Biology of Insects and Pollination

• About 80 percent of all plant pollination is biotic i.e it is carried out by insects such as bees, wasps, and birds.
• The remaining 20 percent of abiotically pollinated species, 98 percent is by wind pollination and 2 percent by water pollination.
  

A tethered structure of the eel grass flower draws in free sailing male flowers for pollination by forming a dimple on water surface. The female flower is also blown by the wind, but it is anchored by its stem. As the breeze tugs at it, so its stem pulls it lower in the water, creating a dimple in the surface. The male ship, moving freely, sails into the dimple, toboggans down its slope and collides so violently with the female flower that the pollen is knocked out of its anthers. The female flower, having achieved fertilization, then closes.

Hydrophily includes plants which are pollinated inside the water. Zostera marina is a submerged marine perennial. The pollen is exceptionally long and needle like. Specific gravity of these pollen is almost the same as that of sea water. Consequently, they can freely float in water any depth. The stigma is also very long in this plant. If the pollen comes in contact with the stigma, it coils around water. 

The most recognized pollinators are the various species of bees, which are plainly adapted to pollination. Bees typically are fuzzy and carry an electrostatic charge. Both features help pollen grains adhere to their bodies but they also have specialized pollen carrying structures; in most bees takes the form of a structure known as scopa, which is on the hind  legs of most bees, and or the lower abdomen made up of thick plumose setae. Honey bees, bumblebees and their relatives do not have a scopa, but the hind leg is modified into a struture called the corbicula. Most bees gather nectar, a concentrated energy source and pollen, which is high protein food, to nurture their young and inadvertently transfer some among the flowers as they are working.

Vallisnaria is the genus of aquatic plant. In this plant, pollination is done by pollinating agent i.e., water. Female flowers have long stalk and appears on the surface of the water. When the male flower releases pollen grain it reaches to the stigma of female flower through water current.

Corss pollination is when pollen from one plant pollinates flowers on a different plant. With maize, cross-pollination is preferred because it is a monoecious crop with male and female flowers in separate parts of the same plant. So, male part produces a large number of pollen grains, which are then distributed by wind to other female parts of another maize plants.
Thus, the correct answer is option (D), 'Cross pollinated by wind'.

The most recognized pollinators are the various species of bees, which are plainly adapted to pollination. Bees typically are fuzzy and carry an electrostatic charge. Both featured help pollen grains adhere to their bodies, but they also have specialized pollen carrying structures; in most bees , this takes the form of a structure known as the scopa, which is on the hind legs of most bees, and the lower abdomen, made up of thick, plumose setae, honey bees, bumble bees and their relatives do not have a scopa, but the hind leg is modified into a structure called as corbicula. Most bees gather nectar, a concentrated energy source and pollen, which is high protein food, to nurture their young and inadvertently transfer some among the flowers as they are working.

Insect-pollinated flowers usually possess sticky and heavy pollens with a rough surface that allow them to stick to insects easily. Flowers also have sweet nectar that attracts insects that go from flower to flower to pollinate the flowers. The pollen grains are also in small quantities, because it is very likely that insects will enter another flower, and the pollen grains would have a higher chance of landing on the stigma. That's why there is no need of pollen grains in large quantities. 

• Pollination is the transfer of pollen from the male anther to the female stigma. It is carried out with the help of animals, birds, insects, water, wind, etc. 
• The pollination carried out by insects is called entomophily. 
• Pollination carried out by water is called hydrophily. Pollination carried out by the wind is called anemophily.
•  Pollination carried out by the animals is called zoophily. 

• The pollination mechanism in Salvia is a unique lever type. The flowers in this genus are arranged in thyrsus inflorescence and they are attractive and well adapted for cross-pollination through the agency of insects. 
• In this lever mechanism of pollination, the Corolla has a spreading upper lip, which acts as a landing place for the insect. When the insects land on the lower lip of the corolla and in its endeavor to obtain nectar that is secreted by the hypogynous disc, pushes the sterile lobes of the stamen inwards.
•  Due to this the upper half of the connective with the fertile lobes acts as a lever. Then the anther lobe comes down and shed the pollen on the back of the insect.

• Blastophaga quadriceps, the legitimate pollinator of Ficus religiosa, possesses two thoracic pockets in which pollen is stored for subsequent introduction into the young figs.  
• Pocket loading takes place in the nearly ripe fig at the male phase. Impregnated female wasps leave the fig via narrow channels bored by the males. 
• Upon entering young receptive figs, the female wasps begin oviposition, during which pocket emptying and pollination takes place.

Pollination through insect is called as entamophily in which insect is attracted by nectar secreted by flower and colorful petals.