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level: 11.4 Reproduction

Questions and Answers List

level questions: 11.4 Reproduction

QuestionAnswer
What is gametogenesis?how gametes are made in gonads (testes / ovary)
what are gonads?testes and ovaries were gametes are made
what are the 3 processes in gametogenesis?mitotic divisions and cell growth meiosis differentiation
Outline the process of spermatogenesis (5)in seminiferous tubules the germline epithelium do mitosis spermatogonia produce spermatocytes w cell growth spermatocytes undergo meiosis (2 divisions) = spermatids differentiates into 4 sperm cells
what are the support cells for sperm called?sertoli cells
what does spermatogenesis depend upon?Testosterone levels made in the leydig cells
outline the process of oogenesis (6)produced in the ovaries oogonia + granulosa cells undergo mitosis oocyte 1 (prophase 1) till puberty oocyte 2 (meiosis 1) + 3 polar bodies (met 2) in puberty meiosis 2 done if oocyte is fertilised = ovum + polar body unequal cytoplasm division
What are the differences between spermatogenesis and oogenesis? (3)number of cells = sperm (4) ovum (1) size = sperm (equal size), ovum (only 1 has all cytoplasm) timing = sperm (continuous production till death), ovum (limited and staggered)
list the order of stages in spermatogenesis using a seminiferous tubule diagram (6)germline epithelium + sertoli cells spermatogonia (mitosis and growth) 1 spermatocyte (meiosis 1) 2 spermatocyte (meiosis 2) spermatid (differentiation) 4 sperms
label a sperm (6)acrosome = hydrolytic enzyme to penetrate jelly nucleus = genetic info centriole = so zygote can divide Mitochondria = ATP for movement flagellum = movement axonome = bends for movement
List the order of stages in oogenesis using a ovary diagram (6)primordial follicles (P1) primary oocytes each month = primary follicle secondary follicle mature follicle = ruptures and released secondary oocyte corpus leutum = produces estrogen and progesterone corpus albicans
What does external fertilisation involve? example? (3)fuse outside and is influenced by the environment (predators and pH) = release a large amount to make up for loss. Aquatic animals Eg: Spawning
What does internal fertilisation involve? (2)gametes formed inside (copulation) prevent exposure + more protection but there is a survival cost to parent
What is it called when gametes are formed inside?copulation
What are the biochemical changes to egg and sperm during fertilisation? (3)capacitation acrosome reaction cortical reaction
What is capacitation? (2)improves sperm mobility by destabilising acrosome cap and cholesterol coat is removed
What is acrosome reaction? (3)sperm binds to jelly and enzymes are released from acrosome digests jelly so sperm nucleus can enter binds to docking proteins
What is cortical reaction?(4)cortical granule in ovary releases enzyme into jelly to destroy sperm binding sites hardens jelly coat prevents polyspermy
label an ovary (4)nucleus = forms after fertilisation cortical granule = releases when fertilised to prevent polyspermy Zona pellucida (jelly) corona radiata (follicular cells to support and nourish)
What are the stages of embryo development? (3)zygote = influx of Ca2+ completes meiosis mitosis = morula differentiates blastocyst = outer outer is trophoblast= placenta
How is the blastocyst implanted? also include the stages of embryo development (5)Day 0 = zygote Day 4 = Morula Day 7 = Blastocyst digestive enzymes released degrade lining and autocrine hormones triggers implantation when implanted blastocyst gets nutrients from endometrial lining
What is HCG? what is its main purpose?Human chorionic gonadotrophin maintains the corpus leutum
which hormones do corpus leutum produce?estrogen and progesterone
what does estrogen do? (2)inhibits PSH + LH production = prevents release of more eggs
what does progesterone do? (2)maintains endometrium lining thickens cervix
How long is HCG maintained for?8-10 weeks
what replaces the job of HCG after it stops being produced? (2)placenta does progesterone secretion and nourishes embryo HCG levels decrease so corpus leutum degenerates
what does the placenta develop from?from trophoblast after implantation
What are the two main jobs of the placenta?exchanges materials bw mom and fetus secretes hormones to maintain pregnancy after corpus leutum degenerates
What are the different parts of the placenta? (5)umbilical cord fetal vein and artery maternal vein and artery chorionic villus intervillous space (lacunae)
What does chorionic villus do?moderates material exchange
What are the features of chorionic villus to aid diffusion?microvilli = increase surface area close to surface = less distance
what gets transferred to the fetal cappillaries?oxygen, water and nutrients
what gets transferred out of the fetal capillaries?CO2 and urea
when does estrogen and progesterone levels peak?3rd trimester
What does estrogen do in 3rd trimester? (2)grows uterine muscles develops mammary glands
What does progesterone do in the 3rd trimester? (2)maintains endometrium decreases contraction
What is the birth process called?parturition
which hormones are involved in the birth process?estrogen and oxytocin
what is the positive feedback loop of the birth process? (5)baby stretches cervix by pushing nerve impulses causes posterior pituitary to release oxytocin oxytocin causes smooth muscle lining to contract less space causes more stretching loop repeats
which hormone is released from the fetus? what does it do?prostaglandin causes more contractions
what does estriol do? (2 oppsites)promotes release of oxytocin from posterior pituitary inhibits progesterone because it prevents contractions
What does oxytocin do? (2 opposites)promotes contractions and inhibits progesterone
what is gestation period?Time taken for fetus to develop and depends on animal size and development level
what is altricial and precocial?undeveloped and developed