Q: Zygotic meiosis is a characteristic of:

A. Correct option A B. Explanation for correct option:When the zygote divides meiotically or when zygote undergoes reduction division after division of nucleus i.e. after karyogamy it is called as zygotic meiosis. Zygote is a stage that is formed after fertilization.Chlamydomonas is haploid plant. Hence, zygotic meiosis occurs in chlamydomonas.

Question 1

Protonema is

Accepted Answer

The predominant stage of the life cycle of a moss (bryophyte) is the &#10;gametophyte which consists of two stages. The first stage is the &#10;protonema stage, which develops directly from a spore. It is a creeping,&#10; green, branched and frequently filamentous stage. The second stage is &#10;the leafy stage, which develops from the secondary protonema as a &#10;lateral bud. It consists of upright, slender axes bearing spirally &#10;arranged leaves attached to the soil through multicellular and branched &#10;rhizoids. This stage bears the sex organs. So, the correct answer is 'Haploid and is found in mosses'.

Question 2

Algae have cell walls made up of

Accepted Answer

The primary cell wall of land plants is composed of the polysaccharides cellulose, hemicelluloses, and pectin.  Algae possess cell walls made of glycoproteins and polysaccharides such as carrageenan, cellulose, hemicellulose and pectins and agar that are absent from land plants. In bacteria, the cell wall is composed of peptidoglycan.Hence, Algae have cell walls made up of Cellulose, Hemicellulose, and Pectins.So, the correct answer is 'Cellulose, Hemicellulose and Pectins'.

Question 3

Explain alternation of generations in bryophytes.

Accepted Answer

Bryophytes are the non-vascular plants. In the life cycle, they are the only embryophytes (plants that produce an embryo) whose life history includes a dominant gametophyte (haploid) stage. Alternation of generations is a life-cycle involving two phases of life, which regularly alternate with each other. In Bryophytes, the first phase is the gametophytic phase, in which gametes are produced, that contain half the number of chromosomes. This is the dominant phase in the life of Bryophytes and reproduces sexually by egg and sperm. Once the egg and sperm fuse to produce a zygote, starts the second phase. The zygote germinates to produce the sporophyte, whose cells possess the complete number of chromosomes. This second phase, the sporophytic phase, is the spore producing phase. The sporophyte cannot exist independently. It is composed of a capsule, a stalk, and a foot that attaches the sporophyte body to the gametophyte. The sporophyte reproduces asexually by means of spores, which are produced by meiosis and are haploid. Each spore germinates to produce a gametophyte, which is the independent phase. This way, the life cycle is completed.

Question 4

A prothallus is

Accepted Answer

Correct Option: CExplanation:  Cryptograms are known as Pteridophyta. The dominant phase, in these plants, is sporophyte. This means a diploid multicellular stage in the present life cycle of a plant. The main body is differentiated into  true stems, roots and leaves.. Found in cool, damp, and shady places because of the need for water for fertilization.Some plant-like selaginella and Salvinia, possess micro and macro-sized spores and are termed heterosporous. The spore germinates and gives rise to small but multicellular free-living, inconspicuous, mostly photosynthetic thalloid gametophytes called prothallus.Hence,  A prothallus is a gametophytic-free living structure formed in pteridophytes.

Question 5

Haplo-diplontic life cycle is found in ____________.

Accepted Answer

Haplo-diplontic type of life cycle involves the clear alternation of generations between a haploid gamete producing gametophyte and a diploid spore-producing sporophyte. Both bryophytes and pteridophytes exhibit this kind of life cycle pattern.So the correct option is D.

Question 6

Zygotic meiosis is a characteristic of:

Accepted Answer

A. Correct option A&#10;&#10;B. Explanation for correct option:When the zygote divides meiotically or when&#10;zygote undergoes reduction division after division of nucleus i.e. after&#10;karyogamy it is called as zygotic meiosis. Zygote is a stage that is formed&#10;after fertilization.Chlamydomonas is haploid plant. Hence, zygotic meiosis occurs in chlamydomonas.

Question 7

Which one of the following statements is wrong?

Accepted Answer

(A) Correct option (D)(B) Explanation of correct answer:Agar-agar is a gelling agent with unbranched polysaccharides and is used in microbiology as a solidifying agent of liquid culture mediums. It is extracted from the cell wall of red algae, mostly from Gelidium species and Gracilaria species.Laminaria and Sargassum are the brown algae and are cultivated as a crop. Algae are green photosynthetic organisms that release oxygen in immediate vicinity through the process of photosynthesis. The cell wall of brown algae has an inner cellulose layer and outer gelatinous coat which is composed mainly of algin, it is used as an emulsifying agent and a stabilizer.

Question 8

Holdfast, stipe and frond constitute the plant body in case of ______________.

Accepted Answer

Phaeophyceae (Brown algae) are eukaryotic marine algae. The body consists of branched filamentous structure in lower forms {e.g. Ectocarpus) and parenchymatous structure in higher forms {e.g. Sargassum). The plant body is often differentiated into holdfast, stipe and lamina (frond). The lamina may be simple or divided variously and is photosynthetic.So the correct option is C.

Question 9

Sporophytic generation is represented only by one celled zygote in

Accepted Answer

Algae are mostly haploid. They show haplontic lifestyle i.e. for the most part of the life haploid is the dominant stage. Fusion of gametes results in diploid sporophyte in algae which undergoes meiosis to form haploid gametophyte. There are no free-living sporophytes. The gametophyte is the dominant phase.So, the correct option is 'Algae'.

Question 10

In a moss, the sporophyte

Accepted Answer

In mosses, the male gamete (sperm released from antheridia) fuses with the female gamete ( egg cells within the archegonium) to result in the immature sporophytes. The sporophyte matures and releases the spores. These spores germinate to form the protonema (an immature transitory stage), that matures into the gametophore (gamete bearing structure). Its tip branches to bear the male and the female gametophytes i.e antheridia and archegonia. So, in mosses, the gametophyte arises from spores produced from the sporophyte and the sporophyte arises from the fusion of gametes.So, the correct answer is 'Produces gametes that give rise to gametophyte'.