Mod 5: Heredity - Reproduction Flashcards
reproduction
1
Q
what is reproduction
A
reproduction is the production of offspring; a procees where one or more parent organism create offspring
2
Q
what the two types of reproduction
A
asexual and sexual reproduction
3
Q
why is reproduction important
A
species must successfully reproduce to pass on their favourable genes to their offspring in order to ensure continuity of species
4
Q
what is asexual repoduction
A
a process that does not invovle gametes or fertilisation whereby ONE parent clones itself to produce an offspring
5
Q
how does asexual reproduction work
A
one parent divides itself to produce gentically identical offspring
6
Q
where is asexual reproduction commonly found
A
in unicellulcar organisms; bacteria, protists
7
Q
advantages of asexual reproduction
A
- rapid growth
- no need for a mate
- not energy nor time intensive
- no requirement to care for offspring
8
Q
what are some disadvantages of asexual reproduction
A
- little to no variation in population - vulnerale to sudden changes in the environemnt
- many of the organisms alternate beween sexual and asexual reproduction - produces a gamete-bearing generation alternation with spore-bearing generation
9
Q
what is sexual reproduction
A
the fusion of two gametes which carry gentic information from both parents that combine to produce diverse offspring that are genetically different to the parents
10
Q
how does sexual reproduction work
A
two gametes (sperm and egg) from two different parents fuse to make a genetically different offsrping to the parent
11
Q
advantages of sexual reproduction
A
- introduces genetic varation and ensures continuity of species
- allows for the population to better survive environmental change and disease events
12
Q
disadvantages of sexual reproduction
A
- requries large amounts of time and energy
- requires a mating partner
- fewer offsrping are produced
13
Q
how is genetic material passed on in sexual reproduction
A
- passed on in the form of chromosomes
- each sepcies have two sets of chromosomes in homologous pairs
- humans have 46 chromosomes
- each parent contributes a gamete to the offspring
- gametes are produced through meiosis
14
Q
some differences between sexual and asexual reproduction
A
- two parents to one parent
- unique to identical offspring
- meiosis divison vs mitosis, binary fission, vegetative propagation and budding divison
- high genetic variation to low genetic variation
*low efficiency to high efficiency - animals, planes nad fungi vs plants, fungi, bacteria and protists
15
Q
what is internal fertilisation
A
when the eggs are fertilised inside of the females body
16
Q
advantages of internal fertilisation
A
- fewer gametes required
- higher chance of fertilisation
- organisms not limited to aquatic/moist environments
- allows more control of mate choice
- natural selection is quicker
17
Q
disadvantages of internal fertilisation
A
- requires mroe energy
- generally produced fewer offspring
18
Q
examples of internal fertilisation
A
most mammals, birds, reptiles
(although most birds and reptiles lay an egg, the eggs are fertilisied within the female’s body before laying the egg)
19
Q
what is external fertilisation
A
when both the spem and the eggs are released into the environemnt and fertilised outside of the body
20
Q
how to help external fertilisation
A
syncing of reproductive cycles, mating behaviours and release of gametes
21
Q
advantages of external fertilisation
A
- lower amount of energy required
- time efficient
- often produced large numbers of offspring
- wide dispersal of young
22
Q
disadvantages of external fertilisation
A
- lower chance of fertilisation/gamete survival
- organisms often limited to aquatic/moist environments to keep gametes alive
23
Q
examples of external fertilisation
A
most fish, crustaceans, molluscs, some amphibians
* coral spawning
* tetra fish
24
Q
what are hormones
A
- messengers within the body that helps with functioning
- comes from the pituitary gland
- gonads only become functional at puberty
25
what is spermatogenesis
a continuous process by which testosterone is used to produce sperm.
