Includes notes on reproduction in flowering plants according to the SAGs document: For example, similarities & differences between sexual & asexual plants, pollination vs fertilisation, plant diagram, how asexual & sexual reproduction historically led to improved food crops, propagation, genetic en...
Reproduction in flowering plants:
Reproduction: The ability of organisms to produce a new generation of themselves.
Importance of reproduction in plants: Replaces plants that die. (Plants are NB for all living
organisms)
ASEXUAL SEXUAL
Number of parents One Two
Processes 1 stage: Mitosis with no 2 stages: Meiosis and
fusion of cells (Therefore fertilisation with fusion of 2
quicker) cells (Therefore slower)
Gamete formation NO gametes formed Gametes formed
End result Offspring are genetically Offspring are genetically
identical to the parent. different to parents.
NO genetic variation. IS genetic variation (alleles
are shuffled during: Meiosis &
fertilisation (join in new
combination)
Value In an unchanging, stable In a changing, unstable
environment → well adapted environment, individuals with
individuals are preserved. variations can adapt to new
conditions.
Reproduction is possible
where there are no/few
mates.
Rate of reproduction Faster (all individuals can Slower (half population are
reproduce offspring) males who do not produce
offspring)
Energy input More efficient, no energy Less efficient, energy input is
input needed needed to produce games,
find and court a mate etc.
Outside agents None needed Pollinators often necessary
for pollination
Ability to adapt to No Yes
environment
Possibility of evolution Low - no genetic variation Good - genetic variation
(therefore no new species) (natural selection)
, Advantages of Asexual reproduction:
● All individuals can reproduce (no energy expenditure to produce gametes & find a mate)
● Process is fast & simple → only involves mitosis
● Useful in unchanging (stable) conditions: If a parent is well adapted to a particular
environment the genetically identical offspring will also be well adapted.
● A favourable mutation can spread rapidly (population will adapt quickly to new
environmental conditions - e.g. resistance to antibiotics)
Disadvantages of Asexual reproduction:
● NO variation in offspring (no recombination of alleles) (unless a mutation occurs)
○ All offspring will inherit weak traits and the population might be unable to adapt to
the new conditions and could die out.
● Overcrowding may occur → short supply of resources.
Advantages of Sexual reproduction:
● Genetic variation:
○ Basis of evolution
○ Gives organisms better chance of survival in unstable environments (better
adaption)
○ May prevent spread of disease (offspring may not inherit it)
Disadvantages of Sexual reproduction:
● High energy expenditure: gamete formation, special reproductive organs need to be
produced (flowers), finding a mate, courtship etc…
● Fewer offspring produced → less survival chances
● Reproduction is a slower process (courtship/ gamete formation)
● Unfavourable mutations & recessive genes CAN be expressed
● Outside agents may be needed in plants (to carry seeds/pollen etc)
Angiosperms: Plants that reproduce by means of seeds that are produced in flowers.
Produce their ovules enclosed in an ovary
Gymnosperms: Plants that reproduce by means of seeds that are produced in cones (NOT
flowers)
What is a flower:
● Contains reproductive organs & will attract pollinators.
● Flowers that make both male & female gametes ⇒ Hermaphroditic.
● Male gametes: found inside pollen grain (produced by anthers)
● Female gametes: found in ovules (enclosed in the ovary)
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