Of the primary topics covered by the AQA GCSE Biology, one of the more common specifications, one is Reproduction, which falls under the Genetic Variation and its Control branch.
One of the main topics covered by Biology at GCSE Level is Reproduction, which examines the human body, in particular the sexual organs, and how women and men reproduce.
While you may have been taught about the human body during sex education in earlier years or even during discussions with your parents, this more advanced course will explain a little more about the functions of the male and female sex organs, as well as exploring hormones, puberty and how a fetus grows.
If, when you were last taught about this subject, you found that you, your friends or your other classmates got the giggles and couldn’t take the lesson seriously, then you can now look forward to discovering how life begins without any disturbances or associated embarrassment.
As fourteen/fifteen/sixteen-year-olds, your group should be mature enough to be taught about their bodies – after all everyones has male and female genitals!
Before moving onto how the respective sex organs work together to create life, we first of all need to have an understanding of how each works independently.
To help you to follow the biological parts, processes and functions described below, we have provided a glossary of terms, put together by the experts at BBC Bitesize, which can be referred to whilst you read this text, or can be saved for future reference. Go to their website for tonnes more guides, tests and other useful references during your course.
Note: Having a list of key terminology can be very useful when you come to revise for your exam, as this topic is likely to come up in at least one question on your paper.
(extracted from BBC Bitesize)
“Ciliated: Cells with tiny hair-like structures on their surface are said to be ciliated.
Circulatory system: Bodily system made up of the heart, blood vessels and blood that delivers nutrients and other essential materials to cells whilst removing waste products.
Diffusion: The movement of particles (molecules or ions) from an area of higher concentration to an area of lower concentration.
Embryo: An organism in the early stages of development.
Gamete: Sex cell (sperm in males and ova/eggs in females).
Hormone: Chemical messengers produced in glands and carried by the blood to specific organs in the body.
Menstruation: Also called a ‘period’. The loss of blood and tissue from the lining of the uterus through the vagina during the menstrual cycle.
Nucleus: The central part of an atom. It contains protons and neutrons, and has most of the mass of the atom. The plural of nucleus is nuclei.
Oviduct: The tube in the female reproductive organ through which an egg passes from an ovary to the uterus.
Placenta: The organ in the uterus of pregnant mammals that allows the transfer of nutrients and waste products between the mother and the fetus through the umbilical cord.
Secondary sexual characteristics: Body features, other than the reproductive organs, that appear during puberty and which are different in males and females (such as breasts and beards).
Sexual reproduction: The formation of a new organism by combining the genetic material of two organisms.
Umbilical cord: The cord that connects the foetus to the placenta. It contains blood vessels.
Uterus: Also known as a womb. This is where the fertilised egg (ovum) develops.
Vulva: The opening to the vagina in the female reproductive system.
Zygote: A fertilised egg cell.”
The male reproductive system is made up of two testes, which are contained inside a bag of skin known as the scrotum. The testes both produce sperm and the male hormone, testosterone.
When sperm, also referred to as sex cells or the male gametes, are produced, the cells make their way through the sperm ducts and combine with fluids produced by glands, which in turn provide them with nutrients. This combination is called semen.
The penis also has two main functions: to pass urine from the bladder and to pass semen during sexual intercourse.
Meanwhile, the urethra is the tube that runs inside the penis and through which the fluids mentioned above are passed from the body. To ensure that the two do not get mixed up, a ring of muscle separates them.
Two ovaries in the female body hold eggs, or ova, which are the female sex cells. Unlike the male gametes, which are continually produced, women have these ova in their bodies from the moment they are born.
The ovaries are connected to the uterus by a Fallopian tube, which is known as an oviduct. This tube is lined with ciliated cells so that the cilia can encourage eggs released during menstruation along towards the uterus.
Understanding the female reproductive system. Photo Source: Wikipedia
The uterus itself is like a bag and is where a baby develops until it is born. The cervix can be found at lower end of the uterus and is like a ring of muscle which keeps the baby safely in place during pregnancy.
The vagina is a muscular tube that leads from the cervix and is where a man’s penis enters during sexual intercourse.
Where this tube meets the outside of the woman’s body, there are folds of skin called labia which, together, form the vulva. The woman’s urethra also opens into her vulva, allowing urine to pass from the bladder. The urethra is separate from the vagina.
Every human undergoes a process called puberty, which is the term used to describe when a child’s body develops into an adult’s body. As the changes take place gradually and can happen at any time between the ages of around ten and sixteen, not all boys and girls will reach puberty at the same time.
It is hormones that cause the body to change, with testosterone produced by the testes causing secondary sexual characteristics to develop in males and oestrogen produced by the ovaries causing secondary sexual characteristics to develop in females.
During puberty, boys and girls can expect to see pubic and underarm hair beginning to grow as well as their sexual organs changing and developing.
There are some additional characteristics which are predominantly seen in boys, which are the breaking of the voice, hair growth on the face and body and muscles beginning to develop. In addition to these visual changes, the testes also start to produce sperm.
One if the first signs of puberty in boys is facial hair. Photo on VisualHunt.com
Girls, meanwhile, will develop breasts, their hips will widen and their voice will deepen slightly. They will also begin to have periods, known as menstruation, during which ovaries will release egg cells.
The menstrual cycle, or period, takes place roughly every 28 days, hence why it is known as ‘that time of the month’. During menstruation, the lining of the uterus prepares itself for pregnancy, even if pregnancy does not occur. When the egg released by the ovaries is not fertilised, the lining is shed which causes a bleed. The whole process is controlled by hormones.
If the female does become pregnant, a new hormone called progesterone is produced by the placenta to maintain the lining of the uterus throughout pregnancy and preventing menstruation from happening.
Reproduction in humans involves the sexual organs of both men and women. Internal fertilisation happens inside the woman’s body and is the fusion of the nucleus of the male and female sex cells or gametes to form a zygote. It is this new cell which matures into an embryo inside the woman’s uterus.
For fertilisation to happen, the female reproductive system releases an egg from the ovary which travels toward the oviduct. If sperm cells are present in the vagina, they will travel up the cervix and meet at the oviduct, where fertilisation occurs.
During fertilisation, the zygote divides into a ball of cells called an embryo, which become embedded in the wall of the uterus. After eight weeks of development, the embryo is referred to as a fetus and can be seen on an ultrasound scan. The amniotic sac produces amniotic fluid which protects the growing embryo or fetus, acting like a cushion.
As early as weeks into development, the fetus can clearly be seen on an ultrasound scan. Photo by edanley on Visualhunt
The placenta develops from the embryo and is connected to the woman’s body by an umbilical cord. The main functions of the placenta are to provide oxygen and nutrients to the fetus and to get rid of waste materials and carbon dioxide.
If you are interested in finding out about other topics on the Biology GCSE curriculum, please see the following blogs: