Unit 16 reproduction Flashcards
what is asexual reproduction
the process resulting in genetically identical offspring
advantages of asexual reproduction
only one parent is needed which saves time and energy
reproduction is very quick
if there are desirable features, offspring will inherit them
disadvantages of asexual reproduction
vulnerable to environmental changes such as disease
what is fertilization
the fusion of the nuclei of two gametes that form a zygote
what are the nucleus of the gamete
haploid because they have a single set of unpaired chromosomes
what are the nucleus of the zygote
diploid and contains two sets of chromosomes
advantages of sexual reproduction
variation making it resistant to environmental change
farmers can produce crops that have the best characteristics. This is known as selective breeding
disadvantages of sexual reproduction
must spend time and energy looking for a mate
much slower to reproduce
what is pollination
the transfer of pollen from the male part of the flower to the female part
what is the features of the male part of the plant
called the stamen, made of the anther and the filament
what are the features of the female part of the plant
called the carpel, has a stigma with a style connecting it to the ovary
where is pollen produced
in the anthers
where do the seeds develop
in the ovary
what is the function of the sepal
to protect the growing flower and keep it from drying out
what is the function of the petal
to attract insects to carry out pollination
what is the function of the anther
produce pollen grains which contains male gametes
what is the function of the stigma
to trap pollen from other flowers
what is the function of the ovary in plants
contains ovules which develop into seeds after fertilization
what are features of pollen that is transferred by insects
have a spiky outer layer
what are features of pollen that is transferred by wind
lighter and smoother with more being produced
what is self pollination
the transfer of pollen grains from an anther to the stigma of the same flower or a different flower on the same plant
what is cross pollination
the transfer of pollen grains from the anther of a flower to the stigma of a flower on a different plant
features of wind pollinated flower
petals are small and dull
anthers are loosely attached and dangle outside the flower to reach wind
stigma is loosely attached and outside the flower to catch pollen
features of insect pollinated flowers
petals large and brightly colored
anther located inside flower to touch insects
stigma located inside flower to touch insects
what happens in plants after pollination
a pollen tube begins to grow towards the ovary and sperm moves through the tube
what do seeds need to germinate
water
oxygen
suitable temperature
what is the function of the testes
produce sperm cells and testosterone
what is the function of the scrotum
contains the testes to keep them at lower temperatures
what is the function of the prostate gland
secretes fluid that nourishes and protects the sperm
mixture of this liquid known as semen
alkaline in nature
what is the function of the sperm duct
tube that connects the urethra to the testes
what is the function of the urethra
allows semen and urine through the centre of the penis
what is the function of the penis
inserted into vagina so that sperm can be transferred into the womans body
what is the function of the ovary
produce egg cells and the hormones estrogen and progesterone
what is the function of the oviduct
tube connecting an ovary to the uterus
what is the function of the uterus
organ in which embryo develops
what is the function of the cervix
ring of muscle between vagina and uterus
what is the function of the vagina
elastic muscular canal where penis is inserted
adaptations of sperm cells
tip of the head(acrosome) secretes digestive enzymes that dissolve the surface of the egg cell
flagellum that moves like a tail for movement
contains lots of mitochrondria to release energy
what do egg cells contain
nucleus
surrounded by cytoplasm containing energy stores
jelly coating that changes after fertilisation
difference between egg cells and sperm cells
egg cells are much longer than sperm cells
40 million- 300 million sperm cells produced per ejaculation but only one egg per month
egg cells cannot move on their own but sperm can
what happens in early development of they zygote
forms an embryo which is a ball of cells
what is the amniotic sac
protective layer that surrounds the fetus
what is amniotic fluid
contains nutrients and protects the fetus
what is the placenta and its functions
grows and attaches to the wall of the fetus
transfers substances from the mother to the fetus
transfers waste substances from the fetus to the mother
provides a barrier to many toxins and pathogens
what isthe main male sex hormone
testosterone
what is the main female sex hormone
estrogen
what is ovulation
when an egg is released every 4 weeks
what is phase one of the menstrual cycle
MENSTRUATION(day 1-5)
unfertilized egg,lining of the uterus and blood exit through the vagina
what is phase 2 of the menstrual cycle
REPAIR PHASE(day 6-12)
blood flow stops
lining of uterus thickens and becomes stable
changes are triggered by FSH which causes rise in estrogen levels
What happens on day 14 of the menstrual cycle
egg is released into the oviduct
level of estrogen peaks and stimulates Luteinising hormone which causes ovulation
since estrogen is high FSH goes down
formation of a corpeus luteum
what is day 22-28 of the menstrual cycle
PRE-MENSTRUATION PHASE
uterus lining degenerates
what hormones are produced by the pituitary gland
Follicle Stimulating Hormones
Luteinising Hormone
what happens when progesterone levels go higher
FSH and LH go down
what is the interaction of the hormones
in beginning FSH is released which causes release of estrogen
as estrogen rises FSH is limited
LH is stimulated which causes egg to be released
progesterone is then produced which inhibits FSH and LH.
what does progesterone do
maintains the lining of the uterus
what are Sexually Transmitted Infections
infections that are transmitted through sexual contact
what is human immunodeficiency virus
HIV is a pathogen that causes an STI which can lead to AIDs
how can STIs be stopped
avoid sexual contact
contraception
what does AIDs do
acquired immune deficiency virus which destroys the bodys immune system
