BL1004 Reproduction - Biology Past Paper PDF

BL1004- Reproduction the production of offspring by a sexual or asexual process: Prof. Sarah Culloty, School of BEES Reproduction Strategies  Asexual reproduction  Requires 1 parent organism  Sexual reproduction  Requires 2 parent organisms and the fusion...

BL1004- Reproduction the production of offspring by a sexual or asexual process: Prof. Sarah Culloty, School of BEES Reproduction Strategies  Asexual reproduction  Requires 1 parent organism  Sexual reproduction  Requires 2 parent organisms and the fusion of male (sperm) and female (egg) gametes to form a zygote  Mechanisms of Asexual Reproduction  Many invertebrates reproduce asexually by fission  The separation of a parent into two or more individuals of approximately the same size  Also common in invertebrates is:  budding  fragmentation,  parthenogenesis (A process in which an egg develops without being fertilized) e.g.Some reptiles Figure 46.2 Sexual reproduction  2 Parents  Each has reproductive organs to produce gametes (reproductive cell)  Testes in the male to produce sperm  Ovaries in the female to produce ova (eggs) Reproduction strategies  Internal vs external fertilisation  Semelparity (octopus, mayfly, salmon, antechinuses) – single reproductive episode before death  Iteroparity (most animals) – multiple reproductive episodes over life span External Fertilisation vs Internal Fertilisation  External: Eggs shed by the female are fertilized by sperm in the external environment Eggs Internal: Sperm are deposited in or near the female reproductive tract, and fertilization occurs within the tract  Reproductive Cycles and Patterns  Most animals exhibit cycles in reproductive activity – Often related to changing seasons  Reproductive cycles – Are controlled by hormones and environmental cues  Hermaphroditism & Alternation of sexes  Simultaneous hermaphroditism Bluehead wrasse female first  Self-fertilisation – both - male version is blue gametes presetn  Sequential hermaphroditism  Protandrous: male first  Protogynous: female first Liver Fluke (sexual and asexual reproduction) Genital pore (Digestive tract) Female organs: Male organs: 3 Uterus 4 Seminal vesicle Yolk gland Yolk duct 3 Sperm duct 2 Oviduct (vas deferens) 1 Ovary 2 Vas efferens Seminal 1 Testis receptacle Figure 46.7 (Excretory pore) Female gametes - Reproduction types  Oviparity  Eggs laid outside body  Ovoviviparity  Eggs hatch in mother’s uterus  Nutrients stored in egg  Viviparity  No eggs. Embryo develops inside the mother  All mammals except monotremes Insects – Have separate sexes with complex reproductive systems 1 Ovary Accessory gland 4 Ejaculatory duct 1 Testis Oviduct Spermatheca 2 Vas deferens 5 Penis 3 Vagina 3 Seminal Accessory vesicle gland (a) Male honeybee. Sperm form in the testes, (b) Female honeybee. Eggs develop in pass through the sperm duct (vas deferens), the ovaries and then pass through the and are stored in the seminal vesicle. oviducts and into the vagina. A pair of The male ejaculates sperm along with fluid accessory glands (only one is shown) from the accessory glands. (Males of some add protective secretions to the eggs species of insects and other arthropods have in the vagina. After mating, sperm are appendages called claspers that grasp the stored in the spermatheca, a sac Figure 46.8a, b female during copulation.) connected to the vagina by a short duct.  Mammalian Reproduction: Males The male gonads, or testes Consist of many highly coiled tubes surrounded by several layers of connective tissue The tubes are seminiferous Seminal tubules (Urinary vesicle bladder) Where sperm form (behind From the seminiferous tubules of bladder) a testis Prostate gland The sperm pass into the coiled tubules of Urethra Bulbourethral the epididymis gland Erectile tissue Scrotum of penis During ejaculation Vas deferens Epididymis Sperm are propelled through the muscular Glans penis Testis Figure vas deferens, the ejaculatory duct, and 46.10 exit the penis through the urethra Spermatogenesis  Accessory Glands  3 sets of accessory glands – A pair of Seminal Vesicles Contributes about 60% of the total volume of semen – The Prostate gland Secretes its products directly into the urethra through Seminal (Urinary several small ducts vesicle bladder) – The Bulbourethral gland (behind bladder) Secretes a clear mucus before Prostate gland ejaculation that neutralizes Urethra Bulbourethral acidic urine remaining in the gland Erectile tissue urethra Scrotum of penis Vas deferens  Semen consists of sperm cells Glans penis Epididymis Testis plus: Figure  Fructose and other energy 46.10 sources for the sperm  Acid-base buffers that create a Testosterone: Sperm production, suitable environment for the secondary sex characteristics, sex sperm drive  Female Reproductive organs: Ovary The female gonads, the ovaries Ovaries Oviduct – Lie in the abdominal cavity Each ovary – Is enclosed in a tough protective capsule and contains many follicles Follicles A follicle Uterine wall Uterus – Consists of one egg cell Endometrium surrounded by one or Corpus luteum more layers of follicle cells Cervix The process of ovulation – Expels an egg cell from Vagina the follicle The remaining follicular tissue then grows within the ovary – To form a solid mass called the corpus luteum,  Oogenesis Oogenesishttps://ib.bioninja.com.au/higher-level/topic-11-animal- physiology/114-sexual-reproduction/gametogenesis.html  Oogenesis  In foetal ovaries, diploid oogonia divide by mitosis to produce many more oogonia  All oogonia undergo the first stage of meiosis during foetal life or shortly afterward, being called primary oocytes  Primary oocytes remain as such until they are ovulated  Primary oocyte completes the first meiotic division at ovulation  The second meiotic division is completed only if the oocyte is fertilised Ovaries. Hormones Tissue Hormone Class of Main hormone functions Ovary Estrogen Steroid Involved in ovulation and pregnancy Ovary Progesterone Steroid Prepares uterus for pregnancy Oviducts and Uterus  The egg cell is released into the abdominal cavity – Near the opening of the oviduct, or fallopian tube  Cilia in the tube – Convey the egg to the uterus  Ovarian cycle Ovulation marks the end of the follicular phase and the start of the luteal phase  Luteal phase  The cells of the ruptured mature follicle form a structure called the corpus luteum  LH after ovulation initiates the transformation of the corpus luteum  If the oocyte in the oviduct is not fertilised, the corpus luteum degenerates  If fertilisation occurs, the corpus luteum grows and continues to secrete hormones, mainly progesterone and estrogens  Estrogens secreted by follicles and corpus luteum stimulates the growth of the endometrium of the uterus and the production of progesterone receptors in the endometrium  Fertilisation  Acrosome reaction  Membrane fusion activates the egg  When sperm makes contact with the egg’s plasma membrane, it triggers a release of calcium from internal organelles starting at the point of sperm entry  Changes membrane potential of egg, prevents other sperm from fusing with egg Gamete production. Meiosis Revision questions  Name some forms of asexual reproduction  Describethe process of oogenesis and ovulation  List the human male’s a) external and b) internal reproductive organs.  Acknowledgements  Majority of text and Powerpoint slides from Campbell’s Biology.  DrJavier delBarco-Trillo, School of BEES for preparing the original version of these slides https://ib.bioninja.com.au/higher-level/topic-11-animal-physiology/ 114-sexual-reproduction/gametogenesis.html