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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.

Pregnancy:

    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:

a) IMPLANTATION

b) OVULATION

c) FOETUS

d) PUBERTY

e) MENSTRUATION

2. What is the function of the following?

Testis

Ovaries

Penis

Scrotum

Uterus

Fallopian tubes

Placenta

Umbilical chord

3. What is an ECTOPIC PREGNANCY?

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.

Assessment: CLASS DISCUSSION

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

[LO 1.3]

Assessment

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.

Memorandum

CLASS ACTIVITY: GROUP DISCUSSION- REPRODUCTION

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 economics important in programming world?
Abdul Reply
What is oppunity cost
Kudzanayi Reply
it refers wants that are left unsatisfied in Oder satisfy another more pressing need
Osei
Thank bro
Kudzanayi
is the second altenative to foregone
swedy
How does monopoly and imperfect competion;public goods externalities ass symmetric information, ommon property ressourses; income distribution Merit goods and Macroeconomic growth and stability causes market failure?
Gcina
it is where by a labour moves from one place to another
Amoako Reply
yh
Osei
another
Amoako
yh
Osei
ok
Amoako
what is mobility of labour
George Reply
who best defined economics
paul Reply
what are the importance of economics
Adwoa Reply
answer
Asamoah
trade should be best
Aakash
help to know how our government operates in which system
swedy
1. To solve economic problems. 2. To predict economic event. 3. It also offer intellectual training to students.
samuel
How price elasticity can affect the markets of certain goods
Rhoda Reply
Heyy thanks for the teaching
Easter Reply
what is labour
Arthur Reply
Mental and physical ability of human being is considered as labour.
JEYARAM
and usually provided by human
KEMAWOR
is all human effort both physical and mental abilities to work
Asamoah
why is it that most countries in Africa abuse available resources
Okeoghene Reply
What is economics
Bright Reply
economics is a science which studies human behaviour as a relationship between ends, scarce means which have alternative uses.
prince
Why is scarcity a mind problem in economics
Alima Reply
because of the problem of allocation of resources
Osola
unequalled distribution of resources
Agyen
thanks
Alima
scarcity is a mind problem due to circumstances like when a particular product is demand in a high rate at the market.
Saihou
scarcity defines limited in supply relative to the demand them. so scarcity is a mind problem in economics because wants are unlimited while resources are also limited.
prince
it is a mind problem because it's one of the fundamental issue address by economics human wants are unlimited and resources available are limited this makes the study of economics essential
rashid
its a fundamental issue
zahid
it's not a mind problem, I think it's a economic problem, how to allocate scarce resources to satisfy need and want of society
Samiullah
Identify the different sectors in the economy
Moses Reply
what is economics
Moses
economic is study of human behaviour according to how they satisfie their numerous want
Osola
Economics is a science which studies human behaviour as a relationship between ends and scares resources.
JEYARAM
economic is study of human behaviour according to how they satisfie their numerous want
Amar
what is the law of demand
Adugbire Reply
the lower the price the higher the quantity demanded vice versa is true
Nadhin
yes
vivek
yes ooh
Asamoah
right
samuel
what are relationship between unemployment and economic growth
Weness Reply
no relationship
Awuah
When there is economic growth, there is increased opportunity in employment. When there is no economic growth mean there is recession causing a decline or downsizing in employment opportunities.
Teescou
unemployment or employment determined by the level of economic growth
Osola
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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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