Biology module 5 - topic 1 (reproduction)

Difference between sexual and asexual reproduction

Sexual reproduction just means combining genetic material from two parents. Asexual reproduction produces offspring genetically identical to the one parent.

define reproduction

one or more parent organisms producing offspring

Haploid

A cell that contains a single set of chromosomes. (e.g gametes aka sex cells)

how are haploid cells produced

meiosis (in germ cells)

zygote

fertilised egg (diploid)

how many chromosomes are in a zygote

46

external fertilisation (with example)

eggs combine with sperm OUTSIDE of female body

ex) spawning:

aquatic females release their eggs and males release their sperm in the same area at the same time, often triggered by environmental signals

what environmental signals may trigger spawning

water temperature, tides, length of daylight

what are the advantages of external fertilisation

1. faster, more abundant

2. parents do not expend energy for gestation and caring for younng

3. females can continue to reproduce without waiting for first young to develop

what are the disadvantages of external fertilisation

1. more gametes must be produced

2. no control of gametes once released

3. decreases chances of successful fertilisation (improved by synchronised release of gametes e.g spawning)

4. Gametes and zygotes are exposed to predation and disease immediately

internal fertilisation

male directly deposits sperm into female body during mating

types of animals that use internal fertilisation

1. Placental mammals - protect offspring in female body

2. Reptiles + Birds - protect offspring in shelled or tough membraned eggs

3. Marsupials - uterus --> womb --> pouch

advantages of internal fertilisation

1. Less gametes have to be produces

2. More likely to be successful as gametes are positioned close together in female reproductive tract

3. gametes/zygotes protected from predation/disease

4. Developing young are fed and protected from predation and disease

disadvantages of internal fertilisation

1. Usually slower with fewer offspring

2. Mating rituals and practice are more complex to get to point of copulation

3. Potential for spread of sexually transmitted diseases throughout population

4. Energetically costly, requires ongoing energy from female parent

4 types of asexual plant reproduction (vegetative propagation)

1. Tubers - potatoes

2. Runners - underground modified stems/roots e.g strawberries

3. Rhizomes - underground HORIZONTAl modified stems e.g grasses

4. Bulbs - underground production of tiny baby bulbs around root of bulb

How do tubers work

1. Tubers - underground organs that can be propagated e.g potatoes

2. Runners/Suckers - underground modified stems/roots e.g strawberries

3. Rhizomes - underground HORIZONTAl modified stems e.g grasses

4. Bulbs - underground production of tiny baby bulbs around root of bulb

How do

what is apomixis

2 types of (seeded) sexual plant reproduction and their difference

1. Angiosperms: plants that produce flowers and bear their seeds in fruit (reproduce through flowers)

2. Gymnosperms: plants that reproduce through cones

what is ‘alternation of generations’ reproduction

plants that have lifecycle in which organism has multicellular haploid stage and multicellular diploid phase

what types of plants reproduce via ‘alternation of generations’ WITH EXAMPLES

seedless - e.g fern and mosses

gametophyte

multicellular haploid plant structure that produces haploid gametes

sporophyte

multicellular diploid plant structure that can produce haploid spores

process of reproduction in ‘alternate generation’ planst

1. Gametophyte produces haploid gametes that fuse to form diploid zygote (SEXUAL REPRODUCTION)

2. Zygote grows by mitosis into diploid plant structure the sporophyte

3. Diploid sporophyte produces haploid spores by meiosis (ASEXUAL) which disperse and grow by mitosis into the gametophyte 

what occurs in gymnosperm reproduction - cones examples

• male cones (grow in lower branches) disperse a large number of pollen grains spread by wind relying on one to reach the right part of another individual of same species by chance

• female cones grow in upper branches

what is F function

anther male part of angiosperm that produces pollen - which contains sperm

what is H function

filament connects the anther to the base of the flower and supports it.

what is E

carpel/pistel — female section!

what is D and function

stigma, it is very sticky made to capture pollen

what is B and function

ovary, it grows to become fruit to protect the seeds

what is A and function

ovules are part of the ovary that is fertilised to become the seeds

what is C and function

style - generates the pollen tube and blocks incompatible pollen from entering the ovaries

difference between self pollination and cross pollination

self pollination: transfer of pollen from the anther to the stigma of the SAME plant

whilst cross pollination is the transfer of pollen between different plants, promoting genetic diversity.

between which plants does cross pollination occur

plants of the SAME SPECIES but different varieties

characteristics of flowers that use wind pollination (+ explain why each part is useful)

plants with flowers grouped together and hang in tassels and blow in the wind easily, anthers are long and pollen is light + numerous

• stigmas: are long and spread out to capture shedding pollen

what is the efficiency of wind pollination + examples that use it

not efficient, as large amounts of pollen must be produced and many Australian grasses use this

characteristics of flowers that bees pollinate

• anthers: lower than stigma and often enclosed by petals to encourage access by bees, which helps in effective pollen transfer.

• large pollen grains in small amounts that are very sitcky

• fragrant, large + colourful

characteristics of flowers that birds pollinate

• anthers are commonly lower that stigma, may be enclosed by petals

• unscented, large + colourful, often in tubular shape

• sticky or powdery pollen - small amout produced

ways that pollen is transferred

wind/water dispersal, bees/insects or birds

what is pollination

it is the transfer and fusion of gametes from anthers to stigma

what are the 2 components of a pollen grain

1. tube cell

2. generative cell

4 steps of Angiosperm reproduction

1. Pollination

2. Fertilisation

3. Seed dispersal

4. Germination

process of pollination

1. pollen transferred to stigma of a flower

2. pollen’s tube cell (formed from tube cell) creates a pollen tube from the stigma towards the ovary

3. pollen’s generative cell divides to form 2 sperm cells

process of fertilisation in plants

1. the 2 sperm cells enter one of the ovules within the plant’s ovary

2. Inside ovule, 1 sperm cell fertilises egg, the other sperm cell combines with polar nuclei to form endosperm (helps to provide nourishment for zygote)

3. After fertilisation, ovule becomes seed containing fertilised egg, and ovary becomes the fruit

2 methods of seed dispersal with examples

1. via dry fruits which have in built ‘explosive’ mechanism for dispersal by air,wind or water - often these plants are very light e.g banksia pods, gumnuts

2. vis flesh fruit which rely on insect/birds/mammals to ingest and transport seeds away from parent plant in their excretion

process of germination

starts once the seed has landed in suitable soil with sufficient water, oxygen + warmth

• the fertilised egg in the seed develops into embryo which consists of:

  • radicle (root) to absorb water and soil nutrients

  • a plumule (stem) that develops green leaves for food production

what are the 6 types of asexual reproduction - and what types of organism reproduces that way

1. Binary fission - bacteria, protists e.g amoebas

2. budding - animals + fungi

3. fragmentation - animals

4. spores - plants e.g mosses, ferns + some fungi

5. vegetative propagation - plants

6. apomixis/pathenogenesis - plants and animals

process of budding in 3 steps

1. adult cell gives rise to bus

2. DNA replication

3. Nucleus division occurs via mitosis, providing each cell with genetically identical nuceus

4. cytokinesis occurs once bud is almost as large as parent

what type of organism reproduces via budding, with examples

fungi (yeast)

animals (eukaryotic) —> jellyfish, hydra, grooved brain coral

disadvantage of budding

if environment changes, entire species may rapidly decline due to identical offspring

what are spores + sporangia?

sporangia (sacs that prod. and store spores) prod large number of

spores - which are tiny unicellular reproductive cells that are very light for easy dispersal via wind

what organisms reproduce via spores?