26
role of hormones in spermatogenesis
* LH stimulate the production of testosterone
* FSH stimulate production of preotein by Sertoli cells
* Inhibin - reduces level of FSH
* GnRH - releases hormones
27
structure of sperm
head, neck , middle piece, tail
head - acrosome cap-like structure for help to break through the zona pellucida and fertilise the egg
middle piece - lots of mitochrondria for energy
tail - mobility of sperm
28
what are gametes
sex cells (sperm and egg), they are hapoid and only have half the amount of chromosommes normal somatic cells have
29
what are the key processes of the female reproductive system
1. ovulation
2. fertilisation
3. implantation
4. pregnancy and birth
30
what is ovulation
happens once every 28 days at around day 14 and is the relesae of an egg from the ovary
31
two phases of the menstrual cycle
follicular phase (days 1-13)
ovulation (day 14)
luteal phase (day 15-28)
32
key hormones during menstrual cycle (4)
FSH
LH
Oestrogen
Progesterone
33
what does fsh do
starts the maturation of the follicle and triggers growth of eggs in the ovarieis to get ready for ovulation
34
what happens in the follicular phase
1. fsh starts maturation of follicle
2. cells lining secrete oestrogen
3. oestrogen promotes production of LH
4. mature follicle known as Graafian follicle
35
what does LH do
helps control menstural cycle and triggers the release of an egg from the ovary
36
what happnes in the luteal phase
1. lh causes burst follile to build up lutein whcih now is called corpus luteum
2. corpus luteum produces progesterone
3 corpus luteum breaks down
37
what does progesterone and oestrogen do in menstrual cycle
prepares the endometirum lining for a fertilised egg by thickening it
38
what does corpus luteum do
it secretes progesterone to prepare the endometrium for an egg
if impantation does occur, the progesterone helps to maintain the pregnancy and keep the foetus alive and protected for 3 months until placenta takes over and then luteum starts to degrade
39
what is fertilisation
the fusion of two haloid gametes to form a diploid zygote that takes place in the fallopian tube
40
how does fertilisation occur (sperm-wise)
sperm must cross three layers
first, must push through the follicle cells
then the acrosome comes into contact with the zona pellucida and releases enxymes to assist that penetration
thirdly, the sperm will reach the plasma membrane and safety proteins only allow one sperm to penetrate and the egg causes electrical charges to prevent other sperm from penetration which immediately starts dividing
41
what happens before implantation
cell divided: from 1 cell --> 2 cell --> 4 cell --> 8 cell --> morula --> early blastocyst --> blastocyst --> implantation
42
what happens during implantation
this occurs around 6-10 days after ovulation where the blastocyst travels down the fallopian tubes and implants into the lining and then the cells continue to divide and form an embryo
43
what happens if egg is not fertilised or implanted
the crpus luteum will degenerate 8 dyas after ovulation and the endometrium breaks down and menstruation starts
44
what happens with the placenta
placenta begins to develop and finished developing in week 10 where it provides the foetus with a supply of nutrients and oxygen from the bloodstream of the mother
45
what are the 6 key hormones of pregnancy
hcg
relaxin
progesterone
prolactin
oestrogen
oxytocin
46
what does progesterone do in pregnancy
correct foetal development, stopping womb contraction until labour, preventing lactation, strengthenign muscles of pelvic wall for labour
47
what does oestrogen do in pregnancy
maintaining, controlling and stimulating the production of other pregnancy hormones, development of many foetal organs, stimulating the growth and correct function of the placenta
promoting the growth of maternal breast tissue
preparing the mother for lactation
48
what does relaxin do in pregnancy
prepares body for childbirth
increasing elasticity of ligaments
explansion of pelvis
hellps soften the cervix
49
what does oxytocin do in pregnancy
causes uterine muscles to contract
causes cervix to relax
50
what does prolactin do in pregnancy
stimulates milk production in the breasts
51
what does hcg do in pregnancy
stimulates corpus luteum to contunue producing progesterone unti placenta takes over at week 10
52
what is the psotive feedback loop to do wiht pregnancy
oxytocin: the reponse to the stimulus is to create more of the stimulus
1. baby pushes head against cervix
2. nerves sends message to brain
3. brain stimuales pituitary gland to release more oxytocin
4. oxytocin cuases muscle lining to contract
5. repeat
53
how is success maximised
internal fertilisation - likihood of gamates meeting
