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Chapter 17: reproduction in plants (Parts of a flower (petal (colourful in…
Chapter 17: reproduction in plants
Asexual reproduction: process resulting in the production of genetically identical offspring from one parent,
without the fusion of gametes
.
Advantages
faster (than sexual repro)
only requires one parent
all beneficial qualities are passed down to offspring
Disadvantages
no genetic variation in the offspring, species are not well-adapted to changes in the environment
Sexual reproduction: process involving the
fusion of a male and female gamete to form a zygote
resulting in the production of genetically dissimilar offspring.
Advantages
offspring may inherit beneficial qualities from both parents
greater genetic variation in the offspring, species is better adapted to changes in the environment
Disadvantages
two parents are required
slower (than asexual repro)
Parts of a flower
petal
colourful in insect-pollinated flowers to attract insects
nectar guides present on insect-pollinated flowers
anther+filament = stamen
contains pollen grains
wind-pollinated: small, light and smooth
insect-pollinated: large and rough
wind-pollinated: long, pendulous stamen and protruding anther
insect-pollinated: not pendulous, anthers do not protrude
stigma+style
wind-pollinated: large and feathery and usually protrude
insect-pollinated: small and compact, do not protrude
ovule
grows into seed
ovary
grows into fruit
can be superior or inferior
sepal
Cross-pollination: transfer of pollen grains from the anther of one flower to the stigma of another flower in another plant of the same species
characteristics
anthers and stigma mature at different times
anthers and stigma situated some distance apart
Advantages
offspring produced may have inherited beneficial qualities from both parents
greater genetic variation, species better adapted to environment
Disadvantages
two parent plants are required
depends on external factors such as insects or wind for pollination
Self-pollination: transfer of pollen grains from the anther of one flower to the stigma of the same flower or another flower of the same plant
characteristics
anthers and stigma mature at the same time
stigma is situated directly below anther
Advantages
only one parent plant required
does not depend on external factors for pollination
higher probability that pollination will occur
Disadvantages
less genetic variation, species is less well-adapted to the environment
probability of harmful recessive alleles being expressed is higher