Fertilization Flashcards
Start of development
“Fertilization: sperm unites with ovum to form a diploid zygote.”
Zygote to embryo
“Zygote transforms into an embryo through the first mitotic division.”
Embryonic development processes
“Cell division
Influence on embryo development
“Reproductive strategy of the organism.”
Embryo in flowering plants
“Enclosed in a seed
Embryonic stages in animals
“Remarkably similar.”
Appearance of young animals
“Generally like miniature adults.”
Growth of young animals
“Increase in size
Control of further development
“Hormones at sexual maturity.”
Development in some animals
“Young hatch into larvae.”
Larval existence
“Independent
Larval characteristics
“Immature
Larval change
“Metamorphosis into miniature adults.”
Metamorphosis definition
“Change in form
Metamorphosis requirements
“Energy and materials.”
Larvae vs. adults
“No resemblance.”
Metamorphosis processes
“All processes of embryonic development.”
Metamorphosis control
“Hormones.”
Toad development stages
“Egg to mature aquatic larva (tadpole) and metamorphosis from tadpole to terrestrial adult.”
Need for larval stage in toads
“Limited yolk in egg
Toad eggs
“Enclosed in long strands of jelly.”
Toad egg fertilization
“Immediately after discharge from female
Jelly covering functions
“Protection (microbes
Toad egg appearance
“Spherical
Zygote nucleus location
“Dark area.”
Yolk location and function
“Lower portion
Development before hatching
“Repeated nucleus division of zygote.”
Embryo formation
“Hollow ball of tiny cells
Resources used
“Energy and material resources.”
Newly-hatched tadpole appearance
“Black
Tadpole attachment
“To jelly strand or water-weed
Tadpole feeding (early)
“Does not feed
Tadpole respiration (early)
“Through delicate skin.”
Tadpole head features
“Pits for eyes
External gills stage
“2-3 days after hatching
External gills function
“Gaseous exchange.”
Water flow over gills
“Cilia movements.”
Mouth opening and feeding
“Mouth opens
Intestine appearance
“Long and coiled
Internal gills stage
“2-3 days after external gills
Head features developed
“Mouth
Changes in gills
“Cement gland and external gills degenerate
Gill cover development
“Operculum grows over gill slits.”
Tadpole respiration
“Like a fish: water in mouth
Opercula closure
“Right side closes completely
Tail appearance
“Fish-like
Tadpole changes over time
“Little change for 2-3 weeks
Hindlimb development
“Bulges on sides of body
Hindlimb function
“Not used for locomotion initially
Tadpole locomotion
“Swims with tail.”
Forelimb development
“Starts same time as hindlimbs
Diet change
“Starts eating small dead animals.”
Intestine change
“Shortens
Lung development
“Develop with limbs
Gill change
“Internal gills degenerate.”
Body size increase
“Continues
Overall tadpole development
“Increase in size and internal organ development continues for 2-3 months.”
End of tadpole feeding
“~3 months old.”
Tail change
“Shortens
Skin change
“Shed
Mouth and tongue change
“Mouth widens
Other changes
“Eyes bulge
Adult vs. larva
“Very different.”
Miniature toad behavior
“Crawls out of pond
Diet change
“Herbivore to carnivore (worms and insects).”
Tail disappearance
“Finally disappears
Sexual maturity
“~3 years old.”
Hormonal control of metamorphosis
“Thyroxine.”
Thyroxine source
“Thyroid gland.”
Thyroxine’s effect
“Absence prevents metamorphosis
Insect reproduction
“Sexual
Insect fertilization
“Internal. Sperms in sacs in female’s body until eggs mature.”
Egg fertilization process (insects)
“Eggs fertilized as they pass oviduct
Insect egg-laying
“Many females lay eggs where young can find food/suitable environment.”
Alternative insect reproduction
“Some insects (aphids
Parthenogenesis result
“Sterile male or female individuals (depending on species).”
Insect development groups
“Incomplete metamorphosis
Incomplete metamorphosis insects
“Cockroach
Incomplete metamorphosis development
“Egg hatches into nymph
Nymph characteristics
“Miniature adult.”
Moulting term
“Ecdysis.”
