Key Themes 2 Types of reproduction sexual amp asexual Both internal and external fertilisation Adaptations to life on land Eggs birds and reptiles Internal gestation mammals Insects Flowering plants ID: 242514
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Slide1
2.4 Reproductive StrategiesSlide2
Key Themes
2 Types of reproduction (sexual & asexual)
Both internal and external fertilisation
Adaptations to life on land
Eggs (birds and reptiles)
Internal gestation (mammals)
Insects
Flowering plantsSlide3
Asexual reproduction
Individuals are genetically identical (clones)
Cells with diploid number are produced by mitosis
Advantages:
Disadvantages:Slide4
Sexual reproduction
Produces offspring that are genetically different
Haploid cells or gametes are produced by meiosis
Advantages:
Disadvantages:Slide5
Males and females produce different sized gametes
Fertilisation involves the fusion of a haploid sperm and a haploid egg
diploid zygoteSlide6
Most aquatic beasties undergo
External Fertilisation
will lay eggs (sometimes in a nest)
then spread sperm over those eggsSlide7
Internal fertilisation
Advantages:Slide8
In many animals the fertilised
egg / zygote actually develops outside of the body
Examples?
When this is the case, a large number are produced to increase survivalSlide9
Adaptations to life on land
Amphibians
Reptiles
Birds
Mammals
All these _____ show increasing adaptations for colonising the landSlide10
Reptiles and Birds
Evolution of the amniotic egg
Anatomy of the egg:
Fluid filled cavity
Membrane
Protective shell
Encloses embryo
inside the yolk sac
Birds incubate eggs, the embryo completing development outside the mothers bodySlide11
Mammals
Young are retained in uterus / womb without a shell
Embryo is nourished there from mother’s blood supply via a placenta
Means that young can be born fairly well advanced in terms of development
discussion point:
Different species have diff strategies on thisSlide12Slide13
Parental care
What animals exhibit parental care?
What are the advantages?
How many offspring do your examples have?
Name something that has no parental care…
How many offspring does that have?
*
As degree of parental care increases, number
*
of offspring decreasesSlide14
Insects
Abundant, Diverse & Widespread
Insects lives and lifestyles affect almost all other terrestrial organisms
Insect zygotes develop into an intermediate form (nymph or larva) before becoming an adult
Slide15
Nymphs
Nymphs resemble the adults
They go through several moults (
instar
)
Incomplete metamorphosisSlide16
Larvae
Different from the adult form
Larval stage followed by pupa
Then complete metamorphosis into the adultSlide17
Flowering Pants
Flowering Plants are well adapted for life on land in terms of their morphology and
reproductionSlide18
They have similar reproductive strategies to animals for colonisation.
… what are they?
http://www.videopediaworld.com/video/22961/11-30-the-private-life-of-plants--03--
flowering
Slide19
Plant relationships
Key to plant success is their relationship with animals:
Pollination
Seed Dispersal Slide20
The Seed
Food store enables embryo to develop until leaves are produced
Resilient coat allows it to withstand adverse conditions