Biology

Outline early embryo development up to the implantation of the blastocyst.

A. fertilized egg called a zygote; B. cell divides by mitosis; C. early divisions of zygote result in reduction in quantity of cytoplasm per cell / no increase in overall size; D. first divisions occur while zygote in fallopian tube / oviduct; E. several divisions result in the formation of a bundle of cells called a morula; F. further divisions result in a hollow ball of cells / fluid filled ball of cells / blastocyst; G. implantation occurs up to seven days after fertilization;

Know comparisons of spermatogenesis and oogenesis

Compare the process of spermatogenesis and oogenesis. 7 marks both involve meiosis Both produce haploid cells LH /FSH involved in both spermatogenesis starts at puberty versus oogenesis starts in the fetus spermatogenesis until death versus oogenesis until menopause millions of sperm versus one egg per month ejaculation of sperm any time versus ovulation in middle of menstrual cycle spermatogenesis involves equal divisions versus oogenesis involves unequal cell divisions no polar bodies in spermatogenesis versus 2 or 3 polar bodies in oogenesis spermatogenesis involves Sertoli versus oogenesis does not testosterone needed for spermatogenesis versus not needed for oogenesis

Hormones in the menstrual cycle- be able to draw and label a graph and give the functions of each of the hormones (and where they come from) (i.e. ovary, anterior /posterior pituitary) (role in oogenesis)

DRAW GRAPH Outline the role of hormones in the menstrual cycle. 6 marks FSH promotes development of a new follicle and leads to the production of estrogen. estrogen brings about repair and growth of uterine lining and causes negative feedback of FSH. Estrogen also brings about LH production. LH stimulates follicle growth and triggers ovulation. Progesterone maintains uterus lining; Lowered level of progesterone leads to menstruation; Explain the role of hormones in the regulation of the menstrual cycle in human females. 8 marks FSH and LH are produced by the anterior pituitary Estrogen and progesterone are produced by the ovary FSH stimulates the ovary to produce a follicle. Developing follicles secrete estrogen. estrogen inhibits FSH. LH stimulates ovulation and causes development of corpus luteum corpus luteum secretes estrogen and progesterone Estrogen and progesterone maintain the lining of the uterus / endometrium estrogen and progesterone inhibit LH and FSH menstrual bleeding begins Outline the levels of each of the hormones that control the menstrual cycle immediately before ovulation. 3 marks (An answer in graphical form is also acceptable) LH levels very high FSH levels are high estrogen levels are high progesterone levels are very low Explain the roles of LH and FSH in the menstrual cycle, including the timing of their secretion during the cycle. 6 marks FSH is secreted at the start of the cycle FSH stimulates follicle development FSH stimulates secretion of estrogen (by the follicle / ovary) LH is secreted in the middle of the cycle LH stimulates ovulation LH stimulates the development of the corpus luteum LH stimulates more progesterone secretion Outline the roles of progesterone and estrogen in the human menstrual cycle. 6 marks FSH stimulates secretion of estrogen; Increase in estrogen stimulates FSH/LH production; estrogen also stimulates thickening of uterus lining; LH causes follicle to produce less estrogen; corpus luteum secretes more progesterone; progesterone stimulates thickening of uterus lining; estrogen and progesterone inhibit FSH and LH secretion; estrogen and progesterone levels fall after day 21-24 if no embryo/fertilization;

Know the pros and cons of IVF

Discuss the ethical issues surrounding IVF. 6 marks pros chance for infertile couples to have children; decision to have children is clearly a conscious one due to difficulty of becoming pregnant; genetic screening of embryos could decrease suffering from genetic diseases; spare embryos can be used for stem cell research; cons IVF is expensive and might not be equally accessible; success rate is low therefore it is stressful for the couple; it is not natural/cultural/religious objections; could lead to eugenics/gender choice; could lead to (unwanted) multiple pregnancies with associated risks;

Structure and function of the placenta

Explain the function and structure of the placenta. 8 marks Disc shaped structure that nourishes the developing embryo; starts forming at implantation of the embryo; embryonic tissue grows into the uterine wall; fetal capillaries exchange material with maternal blood; allows exchange of food, oxygen, and antibodies from mother's blood to fetus; allows exchange of carbon dioxide and waste products from fetal blood to mother; connected to the embryo by an umbilical cord; placenta takes over hormonal role of ovary at approximately 12 weeks; secretes estrogen and progesterone; hormone secretion maintains pregnancy;

Know where fertilization happens and how the sperm gets in the egg (acrosome reaction) and know the cortical reaction (blocks to polyspermy)

