Given below are two statements: One is labelled as Assertion A and the other is labelled as Reason R: Assertion A: The first stage of gametophyte in the life cycle of moss is protonema stage. Reason R: Protonema develops directly from spores produced
in capsule.
In the light of the above statements, choose the most appropriate answer from the options given below:
Explanation:
Assertion A is correct: in moss, the first stage of the gametophyte is the protonema. Reason R is also correct: protonema develops directly from the spores released from the capsule. Since protonema arises from germinating spores and then develops into the leafy gametophyte, R explains how the protonema (the first gametophyte stage) originates. Therefore, option 2 is correct.
? Did You Know?
In mosses, the gametophyte is dominant and photosynthetic, while the sporophyte is dependent on the gametophyte for nutrition.
? NCERT Memory Line:
Germination of a spore produces the protonema, from which the juvenile gametophyte (leafy moss) develops.
Given below are two statements: One is labelled as Assertion A and the other is labelled as Reason R:
Assertion A: In gymnosperms the pollen grains are released from the microsporangium and carried by air currents.
Reason R: Air currents carry the pollen grains to the mouth of the archegonia where the male gametes are discharged and pollen tube is not formed.
In the light of the above statements, choose the correct answer from the options given below:
The incorrect pairing is Ulothrix – Mannitol. Ulothrix, a green alga, stores starch as its reserve food, not mannitol. Mannitol is commonly a storage carbohydrate in brown algae (phaeophytes) and some other algae, but not in Ulothrix as per NCERT. The other pairs are correct: Ectocarpus contains fucoxanthin (brown pigment); Porphyra stores Floridean starch (red algae); Volvox stores starch (green alga).
🧠 Did You Know?
Floridean starch is the storage carbohydrate characteristic of red algae (Rhodophyta).
💡 NCERT Memory Line:
Green algae like Ulothrix store starch; brown algae have fucoxanthin; red algae have Floridean starch.
Gemmae are asexual reproductive bodies found in some liverworts. They develop in structures called gemmae cups and help in rapid, clonal propagation. This aligns with NCERT's description of liverworts using gemmae for reproduction.
🧠 Did You Know?
Gemmae are a common feature of many liverworts, not mosses or Pteridophytes, and are not a typical feature of gymnosperms.
💡 NCERT Memory Line:
“Gemmae cups are present in some liverworts for asexual reproduction.”