Instar definition
“Stage between successive moults.”
Wing development (incomplete metamorphosis)
“Absent in early instars
Adult characteristics (incomplete metamorphosis)
“Fully developed wings
Incomplete metamorphosis synonym
“Gradual growth and development.”
Incomplete metamorphosis stages
“Egg -> First instar nymph -> several moults -> Final instar nymph -> Adult (imago).”
Complete metamorphosis insects
“Mosquitoes
Complete metamorphosis stages
“Egg -> Larva -> Pupa -> Imago (adult).”
Larva characteristics
“Feeds voraciously
Larval diversity
“Larvae have different names (table 23-1).”
Ecological advantage of complete metamorphosis
“Larvae and adults occupy different niches
Pupa stage activity
“Resting stage
Pupa tissue change
“Larval tissues break down
Larval names (examples)
“Mosquito: Wriggler; Butterfly/moth: Caterpillar; Housefly: Maggot; Weevil/beetle/Ant/bee/wasp: Grub.”
Complete metamorphosis definition
“Larva and imago are totally different in form and behavior.”
Hormonal control of metamorphosis (insects)
“Moulting hormone and juvenile hormone interaction.”
Grasshopper metamorphosis type
“Incomplete.”
Grasshopper activity
“Nymph and adult active during day
Grasshopper male attraction
“Produces sound by rubbing hindleg thighs against forewings.”
Grasshopper sound reception
“Tympanum (membrane sensitive to sound) on each side of abdomen.”
Grasshopper mating
“Male grips female’s thorax
Sperm transfer (grasshopper)
“Penis-like structure introduces sperm sac into female’s reproductive tract.”
Sperm storage (grasshopper)
“Sperms stored in sperm pouch inside female’s abdomen.”
Egg shell formation
“Each egg receives a hard shell with a minute hole before being laid.”
Egg fertilization (grasshopper)
“Sperm enters egg via minute hole as egg passes sperm pouch.”
Egg-laying (grasshopper)
“Female digs hole in soil
Hatching time (grasshopper)
“2-3 days if sufficient moisture and warmth.”
Nymph appearance (grasshopper)
“Light brown
Nymph locomotion
“Hopping.”
Nymph diet
“Tender grass shoots.”
Nymph moulting frequency
“Once every 7-10 days.”
Nymph moulting duration
“30-50 days.”
Wing development (grasshopper)
“Wing processes appear as small knobs
Adult development (grasshopper)
“Wings and internal organs fully developed after last moult.”
Sexual maturity (grasshopper)
“Adults become sexually mature soon after emerging.”
Butterfly metamorphosis type
“Complete.”
Butterfly examples
“Citrus swallowtail.”
Butterfly larval impact
“Larva is an agricultural pest.”
Butterfly adult impact
“Adults are important pollinators.”
Butterfly activity pattern
“Daytime insects.”
Butterfly attraction methods
“Visual and smell signals.”
Butterfly smell detection
“Antennae.”
Butterfly vision
“Compound eyes
Male butterfly attraction
“Sexual attractants from wing scales.”
Female butterfly attraction
“Chemicals she releases
Butterfly mating
“Brief courtship flight
Butterfly egg-laying
“Female lays eggs singly on upper surfaces of young citrus leaves
Butterfly egg appearance
“Spherical
Larva hatching time (butterfly)
“~10 days.”
Larva hatching process
“Escapes shell by biting off a piece.”
Young larva appearance (butterfly)
“Black and white patches
Older larva appearance (butterfly)
“Green above
Caterpillar body plan
“Cylindrical
Caterpillar head features
“6 simple eyes
Caterpillar mandible function
“Enable active feeding on young leaves.”
Caterpillar mouthpart modification
“Spinneret (produces silk threads).”
Caterpillar silk thread use
“Forms network to grip slippery leaf surface.”
Caterpillar thorax
“3 segments
Caterpillar claw function
“Firm grip on leaf surface.”
Caterpillar abdomen
“10 segments.”
Caterpillar abdominal segments 3-6
“Each has a pair of prolegs.”
Caterpillar abdominal segment 10
“Has a pair of claspers.”
Caterpillar clasper function
“Fleshy outgrowth with tiny hooks for gripping.”
