inquiry question 1 mod 5 Flashcards
reproduction
production of new offspring
- asexual
- sexual
heredity
the passing of characteristics from one generation to the next through genetics through DNA which is located in the cells nucleus
sexual reproduction
requires the combination of genetics from two individuals to create genetically different individuals
- meiosis
- fuses to form 2n zygote
asexual reproduction
requires one individual to create genetically identical offspring
- mitosis
eg. binary fission, budding, fragmentation, regeneration
eg. starfish,
advantages to asexual reproduction
-Does not place a great energy demand on the organism
- Mate isn’t required
- Offspring can disperse easily to colonise new areas
- Reduces competition for resources → increases survival chances for the parent and offspring
- Reproduce very rapidly → don’t have to wait for fertilisation or the growth of the embryo
disadvantages to asexual reproduction
- No genetic variation
- Dangerous mutations in DNA are passed down
different asexual reproduction methods and examples
- Vegetative propagation → Budding, cutting, layering, grafting → eg. plants, protists
- Binary fission → eg. bacteria, protists
- Fragmentation
- Regeneration
- Parthenogenesis
cutting
part of stem is cut and planted in the soil, gradually growing into another plant
layering
Branch of plant bends down into the soil and develops its own roots while attached to parent plant
grafting
- Two plants are selected and the stem of the base plant (stock) is cut and the other plant cutting (scion) is joined on
- The scion grows into the fruit and flowers
budding + process
when offspring grows off the body of the parent which is identical to the parent eg. fungi, tapeworm
- after breaking off the organism is independent
process:
1. small protrusion on the parent cell grows to form a bud
2. nucleus of parent cell splits –> produces a daughter nucleus –>migrates to the new cell
3. bud pinches off the base –> detaches from the parents base
4. process repeated to form a chain of buds
sporation
through asexual and sexual reproduction sexual spores produce a fruiting body eg. fungus
process:
1. spores grow long hyphae through budding
2. different hyphae meet –> conjugate –> combine genetic material (sexual)
3. produces diploid (2n) fungus –> matures to form a fruiting body
4. process restarts
binary fission
Asexual reproduction of two identical daughter cells eg. bacteria, protists
process:
1. Bacterium contains tightly wound DNA
2. DNA is replicated
3. Each copy of DNA moves to opposite ends of the bacterium as it increases in size
4. A cell wall begins to form in the centre of the bacterium
5. New cell wall completely splits the bacterium in half
6. The new daughter bacteria are complete with DNA, ribosomes and plasmids (tightly wound)
pathogenesis
females produce eggs which develop into young without being fertilised eg. some insects (bees), some fish
- no increase in genetic diversity –> the offspring are genetically identical to the parent
fragmentation
Allows an adult to break up into two or more pieces in order to produce exact copies of itself eg. flatworms
- fragments develop into mature adults
regeneration
If part of the animal if broken or cut off from an individual → the part can develop into a new individual if the body part contains enough genetic information from the parent
advantages to sexual reproduction
- Diverse offspring due to genetic variation –> Better chance of survival from harsh environments
- Plants can resist disease
- Selective breeding –> used to develop plants and animals with desirable traits
disadvantages to sexual reproduction
- Time and energy
- Organisms have to grow and develop until they can produce sex cells
- Searching for a mate may expose the individual to predators, disease or harsh environmental conditions
- Needs to find a mate to be fertilised
- Fertilisation cannot take place during pregnancy → for some mammals it lasts 2 years
fertilisation
Fusion of two sex cells eg. sperms and eggs (gametes) to form a diploid zygote
- union of two haploid (n) gametes → restores the chromosome number back to normal →
- external
- internal
external fertilisation
egg fertilised outside the female’s body
- Male and female gametes are released into the species surrounding → some will fuse to form a zygote
- requires a moist environment
eg. fish
zygote
the first cell of a new organism
