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