Caterpillar spiracles
“9 pairs for breathing.”
Caterpillar spiracle location
“1st thoracic segment
Caterpillar defense adaptation
“Osmeterium (red
Caterpillar defense mechanism
“When disturbed
Caterpillar diet
“Starts with egg shell
Caterpillar feeding timing
“Mainly at night.”
Caterpillar camouflage
“Still and well-camouflaged during day.”
Caterpillar growth
“Rapid
Caterpillar moulting frequency
“~3-4 moults.”
Caterpillar cuticle consumption
“Eats cast cuticle after each moult.”
Fully grown caterpillar size
“~4 cm long.”
Pupa formation (butterfly)
“Caterpillar spins silk pad on twig
Pupa position
“Slanting
Pupa transformation
“Tucks head under thorax
Chrysalis appearance
“Naked and exposed (unlike cocoons)
Imago emergence timing
“Week during rains
Imago emergence process
“Pupa casing splits
Wing expansion
“Wings are initially small/sac-like/crumpled
Final wing state
“Flatten and harden.”
Imago behavior
“Flies off in search of food
Cockroach metamorphosis type
“Incomplete.”
Cockroach habitat
“Nocturnal household pest
Cockroach egg-laying
“Female lays ~10-16 eggs in a horny egg-case.”
Cockroach egg-case carriage
“Female carries it in abdominal pouch for some time.”
Cockroach egg-case deposition
“Safe
Cockroach nymph hatching time
“30-100 days.”
Cockroach nymph appearance
“Small
Cockroach nymph development
“Feeds
Cockroach wing development
“Wing pads appear in later instars.”
Cockroach adult development
“Body and wings reach adult size in last instar.”
Cockroach development time (egg to imago)
“11-20 months.”
Cockroach adult lifespan
“~3-12 months.”
Housefly metamorphosis type
“Complete.”
Housefly lifespan
“~3-4 weeks.”
Housefly egg-laying
“Female lays 2-7 batches of ~130 eggs each in rotting matter.”
Housefly egg appearance
“Long
Housefly larva hatching time
“8-72 hours.”
Housefly larva appearance
“Whitish
Housefly larva habitat
“Rotting matter (food
Housefly larva development
“Feeds
Housefly larva size
“~12 mm.”
Housefly pupation
“Moves to dry place
Housefly pupa appearance
“Oval
Housefly imago emergence time
“3-10 days later.”
Housefly imago emergence mechanism
“Pumps blood into head sac-like organ
Housefly imago behavior
“Flies off when wings are dry.”
Housefly female sexual maturity
“2 weeks to start laying eggs.”
Tsetse-fly disease
“Causes sleeping sickness.”
Tsetse-fly metamorphosis type
“Complete.”
Tsetse-fly reproduction
“Viviparity.”
Tsetse-fly lifespan
“1-3 months.”
Tsetse-fly mating frequency
“Female mates only once in her lifetime.”
Tsetse-fly sperm storage
“Sperms retained in female’s uterus.”
Tsetse-fly larval development
“Female produces ovum
Tsetse-fly larval nourishment requirement
“Female needs adequate blood meal to produce well-developed larva.”
Tsetse-fly larval deposition
“Larva born in shady spot.”
Tsetse-fly larval deposition frequency
“Every 10 days.”
Tsetse-fly larval appearance
“White
Tsetse-fly pupation location
“Larva burrows into ground.”
Tsetse-fly pupation duration
“3-8 weeks.”
Tsetse-fly imago emergence
“Emerges from pupal case
Tsetse-fly imago behavior
“Flies to shady place when wings are dry.”
Mosquito metamorphosis type
“Complete.”
Mosquito habitat (larva/pupa vs. adult)
“Larval/pupal stages are aquatic
Mosquito egg-laying
“Female lays several hundred eggs on freshwater surfaces (various floating mechanisms).”
Mosquito egg hatching time
“2-5 days.”
Mosquito larva name
“Wriggler.”
Wriggler body plan
“Head
Wriggler respiration
“Breathes atmospheric air through spiracle/breathing tube.”
