well...
-do u agree that parents/adults r suggesting that the schools r starting sex education too?
-do u agree that ur parents are not comfortable discussing such issues wif u n give distorded information instead?
or
-do u hav any misunderstanding(lack of understanding) or any doubts(confusion to clear) on such issues?
wad about dis?
-u wnt to noe mre about sexual reproduction in human beings?
if u agree to any of the above qns, U R AT DE RITE SITE!
hu r we?
well...
we r BERMUDA RAECTANGLE n we r students fr JSS currently doing project on topics regarding sexual reproduction n related topics.
we hope that the inforamtion we have here r able to clarify(clear) ur doubts n give u a clearer picture if wad's happening.
About BERMUDA RECTANGLE! [team members]
name: Lim Lay Ping
name:Jasmine Ngoh
name: Koh Eng Leng
name: Lucas Lim
school: JURONG SECONDARY SCHOOL
class: 2-1'08
interest: we share a common interest n tt's BIOLOGY cos..... BIOLOGY ROCKS!
Mini Bio
SPECIAL FEATURES!
video
mindmap
quizzes
OMG! corner
colourful wordings to capture attention
and many mre(:
Tuesday, September 2, 2008
Know your body (: Topic: reproduction in human beings, fertilization, heredity, gestation.
Now, after knowing your body (reproductive system, are you now much more confident to move on? I’m sure you are. Let’s venture (explore) deeper into the topic!
What is reproduction?
è It is the process of producing new offsprings to sustain a species.
If organisms do not reproduce, they will become extinct.
-Human beings have sex cells for reproduction; reproduction involving sex cells is
called sexual reproduction.
In sexual reproduction, male and female sex cells are needed.
The human male sex cell is called a sperm.
The human female sex cell is called an ovum or an egg
èUnlike other cells, the nuclei of sex cells contain only half the number of chromosomes. There are 23 single chromosomes instead of 23 pairs (46) of chromosomes.
| Sperms | Ovum/ egg |
| -Smallest in the body | -largest cell in body |
| -able to swim with the help of a tail | -unable to move by itself. |
| -millions released at each ejaculation | -1 ripen ovum is released from ovary every 28 days. |
It is the fusion of the nucleus in a sperm with the nucleus in an egg to form a new life.
How fertilization occurs:
à Fertilization can occur during sexual intercourse.
1. The penis is inserted into the vagina during sexual intercourse.
2. Millions of sperm are released from the penis and are deposited in the vagina.
3. The sperms swim from the vagina up the uterus and into the fallopian tubes. Many sperms die before they reach these tubes.
4. If a sperm meets an egg in a fallopian tube, fertilization takes place. Only one sperm will fertilize the egg.
5. The fertilized egg begins to divide to form a small ball of cells.
6. The small ball of cells now called the embryo moves down the fallopian tube and enters the uterus.
BUT bear in mind that during fertilization:
-only one sperm will enter the egg;
-head of the sperm penetrate the egg, leaving the tail behind;
-fusion of nucleus of sperm and eggàzygote.
Therefore,
-when a sperm succeeds in penetrating the egg. Membrane of the egg will change and become impenetrable to other sperms;
-Unsuccessful sperms will die.
During fertilization,
Zygote continue to move along the fallopian tube,
Begins to divide, forms a ball of cells à embryo
It takes the embryo about 5 days to reach the uterus.
Embryo attaches itself to the spongy lining of the uterus àimplantation.
Also, during fertilization, the single chromosomes* in the sperm and the egg come together to form a full set of 23 pairs of chromosomes.
*chromosomesà genetic material passed down from our parents.
The fertilized egg is the n able to divide by cell division.
BUT sex cell has 23 single chromosomes.
Miracle of normal fertilization
How is twins form??
àwhen 2 babied develop in the uterus at the same time, they are twins.
