Pistil and Megasporangium MCQ - Practice Questions with Answers

• The gynoecium represents the female reproductive part of a flower. 
• The gynoecium may consist of a single carpel (monocarpellary) or may have more than one carpel (multicarpellary). 
• When there are more than one, the pistils may be fused together (syncarpous) or maybe free (apocarpous).
•  Each pistil has three parts:
  • stigma
  • style 
  • ovary
• The stigma serves as a landing platform for pollen grains. 
• The style is the elongated slender part beneath the stigma. 
• The basal bulged part of the pistil is the ovary. 
• Inside the ovary is the ovarian cavity (locule). 
• The placenta is located inside the ovarian cavity.
• Arising from the placenta are the megasporangia, commonly called ovules. 
• The number of ovules in an ovary may be one (wheat, paddy, mango) to many (papaya, watermelon, orchids).

Megasporangium or Ovule:

• The ovule is a small structure attached to the placenta by means of a stalk called funicle.
• The body of the ovule fuses with funicle in the region called hilum. 
• Thus, hilum represents the junction between ovule and funicle. 
• Each ovule has one or two protective envelopes called integuments. 
• Integuments encircle the nucellus except at the tip where a small opening called the micropyle is organised. 
• Opposite the micropylar end, is the chalaza, representing the basal part of the ovule.
• Enclosed within the integuments is a mass of cells called the nucellus.
• Cells of the nucellus have abundant reserve food materials. 
• Located in the nucellus is the embryo sac or female gametophyte. 
• An ovule generally has a single embryo sac formed from a megaspore.

• Depending on the configuration and orientation of the body of the ovule in relation to funiculus, there are six types of ovules:
  • Orthotropous: erect
  • Anatropous: inverted
  • Hemitropous: half inverted
  • Campylotropous: the body of the ovule is curved
  • Amphitropous: both the body and embryo sac curved
  • Circinotropous: funiculus coiled around the ovule