IB BIO HL: Reproductive System

Reproduction

the biological process by which organisms produce offspring

Sexual reproduction

reproduction involving the fusion of two gametes (sperm and egg) from two parents

Asexual reproduction

reproduction without the fusion of gametes, resulting in offspring genetically identical to the parent

Meiosis

a type of cell division that reduces the chromosome number by half, creating four non-identical gametes

Haploid

a cell with half the normal number of chromosomes

Diploid

a cell with two complete sets of chromosomes, one from each parent

Gamete

a reproductive cell (sperm or cell) with half the chromosome number of the organism

Fertilization

the process where a sperm and egg fuse to form a zygote

Zygote

the fertilized egg cell formed after sperm and egg merge

Sperm

the male gamete

Egg

the female gamete

Scrotum

the pouch of skin that holds and protects the testes

Testis / testes

the male reproductive organs that produce sperm and hormones

Epididymis

the tube where sperm mature and are stored

Vas deferens

the duct that transports sperm from the epididymis to the urethra

Seminal vesicle

glands that produce fluid that nourishes and transports sperm

Cowper’s gland

glands that produce pre-ejaculatory fluid to lubricate the urethra and neutralize acidity

Prostate gland

a gland that produces a fluid that nourishes and protects sperm in semen

Urethra

the tube that carries urine from the bladder and semen from the reproductive system through the penis

Penis

the male external reproductive organ that delivers sperm into the female reproductive tract

Ovary

the female reproductive organ that produces eggs and hormones like estrogen and progesterone

Oviduct

aka fallopian tube

the tube through which an egg travels from the ovary to the uterus

Uterus

the organ in females where a fertilized egg implants and develops into a fetus

Cervix

the lower part of the uterus that connects to the vagina; it produces mucus and helps control the passage of sperm

Vagina

aka birth canal

the muscular canal that connects the external genitals to the uterus in females

Labia

the folds of skin around the opening of the vagina

includes the labia majora and labia minora

Clitoris

a highly sensitive organ located at the top of the vulva

Menstrual cycle

the monthly cycle in females involving the menstruation of an egg, ovulation, and preparation of the uterus for pregnancy

Uterine cycle

the changes in the uterus lining in response to hormone signals, involving menstruation and preparation for pregnancy

Ovarian cycle

the cycle in which an egg matures, is released during ovulation, and either fertilizes or degenerates

Oestradiol (an Oestrogen)

a form of estrogen, a hormone involved in regulating the menstrual cycle, promoting egg maturation, and maintaining reproductive health

Progesteron

a hormone that prepares the uterus for pregnancy and maintains the uterine lining if pregnancy occurs

Follice stimulating hormone (FSH)

a hormone that stimulates the growth and maturation of ovarian follicles in females and sperm production in males

Luteinizing hormone (LH)

a hormone that triggers ovulation in females and stimulates testosterone production in males

Positive feedback

a process where the output of a system amplifies

Negative feedback

a process where the output of a system reduces

Ovulation

the release of a mature egg from the ovary, typically occurring mid-cycle in females

Corpus luteum

the structure that forms in the ovary after ovulation and secretes progesterone to maintain the uterine lining for potential pregnancy

In vitro fertilization

a medical procedure in which an egg is fertilized outside the body and then implanted into the uterus

Superovulation

a process in which multiple eggs are stimulated to mature in the ovaries, often used in fertility treatments

Hermaphrodites

organisms that have both male and female reproductive organs, capable of producing both eggs and sperm

Pollen

the fine powder produced by male reproductive organs in plants, containing male gametes (sperm cells)

Pollen tube

a tube formed by a pollen grain after it lands on the stigma of a flower, through which sperm travel to reach the egg

Pollination

the transfer of pollen from the male to the female productive organs of a flower, enabling fertilization

Seed dispersal

the process by which seeds are spread from the parent plant to new locations, often through wind, water, or animals

Insect-pollination

pollination that occurs when insects, like bees, transfer pollen between flowers as they collect nectar

Wind-pollination

pollination that occurs when pollen is carried by the wind from one flower to another

Sepal

the outermost part of a flower, usually green, that protects the developing bud before it blooms

Petal

the colorful part of a flower that attracts pollinators

Stamen

the male reproductive organ of a flower, consisting of the anther and filament

Anther

the part of the stamen that produces and releases pollen, which contains male gametes