Wriggler development
“Feeds
Wriggler pupation
“Becomes pupa (cephalothorax
Mosquito pupa respiration
“Breathes air through breathing trumpet at water surface.”
Mosquito pupa behavior
“Motionless
Mosquito imago emergence time
“Few hours to few days.”
Mosquito imago emergence behavior
“Rests on split pupal case
Mosquito adult lifespan
“2-3 weeks.”
Aphid common names
“Greenfly
Aphid diversity
“400 kinds.”
Aphid diet
“Plant juices.”
Aphid impact
“Spreads diseases among crop plants.”
Aphid metamorphosis type
“Incomplete.”
Aphid reproductive features
“Parthenogenesis and viviparity.”
Aphid sexual reproduction timing
“Onset of unfavorable season (dry season in tropics).”
Aphid egg-laying
“Female lays eggs glued to stems of host plants.”
Aphid egg hatching timing
“Beginning of favorable season.”
Aphid nymph hatching appearance
“Wingless.”
Aphid nymph development
“Feeds
Aphid nymph maturation
“Matures into wingless females (stem-mothers) in about a week.”
Aphid stem-mother reproduction
“Parthenogenetically (without mating).”
Aphid stem-mother offspring
“Live wingless female nymphs (resemble stem-mothers
Aphid colony expansion
“Series of wingless female generations by parthenogenesis.”
Aphid colony impact
“Large colony feeds on cell sap
Aphid wing development trigger
“Food scarcity.”
Aphid winged female behavior
“Some migrate to other plants
Aphid sexual form development trigger
“Onset of dry adverse conditions.”
Aphid sexual form appearance
“Winged males and females.”
Aphid winged female offspring
“Wingless females (true females).”
Aphid true female reproduction
“Lays fertilized eggs after mating with winged males.”
Aphid true female lifespan
“Dies after laying 1-4+ eggs.”
Aphid egg characteristics
“Tough and resistant (withstand adverse conditions).”
Aphid egg hatching timing
“Favorable conditions.”
Aphid offspring appearance
“Stem-mothers.”
Termite common name
“White ants.”
Termite diet
“Wood and dead plant material (saprophytes).”
Termite habitat
“Logs
Termite social structure similarity
“Live in large colonies/societies (like ants/honeybees).”
Termite society organization
“Several castes
Termite metamorphosis type
“Incomplete.”
Termite caste production
“King and queen produce all castes
Termite reproductive timing
“Long-winged reproductives fly off from nest in large numbers at onset of rainy season (swarming/nuptial flight).”
Termite mating flight behavior
“Pairs isolate themselves
Termite post-flight behavior
“Wings break off
Termite nest founders
“Male (potential king) and female (potential queen).”
Termite mating timing
“~1 week after nest formation.”
Termite queen abdomen change
“Enlarges with developing eggs.”
Termite queen egg-laying rate
“Starts with few eggs
Termite egg-laying duration
“Continuous
Termite egg fertilization frequency
“Mating goes on repeatedly
Termite egg appearance
“Small
Termite offspring appearance
“Nymphs (similar to workers).”
Termite nymph development
“Third moult shows small physical differences
Termite initial parental care
“King and queen nurse/feed first nymphs until enough workers develop.”
Termite king/queen role change
“Eventually function only for reproduction.”
Termite royal chamber
“Workers enclose king/queen in a large chamber.”
Termite worker roles
“Remove eggs
Termite long-winged reproductive emergence trigger
“Favorable conditions for swarming.”
Termite long-winged reproductive functions
“Disperse population
Termite colony composition
“Several generations.”
Termite colony lifespan
“Many years.”
Termite king/queen lifespan
“Long.”
Termite worker lifespan
“1-2 years.”
Human sperm deposition
“Male ejects sperm with force into cervix and upper vagina.”
Sperm movement
“Sperms move through cervix and uterus into upper oviduct.”
Sperm movement assistance
“Uterus and oviduct contractions.”
Sperm-ovum contact location
“Upper part of oviduct.”
Sperm’s acrosomal enzyme function
“Dissolve follicle cells and zona pellucida of ovum.”
Sperm’s entry into ovum
“Sperm moves into ovum
Ovum’s response to sperm entry
“Completes final meiotic division.”
