reproduction in organisms Flashcards
why is reproduction necessary
gives rise to new young ones and enables the continuity of the species
what is asexual reproduction
when offspring is produced by a single parent without the involvement of gamete formation
what is sexual reproduction
when 2 parents participate in reproductive process and also involve fusion of male and female gametes
what are clones
morphologically and genetically similar individuals
how does asexual rep take place in protists and monerans
cell division (the parent cell divides by mitosis into 2 to give rise to new individuals
parthenogenesis
a form of reproduction in which an egg can develop into an embryo without being fertilized by a sperm
how many types of asexual reproductions are there without gametes
binary fission budding sporulation fragmentation vegetative propagation
what is binary fission
when a cell divides into 2 halves and each rapidly goes into an adult. eg- amoeba, paramecium
what is budding
new organism develops from an outgrowth or bud due to cell division at one particular site. eg- yeast
what is sporulation
organisms produce diploid spores that are released in the environment and grow into adults themselves.
what is encystation
under unfavorable condition amoeba withdraws its pseudopodia and secretes a 3 layered hard covering or cyst around itself.
what are zoospores
a motile asexual spore that uses a flagellum for locomotion.
what are conidia (penicillium)
produced at the tip or side of hyphae or on special spore-producing structures called conidiophores. The spores detach when mature.
what is fragmentation
if the body breaks into distinct fragments, each fragment grows into an adult capable of producing offspring
what is vegetative propagation
asexual method of plant reproduction that occurs in its leaves, roots and stem.
how is potato cultivated
when buds of the potato tuber called eyes come in contact with the damp soil/water they produce new plants
what is juvenile phase
certain stage of growth and maturity in an organism’s lif before it can sexually reproduce
what is oestrus cycle
the period from one ovulation to a subsequent ovulation
what is gametogenesis
process of formation of 2 types of gametes i.e male and female. gametes are haploid n
what are homogametes or isogametes
when the 2 gametes are so similar in appearance that it is impossible to categorise them into male and female gametes
bisexual plants are also called
dioecious or heterothallic
eg: papaya, date palm
unisexual plants are also called
monoecious or homothallic.
eg: cucurbit, coconut
what are hermaphrodites
animals that possess both male and female reproductive organs
eg: earthworm, sponge, tapeworm, leech
a haploid parent body produces gametes by _______ division
mitotic
a diploid parent body produces gametes by _______ division
meiotic
in diploid organisms, specialised cells called ____ undergo meiosis
meiocytes (gamete mother cells)
why is the amount of male gametes produced so large in comparison to that of female gametes
to compensate the loss of male gametes during transport, the number of male gametes produced is several thousand times the number of female gametes produced.
what is pollination
transferring pollen grains from the male anther of a flower to the female stigma
fertilisation is also called ____ and results in the formation of _____
syngamy
diploid zygote
disadvantage of external fertilisation
offspring are extremely vulnerable to the predators threatening their survival up to adulthood
what is embryogenesis
process of development of embryo from zygote
what is cell division
increases the number of cells in a developing embryo
what is cell differentiation
helps groups of cells to undergo certain modifications to form specialised tissues and organs
in oviparous animals, the fertilised eggs are covered by _______
hard calcareous shell