àsometimes 2 eggs are released from the ovary at the same time and both are
fertilized. If each of these fertilized eggs develops into a baby, the 2 babies are
called non-identical twins.
àThey are not exactly the same as they came from different eggs and sperms and
so inherit slightly different characteristics from their parents.
à Non- identical twins may be both boys, both girls or one boy and one girl.
Non-identical twins develop from 2 different fertilized eggs.
àsometimes, a single fertilized egg divides into 2 identical parts and each part
develops into a baby.
àThese babies are called identical twins. They are exactly the same as they came
from the same fertilized egg.
àidentical twins must be of identical sex.
àidentical twins do not always remain identical because as children grow up,
external factors eg:, diet, exercise may affect their growth.
àthus, identical twins may develop differences in appearance and personality.
èHeredity
-In reproduction, characteristics of the parents are passed on to children. This is
called heredity.
-Example, a child’s eyes may look like the father’s. The nose may look like the mother’s.
-Half of the chromosomes comes from the father and half from the mother.
-As parents are different, the genes in there are not always the same, therefore, the children inherits characteristics from both the parents.
-Humans have 46 chromosomes or 23 pairs of chromosomes. Chromosomes are made up of long strands of DNA which contain all the body’s genes.
è Gestation.
àis the period of time between conception and birth, during which the fetus
grows and develops inside its mother’s uterus.
àGestational age is the time measured from the first day of the woman’s last
menstrual to the current date. It is measured in weeks. A pregnancy of normal
gestation is approximately 40 weeks, with a normal range of 38 weeks to 42
weeks.
àInfants born before 37 weeks are considered premature. Infants born after 42
weeks are considered post-mature.
àWhen a woman is going to have a baby, she is said to be pregnant.
How the Body Works: From Conception to Birth
| Stages of fetal development. | |
| Week/ months | Development |
| Week 0 | -A sperm unites with an egg in the fallopian tube. [After the embryo reaches the uterus, it implants (attached) itself onto the wall of the uterus. This is known as implantation. Cells division continues] |
| Month 1 | -Has a tiny heartbeat. *placenta develops in the wall of the uterus. |
| Month 2 | -Eyes start to form. |
| Month 3 | -webbed fingers and toes emerge. -hair starts to grow on the head. |
| Month 4 | -begins to hear sounds -begins swallowing and kicking |
| Month 5 | -teeth start to form. |
| Month 6 | -can suck its thumb and hiccup. -grows fingers and toe nails |
| Month 7 | -can open eyes. |
| Month 8 | - |
| Month 9 | -has probably turned head down in preparation for birth. |
| Month 10 | -baby is ready to be born. |
Let’s talk about *Placenta and Amnion shall we?
*Placenta:
àsupport the life of the baby
àlinked to the baby through the umbilical cord.
àcontains many blood vessels.
àIn placenta, nutrients, wastes, and gases are exchanged between the mother’s
blood and the baby’s blood.
Amnion:
àIs clear, yellowish fluid that surrounds and protects the fetus in the uterus.
àIt is contained in the amniotic sac.
Birth
-When to baby is about to be born, the head of the baby faces down. Muscles in
the uterus push the baby down.
-The membrane around the foetus breaks and the liquid comes out.
-With the help of the mother, the muscles push the baby out of the vagina. When
the baby comes out, the umbilical cord is till attached to the baby. The doctor
cuts and ties the cord. The placenta then comes out of the vagina as it is no longer
needed. This is called afterbirth.
-At birth, the baby may have liquid in its nose and mouth. This liquid is removed
so that the baby can breathe through its own nose and mouth.
recent
Know your body (: Topic: structures and function...
Quiz to reflect wad u tink about sexualityFirstly,...
hi members of bermuda rectangle!layping hereblog i...
past
August 2008
September 2008
October 2008
November 2008
US!
layping
jasmine
engleng's grp blog
lucas
links of our frens n information that u might wnt to noe mre on related topics(:
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Question and Answer Time! (: