Grade 12 Life Sciences NSC Paper 1 Terms 2023 Graded A

chorion - The membrane that together with the endometrium, forms the placenta. / The outermost extra-embryonic membrane surrounding the embryo. pregnancy - The period of development of an embryo in the uterus between fertilisation and birth. diabetes mellitus - Disease characterised by a lack of insulin production. eustachian tube - Tube that connects the pharynx and the middle ear. / The structure in the ear that equalises the pressure on either side of the eardrum. eutrophication - A process by which nutrients become highly concentrated in a body of water, leading to increased growth of organisms such as algae. / The accumulation of nutrients in ponds from the over-use of fertilisers on land, stimulating excessive growth of algae. blastocyst / blastula - A stage in the development of humans in which the embryo consists of a layer of cells surrounding a cavity. / A hollow ball of cells formed from the zygote acrosome - The part of the sperm cell that contains enzymes to digest the membrane of the ovum prostate gland - The gland in the male reproductive system of humans that produces an alkaline fluid to counteract the acid environment of the vagina. vas deferens / sperm duct - The duct leading from the testis to the urethra in human males. / The tube in the male reproductive system that connects the epididymis with the urethra oogenesis - The process by which the ovum is formed through meiosis in the ovary. meninges - The membranes which protect the central nervous system. / Collective name for the membranes that protect the brain and spinal cord. gibberellins - A plant growth hormone that stimulates seed germination. peripheral nervous system - The nervous system which consists of cranial and spinal nerves parasympathetic - A branch of the autonomic nervous system that decreases the heartbeat back to normal. aldosterone - The hormone that regulates the salt concentration in the human body umbilical vein - A blood vessel in the umbilical cord that transports nutrients + oxygen rich blood to the foetus. TSH (Thyroid Stimulating Hormone) - The hormone inhibited by an increased level of thyroxin. carbon footprint - Measurement of the total amount of carbon dioxide emissions of an individual, a defined population or a company per year. thermal pollution - The type of pollution caused when water is released into a rivers or oceans after being heated in power stations or industries aqueous humour - The watery fluid that supports the cornea and the front chamber of the eye / A liquid between the cornea and the lens in the human eye. oestrogen - The hormone produced by the Graafian follicle. LH (Leutenising hormone) - The hormone responsible for the formation of the corpus luteum. cristae - The receptors in the ear that detect changes in the direction and speed of any movement of the body. / The sensory receptors found in the semi-circular canals. internal - The type of fertilisation associated with viviparous reproduction. eye accommodation - The series of changes that take place in the shape of the lens and the eyeball in response to the distance of an object from the eye. medulla oblongata - The part of the brain that controls the heart rate. / The part of the brain that regulates breathing. homeostasis - The maintenance of a constant internal environment in the body within certain limits. abscisic acid - The plant hormone that promotes seed dormancy. / A plant hormone that causes leaves to fall off trees in autumn. ozone layer - A layer in the atmosphere that is damaged by chlorofluorocarbons (CFCs).