reproduction Flashcards
when does reproduction occur?
reproduction occurs at the time that offspring have the best chance for survival
-hormones, environmental cues
what is asexual reproduction?
is a type of reproduction by which the offspring only has one parent that does not need to reproduce with another source
- no fusion of gametes
- offspring are genetically identical to parent (clones)
what are the advantages and disadvantages of asexual reproduction?
Advantages:
-speed of reproduction
-Offspring may start off more mature ->higher rate of survival
-Dense clones may block out and reduce competition
-takes less energy -> no gametes, no organs that need to produce gametes, no having to find a mate, no pollinators
Disadvantages:
-lack of genetic variation -> makes more susceptible to disease/environment
-cannot adapt to changing environments
what are the 4 types of asexual reproduction?
- fragmentation
- budding
- fission
- parthenogenesis
what is fragmentation in plants? give example.
Separation of the parent plant into parts that develop into new individuals.
root systems can also give rise to new shoots, that then grow there own separate root/shoot systems
eg. onions and tulips grow from bulbs, some succulent grow roots from fallen off leaves
eg. aspen trees
what is fragmentation in animals? give example
is the regeneration/re-growth of lost body parts, and some species will grow whole new organisms from both sections
eg. sponges, cnidarians, annelids
what is budding? give example
budding is when new individuals arise from outgrowths of the original parent
- offspring may detach or stay attached to parent
eg. some cnidarians, like coral
what is fission? give example
fission is when a parent splits into 2 or more individuals of about the same size
e.g. many invertebrates and some protists
what is parthenogenesis? give example
the production of seeds or new individuals without fertilization
eg whiptail lizards; many types of fishes, amphibians and lizards
what is Apomixis? give example
is the asexual production of seeds from a diploid cell
eg. dandelion
what is sexual reproduction?
the fusion of gametes from two parents to produce a zygote
- involves exchange of genetic information
- offspring have unique combinations of genes
what are the advantages and disadvantages of sexual reproduction?
Advantages:
-increase in genetic variation of offspring
-reproductive success in changing environments
-possible elimination of harmful genes (natural
selection)
-seed dormancy -> allows plants to wait out bad conditions
Disadvantages:
-organisms may take longer to develop
-requires more energy -> eg. finding mates, reproductive organs, attracting pollinators/dispersers
The alternation of … and … is common to
all organisms that reproduce sexually
of meiosis and fertilization
can haploid/diploid cells under go mitosis or meiosis? why?
mitosis: both 2n->2n; n->n meiosis: only diploid 2n->n only diploid cells can undergo meiosis, because it is splitting the chromosomes in half; in haploid cells, there is only one set of chromosomes, so to split these in half would result in too much genetic data lose that could not be replaced from another source
what is an advantage of spores and how are they dispersed?
- water resistant
- by wind
where are the dependent embryos (gametes) held? what does this provide them?
- dependent embryos are held within the tissues of archegonia (female gametangia)
- provides the protection against dehydration and nutrients
moss:
- dominant generation:
- sporophytes grow:
- male/female gametophyte plants are grown:
- sperm is:
- why does moss grow in “carpets”?
- where are spores held?
- gametophyte
- directly off gametophytes
- moss grows separate male and female gametophyte plants
- sperm is flagellated
- forms “carpets” to keep male and female gametophyte plants close to each other, because sperm needs to travel in water (flagellated sperm) to female plant
- spores held in sporangium capsule, on sporophyte
ferns:
- dominant generation:
- sporophytes grow:
- male/female gametophyte plants are grown:
- sperm is:
- how do ferns stop from fertilizing themselves?
- where are spores held?
- sporophyte
- Sporophyte grows out of gametophyte
- gametophyte have male and female parts on the same plant (unlike moss)
- flagellated
- Archegonia and antheridia mature at different times to encourage not self fertilizing
- spores are held in sori on bottom of fronds, when they reach maturity, pop open
what is the life cycle of moss?
FERTILIZATION ->
zygote (diploid) held in archegonium -> mitosis
into sporophyte (on female gametophyte plant) ->
sporangium -> MEIOSIS
spores (haploid) -> mitosis
1. female gametophyte (haploid) plant -> mitosis
gametangia (archegonia) ->
gametes (egg)
2. male gametophyte (haploid) plant -> mitosis
gametangia (antheridia) ->
gamates (sperm)
FERTILIZATION
what is the life cycle of a fern?
FERTILIZATION -> zygote (diploid) -> mitosis sporophyte (diploid) -> sporangium -> MEIOSIS spores (haploid) -> mitosis gametophyte -> female and male gametes (released at different times) -> FERTILIZATION
seed plants:
- dominant generation:
- male/female gametophyte plants are:
- sperm is:
- where is pollen formed/held?
