10.1.11 Reproduction in plants

• Asexual reproduction


  Reproduction that does NOT involve fusion of gametes (sex cells)
• Offspring of asexual reproduction

  Genetically identical (clones)
• Advantages of asexual reproduction

  Population can increase rapidly (time and energy efficient)

  • Only one parent needed

  • Offspring are genetically identical ie. a favourable characteristic can help survival in the environment or for crops (eg disease resistant, high yield)

  • Rapid colonization of favourable

  environments.

  
• Sexual reproduction


  Reproduction that involves the FUSION of the NUCLEI of two GAMETES (sex cells)
• Offspring of sexual reproduction


  Genetically different
• Sexual reproduction normally takes longer than asexual reproduction
• Advantages and disadvantages of sexual reproduction

  • No details given
• Sexual reproduction in plants

  1. Pollination (self or cross)

  2. Fertilisation (fusion of gamete nuclei)
• Structures of a flowering plant

  • No details given

  
• Self-pollination


  Pollen transferred from anther to stigma of same plant

  
• Advantages of self-pollination


  • Efficient (pollen doesn't travel far), less energy wasted, doesn't rely on external factors
• Cross-pollination


  Pollen transferred from anther to stigma of different plant
• Advantages of cross-pollination


  • Encourages genetic variation, less risk of extinction or disease
• Disadvantages of cross-pollination


  • Relies on external factors (e.g. wind, insects), pollen can be lost
• Features of insect-pollinated flowers


  • Brightly coloured, scented, produce nectar, moderate pollen, stamen and carpel inside

  
• Features of wind-pollinated flowers


  • Small, unscented, no nectar, produce large amounts of pollen, stamen and carpel hang outside

  
• What happens after pollination

  Pollen tube created, grows down to ovary, male gamete fuses with female gamete in ovule
• Fertilisation


  Nucleus of pollen combines with nucleus of ovule, forming a diploid zygote that divides to become an embryo
• Germination


  Growth of an organism from a seed, usually in soil

  
• Conditions required for germination


  • Water
  • Oxygen
  • Warmth
• Disadvantages of Asexual Reproduction

  • *No genetic variation so any change in environmental conditions can affect plant

  population (ie a disease can wipe out an entire population easily)