bio q4 lesson 1

• Flower

  Reproductive shoots of the angiosperm sporophyte, typically composed of four whorls of highly modified leaves called floral organs
• Flowers

  • They are determinate shoots, meaning that they stop growing after the flower and fruit are formed
• Floral organs

  • Sepals
  • Petals
  • Stamens
  • Carpels (pistils)

  
• Sepals


  Enclose and protect the floral bud before it opens, usually green and more leaflike in appearance
• Petals


  More brightly colored than sepals and attract the flower to insects and other pollinators
• Stamen


  Consists of a stalk called the filament and a terminal structure called the anther, within which pollen is produced
• Carpel


  Has an ovary at its base, a long slender neck called the style, and a sticky stigma at the top that serves as a landing platform for pollen
• Pistil


  Term sometimes used to refer to a single carpel or to a group of fused carpels
• Whorls


  An arrangement of sepals, leaves, petals, carpels or stamens, radiating from a specific point and wrapping around the stalk or stem
• Complete flower


  A flower that is built with four parts: sepals, petals, pistils, and stamens

  
• Incomplete flower


  A flower that is missing any of the sepals, petals, pistils, and stamens
• Perfect/Bisexual flower


  A flower that has both male and female reproductive structures present
• Imperfect/Unisexual flower


  A flower that does not have both male and female structures, either staminate (male) or carpellate/pistillate (female)
• Gametophyte


  A stage in the life cycle that is found in all plants and certain species of algae, the multicellular haploid generation

  
• Sporophyte


  The multicellular diploid generation in the plant life cycle
• Diploid


  Refers to two sets of chromosomes in the cells, normally written as "2n"
• Haploid


  Only one set of chromosomes in the cells, written as "n"
• Double fertilization


  Pollen grain lands on stigma, absorbs moisture, and germinates to produce pollen tube that extends down to ovary
• From ovule to seed


  1. After double fertilization, ovule develops into seed, ovary develops into fruit enclosing seed(s)

  2. Embryo develops from zygote, seed stockpiles proteins, oils, and starch

  3. Storage function of endosperm taken over by swelling cotyledons of embryo
• From ovary to fruit


  1. Fertilization triggers hormonal changes that cause ovary to transform into fruit

  2. Ovary wall becomes pericarp, other flower parts wither and are shed
• Asexual reproduction


  Creation of new individuals whose genes all come from one parent without fusion of egg and sperm
• Advantages of asexual reproduction


  • Enables animals living in isolation to produce offspring without mates
  • Can create numerous offspring rapidly, ideal for colonizing habitats
  • Perpetuates successful genotypes in stable, favorable environments
• Sexual reproduction


  Creation of offspring by fusion of haploid gametes to form diploid zygote

  
• Advantages of sexual reproduction

  • Increases genetic variability among offspring
  • May enhance reproductive success when environmental factors change rapidly
• Mechanisms of asexual reproduction

  • Fission
  • Budding
  • Fragmentation
  • Regeneration
• Fission


  Separation of parent into two or more individuals of approximately equal size
• Budding


  New individuals arise from outgrowths of existing ones, offspring may or may not detach
• Fragmentation


  Breaking of body into several pieces, some or all of which develop into complete adults
• Regeneration


  Regrowth of lost body parts, usually accompanied by fragmentation
• Types of fertilization

  • Internal
  • External
• Internal fertilization


  Male delivers sperm cells directly into female's body, her moist tissues provide medium for sperm movement
• External fertilization


  Mating partners release eggs and sperm into water simultaneously
• Male reproductive system

  • Testis (male gonad)
  • Sperm duct
  • Penis
• Female reproductive system

  • Ovary (female gonad)
  • Oviduct
  • Vagina
• Metagenesis


  Alternation of asexual and sexual generations
• Male reproductive anatomy

  • Male gonad (testis)
  • Sperm duct
  • Penis
• Testis


  Where sperm are produced
• Sperm duct


  Used for the transport of sperm to the exterior of the body
• Penis


  The terminal part of the sperm duct which opens onto or into a copulatory organ
• Female reproductive anatomy

  • Female gonad (ovary)
  • Oviduct
  • Vagina