why does external fertilisation require a moist environment
- Prevents the desiccation of gametes
- Provides a medium of transport
how do animals overcome issues during external fertilisation
- mass spawning
- timing release of gametes
- frogs have complex mating behaviours
internal fertilisation
eggs are fertilised by the sperm inside the females body through specialised functions in the male
- male and female must be in close proximity
- males have specialised copulatory organs (penis)
example of male specialised copulatory organ
penis
stages of the reproductive cycle
- internal fertilisation
- implantation of embryo
- pregnancy
hormones
chemical messengers of the body
pituitary gland
stimulates endocrine glands that control the secretion of hormones
oestrus
fertile
advantages and disadvantages of internal fertilisation
advantages:
- high probability of successful fertilisation
- less gametes needed
- external water source is not needed
disadvantages:
- organisms need to be in close proximity
- energy demands to find mate and protect offspring is high
- few offspring can be produced
advantages and disadvantages of external fertilisation
Advantages
- Offspring can disperse easily
- Mate is not required
Disadvantages
- Gametes may be eaten by predators
- strong currents can sweep them away
hermaphrodite animals
organism that produces both female and male gametes
parts of the male reproductive system
semen
urethra
testes
scrotum
epididymis
penis
prostate gland
seminal vesicles
vas deferens
testes
structure: oval structure
function: responsible for secreting the hormone testosterone and produces sperm
semen
sperm + prostate fluid exists body via urethra
penis
structure: the organ used for urination and sexual intercourse, contains the urethra
function: Spongy tissue → can fill with blood to cause an erection
scrotum
structure: loose bag of skin that hangs outside the body behind the penis
function: holds testes in place and keeps sperm at a lower temperature
epididymis
structure: highly coiled tube that lies at the back of the testes
function: all sperm must pass through this structure where they mature and start to swim
vas deferens
structure: thick walled tube joined to the epididymis
function: carries sperm from the epididymis up to the prostate gland and urethra
prostate
produces fluid secretions that support and nourish the sperm
urethra
structure: Tube that extends from the bladder to the external opening at the end of the penis
function: carries both urine and sperm (gametes)
seminal vesicles
structure: 2 small glands above the prostate gland
function: makes up much of the fluid in semen
how often does a women produce an egg
every 28 days
roles of the female reproductive system
- Production of female gametes in the ovaries
- Delivers the ovum to the oviducts where fertilisation occurs
- Prepares the lining of the uterus for implantation and development of embryo
- Produces main female sex hormones → oestrogen
what is the female reproductive system involved in
- childbirth
- fertility
- sexual activity
- pregnancy
parts of the female reproductive system
ovaries
fallopian tubes
uterus
cervix
vagina
endometrium
ovaries
structure: two ovaries –> one on each side of the fallopian tubes
function:
- Oestrogen and progesterone are produced
- Eggs are stored to mature
- Where ovulation occurs → once a month an egg is released
fallopian tubes
structure: 2 thin tubes
function: connects the ovary to the uterus and the place of fertilisation
uterus
structure:
function: place of implantation of zygote and placenta formation
- pregnancy occurs –> Fertilised egg will implant in the uterus and grow into a foetus
- pregnancy doesn’t occur –> menstruation occurs and lining flows out of the body
cervix
structure: lower part of the uterus
function: canal connecting uterus and vagina
vagina
structure: birth canal
function: connects the cervix to the outside body
endometrium
structure: inner layer of uterus mucous layer
function: Functional layer → thickens and becomes rich in blood vessels → shed in menstruation
- helps maintain pregnancy if implantation occurs and menstruation in the absence of pregnancy
Spermatogenesis
production or development of mature spermatozoa (sperm)
spermatozoa
mature motile male gamete by which the ovum is fertilised
sperm
(n) haploid male gamete cells
- Flagellum - tail
- Neck - contains energy producing mitochondria
