Part 4 — Gymnosperms: Structure, life cycle, diversity (Questions 76–100)

Part 4 — Gymnosperms: Structure, life cycle, diversity (Questions 76–100)

76. Gymnosperms are characterized by:
A. Seeds enclosed in ovary (fruit)
B. Naked seeds not enclosed by ovary
C. Flowers and double fertilization
D. Lack of seeds
Answer: B — Naked seeds.
Explanations:
A. Seeds enclosed in ovary are angiosperms (flowers).
B. Correct: gymnosperms bear naked seeds, often on cones or scales.
C. Flowers/double fertilization are features of angiosperms.
D. Gymnosperms produce seeds.

77. Which of the following is NOT a gymnosperm?
A. Pinus
B. Cycas
C. Ginkgo
D. Magnolia
Answer: D — Magnolia.
Explanations:
A. Pinus — a conifer (gymnosperm).
B. Cycas — a cycad (gymnosperm).
C. Ginkgo — Ginkgo biloba, a gymnosperm.
D. Magnolia — angiosperm (a flowering plant).

78. In gymnosperms, pollen grains are produced in:
A. Ovules
B. Microsporangia (pollen sacs) of male cones
C. Archegonia
D. Megasporangia
Answer: B — Microsporangia of male cones.
Explanations:
A. Ovules contain megasporangium; pollen produced elsewhere.
B. Correct: pollen grains develop in microsporangia (pollen sacs) on male strobili (cones).
C. Archegonia are female sex organs, not pollen producers.
D. Megasporangia produce megaspores, not pollen.

79. Which gymnosperm group includes species with motile sperm (flagellated) even though they are seed plants?
A. Conifers (Pinaceae)
B. Cycads and Ginkgo
C. Gnetales
D. All gymnosperms have non-motile sperm
Answer: B — Cycads and Ginkgo.
Explanations:
A. Conifers — generally have non-motile sperm delivered by pollen tube.
B. Correct: cycads and Ginkgo retain large flagellated sperm that swim short distances within the ovule.
C. Gnetales — non-motile sperm delivered via pollen tube.
D. False — some gymnosperms have motile sperm.

80. The female reproductive structure that develops into the seed in gymnosperms is the:
A. Ovary
B. Ovule
C. Carpel
D. Fruit
Answer: B — Ovule.
Explanations:
A/C/D — terms associated with angiosperms; gymnosperm ovule develops into seed without an enclosing ovary or fruit.
B. Ovule — correct: the ovule containing the megasporangium yields the seed after fertilization.

81. Which of the following represents the correct order of structures from outside to inside in a pine ovule?
A. Integument → Nucellus → Megasporangium → Embryo sac
B. Nucellus → Integument → Ovary → Fruit
C. Gametophyte → Sporophyte → Integument
D. Funicle → Style → Stigma
Answer: A (with clarification).
Explanations:
A. Integument surrounds nucellus; nucellus contains megasporangium (often the terms nucellus and megasporangium are used interchangeably in gymnosperms), and inside the female gametophyte develops (archegonia and egg). So this sequence is acceptable: integument outside, nucellus (megasporangium) inside, then gametophytic tissues.
B-D. Incorrect/angiosperm terms.

82. Which structure in Pinus is diploid and produces haploid microspores by meiosis?
A. Microsporangium (pollen sac) containing microsporocytes (microspore mother cells)
B. Pollen grain
C. Male gametophyte
D. Ovule
Answer: A.
Explanations:
A. Correct: diploid microspore mother cells (microsporocytes) in microsporangia undergo meiosis to form haploid microspores.
B. Pollen grain is haploid or multicellular male gametophyte.
C. Male gametophyte is haploid and arises from microspore.
D. Ovule is female structure.

83. Cycas is distinct among gymnosperms because it:
A. Lacks vascular tissue
B. Has pollen tubes that do not reach egg (no fertilization)
C. Has pinnate leaves and persistent, flagellated sperm in pollen tubes released near archegonia
D. Produces flowers
Answer: C.
Explanations:
A. False — cycas has vascular tissues.
B. False — pollen tubes in cycads deliver motile sperm which then reach the egg.
C. Correct: cycads have pinnate leaves and retain motile sperm (an ancient feature) which are released from pollen tube.
D. Cycas does not produce flowers.

