reproduction Flashcards
gametes
haploid cells produced by the process of meiosis in the sex organs
reproduction
producing offspring within a species
advantages of sexual reproduction.
creates variation amongst offspring
adaptations of sperm
-flagellum so they can swim
-mitochondria so they can produce energy (ATP)
-haploid cells
adaptations of an egg
haploid cells
scrotum
sac to protect testes
penis
organ that carries sperm to the vagina
urethra
carries urine or fluid containing sperm down the penis
testes
production of sperm
prostate gland
produces secretions which carry the sperm
sperm duct
carrie’s sperm to the urethra
cervix
restricts opening of the uterus and widens during birth
ovary
produces eggs (ova)
vulva
allow entry of penis for fertilisation
oviduct
site of fertilisation carries ova to uterus
vagina
penis places sperm here during sexual intercourse
uterus
allows development of fertilised ovum and produces structures to help its growth
fertilisation
when the nucleus of sperm fuses with the nucleus of the egg to produce a diploid zygote
ovulation
the release of the egg from the ovaries
implantation
when the embryo enter the uterus it becomes embedded in the lining becomes attached and receives nourishment
zygote
a cell that’s produced when egg and sperm nuclei join at fertilisation
how the zygote changes as it moves down the oviduct towards the uterus
zygote divides by mitosis and grows into a ball of cells
zygote development
-after implantation in the uterus lining the ball of cells continues to divide but with differentiation meaning a variety of tissues is developed
-when the embryo develops in the uterus the placenta and umbilical cord form
how the embryo is protected in the uterus
-the protective membrane (amnion) which contains amniotic fluid which cushions the growing embryo
exchange at the placenta
a placenta and umbilical cord allow an exchange of material including nutrients diffusing from the mothers blood to foetal blood
placenta
contains a rich supply of mothers blood vessels and is highly adapted (LSA and villi) for the exchange of substances between material and foetal blood
umbilical cord
connect foetus and placenta contains umbilical artery and vein
why’s it important that mother and foetus blood don’t mix
mothers white blood cells would attack the foetal red blood cells which could be very dangerous for the foetus
how placenta is adapted for diffusion
-many folds and villi create a LSA for diffusion to occur
-good blood supply maintains the diffusion gradient so layers can be exchanged continuously
-capillaries that are one cell thick and close to foetus’ capillaries create a short diffusion distance which means rapid exchange of materials
umbilical artery
carries waste products away from baby towards placenta eg carbon dioxide and urea
umbilical vein
carries oxygen glucose and amino acids to baby from mothers blood
contraception
method of preventing pregnancy
mechanical contraception
male and female condoms
how mechanical contraception works
prevent sperm entering woman
prevent sperm passing up through female reproductive system
advantages of mechanical
easily obtains
prevent STIs
disadvantages of mechanical
unreliable if not used properly
chemical contraceptive
contraceptive pills
implants
how chemical works
prevents ovaries releasing eggs by changes in hormone levels
disadvantages of chemical
can cause side effects
have to be taken regularly or innefective
don’t protect from STIs
surgical contraception
vasectomy
female fertilisation
how surgical works
sperm tubes are cut to prevent sperm entering penis
oviducts are cut to prevent ova being fertilised
disadvantage with surgical
don’t protect against STIs
cannot be reversed
natural contraception
rhythm method
how natural works
avoid having sex when ovulation occurs by tracking menstrual cycle
disadvantages of natural
difficult to judge as some women have irregular menstrual cycles
don’t protect against STIs
advantage of natural
requires no contraception so is more ethically acceptable for some ppl
primary characteristic of sexual maturity
sperm production begins and ovulation begins
male secondary sexual characteristics
body and pubic hair develop
body becomes muscular
voice deepens
sexual organs enlarge
sexual awareness and drive increases
secondary sexual characteristics in females
menstruation begins
body and pubic hair develop
pelvis and hips widen
sexual organs enlarge and breast develop
sexual awareness and drive increases
what hormones cause body change
testosterone and oestrogen
what is menstruation
blood flows out of vagina due to uterus lining breaking down
how long does cycle last
28 days
oestrogen levels
high at middle of cycle
low at start of cycle
progesterone levels
high during days following ovulation
low during ovulation
effect of oestrogen
important in initial build up of uterine lining and causes release of egg
effect of progesterone
builds up and maintains the thick uterine lining and subsequent development of placenta
when does menstruation occur
day 1-5
when does uterine wall repair
day 6-12
when does ovulation occur
day 14
when can sperm in oviducts cause fertilisation
day 13-15