- Head - contains DNA and genetic material
sertoli cells
facilitate the maturation of sperm
process of spermatogenesis
- sperm cells produced in seminiferous tubules inside the testicles
- after developing flagella and nearly mature (through the help of sertoli cells) they leave the testicles and enter the epididymis
- leave epididymis –> enter vas deferens –> exit penis through urethra in the form of semen
hormones involved in male sperm production
GnRH, LH, FSH, Testosterone
process of sperm production in terms of hormones
puberty –> hypothalamus causes release of gNRH –_> stimulates the anterior pitaury gland –> secretes FSH and LH
- FSH and LH enter the seminiferous tubes
- stimulates leydig cells and sertoli cells –> secretes testostosterone and androgynous binding proteins
- ABP and testosterone begins spermatogenesis
- negative feedback system occurs
- rising T acts on the release of GnRH and LH
- when sperm is too high inhibin is released which inhibits the release of GnRH and FSH
lutenising hormone (male)
- targets and binds to receptors on leydig cells (secrete testosterone) in the semiiferous tubes
testosterone
male hormone –> stimulates development of sexual characteristics
– secreted by Leydig cells
deepening voice, growth of facial hair
GnRH (male)
secreted by hypothalamus and targets the pitaury glands which stimulates the secretion of FSH and LH
LH (male)
secreted by the pituitary gland and targets the leydig cells to stimulate production of testosterone
FSH (male)
secreted by the pituitary gland and targets the sertoli cells to stimulate the beginning of spermatogenesis
oogenesis
process of the creation of ova eggs
- ovary contains follicles –> follicles have oocytes –> matures during menstrual cycle –> ovulation –> release of ovum from follicle –> remaining follicular tissues grows within the ovary –> forms corpus luteum
oocytes
immature female egg cells that mature during the menstrual cycle to become ovum
ovarian cycle
monthly cycle of egg development in the ovary
menstruation cycle
cyclic preparation of the endometrium of the uterus for pregnancy in females
hormones in the menstrual cycle
FSH
LH
oestrogen
progesterone
GnRH
GnRH (women)
secreted by the hypothalamus and targets the pituitary gland which stimulates FSH secretion
FSH women
secreted by the pituitary gland that targets the ovaries
- follicular growth
- increases until ovulation day 14 then decreases
- stimulate oestrogen secretion
LH women
secreted by the pituitary gland and stimulate oestrogen production in the ovary
- spike in this hormone causes ovulation
oestrogen
secreted by the follicles in the ovaries
- Stimulates the pituitary to secrete LH and less FSH (negative feedback)
- Thickens the endometrium layer
- Produced by the ovaries in response to LH and FSH
progesterone
- secreted by the corpus luteum
- endometrium to thicken and stabilise which allows the egg to be implanted
- if pregnancy doesnt occur –> levels decrease –> menstruation occurs –> corpus luteum degenerates
4 key phases in the female reproductive cycle
- follicular phase
- luteal phase
- ovulation
- menstrual phase
follicular phase
Hypothalamus releases GnRH to the pituitary gland
FSH → secreted from pituitary gland
Dominant follicle survives → produces oestrogen → inhibits FSH secretion to prevent other follicles from growing → also acts on the uterus → thickening the endometrium layer
ovulation phase
Oestrogen → stimulates the pituitary gland to secrete LH → less FSH (negative feedback)
LH → causes follicle to rupture → releases ovum
luteal phase
- Starts after ovulation
- Ends with first day of period
Ruptured follicle develops into the corpus luteum
Corpus luteum:
Secretes high levels of progesterone and lower levels of oestrogen
Inhibit FSH and LH → Negative feedback in order to prevent any other follicles to develop
Progesterone → Endometrium to thicken and stabilise → allows the egg to be implanted
Blood vessels to grow → supplies nutrients and oxygen for the embryo
menstrual phase
Fertilisation does not occur → corpus luteum degenerates → forms corpus albicans → progesterone and oestrogen levels decrease
Endometrium layer and the egg are shed → menstrual cycle
Then the cycle begins again
- during the follicular phase
process of fertilisation
- during copulation contractions in the vas deferens move sperm towards urethra → using their tails to swim in a corkscrew motion