- sporophyte
- usually microscopic and found in reproductive organs
- pollen (non-flagellated)
- in the anther in chambers called microsporangia (pollen sacs)
what is pollination? what is the advantage, and how is it carried out?
is the transfer of pollen to the part of a seed plant containing the ovules
- eliminates the need for water to move sperm
- can be dispersed by animals or wind
a seed develops from:
while a fruit develops from:
ovule
ovary
what is a seed
is a sporophyte embryo, along with its food supply, packaged in a protective coat
what is a flower?
The flower is an angiosperm structure specialized for sexual reproduction
-the reproductive shoots of angiosperm sporophytes
what is the male structure of the flower? what are the parts of it, and what do they do?
Stamen
- Anther
- produces pollen - Filament
- holds anther up so that pollinators can reach pollen
what is the female structure of the flower? what are the parts of it, and what do they do?
Carpel
- Stigma
- where pollen from pollinators land - Style
- tube that brings pollen from stigma to ovules - Ovary
- houses ovules which contain eggs
what are the three key derived traits of angiosperm reproduction?
- flowers
- double fertilization
- fruits
where are female/male gametophytes found in angiosperms?
female gametophytes are found in the ovule
male gametophytes are found in pollen grains?
what is a pollen tube, how is it formed?
A tube that forms after germination of the pollen grain and that functions in the delivery of sperm to the ovule
what is the reproduction cycle in animals?
FERTILIZATION -> zygote (diploid) -> mitosis -> diploid multicellular organism -> MEIOSIS -> gametes (sperm/ovum) -> FERTILIZATION
where are gametes in animals produced?
gonads
what are advantages of having both sexual and asexual
reproduction capabilities?
-able to reproduce whether or not there are mates around
what is an hermaphrodite, what types of animals does this benefit? give examples
- an individual that has both male and female reproductive systems
- can self-fertilize but can also fertilize each other (both can produce offspring)
- this is beneficial for organisms that seldom encounter a mate
- eg. earthworms, flatworms, some mollusks (slugs)
what are sequential hermaphrodites, what type of organisms does this typically occur in?
- individuals of a species that can undergo sex reversals
- often occurs in groups where there is 1 dominant male or female, who live in a group of opposite sex eg queen bee in beehive
- can be either male ->female (oysters), or female -> male (some fish)
what are 3 things that can mediate timing of fertilization?
- environmental cues
- pheromones
- courtship behaviour
what are the 2 types of fertilization?
internal and external
what kind of environment does external fertilization need to occur in? why?
- in moist environments
- so that the sperm can swim
- and so that eggs do not dry out (amniotic eggs are not fertilized externally)
why is gamete release synchronized?
-because it takes place in water and significant dilution of gametes will occur
where does internal fertilization occur? why is this significant in evolution?
- fertilization occurs in within the female reproductive tract
- significant because it is not dependent on water, and allows for movement away from aquatic habitats
how does the number of eggs deposited relate to parental care, and internal/external fertilization/
Number of eggs deposited is inversely proportional to the degree of parental care
- Little parental care —> many eggs, to make sure some survive
- Large parental care —> few eggs, to take care of
- organisms with external fertilization have no to little parental care and therefore produce more gametes than organisms with internal fertilization
what are 3 types of parental care?
- oviparous
- ovoviviparous
- viviparous
what are oviparous animals? is fertilization internal or external? what is the extent of parental care? give examples
animals that lay eggs directly into environment
-fertilization can be internal or external
-“make egg, lay egg” - potential for parental care in trying to protect them before they hatch, but not giving nutrients
-most invertebrates, some fish, amphibians, reptiles,
birds, monotreme mammals
what are ovoviviparous animals? is fertilization internal or external? what is the extent of parental care? give examples
animals that produce and hatch eggs within their body
- internal
- “make egg, keep egg internal, don’t feed egg” - although protecting egg internally, mother does not nourish the embryo, nourishment is coming from inside the egg
- fresh water clams, oysters, seahorses, lizards, some snakes
what are viviparous animals? is fertilization internal or external? what is the extent of parental care? give examples
animals that have embryos that develop inside of their body
-internal
-“make embryo, nourish embryo” - mother provides nutrients via a placenta, until birth
-eg. placental and marsupial mammals, some
sharks (hammerheads)
what are the 2 components of sexual systems in animals? what are they made of?
- Primary organs
- Gonads that produce sperm, eggs and sex hormones - Accessory organs
- Assist gonads in formation and delivery of gametes and may support embryos (ducts and glands)