Filament

the slender stalk that supports the anther in a flower

Carpel

the female reproductive organ of a flower, consisting of the stigma, style, and ovary

Stigma

the part of the carpel that receives pollen during pollination

Style

the narrow part of the carpel that connects the stigma to the ovary

Ovary

the part of the carpel that contains the ovules (female gametes); after fertilization, it develops into the fruit

Self-pollination

the process where pollen from the same flower or plant fertilizes its own ovules, resulting in offspring genetically similar to the parent

Cross-pollination

pollination where pollen from one flower fertilizes the ovules of a different flower, promoting genetic diversity

Germination

the process by which a seed develops into a new plant, starting with the absorption of water and ending with the sprouting of the seedling

Gibberellin

a plant hormone that promotes growth, especially in seed germination and stem elongation

Puberty

the developmental stage during which a child’s body matures into an adult, capable of sexual reproduction, involving physical and hormonal changes

Gonadotropin-releasing hormone

a hormone produced by the hypothalamus that stimulates the release of gonadotropins from the pituitary gland, regulating the reproductive system

Secondary sexual characteristics

physical traits that distinguish the sexes but are not directly involved in reproduction, such as body hair, breast development, and voice changes

Gametogenesis

the process of forming gametes through cell division and differtiation

Spermatogenesis

the process of sperm production in the testes, involving the division and maturation of spermatogonia into spermatozoa

Oogenesis

the process of egg (ovum) production in the ovaries, involving the formation and maturation of oocytes

Spermatozoa (sperm)

the mature male gametes, which are involved in fertilizing the female egg

Ovum / ova (eggs)

the female gametes, which, when fertilized by sperm, can develop into a zygote

Spermatogonia

the diploid cells in the testes that give rise to sperm cells through spermatogenesis

Primary spermatocytes

diploid cells formed form spermatogonia that undergo meiosis to form secondary spermatocytes

Secondary spermatocytes

haploid cells produced from the division of primary spermatocytes, which then undergo the second meiotic division to form spermatids

Spermatid

the haploid, non-motile cells that are the result of the second meiotic division of secondary spermatocytes

Oogonia

the diploid cells in the ovaries that give rise to primary oocytes during fetal development

Primary oocyte

the diploid cell in females that is arrested in prophase of meiosis I and will resume development at puberty during the menstrual cycle

Secondary oocyte

the haploid cell that is produced after the first meiotic division of the primary oocyte; released during ovulation and can be fertilized by sperm

Polar body

a small cell produced during oogenesis that contains little cytoplasm and is usually discarded

Acrosome

the cap-like structure on the head of a sperm cell that contains enzymes necessary for penetrating the egg during fertilization

Acrosome reaction

the process in which the acrosome releases enzymes to break down the outer layers of the egg, allowing sperm to fuse with the egg membrane

Cortical granules

small vesicles located in the cytoplasm of the egg that release enzymes during fertilization to prevent polyspermy

Cortical reaction

the process by which the cortical granules release their enzymes to alter the egg’s membrane and prevent multiple sperm from fertilizing the egg (polyspermy)

Polyspermy

a condition where more than one sperm fertilizes an egg, which usually leads to abnormal development and is prevented by the cortical reaction

Embryo

the early stage development after fertilization, before becoming a fetus. it begins as a zygote and undergoes stages of division and differentiation

Morula

a solid ball of cells formed after the zygote undergoes multiple rounds of cell division (cleavage) following fertilization, before it becomes a blastocyst

Blastocyst

a very early stage of a developing embryo

Implantation

the process where the blastocyst attaches itself to the lining of the uterus to start growing and developing into a baby

Monoclonal antibodies

special proteins made in a lab that can target and attach to specific cells or substances in the body. They are used in medicine to treat diseases like cancer, by targeting harmful cells

Placenta

an organ that forms in the uterus during pregnancy; pprovides nutrients and oxygen to the growing baby and removes waste products from the baby’s blood

Chorionic villi

tiny finger-like structures that grow from the placenta; help exchange nutrients, oxygen, and waste between the mother and baby’s blood

Oxytocin

a hormone that plays a key role in childbirth and breastfeeding; helps uterus to contract during labor

Hormone replacement therapy

treatment where hormones are given to replace the ones the body is no longer making enough of