Test: Spirogyra - Class 11 MCQ

It has two regions called the origin of Spirogyra replication and the terminus of replication, which are located diametrically opposite to one another on the chromosome. A septum (wall) forms down the middle of the cell, partitioning it into two new cells, each with one of the two (now-complete) bacterial chromosome copies.

Zygospore undergoes zygotic meiosis and forms 4 haploid nuclei of these three degenerate. So one haploid nuclei take part and one new filament is formed.

Spirogyra filaments are slippery and float in large masses. Spirogyra is a genus of green algae that belong to the order Zygnematales. These free-flowing, filamentous algae are characterized by ribbon-shaped chloroplasts that are arranged in a helical manner inside the cells.

Pond silk and Water silk is the common name of Spirogyra (algae) because it is very slimy.
Spirogyra is a  genus (about 400 species) of freshwater green algae which are found in shallow ponds, ditches and amongst vegetation at the edges of large lakes, generally growing free-floating.
Cells are joined end-to-end in an unbranched, largely unspecialised, stiff filament and are cylindrical with one or two spirally-wound chloroplasts on which many pyrenoids are borne. The cell wall is of two layers, the outer of cellulose and the inner of pectin. Filaments can be several centimeters in length. It generally has a rather silky feel and a shiny green colour.

A flagellate is a cell or organism with one or more whip-like appendages called flagella. The word flagellate also describes a particular construction (or level of organization) characteristic of many prokaryotes and eukaryotes and their means of motion.

Green algae, Spirogyra (Chlorophyta), are found in a wide range of habitats including small stagnant water bodies, rivers, and streams.

Most of the members have one or more storage bodies called pyrenoids located in the chloroplasts. Pyrenoids contain protein besides starch. Some algae may store food in the form of oil droplets. Some commonly found green algae are: Chlamydomonas, Volvox, Ulothrix, Spirogyra and Chara.

Sexual reproduction in Spirogyra takes place by the process of conjugation. In Spirogyra, the process of conjugation may be of two types: scalariform conjugation and lateral conjugation. Scalariform conjugation occurs in heterothallic species. Lateral conjugation occurs between the adjacent cells of the same filament of homothallic species of Spirogyra. Lateral conjugation are of two types. They are indirect lateral conjugation (chain type) and direct lateral conjugation.

In flowering plants , the male gamete is not motile ( so called pollen grain ) and through pollinating agent ( like water, wind , insects depending upon the plants types ) they are reach up to the carpel terminal ( also called style) Spirogyra  from then on , filiform apparatus of synergid cells ( present in the ovary ) help and directs the pollen grain with the help of pollen tube; through style and ultimately reaches the ovary where syngamy (fertilisation) occurs.
Also , a species of Red alga (name not sure; it should be Polysiphonia)  have a non-motile sperm (antherozoid) and non motile a egg or ovum. The syngamy occur in the water itself as the medium and they are carried passively through the water ; released egg and sperm from carpogonium and spermatangium are in large numbers to increase chances of syngamy.

Spirogyra species can reproduce both sexually and asexually. Asexual, or vegetative, reproduction occurs by simple fragmentation of the filaments. Sexual reproduction occurs by a process known as conjugation, in which cells of two filaments lying side by side are joined by outgrowths called conjugation tubes.

In Spirogyra, the sexual reproduction involves a cycle alternation between a haploid vegetative filament (gametophyte plant) and a diploid zygospore, towards the end of growing season the Spirogyra filament produce aplanogametes in vegetative cells called gametangia The gametes fuse to form a zygospore (2n).

Sexual reproduction involves neighboring filaments, that send out processes, which fuse into tubes. The contents of one cell pass through the conjugation tube into a partner cell and go through process, that lead to the formation of a reasonably resistant zygospore.

Named for their beautiful spiral chloroplasts, spirogyras are filamentous algae that consist of thin unbranched chains of cylindrical cells. They can form masses that float near the surface of streams and ponds, buoyed by oxygen bubbles released during photosynthesis.

Scalariform conjugation : This is the most common and advanced type of conjugation. It involves two filaments of Spirogyra and takes place between two recently formed cells.It stimulates the formation of similar papilla in cells lying opposite to them.

In spring Spirogyra grows under water, but when there is enough sunlight and warmth they produce large amounts of oxygen, adhering as bubbles between the tangled filaments. The filamentous masses come to the surface and become visible as slimy green mats.

In Spirogyra, the sexual reproduction involves a cycle alternation between a haploid vegetative filament (gametophyte plant) and a diploid zygospore, towards the end of growing season the Spirogyra filament produce aplanogametes in vegetative cells called gametangia The gametes fuse to form a zygospore (2n).

