reproduction Flashcards
define asexual production
give examples
a process resulting in the production of genetically identical offspring from ONE parent
e.g strawberries using runners, bacteria, tulips using bulbs, fungi spores, potato
advantages of asexual production
- lots of offspring produced very quickly
(bacteria such as e.coli divide every half hour to colonise a new area very quickly) - no need to attract mate, less energy needed
- rapid colonisation of favorable environment –> large yields with benefical features reproduces asexually –> offspring inherit same feations –> consistent products.
- no need for pollination –> benefical in environments where scare pollinators.
- crop plants can be grown asexually from cuttings (of parent plant) plants can reach maturity quicker –> harvestation sooner.
disadvantages of asexual production
- no genetic variation; organisms unlikely to adapt to changes in environemnt
- overpopulation if too many offspring produced
- parent = no resistance to disease = entire population affected
define sexual production
process involving the
fusion of the nuclei of 2 gametes to form a zygote
& the production of
offspring that are genetically different form each other
define fertilisation
the fusion of the nuclei of gametes
advantages of sexual reproduction
- genetic variation = outbreak of disease = unlikely every individual affected
- diversity/biodiversiy = natural selection & evolution = species become better adapted to environment
- selective breeding can be used = improves crop production & quality.
disadvantages of sexual reproduction
- more time & energy required to find mate = organisms produce fewer offspring in lifetime
- isolated organisms unable to reproduce sexually
- variation may lead to organisms w/o desired features
- could lead to reduced/unpredictable harvests
state the gametes in animals & plants in both sex
female - plant - nucles in ovule
male - plant - pollen in anther
female - animal - egg cell
male - animal - sperm
state the name of the male reproductive system in plants & its components
stamen
* anther - contains pollen grains - male gametes
* filament - holds up anther
state the name of the female reproductive system in plants & its components
carpel
* stigma - pollen grains attach here/received
* style - supports stigma, connects stigma to ovary
* ovary - contains female gametes inside ovules which develop into seed after fertilisation
define pollination
- tranfer of pollen grains from an anther
- to a stigma
define self pollination
- transfer of pollen grains
- from the anther of a flower
- to the stigma of the same flower
- or a different flower on the same plant
define cross pollination
- transfer of pollen grains
- from the anther of a flower
- to the stigma of a flower on a different plant
- of the same species
in plants
adv & disad of self pollination
ad
* no need to reply on pollinators -> easier to spread in locations where pollinators scarce
disad
* less variation bc gene pool smaller. less likely to adapt to changing environment
in plants
adv & disad of cross pollination
ad
* variation; more likel to changing environemnt
disad
* reliance on pollinators; pollinator population decline = harder to reproduce.
how plants are adapted for pollination by insects
- petals large, brightly colored; attract insects
- scent & nectar nectaries secrete nectar. scent strong
- stigma sticky - pollen picked by insect on other plants will stick
- pollen big, sticky, spiky, stick to insects
how plants are adapted for pollination by wind
- petals small, dull
- no nectaries/strong scents
- filament long, hang anthers outside flower; pollen gets blown
- stigma large, feathery to catch pollen. hangs outside flower
- pollen small, lightweight, smooth - can be easily carried to other plants by wind.
define fertilisation in plants
occurs when a pollen nucleus
fueses with a nucleus in an ovule
describe the process of fertilization in plants
- pollen grains lands on stigma of flower
- pollen tube grows out of pollen grain, down through the style, through micropyle, to the ovary, into the nucleus.
- nucleus from male gamete moves down tube to join with female gamete in ovule.
- fertilization happens. gametes fuse together to make zygote. divides by mitosis to form embryo.
- each ovule containing fertilizied female gamete forms a seed - can grow into new plant.
conditions for germination
- water to activate enzymes breaking down food reserves in seed
- oxygen for respiration, which transfers energy from food for growth
- suitable temp for enzymes inside to work
parts of male reproductive system and their function
- testes where sperm are made; contained in scrotum
- scrotum sacs - contains & supports testes
- sperm ducts muscular tube. transports sperm from testis towards urethra
- prostrate gland produces semen (provides sperm cells w nutrition)
- urethra tube. carries sperm through penis during ejaculation. urine also passes here to exit body.
- penis swells when filled w/ blood for introducing sperm into female. contains urethra.
parts of female reproductive system and their function
- ovaries produces egg cells & sex hormones
- oviducts/fallopian tubes muscular tube. carries ovum from ovary to uterus.
- uterus/womb muscular w/ soft lining. fertilised egg cell implanted here to develop into fetus. protects fetus.
- cervix neck of uterus/ring of muscle at lower end of uterus. keeps fetus in place during pregnancy.
- vagina where sperm are deposited.
definition of fertilization in humans/animals
fusion of the nuclei from a male gamete (sperm)
& a female gamete (egg cell)
adaptive features of egg cell
- Energy stores in cytoplasm provides nutrients for zygote so it can divide faster after fertilisation & form an embryo.
- Jelly coating changes at fertilisation. after fertilisation, hardens to stop any more sperm getting in. makes sure offspring end up w/ right amount of DNA.
