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Section 4 – Reproduction
National 4 & 5 - Multicellular Organisms
Learning OutcomesBy the end of this lesson I will be able to:- identify the difference between asexual &
sexual reproduction- identify the sites of gamete production in
plants- identify the key structures of these sites- explain what happens during fertilisation- compare the methods of fertilisation in
different plants
ReproductionThe production of new members of a speciesCan be sexual:Requires sex cells (gametes)These contain half the information needed to
make a new organismWhen they combine, a full set of information
is formedor asexual:- does not require sex cells
Gametes and reproductionAll body cells have two sets
of chromosomes - 1 set from each parentThese cells are said to be
diploidGametes are formed by
meiosis - a type of cell divisionGametes contain one set of
chromosomes- half of the original cellsThey are said to be haploidWhen two haploid cells join
together = fertilisationA new diploid cell is formed- this is a zygote
Site of gamete production - plantsThe reproductive
parts of a plant are found in the flower
The male sex cells are found in pollen grains
These are found inside an anther
Female egg cells are called ovules
- found within the ovary
Reproduction in plants - pollinationThe transfer of
pollen from an anther to a stigma
The stigma is the top of the female part of the flower
Pollen can be transferred in two ways
- by the wind- by insects
Insect Pollination vs. Wind PollinationWhat are the differences in
appearance/structure between insect and wind pollinated flowers?WIND INSECT
Insect Pollination vs. Wind Pollination
WIND POLLINATED FLOWERS
INSECT POLLINATED FLOWERS
Structural Feature
Reason Structural Feature
Reason
Small, dull flowers with no scent or nectar
Large, colourful flowers with nectar and scent
Anthers hanging out of flower
Anthers firmly attached inside flower
Stigmas hanging out of flower
Stigmas inside the flower, with sticky surface
Light and smooth pollen
Sticky and rough pollen
Large quantity of pollen
Small quantity of pollen
Complete the following table
Insect Pollination vs. Wind Pollination
WIND POLLINATED FLOWERS
INSECT POLLINATED FLOWERS
Structural Feature
Reason Structural Feature
Reason
Small, dull flowers with no scent or nectar
Insects not needed
Large, colourful flowers with nectar and scent
To attract insects
Anthers hanging out of flower
So pollen is easily blown away by the wind
Anthers firmly attached inside flower
To brush against insects, so pollen is picked up
Stigmas hanging out of flower
So pollen can be caught and trapped
Stigmas inside the flower, with sticky surface
To ensure pollen attached to stigma
Light and smooth pollen
Easy to be lifted and carried by the wind
Sticky and rough pollen
Easy for pollen to stick to insects
Large quantity of pollen
Low chance of pollen landing on another plant
Small quantity of pollen
More likely to be transferred by insect
Complete the following table
Reproduction in plants - fertilisationOnce transferred, the pollen then needs to travel down
the stigmaIt uses sugar on the stigma as an energy sourceIt uses this to form a pollen tube
The male gametes then travel down to the ovule
Once inside, the male and female sex cells join togetherThis is fertilisation
Plant sexual reproduction video
Asexual ReproductionWhen a new organism is
produced from a single parentDoesn’t involve sex cells or
fertilisationAll offspring are identical to
their parentPlants- also known as vegetative
propagationPlants can form offspring from
their stemsE.g. runners from
strawberry/spider plantOthers can form offspring from
their rootsE.g. onion , potato
Plants asexual-reproduction video
Asexual vs Sexual Reproduction
Asexual Sexual
Young plant has food source from parent or
food store
New plant has a mixture of characteristics from different
parents - variation
Young plant grows in a suitable environment
Plants well distributed
No need to depend on pollination
Both types of reproduction have advantages