- Egg and sperm travel in opposite directions →meet in the fallopian tube
- Sperm uses acrosome enzymes (in the head) → break down the protective jelly coat that surround the egg
- Jelly coat releases chemical to attract sperm
- Nuclei from sperm and egg fuse together –> form a zygote
- Jelly coat then separates from the egg → prevents fertilisation by multiple sperm
process after fertilisation
- Zygote (2n) - fertilised ovum travels through the fallopian tubes towards the uterus
- Morula - 3-4 days post fertilisation where the zygote undergoes mitosis and becomes 2 cells or more → unspecialised ball of cells
- Blastocyst - 4-5 days of post fertilisation → attaches to the endometrium of the uterus (inner wall)
4.Placenta - organ that develops in the uterus during pregnancy, provides nutrients and removes waste from the baby’s blood → attaches to the wall of the uterus and the umbilical cord arises from it - Embryo - early stage of development of a multicellular organism → has not differentiated adult features
- Foetus - 9th week , adult features are developing
pregnancy hormones
- hCG –> stops ovulation (s placenta)
- oestrogen –> assist in development of organs (s corpus luteum)
- progesterone –> stops uterine contractions (s corpus luteum)
- relaxin –> cervix –> loosens (s corpus luteum)
why do plants prefer asexual methods
- requires less energy
variability is not essential if environment is stable - when colonising a new area finding a mate may be hard
forms of asexual reproduction in plants
budding - Plantlets arise from tissue located in notches along the leaves
When mature → plantlets separate from the leaves and drop to the soil → take root and develop into a mature plant
Cutting
Segment cut diagonally across the stem
Fragmentation
Runners (stolons) eg. strawberries
Plants that reproduce by runners (long slender stems that grow along the surface of the soil)
Asexual reproduction → clones
Runners grow from the parent plant and develop into nodes → nodes develop into a new cloned plant with leaves. Roots and flowers
methods of plant and animal reproduction in agriculture
- selective breeding: practice of choosing particular desirable characteristics and breeding individuals that possess these traits together to produce offsprings that exhibit most favourable characteristics
- artificial pollination: Pollen manually transferred from stamen to the stigma to facilitate artificial pollution
- artificial insemination :Process of transferring semen into a female reproductive tract manually
- cloning
- hybridisation
sexual reproduction in plants
male plant parts
anther
gamete: pollen found in the anther
female parts
egg
ovary
stigma
style
gamete: egg found in the ovary
stigma
receives pollen during fertilisation
style
tube on top of the ovary
ovary
female reproductive organ that produces and stores eggs
ovule
Reproductive cell that will become the seed when fertilised by pollen
anther
Contains the male reproductive cell, pollen
filament
Holds the anther
petals
Often brightly coloured to attract pollinators
Sepal
Small leaves under flower
process of reproduction in plants
- pollen is deposited on the plants stigma
- through either self-pollination or cross pollinations - growth of pollen tube
- pollen tube grows down the style into the ovary
- pathway for sperm to reach egg
- nucleus of pollen moves down the tube to fertilise the female gamete nucleus inside ovule - penetration of ovum
- pollen tube penetrates the ovum which contains the female gamete - fertilisation
- sperm travels down ad fertilised the egg
- zygote is formed
- ovule becomes seed –> fruit –> seed dispersed in wind, animals, fire
self- pollination
a plants own fertilisation of its own ovum
cross pollination
-transfer of pollen from the anther of one plant to the stigma of another
- - promotes genetic diversity
birds –> attracted to nectar in flowers and transfer pollen via bills
insects –> Bees are attracted to flowers and transfer pollen
wind: anthers release pollen containing male gametes in the air
moss
asexual and sexual reproduction methods
- diploid zygote formed
- sporophyte produces calyptra –> filled with haploid spores –> releases spores that bud asexually
plant adaptations
wind: LONG FILAMENT, LARGE FEMALE STIGMAS
insects: scented, colours
birds: stick pollen, long
days luteal phase
15-28
days follicular includes menstruation
1-13
ovulation
14
