Reproduction Flashcards
Define sexual reproduction
A form of reproduction which involves gametes (sex cells). It produces genetically varied offspring and involves mitosis and meiosis.
Define asexual reproduction
A form of reproduction that doesn’t involve gametes. It produces genetically identical offspring (clones) and only involves mitosis.
What is the difference between mitosis and meiosis
By mitosis, a cell splits to create two identical copies of the original cell. In meiosis cells split to form new cells with half the usual number of chromosomes, to produce gametes for sexual reproduction
Where are human gametes produced and what are they called
The male gamete is called the sperm and is produced in the testes. The female gamete is called the ova and are produced in the ovaries.
Name one difference between the sperm and egg cell
Either:
- The sperm cell has a tail-like flagellum, helping it move around in liquids.
- The ova is much bigger than the sperm cell
Name three parts of the male reproductive system
Any three from:
- Scrotum
- Foreskin
- Testis
- Urethra
- Sperm duct
- Penis
- Prostate gland
Name three parts of the female reproductive system
Any three from:
- Oviduct
- Ovary
- Uterus
- Cervix
- Vagina
- Urethra
Name and define the types of fertilisation, and give an example of a species who does this type of fertilisation.
External fertilisation, when the sperm and ova fuse outside of the body. Species example can be fish
Internal fertilisation, when the sperm and ova fuse inside the body. Species example can be any type of mammal or bird.
What are the risks of external fertilisation
External fertilization requires the presence of water to carry the sperm to the egg. That means animals with external fertilization must return to water to lay their eggs and fertilize them there. If the water current is too strong, it may carry the sperms away from the eggs, leaving many eggs unfertilized.
How does the sperm fertilise the ova
When the sperm reaches the ovum, its nucleus enters the ovum and fuses with the ovum’s nucleus.
How many chromosomes does each human gamete have?
Each human gamete has 23 chromosomes.
List the order in which a fertilised egg develops in with these four words:
Gamete, embryo, fetus, zygote
- Gamete
- Zygote
- Embryo
- Fetus
How do sperm each the ova
The sperm is carried into the sperm duct, mixes with a fluid and becomes semen. This is ejaculated from the penis into the vagina. The sperm cells then swim towards the oviducts. If an ovum is present, fertilisation may occur.
Where do the ova come from
The ova comes from the ovaries. One ovum is released from an alternating ovary each month.
How does the ova become an embryo
When the ovum is fertilised, it becomes a zygote. The zygote will travel down the oviducts, whilst turning into an embryo via mitosis, where the cells split identically into two, then four, then eight and so on before becoming an embryo
How does the embryo become a fetus
The embryo exits the oviducts and reaches the uterus. The uterus lining is thick in order to support the developing embryo and stop it aborting, thanks to the hormone progesterone. Mitosis keeps occurring until the embryo looks human, which is when it’s referred to as a fetus
What happens in the womb during pregnancy
Any of these things:
- The amnion membrane encloses itself around the fetus. This membrane then produces amniotic fluid, protecting the fetus against jolts and bumps, keeps the baby warm and stops the baby from drying out.
- The umbilical cord connects the fetus to a placenta. This anchors the embryo in the uterus, as well as allowing gas and nutrient exchange between the mum and the baby
How do oxygen and nutrients enter the body
The mother’s artery supplies oxygen and nutrients via diffusion into the placenta. They then go through the fetal vein in the umbilical cord to the developing embryo/fetus.
How do carbon dioxide and other waste materials exit the fetus/embryo
The fetal artery, located in the umbilical cord, carries CO2 and urea to the placenta. They then diffuse through a membrane into the mother’s artery, via capillaries. The capillaries lead into the vein, where the waste is then excreted from the body.
List a reason as to why the mother’s circulatory system isn’t directly connected to the baby’s circulatory system.
Either:
- The baby’s blood type may be different to the mothers. This means that the white blood cells will attack the embryo’s blood, eventually killing the embryo/fetus (as they see the embryo/fetus’ blood as a foreign body)
- The blood pressure of the mother will be far greater than the embryo/fetus’, which means that if they were connected then the blood will spray into the embryo/fetus’ tissues, deforming and possibly breaking them, which can kill the embryo/fetus.
Name two hormones in females which affect their reproductive system.
Oestrogen - lining of the uterus becomes repaired and thickened after menstruation, released is triggered by the hypothalamus.
Progesterone - secreted from the placenta during pregnancy and the corpus luteum during menstration.
