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2.4 Reproductive Strategies 2.4 Reproductive Strategies

2.4 Reproductive Strategies - PowerPoint Presentation

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2.4 Reproductive Strategies - PPT Presentation

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

parental offspring birds flowering offspring parental flowering birds advantages land life eggs animals reproduction embryo care insects produced number

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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 thisSlide12
Slide13

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