What is Nemec phenomena?

What is Nemec phenomena?

Pollen embryo sacs are also called NEMEC PHENOMENON, as Nemec discovered them for the first time. According to Nemec, pollen embryo sacs are produced by the repeated divisions of vegetative nucleus while the generative nucleus degenerates.

What is pollen grain embryo sac?

When the embryo sacs have one, two, four, or eight nuclei, the pollen grains have a single and eccentrically located nucleus. By the time the embryo sac has proliferated antipodal cells, the pollen grains are two-nucleate. When the embryo sac becomes mature, the pollen grains are in the three-nucleate stage.

In which of the following plant embryo sac like pollen grains are observed?

POLLEN-EMBRYO SACS IN HEUCHERA MICRANTHA DOUGL. NEMEC (1898) observed embryo sac-like pollen grains in the petaloid anthers of Hyacinthus orienta/is. He believed that they are formed by 3 successive divisions of the vegetative nucleus.

Who discovered pollen embryo sac?

Giovanni Battista Amici
Pollen tubes were first discovered by Giovanni Battista Amici in the 19th century. They are used as a model for understanding plant cell behavior.

What is meant by Mesogamy?

Answer: Mesogamy is a type of fertilization observed in all Cucurbit plants, such as pumpkin, ridge gourds, bitter gourd and other gourd plants. In this type of fertilization, the pollen tube enters the ovule through its middle part or through the integuments of the ovule.

What are pollen sacs?

The structure in seed plants in which pollen is produced. In angiosperms there are usually four pollen sacs in each anther; they contain the microspore mother cells. In gymnosperms variable numbers of pollen sacs are borne on the microsporophylls that make up the male cone.

Where is the embryo sac located in the flower?

ovule
noun Botany. the megaspore of a seed-bearing plant, situated within the ovule, giving rise to the endosperm and forming the egg cell or nucleus from which the embryo plant develops after fertilization.

Which of the following develops into an embryo sac?

Ovules
Ovules develop into embryo sac.

How is pollen grain and embryo sac formed?

The germ cell in the pollen grain divides and releases two sperm cells which move down the pollen tube. Once the tip of the tube reaches the micropyle end of the embryo sac, the tube grows through into the embryo sac through one of the synergids which flank the egg.

How is pollen sac formed?

Each anther lobe develops two pollen sacs. Then, a two-lobed anther develops four pollen sacs that situate at four corners of the anther. Development of pollen sacs begins with the differentiation of archesporial cells in the hypodermal region below epidermis at four corners of the young anther.

What was the origin of the Nemec phenomenon?

De Mol (1923) observed this so-called “Nemec-phenomenon” in the anthers of other varieties of Hyacinthus orientalis which had been subjected to certain special conditions in order to obtain early flowering. He attributed the origin of the abnormality to a duplication of the generative nuclei.

What kind of football does Adam Nemec play?

Adam Nemec ( Slovak pronunciation: [ˈadam ˈɲɛmɛts]; born 2 September 1985) is a Slovak professional footballer who plays as a forward for Pafos and formerly the Slovakia national team. In his career, he has played in 7 different countries but mostly for teams in Germany.

How many caps does Adam Nemec have for Slovakia?

Adam Nemec ( Slovak pronunciation: [ˈadam ˈɲɛmɛts]; born 2 September 1985) is a Slovak professional footballer who plays as a forward for Pafos and formerly the Slovakia national team. In his career, he has played in 7 different countries but mostly for teams in Germany. During 13 years international career, he won 43 caps and scoring 13 goals.

Who is the actor known as Corin Nemec?

Joseph Charles Nemec IV (born November 5, 1971), known professionally as Corin Nemec, is an American actor, producer, and screenwriter.