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The exine of a pollen grain is not a continuous layer because it has openings called germ pores or colpi, which allow for the entry of pollen tubes during fertilization. These pores are necessary for the reproductive success of the plant as they facilitate the transfer of genetic material from the male gametophyte to the female reproductive structures.
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What are the 3 parts of a pollen grain?
The three parts of a pollen grain are the exine (outer layer), intine (inner layer), and the cytoplasm containing the male gametes. The exine is composed of sporopollenin and helps protect the pollen grain during transportation and fertilization.
How stigma helps in the wind pollination?
Depending on the type of pollinators, the pollen grains may be sticky or light. Exine present on the pollen grains as the outermost covering layer is contributed by the tapetum cells. Reaching on the stigma after pollination, the stigmatic cells interact with the material of exine to determine the compatibility of the pollen to allow its germination for fertilization.
Is there pollen grain inside the pollen cell?
A single pollen grain contains the generative material that forms the male gametes. It also contains the material that will form the pollen tube when the pollen lands on the pistil. These are covered by a thin layer called the intine or endospore as well as a thick protective wall called the exine or exospore.
What is the number of germ pores in a pollen grain of dicoits?
In dicotyledonous plants (dicots), pollen grains typically have three germ pores. These pores are openings in the outer layer of the pollen grain, allowing for the emergence of the pollen tube during fertilization. The presence of multiple germ pores is a characteristic feature that distinguishes dicots from monocots, which usually have one.
What is the Outer layer of grain?
The outer covering of the grain is called Husk. :) - HAO -
What are the 3 parts of a pollen grain?
The three parts of a pollen grain are the exine (outer layer), intine (inner layer), and the cytoplasm containing the male gametes. The exine is composed of sporopollenin and helps protect the pollen grain during transportation and fertilization.
What are exine seeds?
In botany 'exine' is the outer coat, or the outer layer, of the wall of a pollen grain. It is composed of a durable organic polymer
Why the exine should be hard?
The exine, the outer layer of the pollen grain, should be hard to protect the delicate genetic material inside from environmental stresses, such as UV radiation, desiccation, and microbial attack. A tough exine ensures that the pollen can survive the journey to the stigma of a compatible flower, which is crucial for successful fertilization and reproduction. Additionally, a hardened exine aids in the dispersal of pollen by wind or animals, ensuring that it reaches appropriate locations for germination.
What is sporoderm?
Sporoderm is the outermost protective wall around the pollen grain or microspore. It is made up of many layers. The two main layers are Exine and Intine. Exine is outer while Intine is inner layer of sporoderm.
How stigma helps in the wind pollination?
Depending on the type of pollinators, the pollen grains may be sticky or light. Exine present on the pollen grains as the outermost covering layer is contributed by the tapetum cells. Reaching on the stigma after pollination, the stigmatic cells interact with the material of exine to determine the compatibility of the pollen to allow its germination for fertilization.
Is there pollen grain inside the pollen cell?
A single pollen grain contains the generative material that forms the male gametes. It also contains the material that will form the pollen tube when the pollen lands on the pistil. These are covered by a thin layer called the intine or endospore as well as a thick protective wall called the exine or exospore.
What is the number of germ pores in a pollen grain of dicoits?
In dicotyledonous plants (dicots), pollen grains typically have three germ pores. These pores are openings in the outer layer of the pollen grain, allowing for the emergence of the pollen tube during fertilization. The presence of multiple germ pores is a characteristic feature that distinguishes dicots from monocots, which usually have one.
What is the pollen case?
What is usually meant by pollen case is the outer protective coat of the pollen grain. It is a highly modified cell wall, with two layers. The interior layer is largely pectocellulose (a combination of pectin and cellulose) with a bit of callose, and the exterior is made of sporopollenin. Sporopollenin is so tough that its exact chemical structure has not been figured out. Atop the sporopollenin layer is a deposit of sticky goo made of pollenkitt and/or tryphine.
What is a description of the Sporoderm Stratification?
Sporoderm stratification refers to the layering of the sporoderm, which is the outer layer of a pollen grain or spore. This stratification can consist of different layers with distinct compositions and functions, such as protecting the genetic material inside the pollen grain or aiding in dispersal. The structure and composition of sporoderm layers can vary among different plant species.
What is the Outer layer of grain?
The outer covering of the grain is called Husk. :) - HAO -
The tunica interna is continuous with this layer of the heart?
Endocardium
The internal layer of the tissue in the heart is the epicardium?
Epicardium is the outer layer of heart tissue. When considered as part of the pericardium, it is the inner layer, continuous with the serial layer.
