Questions: Plant Kingdom

Q1 Why do taxonomists no longer count fungi and cyanobacteria as plants?

Answer: The boundary of Kingdom Plantae is now drawn on cell structure and nutrition, not on the mere presence of a cell wall. Fungi have chitinous walls and absorb food from outside, so they sit in their own kingdom. Cyanobacteria are prokaryotes, so they belong in Monera, and they are no longer called algae. The earlier habit of putting every walled organism under plants was what the five kingdom system corrected.

Hinglish: Ab Plantae ki boundary cell wall se nahi, cell structure aur nutrition se banti hai. Fungi ki wall chitin ki hai aur woh bahar se khana absorb karte hain, isliye alag kingdom mein hain. Cyanobacteria prokaryote hain, isliye Monera mein hain aur ab algae nahi kehlate.

Q2 Give the basis of classification of algae.

Answer: Algae are classified mainly on four characters. The pigments inside the cell, especially the main photosynthetic pigment, give a class its colour. The stored food separates starch, mannitol or laminarin, and floridean starch. The chemistry of the cell wall separates cellulose, cellulose with algin, and cellulose with pectin. The number and position of flagella add another difference. Together these give the three classes Chlorophyceae, Phaeophyceae and Rhodophyceae.

Hinglish: Algae ki classification char cheezon par hoti hai: pigments, stored food, cell wall ki chemistry, aur flagella ki number aur position. Inhi se teen classes banti hain: green, brown aur red algae.

Q3 Describe the plant body and reproduction of a brown alga.

Answer: Brown algae are mostly marine and vary greatly in size, from simple filaments such as Ectocarpus to kelps that may reach a hundred metres. The body is held to a surface by a holdfast, and it has a stalk called the stipe and a leaf-like photosynthetic frond. The colour comes from the xanthophyll called fucoxanthin along with chlorophyll a and c. Food is stored as laminarin or mannitol. The wall is cellulosic and is covered on the outside with a gelatinous layer of algin. Fragmentation handles the vegetative route. The asexual route uses biflagellate pear-shaped zoospores, while the sexual route may be isogamous, anisogamous or oogamous.

Hinglish: Brown algae mostly marine hain. Body holdfast se chipki hoti hai aur usme stipe aur frond hote hain. Colour fucoxanthin se aata hai, aur food laminarin ya mannitol ke roop mein store hota hai. Asexual reproduction zoospores se aur sexual reproduction isogamous, anisogamous ya oogamous ho sakta hai.

Q4 Why are bryophytes called amphibians of the plant kingdom?

Answer: Bryophytes live on land, grow in damp shaded places, and have a plant body that can lose water to the air. For sexual reproduction, however, they need water: the antherozoids must swim through a film of water to reach the archegonium. The two sides together are the reason for the name. They cannot complete sexual reproduction without a wet surface, and they cannot live fully in water either.

Hinglish: Bryophytes zameen par rehte hain par sexual reproduction ke liye paani chahiye, kyunki antherozoids ko archegonium tak tairna padta hai. Zameen aur paani dono ki zaroorat ki wajah se inhe plant kingdom ke amphibians kehta hai.

Q5 Compare the gametophyte and the sporophyte of a moss.

Answer: The gametophyte is the dominant stage in a moss, and it is haploid. It begins as a protonema, a green branched filament that grows from a spore, and then produces the leafy stage with upright axes and spirally arranged leaves. Antheridia and archegonia sit at the tip of the leafy shoot. The sporophyte is diploid and dependent. It grows from the zygote and has a foot, a seta and a capsule. The capsule makes spores by meiosis, and the spores grow into new gametophytes.

Hinglish: Moss mein gametophyte dominant aur haploid hota hai: pehle protonema, phir leafy stage, aur tip par antheridia aur archegonia. Sporophyte diploid hai aur gametophyte par depend karta hai; uske foot, seta aur capsule hote hain, aur capsule mein meiosis se spores bante hain.

Q6 Describe the life cycle of a fern.

Answer: The fern plant we see is the sporophyte, and it is diploid. It bears sporangia on sporophylls, and spore mother cells inside the sporangia divide meiotically to make haploid spores. A spore grows into the prothallus, a small green free-living gametophyte. The prothallus carries antheridia and archegonia. Water carries the antherozoids to the archegonium, the egg is fertilised, and the diploid zygote grows into the new sporophyte. The sporophyte does not spend its early life attached to the gametophyte, which is one difference from bryophytes.

