Pteridophytes Part - II

The gametophytic generation of fern is known as the prothallus. This is a small, heart-shaped structure that forms from the spores of the fern. The prothallus is the haploid stage of the fern life cycle and is responsible for producing the gametes (sperm and eggs) through mitosis. Once fertilization occurs, the diploid sporophyte generation begins to develop. Therefore, the correct answer is Prothallus.

After fertilization, the diploid zygote develops a protective wall around it, which is known as an oospore. This protective wall helps to protect the developing embryo and provides it with necessary nutrients for growth and development. The other options, such as egg and ovum, do not accurately describe the protective wall formed after fertilization. Therefore, the correct answer is oospore.

The correct answer is "All of the above." The cells of Prothallus in Nephrolepis have thin walls, contain chloroplasts, and lack stomata. This means that they have thin cell walls which allow for efficient gas exchange, contain chloroplasts for photosynthesis, and do not have stomata which are small openings that regulate gas exchange in plants. Therefore, all of the given features are true for the cells of Prothallus in Nephrolepis.

The correct answer is air because Nephrolepis is a type of fern that reproduces through spores. These spores are lightweight and can be easily carried by air currents. This method of dispersal allows the spores to reach new areas where they can germinate and grow into new fern plants.

The correct answer is Monoecious. In fern Nephrolepis, the prothallus is monoecious, which means it has both male and female sex organs on the same individual. This allows for self-fertilization to occur, as the prothallus can produce both sperm and eggs.

The antheridial wall in Nephrolepis is composed of three types of cells: First Ring cells, Second Ring cells, and Cap cells. Therefore, the correct answer is "All of the above."

Oogamous is the correct answer because Nephrolepis exhibits oogamy, which is a type of sexual reproduction where the female gamete (egg) is larger and nonmotile, while the male gamete (sperm) is smaller and motile. This type of reproduction is commonly found in plants and algae, where the male gamete has to swim to reach and fertilize the larger, immobile female gamete.

In the Prothallus of Nephrolepis, the location of sex organs is such that the antheridia are found near the rhizoids, while the archegonia are located below the apical notch and are partially embedded in a cushion. This arrangement allows for efficient fertilization as the antheridia are close to the rhizoids where they can release sperm, and the archegonia are positioned below the apical notch where they can receive the sperm for fertilization. The cushion provides protection and support for the archegonia.

The mucilage released from the archegonium of fern contains malic acid. Malic acid is a type of organic acid that is commonly found in fruits and vegetables. It is known for its sour taste and is often used as a food additive. In the case of the fern's archegonium, the presence of malic acid in the mucilage may serve various functions, such as aiding in the protection and nourishment of the developing embryo within the archegonium.

Protandry is the correct answer because it refers to the condition where the antheridium, which is the male reproductive organ in plants, matures first before the archegonium, which is the female reproductive organ. This term is commonly used in botany to describe the sequential maturation of reproductive organs in plants. Protogyny, on the other hand, is the opposite condition where the archegonium matures first. Protandrygyny is not a recognized term, and "None of the above" is incorrect because Protandry is the correct term for this specific scenario.

The correct answer is Zygote. In the life cycle of Nephrolepis, the zygote is formed when the sperm fertilizes the egg. The zygote then develops into the sporophyte, which is the diploid phase of the plant. The sporophyte produces spores through meiosis, which eventually develop into the gametophyte phase. Therefore, the zygote is the key cell that leads to the development of the sporophyte in Nephrolepis.

Chemotaxis is the correct answer because it refers to the phenomenon where certain substances, such as mucilage, attract or repel cells or organisms. In this case, when mucilage is dissolved in water, it attracts swarms of antherozooids (male gametes) towards the archegonium (female reproductive structure). This process is essential for fertilization in plants, as it helps in bringing the male and female gametes together for reproduction. Phytotaxis and gamotaxis are not applicable in this context.

The androcytes, or antherozoid mother cells, present in the antheridium, are haploid. This means that they have half the number of chromosomes compared to the diploid cells. Haploid cells are produced through the process of meiosis, which reduces the chromosome number by half. These haploid cells will eventually develop into antherozoids, which are the male gametes in plants.

The single neck canal cell in the archegonium of Nephrolepis bears two nuclei. This is because the neck canal cell is involved in the process of fertilization in plants. One of the nuclei fuses with the sperm nucleus to form a zygote, while the other nucleus degenerates. Therefore, the presence of two nuclei in the neck canal cell is essential for successful reproduction in Nephrolepis.

The antherozoids in fern are spirally coiled and multiflagellate. This means that they have a spiral shape and multiple flagella, which are whip-like structures that help with movement. The spiral shape allows the antherozoids to move efficiently through water, while the multiple flagella provide additional propulsion. This adaptation is important for the antherozoids to be able to swim towards the egg for fertilization in ferns.

The correct answer is Asexual Reproduction. Asexual reproduction is a type of reproduction where offspring are produced without the involvement of gametes or fertilization. In the case of sporophytes, which are the diploid stage in the life cycle of plants, they can produce gametophytes asexually through processes such as spore formation or vegetative propagation. This allows for the production of genetically identical offspring without the need for the fusion of gametes.

Ferns reproduce through sexual reproduction, where the gametophyte produces the sporophyte. In this process, the male and female gametes (sperm and egg) are produced by separate gametophytes. The sperm fertilizes the egg, resulting in the formation of a zygote, which develops into a sporophyte. This sporophyte then produces spores through meiosis, which germinate and grow into new gametophytes, completing the life cycle of ferns.

Nephrolepis exhibits cross fertilization. Cross fertilization refers to the process where the male gametes from one individual fertilize the female gametes of another individual. This type of fertilization promotes genetic diversity and is commonly observed in plants that have separate male and female reproductive structures. Self fertilization, on the other hand, occurs when the male and female gametes come from the same individual. Since Nephrolepis exhibits cross fertilization, it means that it requires two different individuals for reproduction.

The correct answer is Gametophyte. In Nephrolepis, the haploid sexual generation refers to the gametophyte stage. The gametophyte is the multicellular, haploid phase of the plant life cycle that produces gametes (reproductive cells). In Nephrolepis, the gametophyte produces male and female gametangia, which then fuse to form a diploid zygote, leading to the development of the sporophyte generation. Therefore, the gametophyte stage is the correct answer for the haploid sexual generation in Nephrolepis.

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