Biology Unit on Sexual Reproduction

Reproduction is a biological process where a cell or organism produces new cells or organisms similar to itself, ensuring the continuation of its species.

Asexual reproduction is a type of reproduction where a single parent produces offspring that are genetically identical to itself, involving only mitosis.

Sexual reproduction involves the fusion of two specialized reproductive cells called gametes (sperm and egg), leading to offspring with genetic variation from both parents.

Spermatogenesis is the process of sperm cell formation in the male testes, involving meiosis to reduce the chromosome number.

Oogenesis is the process of egg cell formation in the female ovaries, also involving meiosis to reduce chromosome number.

Fertilization is the fusion of a sperm cell and an egg cell, forming a diploid zygote, the first cell of a new organism.

Embryogenesis is the process of development from a single fertilized egg to a multicellular organism, involving cell division, differentiation, and tissue formation.

Gestation is the duration of pregnancy, the period during which a developing embryo or fetus grows in the mother's womb.

The innermost layer of a microsporangium, composed of large cells with thick cytoplasm and multiple nuclei. It provides nourishment to developing pollen grains.

A process where the second male gamete from the pollen tube fuses with two polar nuclei in the central cell of the embryo sac, forming a triploid (3n) primary endosperm nucleus.

The fusion of a male gamete (sperm) with the egg cell, resulting in the formation of a diploid zygote.

The nutritive tissue inside the seed that provides nourishment to the developing embryo.

The process of development of the female gametophyte (embryo sac) inside the ovule of a flower.

The single diploid cell in the nucellus of the ovule that undergoes meiosis to produce four megaspores.

The process of meiotic division in the megaspore mother cell to produce four haploid (n) megaspores.

Only one of the four megaspores produced during meiosis survives and develops into an embryo sac. The other three degenerate.

The male reproductive system is responsible for producing sperm and delivering it to the female reproductive system.

It's made up of the testes (where sperm is produced), accessory ducts (tubes that transport sperm), and accessory glands (which produce fluids that nourish and protect sperm).

The testes are responsible for producing sperm cells, which are the male gametes needed for fertilization.

The epididymis is where sperm is stored and matures.

It's a long coiled tube that sits on the surface of the testis.

The vas deferens are long, muscular tubes that transport mature sperm from the epididymis to the urethra.

The urethra is the final channel that carries both urine and sperm from the bladder and the vas deferens to the outside of the body.

The seminal vesicles are glands that secrete a viscous fluid that provides energy to sperm cells.

This keeps them swimming strong and ready to fertilize.

The prostate gland secretes an alkaline fluid that neutralizes the acidity of the urethra and vaginal fluid.

This helps the sperm survive in the female reproductive system.

The bulbourethral gland secretes a clear, viscous fluid that lubricates the urethra during sexual arousal.

This makes it easier for sperm to pass through the urethra.

Spermatogonia are the primitive germ cells responsible for sperm production. These cells undergo mitosis to continuously replenish the supply of cells that will differentiate into sperm.

Sertoli cells are supporting cells found in the seminiferous tubules of the testes. They provide nourishment to developing sperm cells, regulate their development, and create a favorable environment for spermatogenesis.

Leydig cells are located in the interstitial spaces between the seminiferous tubules in the testes. These cells produce testosterone, the primary male sex hormone essential for sperm production and other male characteristics.

Testosterone is the major male sex hormone, produced by Leydig cells in the testes. It plays a crucial role in initiating and maintaining spermatogenesis, developing male secondary sexual characteristics, and regulating male reproductive functions.

The epididymis is a coiled tube located on the posterior (back) surface of each testis. It stores newly produced sperm, allowing them to mature and gain motility (ability to move) before being transported to the vas deferens.

The vas deferens is a muscular tube that carries mature sperm from the epididymis to the urethra. During ejaculation, it contracts, propelling the sperm towards the urethra for expulsion.

The urethra is a tube that serves as the passageway for both urine and semen. During ejaculation, sperm travels through the urethra to be expelled from the penis, while urine flows through it during urination.

The penis is the external male reproductive organ. It serves to deliver sperm to the female reproductive tract during sexual intercourse and also plays a role in urination.