mosses, ferns and fungi (moulds and mushrooms)

are fungi eukaryotic or prokaryotic

eukaryotic, and can be either multicellular or unicellular

why is fungi important to ecosystems

they help decomposition of organic matter - they secrete enzymes to break down environmental nutrients for absorption

name and outline functions of the 3 main parts of a multicelluar fungi

1. hyphae - spreads through material on which fungi feeds

2. sporangium - storage of spores

3. mushroom - ‘fruiting body’ releases spores into environment

what is interwoven mass of hyphae called

mycelium - visible to naked eye

how are spores produced

mitosis of haploid nuclei

what happens in sexual reproduction in fungi

two fungi temporarily fuse to create a diploid structure

process of binary fission

bacterial chromosome duplicates, beginning at origin of replication

After origin is duplicated, it moves to other end of cell and once entire chromosome is duplicated, cell begins to elongate

cytokinesis (plasma membrane growing inwards) splits cell into 2 identical cells

2 examples of organism that use binary fission for reproduction

prokaryotic unicellular - bacteria

eukaryotic unicellular - protists (e.g amoeba)

organelles inside eukaryotic cells - mitochondria

briefly describe the features of the 4 types of vegetative propagation

1. tubers - propagation of underground organs e.g potatoes

2. runners/suckers - modified underground stems/roots e.g strawberries

3. rhizomes - undergound HORIZONTAL modified stems e.g grasses

4. bulbs - underground production of baby bulbs around root of baby bulbs - e.g onions/tulips

what are the steps involved in sexual reproduction of mammals

1. ovulation

2. internal fertilisation

3. implantation

4. pregnancy

5. birth

3 types of mammals

monotremes egg laying

marsupial: pouched

Eutherians: placental

what is 1 and its function

scrotum - double walled pouch aids in regulating temperature of testes for optimal sperm production

name 2 and its function

testicale (testes) - male gonads are responsible for prod. male gametes and secreting testosterone

name 3 and its function

epididymus - coiled tube where sperm is stored temporarily while they mature

name 4 and its function

vas deferens - aka sperm duct a tubule that carries sperm from epididymus to the urethra

name 5 and its function

name 7 and its function

seminal vesicle: - secrete fluid to nourish aperm + allow sperm to swim

name 11 and its function

penis - used in intercourse to ejaculate semen containing sperm into female reproductive system

name a and its function

vagina - a canal with muscular walls through which baby is born, if no fertilisation occurs, lining shreds and menstruation results

name b and its function

cervix - the lower part of the uterus, it is a narrow channel allowing sperm to enter the uterus and blood to leave during menstruation

name d and its function

ovary - contains cells that divide to make female gametes

• makes female reproductive hormones

• ovulation occurs here

name g and its function

fallopian tube - transports the ovum to the site of fertilisation

• fertilisation occurs here???

outline the 6 general steps of sexual reproduction from intercourse to birth

1. male + female have intercourse

2. Ejaculation causes semen from male to move ino female vagine

3. sperm cell travels through female reproductive tract —> through cervix —> into uterus —> into fallopian tube (oviduct)

4. single sperm cell fertilises available egg(s) (if it is fraternal twins) resulting in zygote(s)

5. zygote travels down fallopian tube into the uterus —> begins to grow through mitosis into blastocyst

6. blastocyst implant in endometrial wall of uterus to continue developing

   embryo nourished by mother’s body via placenta —> grows to foetus —> baby

ovulation

when the egg (ovum) bursts out of the follicle in the middle of the cycle

difference between ovarian and menstrual cycle

ovarian cycle occurs in ovaries and prepares egg for fertilisation

menstural cycle occurs in uterus and prepares uterus wall to recieve fertilised egg

what occurs in the follicular phase of the ovarian cycle (in terms of hormones!!)

