FLOWERING PLANTS as all individuals can
- reproduction = ability of reproduce offspring
organisms to produce a new - more efficient, no energy
gen of themselves input needed
- extremely NB for - no outside agents needed
survival/evolution of a species - low possibility of evolution as
because through reproduction, here is
individual passes genes to - no ability to adapt to
next gen environment
- two types of natural - usually no genotype variation
reproduction: Sexual
asexual – production of - two parents, two genders
new gen of same species - two stages, i.e. meiosis and
by one parent fertilisation w/ fusion of two
sexual – production of cells, therefore is slower
new gen of same species - gametes formed
by bringing together - offspring are genetically diff to
genetic material of two parents, i.e. there is variation
parents because alleles are shuffled
during:
What are the similarities meiosis when gametes are
between asexual and sexual formed
reproduction? fertilisation when alleles
- both produce same kind of are joined in new
organisms to prevent their combinations
species dying out/becoming - in unstable environment,
extinct individuals w/ variations can
- result in food being produced adapt to new conditions
- slower process
What are the differences - less efficient, energy input
between asexual and sexual needed to produce gametes
reproduction? and find/court a mate
Asexual - pollinators often necessary for
- one parent, i.e. all individuals pollination
can produce offspring - there is ability to adapt to
- one stage, i.e. mitosis w/ no environment
fusion of cells therefore is - good chance of evolution as
quicker there is genotype variation
- no gametes formed
- offspring are genetically Advantages of asexual
identical to parent, i.e. no reproduction
variation because alleles - no expenditure of energy to
aren’t shuffled produce gametes or find mate
- in a stable environment, well - process is simple/fast as it
adapted individuals are only involves mitosis
preserved - very useful in stable
- reproduction possible when conditions, i.e. if parent is well
there are no/few mates adapted to a particular
, environment, the genetically - outside agents may be
identical offspring will also be needed in plants to carry
well adapted pollen/seeds
- a favourable mutation can
spread rapidly enabling How does sexual reproduction
population to adapt quickly to take place?
new environmental conditions - diploid parents produce
gametes (sex cells) in the
Disadvantages of asexual gonads (sex organs) by
reproduction meiosis
- unless there is a mutation, no - gametes are haploid as they
variation in offspring as there contain one set (n) or half the
is no recombination of alleles number of chromosomes
– if environment changes, - male and female gametes are
population might be unable to brought together by
adapt to the new conditions pollination (plants) or mating
and could die out (animals)
- overcrowding may occur and - gamete nuclei then fuse,
resources might be in short process known as fertilisation
supply - new cell, zygote, is diploid
Advantages of sexual (2n) as it has two sets of
reproduction chromosomes
- is the basis of evolution - zygote grows by mitotic
- gives organisms better chance division into a new individual
of survival in an unstable
environment as offspring may The gametes
be able to adapt to new - female gamete is quite large
conditions and not motile
- may prevent spread of - male gamete is small and
disease as offspring could be motile in animals
genetically resistant to a - in animals, male gamete =
particular disease sperm and female =
- may reduce chance of egg/ovum
inheriting a disease from a - in many plants, male gamete
parent = nucleus in a pollen grain
and female gamete = egg cell
Disadvantages of sexual (ovum) in an embryo sac
reproduction
- high expenditure of energy as
in plants, special organs of
reproduction need to be
produced, i.e. flowers
- reproduction process is slower
– takes time for gamete
production and meeting of
gametes
- unfavourable mutations and
recessive genes might be
expressed in offspring