Hinglish: Fern ka jo plant dikhta hai woh sporophyte aur diploid hai. Sporangia mein meiosis se haploid spores bante hain, jinse chhota free-living prothallus yaani gametophyte banta hai. Usme antheridia aur archegonia hote hain; paani se antherozoids archegonium tak jaate hain, fertilisation se zygote banta hai aur naya sporophyte ugta hai.

Q7 What is heterospory, and why is it important?

Answer: Heterospory is the production of two kinds of spores by one plant: larger megaspores and smaller microspores. These grow into female and male gametophytes respectively. In heterosporous pteridophytes such as Selaginella and Salvinia, the female gametophyte stays on the parent sporophyte and the embryo develops inside it. That retention is a precursor of the seed habit, so heterospory is an important step in plant evolution.

Hinglish: Heterospory mein ek plant do tarah ke spores banata hai: badi megaspores aur chhoti microspores. Selaginella aur Salvinia mein female gametophyte parent par rukta hai aur embryo wahin banta hai, jo seed habit ka precursor hai.

Q8 Explain the structure of a gymnosperm ovule and how the pollen tube reaches it.

Answer: The ovule has a megaspore mother cell inside a nucellus, and the nucellus is protected by envelopes. The mother cell divides meiotically into four megaspores, and one of them grows into a many-celled female gametophyte with two or more archegonia. The female gametophyte stays inside the megasporangium. The pollen grain, which is the reduced male gametophyte, is released from the microsporangium and carried by air to the opening of the ovule. It grows a pollen tube towards the archegonia and discharges the male gametes there. Fertilisation gives a zygote, the ovule becomes a seed, and the seed stays naked.

Hinglish: Gymnosperm ke ovule mein nucellus ke andar megaspore mother cell hoti hai, jo meiosis se chaar megaspores banati hai; unme se ek female gametophyte banta hai jisme archegonia hoti hain. Pollen grain hawa se ovule ke opening tak pahunchta hai aur pollen tube archegonia tak badhta hai. Fertilisation ke baad ovule naked seed ban jaata hai.

Q9 How do gymnosperms and angiosperms differ?

Answer: Gymnosperm ovules are exposed on megasporophylls and the seeds stay naked, whereas angiosperm ovules are enclosed inside an ovary that becomes a fruit. Gymnosperm reproductive organs are cones, and angiosperm organs are flowers with stamens and carpels. The gymnosperm female gametophyte is many-celled and sits inside the megasporangium; the angiosperm embryo sac is smaller. Both groups are heterosporous and both form seeds, which is why they are kept close in the plant kingdom and separated on the enclosure of the seed. In both, the seed is the same invention; the covering around it is not.

Hinglish: Gymnosperms mein ovules aur seeds naked hote hain, angiosperms mein ovules ovary ke andar aur seeds fruit ke andar. Gymnosperm ke reproductive organs cones hain aur angiosperm ke flowers. Dono heterosporous hain aur seeds banate hain, farq seed ke cover aur flower ka hai.

Q10 Describe the three life cycle patterns of plants.

Answer: In a haplontic cycle the haploid gametophyte is the dominant many-celled plant, and the zygote is the only diploid stage; it divides meiotically at once. Most algae follow this pattern. In a diplontic cycle the diploid sporophyte is dominant and the gametophyte is reduced and short-lived; gymnosperms and angiosperms follow it. In a haplo-diplontic cycle both phases are many-celled, and both may be free-living; many bryophytes and pteridophytes follow it, though the two phases are not equally large. The pattern decides the ploidy of the plant a student is looking at.

Hinglish: Haplontic mein haploid gametophyte dominant hota hai aur zygote hi ek diploid stage hai, jaise zyadatar algae mein. Diplontic mein diploid sporophyte dominant hota hai, jaise gymnosperms aur angiosperms mein. Haplo-diplontic mein dono phases many-celled hote hain, jaise kai bryophytes aur pteridophytes mein. Ploidy ka sawaal aane par pehle yeh pattern pehchano.

That completes the ten written answers. The five-question quiz below checks the classification systems, the algal classes, the bryophyte cycle and the seed plants.