BIOLOGY PRELIMINARY NOTES
KIARA DURKIN
REPRODUCTION IN FLOWERING PLANTS
Reproduction is the ability of an organism to produce a new generation of themselves
Importance: survival and evolution – through reproduction, an individual passes on its genes to the
next generation
Asexual reproduction: production of the same species by one parent
Sexual reproduction: production of a new generation of the same species by bringing together the
genetic material of two parents
Similarities between sexual and asexual reproduction
• Both processes:
- Produce same type of organisms to prevent the extinction of their species
- Result in food being produced
Differences between asexual and sexual reproduction
Characteristics Asexual Sexual
Number of One Two, with 2 genders
parents
Processes One stage (mitosis) Two stages (meiosis and
fertilization with fusion of two cells)
Gamete No gametes formed Gametes formed
formation
Result Offspring genetically identical to parent Offspring genetically different to
(no shuffled alleles = no variation) parents (alleles shuffled during
meiosis and fertilization)
Value Stable environment = well adapted Unstable environment = individuals
individuals preserved with variations can adapt to new
conditions
Rate of Faster – all individuals can reproduce Slower – half population (males)
reproduction cannot produce offspring
Energy input More efficient, none Energy needed to produce gametes
and find a mate
Outside agents None needed Pollinators necessary
Adaptability None Present
Possibility of Low – no genotype variation Good – genotype variation
evolution
Advantages of asexual reproduction
• All individuals can reproduce (no energy expenditure on courting and forming gametes)
• Process = simple and fast (only involves mitosis)
• It is useful in stable environments (parent well adapted = offspring well adapted)
• Favourable mutation spread rapidly (enables population to adapt to new conditions)
Disadvantages of asexual reproduction
• Without a mutation = no variation in offspring = higher risk of extinction in an unstable
environment
, • Overcrowding may occur (rapid reproduction) – resources such as food in short supply
Advantages of sexual reproduction
Variation:
• Is the basis of evolution
• Gives organisms better chance of survival in unstable environment
• Prevent spread of disease as offspring may be genetically immune to certain diseases
• Reduces the chance of inheriting a disease from a parent
Disadvantages of sexual reproduction
• High expenditure of energy – special organs need to be developed
• Reproduction process is slower
• Unfavorable mutations and recessive genes may be expressed in offspring
• Outside agents needed for meeting of gametes
How does sexual reproduction take place?
• Diploid parent produces gametes in gonads by meiosis
• Gametes = haploid as they contain half the number of parent chromosomes
• Male + female gametes brought together by pollination
• Gamete nuclei fuse = fertilisation
• Zygote = diploid; grows by mitotic cell division into individual
The gametes
• Female gamete is large + immotile; male gamete = small
• Male gamete = nucleus in pollen grain; female gamete = ovum in embryo sac
Angiosperm reproduction
Plants with flowers which produce their ovules enclosed in an ovary
What is a flower?
Organ of sexual reproduction
• Contains reproductive organs; attracts pollinators
• Many make both male and female gametes = hermaphrodites (bisexual)
• Male gametes = in pollen grains produced by anthers; female gametes inside ovules
enclosed in ovary
Structure of a flower
• Sepal (whorl of modified leaves)
• Calyx (protects unopened bud)
• Corolla (petals; attracts pollinators)
• Stamen (male whorl – anther and filament)
• Carpel (female whorl – stigma (sticky; pollen adheres to it), style (joins stigma to ovary),
ovary (matures into fruit after fertilisation) and ovule (becomes seed after fertilisation))
• Receptacle (supports floral parts)
Female part of flower (carpel)
• Each mature ovule contains gamete
KIARA DURKIN
REPRODUCTION IN FLOWERING PLANTS
Reproduction is the ability of an organism to produce a new generation of themselves
Importance: survival and evolution – through reproduction, an individual passes on its genes to the
next generation
Asexual reproduction: production of the same species by one parent
Sexual reproduction: production of a new generation of the same species by bringing together the
genetic material of two parents
Similarities between sexual and asexual reproduction
• Both processes:
- Produce same type of organisms to prevent the extinction of their species
- Result in food being produced
Differences between asexual and sexual reproduction
Characteristics Asexual Sexual
Number of One Two, with 2 genders
parents
Processes One stage (mitosis) Two stages (meiosis and
fertilization with fusion of two cells)
Gamete No gametes formed Gametes formed
formation
Result Offspring genetically identical to parent Offspring genetically different to
(no shuffled alleles = no variation) parents (alleles shuffled during
meiosis and fertilization)
Value Stable environment = well adapted Unstable environment = individuals
individuals preserved with variations can adapt to new
conditions
Rate of Faster – all individuals can reproduce Slower – half population (males)
reproduction cannot produce offspring
Energy input More efficient, none Energy needed to produce gametes
and find a mate
Outside agents None needed Pollinators necessary
Adaptability None Present
Possibility of Low – no genotype variation Good – genotype variation
evolution
Advantages of asexual reproduction
• All individuals can reproduce (no energy expenditure on courting and forming gametes)
• Process = simple and fast (only involves mitosis)
• It is useful in stable environments (parent well adapted = offspring well adapted)
• Favourable mutation spread rapidly (enables population to adapt to new conditions)
Disadvantages of asexual reproduction
• Without a mutation = no variation in offspring = higher risk of extinction in an unstable
environment
, • Overcrowding may occur (rapid reproduction) – resources such as food in short supply
Advantages of sexual reproduction
Variation:
• Is the basis of evolution
• Gives organisms better chance of survival in unstable environment
• Prevent spread of disease as offspring may be genetically immune to certain diseases
• Reduces the chance of inheriting a disease from a parent
Disadvantages of sexual reproduction
• High expenditure of energy – special organs need to be developed
• Reproduction process is slower
• Unfavorable mutations and recessive genes may be expressed in offspring
• Outside agents needed for meeting of gametes
How does sexual reproduction take place?
• Diploid parent produces gametes in gonads by meiosis
• Gametes = haploid as they contain half the number of parent chromosomes
• Male + female gametes brought together by pollination
• Gamete nuclei fuse = fertilisation
• Zygote = diploid; grows by mitotic cell division into individual
The gametes
• Female gamete is large + immotile; male gamete = small
• Male gamete = nucleus in pollen grain; female gamete = ovum in embryo sac
Angiosperm reproduction
Plants with flowers which produce their ovules enclosed in an ovary
What is a flower?
Organ of sexual reproduction
• Contains reproductive organs; attracts pollinators
• Many make both male and female gametes = hermaphrodites (bisexual)
• Male gametes = in pollen grains produced by anthers; female gametes inside ovules
enclosed in ovary
Structure of a flower
• Sepal (whorl of modified leaves)
• Calyx (protects unopened bud)
• Corolla (petals; attracts pollinators)
• Stamen (male whorl – anther and filament)
• Carpel (female whorl – stigma (sticky; pollen adheres to it), style (joins stigma to ovary),
ovary (matures into fruit after fertilisation) and ovule (becomes seed after fertilisation))
• Receptacle (supports floral parts)
Female part of flower (carpel)
• Each mature ovule contains gamete
