Reproduction

• Sexual reproduction involves the fusion of the female and male reproductive cells to form a fertilized egg that grows into an organism.
• Organisms in which both male and female gametes are present in the same individual are called hermaphrodites.
• During sexual reproduction, the sperm and ovum fuse together to form a third cell called the zygote. This fusion of the sperm and ovum is called fertilization.
• In internal fertilization, the male deposits the sperms inside the reproductive system of the female. Fertilization occurs and the zygote is formed inside the female's body
• In males, the reproductive organs are a pair of testes, these produce sperm and secrete the male hormone testosterone.
• The sperms leave each testis through a vas deferens. As the sperms move through this, fluids from three glands pour the secretions into the ducts. The mixture of fluids and sperms is called semen.
• The ovaries produce the ovum. The release of the ovum from the ovary is called ovulation.
• The ovum is a single cell
• The ovaries produce the ovum and also secrete the demale hormones oestrogen and progesterone.
• The female sexual organs produce the egg cells (aka ova and ovum (singular))
• The ovum travels through the oviduct to the uterus (womb)
• The uterus is a muscular bag within which the baby develops after fertilization. The uterus opens to the outside through vagina.
• After the sperms are deposited into the vagina by the penis, the sperms swim into the uterus and up the oviducts. If an ovum is present in an oviduct, one of the sperms may fuse with the ovum and fertilization takes place.
• During fertilization, the fusion of the sperm and ovum creates zygote.
• If the ovum is not fertilized by a sperm, it is expelled from the uterus along with some uterine muscles and blood is known and menstruation.
• Cats, dogs and rabbits produce more than one egg at a time, so more babies are born at the same time.
• After fertilization, the zygote travels down the oviduct and divides over and over again to form a ball of cells, this is known as cell division. The cell then begins to develop into different tissues and organs of the body.
• First eight weeks is called the embryo.
• The stage at which all body parts of the embryo could be recognized is called the foetus.
• The animals that give birth to young ones are called viviparous animals.
• Animals that lay eggs are called oviparous animals.
• The complete change of form of an animal as it develops from young one into an adult is called metamorphosis.
• In binary fission, the fully grown parent cell splits into two halves producing two new cells. This occurs in Amoeba and Paramecium.
• In budding, a new organism grows in the form of a bulb like projection called a bud from the parent organism. This occurs in Yeast and Hydra.
• Fertilization takes place in the fallopian tube (oviduct) where the sperm and egg (ovum) fuse together.