Q48. Which ONE of the following statements regarding spores and gametes is
CORRECT?
(A) Spores can directly undergo mitosis whereas gametes cannot.
(B) Gametes can directly undergo mitosis whereas spores cannot.
(C) Neither spores nor gametes can directly undergo mitosis.
(D) Both spores and gametes can directly undergo mitosis.
Spores can directly undergo mitosis to develop into multicellular gametophytes, while gametes fuse first to form a zygote before undergoing mitosis.
Option Analysis
(A) Spores can directly undergo mitosis whereas gametes cannot.
Spores, typically haploid, germinate and undergo mitosis to form multicellular haploid gametophytes in plants and fungi. Gametes, also haploid, do not divide directly; they fuse during fertilization to create a diploid zygote that then divides mitotically. This option correctly captures the key distinction in their reproductive roles.
(B) Gametes can directly undergo mitosis whereas spores cannot.
Gametes cannot undergo mitosis directly, as their role ends upon fusion into a zygote, which then initiates mitotic divisions to form the sporophyte. Spores routinely germinate via mitosis, making this option incorrect.
(C) Neither spores nor gametes can directly undergo mitosis.
Spores directly germinate and divide mitotically to produce gametophytes, so this is false. Gametes also cannot, but the “neither” claim fails due to spores.
(D) Both spores and gametes can directly undergo mitosis.
While spores do, gametes do not; they require fertilization first. This makes the statement inaccurate.
Correct Answer: (A)
Introduction to Spores and Gametes Mitosis
In plant life cycles and fungal reproduction, understanding spores and gametes mitosis is crucial for exams like CSIR NET Life Sciences. Spores initiate asexual-like development via mitosis, while gametes drive sexual fusion. This distinction explains why spores can directly undergo mitosis whereas gametes cannot.
Key Differences in Cell Division
-
Spores: Haploid cells produced by meiosis in sporophytes; they germinate directly, undergoing mitosis to form multicellular haploid gametophytes.
-
Gametes: Haploid cells from mitosis in gametophytes; they fuse to form diploid zygotes, which then undergo mitosis—no direct division.
-
Ploidy and Role: Both haploid, but spores enable independent growth, gametes require pairing for genetic recombination.
| Feature | Spores | Gametes |
|---|---|---|
| Production | Meiosis (sporophyte) | Mitosis (gametophyte) |
| Direct Mitosis? | Yes, post-germination | No, post-fertilization |
| Outcome | Gametophyte | Zygote → Sporophyte |
| Reproduction Type | Asexual/Alternation | Sexual |
Life Cycle Context
Plants alternate generations: diploid sporophyte produces spores via meiosis; spores mitose into gametophytes, which produce gametes via mitosis. Fertilization yields sporophyte. This reinforces option (A) accuracy.
Exam Relevance
For CSIR NET, focus on alternation of generations—spores germinate mitotically, gametes do not. Practice MCQs on spores and gametes mitosis to master molecular biology.