Spirogyra (common names include water silk, mermaid's tresses, and blanket weed) is a genus of filamentous charophyte green algae of the order Zygnematales, named for the helical or spiral arrangement of the chloroplasts that is characteristic of the genus.

A zoospore is a motile asexual spore that uses a flagellum for locomotion. Also called a swarm spore, these spores are created by some protists, bacteria and fungi to propagate themselves.

Spirogyra is also known as pond silk, as its filaments shine like silk due to the presence of mucilage. Spirogyra is a genus of green algae that belong to the order Zygnematales. These free-flowing, filamentous algae are characterized by ribbon-shaped chloroplasts that are arranged in a helical manner.

The spiraled ribbon-shaped chloroplasts are embedded in this cytoplasm layer. The number of chloroplast strands in each cell may vary between 1 to 16. Each chloroplast strand has several round bodies called 'pyrenoids', which are responsible for starch production.

The cell wall consists of an inner layer of cellulose and an outer layer of pectin, which is responsible for the slippery texture of the algae. Spirogyra species can reproduce both sexually and asexually.

Cell wall is the outermost protective double layered structure. Each cell of Spirogyra is surrounded by two layered cell wall. The inner layer of which is made of cellulose and the outer layer contains pectose. The outermost lining of pectose turns into pectin and get dissolved in water to form mucilage, which surrounds the filament and forms mucilagenous sheath.

Spirogyra species can reproduce both sexually and asexually. Asexual, or vegetative, reproduction occurs by simple fragmentation of the filaments. Sexual reproduction occurs by a process known as conjugation, in which cells of two filaments lying side by side are joined by outgrowths called conjugation tubes.
In Ulothrix, sexual reproduction takes place by the fusion of biflagellate gametes from different filaments. Ulothrix like Chlamydomonas shows the simplest and primitive type of sexual reproduction or Isogamy where two morphologically identical flagellated gametes take part in fusion resulting in zygospores.
Hence, the correct option is Option A.

Scalariform conjugation occurs between the two filament and seen in heterothallic / dioeious species. 
Two filament of opposite strands come closer and lie parallel to each other throughout their length and get surrounded by commom mucilagenous sheath.The opposite cells of two filaments produce small papillae outgrowth / processes from their opposite walls. These papillate outgrowth increase in their size and join through their anterior end. By this time filament secretes enzyme cytase. Two filament secrete the enzyme cytase due to the activity of which the partition wall is dissolved between the two process forming a continuing passage conjugation tube. 
The ladder like structure is formed due to conjugation of many cells. Same time the protoplast gets contracted and form gametes, known as gametangia. 
Thus, formed gametes are isogametes in gametangia, out of the isogametes one gamete shows motility and can be determined as male gamete. The male gametes enters through conjugation and enters the female gametangia and fuse with female gamete and forms zygote. This zygote after the secretion of thick wall forms zygospore.

Archegonium, the female reproductive organ in ferns and mosses. An archegonium also occurs in some gymnosperms, e.g., cycads and conifers. A flask-shaped structure, it consists of a neck, with one or more layers of cells, and a swollen base—the venter—which contains the egg. Spirogyra is a genus of filamentous charophyte green algae of the order Zygnematales, named for the helical or spiral arrangement of the chloroplasts that is characteristic of the genus.

Zygospore is the union of the protoplasmic mass of two gametes which is called zygote. The diploid zygospore nucleus undergoes meiosis and forms 4 nuclei, three of these aborts and only one is functional prior to germination. It undergoes transverse division to give, rise single filament.
So the correct option is 'Only one haploid nucleus is functional.'

Chloroplasts are the food producers of the cell. The organelles are only found in plant cells and some protists such as algae. Animal cells do not have chloroplasts. Chloroplasts work to convert light energy of the Sun into sugars that can be used by cells.

Sexual reproduction in Spirogyra is an advanced feature. In Spirogyra, the sexual reproduction involves the fusion of two morphologically similar isogametes and physiologically differentiated sex organs or anisogametes. The male is an active gamete and the female is a passive gamete.
Thus, the correct answer is 'Physiologically differentiated sex organs.'

Spirogyra species can reproduce both sexually and asexually. Asexual, or vegetative, reproduction occurs by simple fragmentation of the filaments. Sexual reproduction occurs by a process known as conjugation, in which cells of two filaments lying side by side are joined by outgrowths called conjugation tubes.

Life cycle in Spirogyra is haplontic as dominant phase in life cycle is haploid (n) and diploid phase is represented by only zygospore and it undergoes meiosis.