Fertilisation generally occurs in the oviduct (fallopian tube) Acrosome reaction: Sperm cells that penetrate the follicle cells bind to receptors on the zona pellucida of the egg and release hydrolytic enzymes from their acrosome to digest through it, this is called the acrosome reaction. Cortical Reaction: Calcium ions stimulate it to prevent more than one sperm entering the egg (polyspermy). Vesicles called cortical granules are stored in the egg cytoplasm just inside the plasma membrane. Vesicles fuse with the plasma membrane. Vesicle fusion releases enzymes that destroy the sperm-binding proteins on the egg plasma membrane. Creates a fertilization membrane. Outline the process of fertilization in humans sperm enters oviduct (fallopian tube); sperm attracted to egg; release of (hydrolytic) enzymes from acrosome in order to penetrate the zona pellucida; membranes of egg and sperm fuse; cortical reaction / granules released to the outside of egg; zona pellucida hardens / fertilization membrane forms to prevent polyspermy; nucleus of secondary oocyte completes meiosis II; fusion of nuclei / (diploid) zygote forms;

hormones involved in spermatogenesis

LH: Released by the anterior pituitary gland. Stimulates the interstitial cells (Leydig cells) to produce testosterone. FSH: released by the anterior pituitary gland. Stimulates the (first) meiotic division of spermatogonia and action of testosterone on Sertoli cells. Testosterone: Secreted by the testicles. Causes development of male genitalia during embryonic development and development of secondary sex characteristics during puberty. Maintains sex drive. Stimulates meiosis II in secondary spermatocytes producing 4 haploid spermatids and stimulates Sertoli cells.

Outline the role of human chorionic gonadotropin (HCG) in early pregnancy 2 marks

Maintains the corpus luteum Stimulates secretion of estrogen and progesterone maintains uterine lining

Be able to describe the process of IVF

Outline the process of IVF, including one example of a situation when it is used. 9 marks IVF is fertilization outside the body; drugs used to down-regulate the menstrual cycle; FSH injected to stimulate many follicles to develop; HCG injected to cause the follicles to mature; eggs are harvested; semen sample collected; semen is processed to concentrate it and healthy sperm are selected; ICSI/IntraCytoplasmic Sperm Injection where sperm is directly injected into egg when low numbers of motility is a factor; semen mixed with eggs in a dish; kept at 37°C allows embryos to develop; dish examined to choose healthiest embryo; embryos placed in uterus; Up to four embryos implanted; pregnancy test/scan used to see if procedure has been successful; Used in cases of low sperm count and infertility.

Know the process of spermatogenesis (hormones involved and where they come from and their functions)

Outline the process of spermatogenesis in humans. 5 marks production of sperm in the testes; first stage of sperm production requires divisions by mitosis; cells then undergo a period of growth; future sperm cells then undergo two meiotic divisions; cells then differentiate to form sperm cells; nourished by Sertoli cells number becomes haploid so 46 to 23 chromosomes;

Know functions of the ovary, fallopian tube (oviducts), uterus/endometrium, corpus lutem and follicle cells (Male)testicle, epididymus, seminal vesicle, prostate gland, sertoli cells

Ovary - They produce oocytes (eggs) for fertilisation and they produce the reproductive hormones, oestrogen and progesterone. Oviduct - tube that links the ovary to the uterus and which the ovulated oocyte travels down to become fertilised by sperm present in the female tract. Uterus/Endometrium - nurturing the fertilized ovum that develops into the fetus and holding it till the baby is mature enough for birth. Corpus lutem - secretion of the hormone progesterone, which is required for maintenance of normal pregnancy in mammals. Follicle cells - The follicle cells protect and nourish the egg prior to its release into the oviducts during ovulation. The follicular tissue also release estrogens. Male testicle - The testes are responsible for making testosterone, the primary male sex hormone, and for generating sperm. Within the testes are coiled masses of tubes called seminiferous tubules. These tubes are responsible for producing sperm cells. Epididymis - that stores sperm and transports it from the testes. Seminal vesicle - holds the liquid that mixes with sperm to form semen. Prostate gland - The prostate secretes fluid that nourishes and protects sperm. Sertoli cell - Sertoli cells keep the germ cells that start the process healthy and nourished. They also function at the end of spermatogenesis by absorbing extra cytoplasm from newly created spermatozoa, just prior to their release into the lumen of the seminiferous tubule.

Hormones involved in birth (names, functions, where they are secreted from)

The process of childbirth is called parturition and is controlled by the hormones oxytocin, secreted from the posterior pituitary gland and prostaglandins secreted from the fetus. After nine months, the fetus is fully grown and takes up all available space in the uterus, stretching the walls of the uterus This causes a signal to be sent to the brain, releasing oxytocin from the posterior pituitary Oxytocin inhibits progesterone, which was inhibiting uterine contractions Oxytocin also directly stimulates the smooth muscle of the uterine wall to contract, initiating the birthing process The contraction of the uterine wall causes further stretching, which triggers more oxytocin to be released (causing even more contraction) Additionally, the fetus responds to the cramped conditions by releasing prostaglandins which cause further myometrial contractions As the stimulus causing oxytocin release is increased by the effects of oxytocin, this creates a positive feedback pathway Contractions will stop when labour is complete and the baby is birthed (no more stretching of the uterine wall) Oxytocin triggers lactation

Compare the roles of LH and HCG in female reproduction. 2 marks

both stimulate the development of the corpus luteum both stimulate the secretion of progesterone before fertilisation by LH and after by HCG

Draw and label sperm and egg

http://www.ib.bioninja.com.au/higher-level/topic-11-human-health-and/114-reproduction.html

Identify structures on a diagram of the male/female reproductive system

http://www.ib.bioninja.com.au/standard-level/topic-6-human-health-and/66-reproduction.html