implantation into the uterine wall - humans/animals with internal development of young
protected young/internal development
54
what are the gametes of plants
spores, pollen and ova
55
how to increase genetic variation in sexual reproduction in plants
rely on winds,, water or animals for fertilisaitona dn distance in order to get to different plants
56
where are the gametes found in plants
gymnosperms: found within the cones
angiosperms: male part is stamen (anther and filament) - pollen found on anther
female part is pistil/carpel (stigma, style and ovary) - ovum found in ovary
57
what is pollination
the transfer of pollen from anthers to the stigma generally through the use of pollinators that move from flower to flower transferring pollen and when the eggs are fertilised, they become seeds and develops into the fruit
58
what are the types of pollination
self-pollination and cross-pollination
59
what is self-pollination and advantages
when the pollen fertilises the ova of the same plant:
less energy - no need for petals or attractions
having the reproductive cycle at the same time - producing pollen and egg at the same time
60
what is cross pollination and advantages
pollen fertilises the ova of a different plant:
requires more energy - producing attractions and needing pollinating agents
introducing genetic variation in offspring
stamens and stigma ripen at different times
61
steps of flower fertilisation
1. male gametes inside pollen is carried to female stigma
2. pollen has a tube cell and generative cell, when it reaches the stigma - the tube cell creates a pollen tube from stigma down the style to the ovary, the generative cells travel down this tube
3. generative divides into two sperm cells and enter the ovules. One fertilies the egg to form a zygote and the other combines with the nuclei to form endosprem
4. ovule matures to seed and then seed dispersed to germinate
62
advantages of seed dispersal
prevents overcrowding, competition of resources (light, water, soil nutrients)
increase chances of continuity of species
63
different types of asexual reproduction in plants
cuttings
runners
rhizomes
suckers
tubers
bulbs
plantlets
64
what are cuttings
when part of the plant is cut, put into rooting hormones and then planted in soil and new plant grown
65
what are runners
when the stem grows horizontally and creates a bud by which a new plant is grown
e.g. strawberries, mint, spider plant
66
what are rhizomes
stem grows horizontally underground to produce shoots that become new plants
e.g. bamboo, ginger, many ferns
67
what are suckers
some root are modified and they become suckers and give rise to new plants from the same root bulb
e.g. reeds, wattles, blackberries
68
what are tubers
large undergorund food strucutre bud and produce more plants
e.g. potatoes, sweet potatoes, dahlias
69
what are bulbs
short stems that produce new plants
e.g. onions, garlic, lilties, tulips
70
advantages of asexual reproduction
reproduce quickly without having to find a mating partner (sessile organisms)
helps in harsh environments - no benefits of variation
works in favourable conditions to quickly populate
71
types of asexual reproduction in organisms
buddings, bunary fission, sporogenesis, fragmentation, parthnogenesis
72
how does reproduction in fungi by spore happen
spores are produced in great numbers and when it lands in mixtures and food, it will germinate and produce hyphae which branch out and develop into mycelium which turns into a zygote and then are spores again throuhg meiosis
73
what happens in fragmentation
a muticellular fungus divides in fragments and each fragment becomes a separate organimss with identical genetic information
74
reproduction in fungi by budding
yeasts reproduce by buddings where a bulge forms on the side and and a new cell begins to form and when ready, the bud detaches from the parent
75
bacterial reproduction in binary fission
basically mitosis - dna is replicated and then split apart
76
what is selective breeding
two parents with desirable traits are selected and bred together and is used to produce humans ideal strains
77
what is artificial pollination
manually transferring pollen from the stamen of one plant to the stigma of another
78
what is artificial insemination
when semen is taken from a male and inserted into a female of choice
79
what is hybridisation
organisms with desirable traits for paretns of two different species
e.g. geep, mules, liger
80
disadvantages of manipulating plants and animals
* losing traits of these organisms
* monoculture - only few variants exist
81
what is ivf
in vitro fertilisation - donor mother produced multiple mature eggs and eggs are extracted surgically and then the eggs are mixed with the donated sperm in a test tube
82
