiosis in HUMANS, a special kind of cell (germ cell)
starts out with the normal number of 46 chromosomes; it is described as being (8)__________ at the start. The
first 4 meiosis phases are called (9)______________ _____ and look very similar to mitosis except there is a
key difference: the (10)________________ DO NOT separate yet. These first 4 phases produce (11)_______
how many ?
cells. The following 4 phases are called (12)______________ ____ and another cell division takes place at
which time the (13)___________________ DO separate. These last 4 phases result in a total of (14)_________
how many ?
cells by the end of meiosis. These final cells produced through meiosis can now be described as being
(15)_____________ because they have half the number of chromosomes found in typical body cells. In
HUMANS these cells will have (16)______ chromosomes.
how many ?
In summary, for humans the egg and sperm are described as (17)_______________ because they have
(18)_______ chromosomes (half the typical number) unlike the rest of the body cells which are described as
how many ?
(19)_______________ because they have (20)________ chromosomes; the typical number found in regular
how many ?
human cells. When an egg and sperm join, the event is called (21)___________________ and produces a new
unique cell called a (22)_________________. This new cell will divide by mitosis and develop into the new
organism. This whole process is called (23)_______________ ___________________. The process that
produces the haploid egg and sperm is called (24)________________. It happens in 8 phases the first 4 called
(25)______________ _____ and the last 4 called (26)______________ _____. The first 4 produce
(27)________ cells but by the end of the 8 phases there are (28)_______ cells. The final cells if produced in a
how many ?
how many ?
male are called (29)______________ cells and if produced in a female are called (30)___________ cells.
Question 1: House flies have 12 chromosomes in their body cells. How many chromosomes are in the haploid
sex cells of this organism? (31)_________
Applying Science / page 109: (“Solving the Problem” questions)
how many ?
1. _________
2. _________
3. __________________________________________________________
4. _____________________________________________________________________________________
SKIP QUESTION 2 FOR NOW AND THEN RETURN HERE ONCE THE NOTE PACKET IS COMPLETE
AND ANSWER QUESTION 2
Question 2: There are persons out in the world who have a slightly different number of chromosomes than one
might normally expect. For instance, some people are born with all their cells having 47 chromosomes. Given
what you have learned about meiosis, what explanation can there be for such an outcome?
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4.2 Sexual Reproduction and Meiosis Part II
SUMMARY OF MEIOSIS: (paraphrase from pg 109)
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Sex Cells
A
B
C
D
Using complete sentences, explain in what phase meiosis goes wrong and what exactly happens that you can see
is an error in the diagram above. Now, what is the resulting chromosome #’s for each sex cell produced?
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Fill in caption(s) below
“During _____________ ___________________,
two sex cells, sometimes called an __________
formed in the female reproductive organs and a ____________ formed in the
male reproductive organs join forming a new cell called a ______________”.
GO BACK AND ANSWER QUESTION 2 AT THIS TIME