Diversity Of Reproductive Strategies Flashcards Preview

Grade 12 LS 2016 > Diversity Of Reproductive Strategies > Flashcards

Flashcards in Diversity Of Reproductive Strategies Deck (20):
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Fertilisation inside the organisms body

Internal fertilisation

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Fertilisation outside the organism's body

External fertilisation

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Type of fertilisation mainly occurring in aquatic environments

External fertilisation

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Hermaphrodite organism

Having both male and female sex organs

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Inseminated

Semen is deposited in the female body parts

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Advantages of internal fertilisation

  • Increased protection of sperm and eggs
  • prevents waste of gametes
  • specific mate selection (cf. sexual selection in evolution section )

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Oviparous

  • Eggs laid outside parents body
  • protection by gelatinous mass or shell and membranes
  • embryo develops inside egg -egg yolk feeds embryo -offspring hatches

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Ovoviviparous

  • Eggs kept inside parents body
  • protection by soft shell and membranes
  • embryo develops inside egg
  • egg yolk feeds embryo
  • offspring hatches inside body
  • live young born from parent

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Viviparous

  • Eggs kept inside body
  • protected by uterus and membranes
  • embryo develops inside uterus
  • mother feeds embryo through placenta and umbilical cord
  • pregnancy followed by birth of offspring
  • parental care follows e.g. Suckling

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Amniotic eggs

  • eggs that have a membrane called the amnion
  • surrounds developing embryo of fertilised eggs
  • found in reptiles, birds and mammals

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Function of yolk sac in amniotic egg

Source of vitamins, minerals and fats for embryo

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Function of chalaza in chicken egg

  • Holds yolk and embryo in place
  • Absorbs shock

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The germinal disc in a bird egg

Small spot on the surface of the yolk from which the embryo develops

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Chorion membrane

Encloses and protects the yolk sac and developing embryo

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Function of air chamber in bird egg

  • Helps with gaseous exchange
  • protects against shock

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Major source of protein for developing young in bird egg

Albumen ('egg white')

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Precocial development

  • Eggs often contain more yolk
  • Born/hatched with eyes open
  • Covered with fur/down
  • Mobile in less than two days
  • Follow parents, learning how to feed E.g. Ducks, buck

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Altricial development

  • Eggs contain less yolk
  • Young hatch/born with eyes closed
  • Little or no down/fur
  • Unable to leave nest until independent
  • Fed by parents until independent
  • E.g. Pigeons, rodents

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Parental care

  • Parents caring for eggs or juveniles to ensure survival
  • general decrease in energy used to produce vast numbers of offspring as parental care increases

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