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Natural sciences

Grade 9

Life processes: healthy life

Module 7

Human reproduction

  • Reproduction is the process by which offspring are created.
  • During this process, GAMETES (generative sex cells) have to unite.
  • The male gametes are called SPERM CELLS and female gametes are OVA , or egg cells. Both gametes carry the genetic characteristics of the new individual.

Sperm cell and ovum

  • In both sexes, gametes only begin to be produced after PUBERTY . Hormones from the brain control maturation.
  • The cells are formed in the sexual organs, namely in the TESTES of the male and in the OVARIA of the female.

Male sexual organs:

    1. 2 TESTES in the external SCROTUM
  • SPERM TUBES that carry sperm cells from the testes to the PROSTATE GLAND and other glands.
  • The PENIS , which is responsible for transferring the SEMEN (sperm cells and nutrients) to the female system. The release of semen is called EJACULATION .

Female sexual organs:

    1. Two FALLOPIAN TUBES for guiding the ova from the ovaries. FERTILIZATION normally occurs here.
  • A UTERUS situated just behind the bladder and in which an infant will develop.
  • A VAGINA that receives the sperm cells from the penis and which also serves as birth canal.

Male and female sexual organs:

The menstrual cycle:

    1. A cycle that commences in girls once they have reached puberty (commencement varies between the ages of 10 and 15).
  • This cycle prepares the female body for possible pregnancy.
  • It involves the thickening of the ENDOMETRIUM inside the lower portion of the uterus in the area where an embryo will attach itself.
  • Various hormones such as progesterone and ESTROGEN are involved in preparing the body for possible pregnancy. The levels of these hormones rise and recede and cause a variety of changes that may be very uncomfortable for a girl, e.g. moodiness, tenderness of the breasts, water retention.
  • Halfway through the cycle, the egg cell (ovum) is released from the ovary. This is known as ovulation .
  • The normal duration of the cycle is 28 days. At the end of this period the endo­metrial layer loosens from the uterus and is discarded. This casting off of the endometrial tissue is known as MENSTRUATION and the process takes 3 to 7 days.
  • Girls use protective sanitary pads or tampons to absorb the flow of blood.

Fertilization: the combination of a male sperm cell with a female ovum to form a zygote

    1. This occurs in the Fallopian tube
  • A special chemical membrane develops immediately to prevent other sperm from penetrating the ovum.


    1. The zygote immediately begins to divide repeatedly to form an embryo .
  • A chemical message that travels through the woman’s body stimulates further changes.
  • The developing EMBRYO attaches itself to the ENDOMETRIUM , the lining of the wall of the UTERUS . This process is known as IMPLANTATION .
  • A PLACENTA develops where the embryo is attached and this nourishes the embryo while it is developing into a foetus. The foetus is attached to the placenta by means of the UMBILICAL CHORD .
  • The developing foetus is supplied with nutrients and oxygen through the UMBILICAL CHORD and waste materials from the foetus, like carbon dioxide, are also removed through this chord.
  • When the embryo is nine weeks old, it is called a FOETUS.
  • The development of the foetus is completed in approximately 280 days or 9 months.

Class Activity: Discussion on reproduction

1. Explain what is meant by:






2. What is the function of the following?






Fallopian tubes


Umbilical chord


4. Explain how the following sets of twins develop:

a) identical or monozygotic (uniovular) twins;

b) non-identical or dizygotic (fraternal) twins

c) Siamese twins

5. What determines whether the baby will be male or female? Explain.


Were you able to complete the table and answer the questions?

[LO 1.3]


Learning Outcomes 1 : Scientific Investigation

The learner will be able to act confidently on curiosity about natural phenomena, and to investigate relationships and solve problems in scientific, technological and environmental contexts.

We know this when the learner:

  • evaluates data and communicates findings.



1. a) implantation of embryo into the wall of the uterus

b) release of ovum from ovary

c) developing embryo after two months

d) sexually mature phase in boys and girls

e) shedding of preparatory layer in the monthly cycle

2. Complete:

Umbilical cord Tube connecting foetus and placenta

3. a pregnancy in which the embryo is implanted in the wall of the Fallopian tube instead of the uterus

4. a) a single zygote that divides early in its development – identical information; always of the same sex

b) two zygotes and two different sperm cells; two different individuals

c) uncompleted identical division

5. father donating X or Y chromosome

Questions & Answers

Is there any normative that regulates the use of silver nanoparticles?
Damian Reply
what king of growth are you checking .?
What fields keep nano created devices from performing or assimulating ? Magnetic fields ? Are do they assimilate ?
Stoney Reply
why we need to study biomolecules, molecular biology in nanotechnology?
Adin Reply
yes I'm doing my masters in nanotechnology, we are being studying all these domains as well..
what school?
biomolecules are e building blocks of every organics and inorganic materials.
anyone know any internet site where one can find nanotechnology papers?
Damian Reply
sciencedirect big data base
Introduction about quantum dots in nanotechnology
Praveena Reply
what does nano mean?
Anassong Reply
nano basically means 10^(-9). nanometer is a unit to measure length.
do you think it's worthwhile in the long term to study the effects and possibilities of nanotechnology on viral treatment?
Damian Reply
absolutely yes
how to know photocatalytic properties of tio2 nanoparticles...what to do now
Akash Reply
it is a goid question and i want to know the answer as well
characteristics of micro business
for teaching engĺish at school how nano technology help us
Do somebody tell me a best nano engineering book for beginners?
s. Reply
there is no specific books for beginners but there is book called principle of nanotechnology
what is fullerene does it is used to make bukky balls
Devang Reply
are you nano engineer ?
fullerene is a bucky ball aka Carbon 60 molecule. It was name by the architect Fuller. He design the geodesic dome. it resembles a soccer ball.
what is the actual application of fullerenes nowadays?
That is a great question Damian. best way to answer that question is to Google it. there are hundreds of applications for buck minister fullerenes, from medical to aerospace. you can also find plenty of research papers that will give you great detail on the potential applications of fullerenes.
what is the Synthesis, properties,and applications of carbon nano chemistry
Abhijith Reply
Mostly, they use nano carbon for electronics and for materials to be strengthened.
is Bucky paper clear?
carbon nanotubes has various application in fuel cells membrane, current research on cancer drug,and in electronics MEMS and NEMS etc
so some one know about replacing silicon atom with phosphorous in semiconductors device?
s. Reply
Yeah, it is a pain to say the least. You basically have to heat the substarte up to around 1000 degrees celcius then pass phosphene gas over top of it, which is explosive and toxic by the way, under very low pressure.
Do you know which machine is used to that process?
how to fabricate graphene ink ?
for screen printed electrodes ?
What is lattice structure?
s. Reply
of graphene you mean?
or in general
in general
Graphene has a hexagonal structure
On having this app for quite a bit time, Haven't realised there's a chat room in it.
what is biological synthesis of nanoparticles
Sanket Reply
how did you get the value of 2000N.What calculations are needed to arrive at it
Smarajit Reply
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Source:  OpenStax, Natural sciences grade 9. OpenStax CNX. Sep 15, 2009 Download for free at http://cnx.org/content/col11069/1.1
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