(day 1-14)

hypothalamus secretes GnRH which stimulates the pituatary gland to secrete Follicle Stimulating Hormone (FSH) which travels from bloodstream to ovaries stimulating the growth/maturation of a follicle containing an egg

• this releases oestrogen stimulating endometrium ot thicken with blood vessels

hormonal situation during/causing ovulation

the follicle bursts to release the ovum

• this is caused by a sudden peak in lutenising hormone secreted by pitutary gland, which is released as the egg matures

what occurs in the luteal phase of ovarian cycle (hormones!)

day 15-21: remnants of burst follicle form the corpus luteum, which releases progesterone and oestrogen —> endometrium stabilises and thickens

Day 21-28: iff egg is not fertilised, corpus luteum disintegrates, decreasing progesterone + oestrogen triggering menstruation

another word for uterine lining

edometrium

another word for oviduct

fallopian tube

ovum

egg cell

what is a zygote

single cell result of fusion of gmetes

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what 2 things must happen in order for successful fertilisation to occur?

1. sperm must be deposited into vagina within 24-72 hours after ovulation

2. sperm must travel through cervix —> uterus —> up fallopian tube —> to meet ovum

what happens immediately after fertilisation

• once sperm enters egg, enzymes form to stop 2nd sperm from entering

• after fertilisation, zygote remains in fallopian tube for about 72 hours developing rapidly via mitosis

what occurs in implantation (following fertilisation off egg in the oviduct, how does it develop?)

1. fertilised ovum (zygote) travels down to uterus for further cell division (also undergoing through mitosis in oviduct)

2. once fertilised cell arrives in uterus it is a blastocyst ready for implantation

3. upon implantation there is a spike in HCG and division continues gastrula —> embryo —> fetus

what are the 3 parts of a blastocyst and what do they become

inner cell mass —> embryo

outer cell mass —> initiates formation of placenta

trophoblast —> outer layer of blastocyst that secretes enzymes to break down some endometrial cells, allowing blastocyst to enter lining

purpose of HCG + how it is used in pregnancy testing

maintains corpus luteum (in ovary), allowing it to continue to secrete progesterone

• as it is in such high concentration, it often is detectable in urine - so HCG is what is tested for in urine for pregnancy tests!

purpose of progesterone

ensures uterus lining remains receptive to embryo (continues feeding it)

difference between oestrogen and progesterone

estrogen builds up the uterine lining while progesterone stabilizes it to support implantation and pregnancy. 

what happens in 1st trimester

• HCG rises rapidly to maintain corpus luteum, which temporarily allows continued production of oestrogen and progesterone which help maintain uterus lining

• high levels of progesterone during this time also enlarge uterus, form mucous plug to seal the cervix + aids breast growth

what happens in 2nd trimester

• production of HCG declines and corpus luteum deteriorates

  • placenta takes over role of corpeus luteum, producing oestrogen and progesterone

what happens in 3rd trimester

• increased oestrogen is released

• oestrogen induces receptors to form on uterus wall that cna bind with hormone oxytocin - a hormone critical to triggering and maintaining labour

what hormones are involved in birth + how?

• oxytocin (prod. by pitutary gland) —> causes muscular contractions of uterus, which push baby towards cervix and vaginal opening

  • as baby’s head pushes against the cervix, nerve pulses stimulate more production of oxytocin (positive feedback cycle)

• adrenaline acts as pain relief + energy for baby to be pushed out

• oxyocin also is released to help placenta to be expelled

• after baby is born, prolactin + oxytocin help in breastfeeding

how are oxytocin and prolactin play diff roles in breastfeeding

prolactin —> stimulates milk prod

oxytocin —> stimulates release of milk from storage

what is assisted reproduction used for

allows favourable traits to be passed onto offspring —> higher quality food in agriculture

3 methods of assisted reproduction

1. selective breeding (artificial selection)

   • hybridisation

   • inbreeding

2. Artificial insemination

3. Artificial pollination

what is selective breeding + how does it work?

selective breeding: when farmers intentionally select and breed individual animals/plants with more desirable characteristics, with hopes that offspring will express such traits

how does it work: there must be a wide variation of genetic traits for selective breeding to occur, with new trains introduced through genetic mutation