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Name ___________________________ Period________ Score:________=________%
40
The Story of Conception
Directions: Use the word bank below to complete the story with the correct terms.
umbilical cord
egg cell
trimesters
amniocentesis
fetus
breeched
conception
placenta
dominant traits
chromosomes
amniotic sac
missed period
ultrasound
genes
zygote
pregnancy
sperm cell
water breaks
recessive traits
afterbirth
X
Y
XX
embryo
XY
X
40
23
46
The female sex cell is called the (1)__________________ and always carries the
(2)_____ sex chromosome. The male sex cell is called the (3)____________________ and
could carry the (4)_____ or (5)_____ sex chromosome, and therefore, determines the sex
of the baby. There are 46 chromosomes in normal body cells, but only (6)______
chromosomes in the sex cells.
When the male sex cell penetrates the female’s sex cell, this is called fertilization or
(7)____________________________. The single cell that is formed by this union is
called a (8)__________________________, which contains all the genetic material from
both the mother and the father. The female will suspect she is pregnant because she will
have a (9)_______________________________.
Within 24 hours after conception, this single cell goes through cell multiplication and
becomes a larger mass of cells called an (10)____________________________. This
multi-celled mass travels to the uterus to find a nice, cushy spot on the uterine lining. The
outer edges of the cell mass will grow into the uterine lining forming a
(11)_______________________ which will keep the mass of cells attached to the uterine
wall. This structure also filters nutrients and oxygen from the mother’s blood and sends
them to the cells through the (12)_______________________________, which is like a
life-support system to the growing baby. The baby is surrounded by a thin, but strong
membrane called the (13)____________________________________, which cushions
and protects it and regulates the temperature inside. After about two months of
development, the mass of cells starts to take on human-like features, and is now called a
(14)______________________.
The baby will continue to grow for another 7 months until it is fully developed. This
total 9-month (or 40-week) period from the time conception occurs until the baby is ready
to come out of the body is called (15)__________________________. It is divided up
into 3 three-month periods called (16)_____________________________, which help
doctors to monitor the baby’s growth.
To determine whether there are any genetic abnormalities in the fetus, fluid is drawn
from the amniotic sac in a procedure called an amniocentesis. The chromosomes in the cells
that have fallen from the fetus’ skin are paired up and analyzed. The 23rd pair of
chromosomes, the sex chromosomes, can also be analyzed to find the sex of the baby. If
the 23rd pair of chromosomes has an (17)________ combination, then this is the genetic
code for a girl. If the 23rd pair of chromosomes has an (18)______ combination, then this is
the genetic code for a boy.
Each sex cell has twenty-three (19)_____________________________________
that carry (20_____________________, which contain the genetic codes that determine
the characteristics the baby may have. The characteristics that show up most often in
babies are considered to be dominant, and those that show up less often are called
(21)_________________________________.
At the end of the pregnancy, a female will know she’s about to give birth because her
(22)___________________________________. If the baby is not in the normal upside
down position, it is called a (23)_________________________ birth and the mother may
need to have a C-section. Shortly after the birth of the baby, the placenta will also be
pushed out of the womb, which is known as the (24)______________________________.
Directions: Number the stages of pregnancy and childbirth in the correct order that
they occur. (9 points)
_____ Embryo is now called a fetus
_____ Cells multiply to form the placenta
_____ The fertilized egg implants itself
_____ Pregnancy is full term
_____ The egg and the sperm cell join
_____ The baby Is referred to as an embryo
_____ Placenta and umbilical cord are pushed out
_____ The cervix dilates to 10 cm
_____ The baby is pushed out
Directions: Label the structures you see in the diagram.
1._____________________________
2._________________________
____________________________5.
3.______________________
4.__________________________
Word Bank
fetus
amniotic sac
umbilical cord
cervix
birth canal
uterus
placenta
____________________________6.
______________________________7.