Zygote formation
“Sperm nucleus fuses with ovum nucleus (diploid zygote).”
Zona pellucida’s post-fertilization change
“Prevents other sperms from penetrating.”
Number of sperms that fertilize an ovum
“Only one.”
Front
Back
Human fertilization location
“Upper part of the oviduct.”
Sperm movement force
“Male ejects sperms with force.”
Sperm movement pathway
“Through cervix
Factors aiding sperm movement
“Sperm’s own movement and uterus/oviduct contractions.”
Sperm’s acrosomal enzyme function
“Dissolve follicle cells and zona pellucida of ovum.”
Sperm’s entry into ovum
“Sperm moves into ovum
Ovum’s response to sperm entry
“Completes final meiotic division.”
Zygote formation (human)
“Sperm nucleus fuses with ovum nucleus (diploid zygote).”
Zona pellucida’s post-fertilization change
“Prevents other sperms from penetrating.”
Number of sperms that fertilize an ovum
“Only one.”
Early cell divisions
“Zygote undergoes mitosis as it moves down oviduct.”
Morula formation
“Solid ball of cells.”
Blastocyst formation
“Morula develops into a hollow ball of cells.”
Implantation timing
“~7 days after fertilization.”
Implantation location
“Blastocyst becomes embedded in the endometrium.”
Embryonic membrane formation
“Trophoblast (outer layer of blastocyst) and inner cell mass form them.”
Amnion function
“Encloses embryo in fluid-filled amniotic cavity
Yolk sac function (early)
“First site of blood cell formation.”
Allantois function
“Forms umbilical cord blood vessels
Chorion function
“Outermost membrane
Gastrulation
“Inner cell mass cells differentiate into three germ layers.”
Three germ layers
“Ectoderm
Ectoderm derivatives
“Epidermis
Mesoderm derivatives
“Muscles
Endoderm derivatives
“Lining of digestive tract
Organogenesis
“Germ layers interact and differentiate into organs.”
First trimester
“Most of organogenesis occurs.”
Second trimester
“Continued development and growth.”
Third trimester
“Rapid growth
Placenta origin
“Develops from both embryonic and maternal tissues.”
Placenta connection
“Umbilical cord.”
Placenta functions
“Gaseous exchange
Placental hormones
“Progesterone and oestrogen (maintain endometrium).”
Human gestation period
“~266 days (9 months).”
Birth trigger
“Complex hormonal and mechanical factors.”
Birth stages
“Dilation
Dilation stage
“Uterine contractions increase
Expulsion stage
“Baby is expelled through the vagina.”
Placental stage
“Placenta is expelled as the afterbirth.”
Lactation
“Milk production by mammary glands.”
Milk composition
“Rich in nutrients for newborn.”
Milk production hormone
“Prolactin.”
Milk release hormone
“Oxytocin (stimulated by suckling).”
Colostrum
“First milk
Weaning
“Gradual introduction of solid food
Twins
“Two offspring born from one pregnancy.”
Types of twins
“Identical (monozygotic) and fraternal (dizygotic).”
Identical twins origin
“One fertilized egg splits.”
Identical twins genetic similarity
“Genetically identical.”
Fraternal twins origin
“Two eggs are fertilized.”
Fraternal twins genetic similarity
“No more alike than siblings.”
Multiple births
“More than two offspring (e.g.
Causes of multiple births
“Multiple ovulations
Developmental abnormalities
“Can occur due to genetic or environmental factors.”
Teratogens
“Substances that cause birth defects (e.g.
Importance of prenatal care
“Reduces risk of developmental abnormalities.”
Human growth after birth
“Rapid in infancy
Factors influencing growth
“Genetics
Puberty
“Period of rapid growth and sexual maturation.”
Hormonal control of puberty
“Gonadotropins (FSH and LH).”
Primary sexual characteristics
“Organs directly involved in reproduction.”
Secondary sexual characteristics
“Other features that distinguish sexes (e.g.
Adulthood
“Physical maturity is reached.”
Aging
“Gradual decline in physiological functions.”
Menopause
“Cessation of menstruation in women.”
Longevity
“Length of life.”
Factors influencing longevity
“Genetics