84. Which gymnosperm group is represented by a single living species Ginkgo biloba?
A. Gnetales
B. Cycadales
C. Ginkgoales
D. Pinaceae
Answer: C — Ginkgoales.
Explanations:
A. Gnetales — group includes Ephedra, Gnetum, Welwitschia.
B. Cycadales — cycads like Cycas, Zamia.
C. Ginkgoales — correct: Ginkgo biloba is the sole extant species of this order.
D. Pinaceae — conifer family including Pinus.

85. Which of the following correctly distinguishes gymnosperm ovules from angiosperm ovules?
A. Gymnosperm ovules are enclosed in carpels; angiosperms have exposed ovules.
B. Gymnosperm ovules are naked (exposed on scales/cones); angiosperm ovules are enclosed within an ovary.
C. Both have ovules enclosed in an ovary.
D. Gymnosperms lack ovules.
Answer: B.
Explanations:
A. Reverse of true.
B. Correct: gymnosperm ovules/seeds are not enclosed in an ovary.
C/D. Incorrect.

86. Double fertilization (leading to endosperm formation) is a feature of:
A. Gymnosperms only
B. Angiosperms only (typical)
C. Both gymnosperms and angiosperms equally
D. Pteridophytes
Answer: B — Angiosperms only (typical).
Explanations:
A. Gymnosperms do not exhibit the classic angiosperm double fertilization producing endosperm (though some gymnosperms have complex events); typical double fertilization is an angiosperm hallmark.
B. Correct.
C/D. Incorrect.

87. Cones of Pinus (pine) are categorized as:
A. Only male cones (pollen-bearing) and female cones (ovule-bearing) — separate strobili
B. Flowers
C. Fleshy fruits
D. Modified leaves without reproductive function
Answer: A.
Explanations:
A. Correct: conifers have distinct male (microstrobili) and female (megastrobili) cones.
B/C/D. Incorrect.

88. Which term describes the massive secondary growth (wood formation) typical in conifers?
A. Monocot secondary thickening
B. True secondary growth via vascular cambium producing secondary xylem (wood)
C. No secondary growth exists in conifers
D. Primary thickening only
Answer: B.
Explanations:
A. Monocot thickening is different.
B. Correct: conifers show secondary growth via vascular cambium forming wood (secondary xylem) and secondary phloem.
C/D. Incorrect.

89. The transfer of pollen to the ovule in gymnosperms typically occurs by:
A. Water currents only
B. Wind (anemophily) in most conifers
C. Insects always
D. Self-fertilization only via pollen tube without pollination
Answer: B — Wind in most conifers.
Explanations:
A. Water pollination rare; cycads had zoochory historically.
B. Correct: many gymnosperms (Pinus) are wind-pollinated.
C. Some gymnosperms may use insects, but not always.
D. Incorrect.

90. Which of the following illustrates the order of developmental stages in a gymnosperm ovule after pollination?
A. Pollen adhesion → pollen germination → pollen tube formation → fertilization (with or without motile sperm) → zygote → embryo → seed
B. Fertilization → pollen adhesion → zygote
C. Seed → pollen tube → zygote
D. Gametophyte → sporophyte → gametophyte
Answer: A.
Explanations:
A. Correct sequence after pollination.
B/C/D. Incorrect orders or irrelevant.

91. Which gymnosperm group includes Welwitschia, a bizarre plant adapted to deserts?
A. Cycadales
B. Gnetales
C. Coniferales
D. Ginkgoales
Answer: B — Gnetales.
Explanations:
A. Cycads — tropical/subtropical.
B. Gnetales — correct: Gnetum, Ephedra, Welwitschia belong to Gnetales; Welwitschia mirabilis adapted to deserts with two persistent leaves.
C/D. Incorrect.

92. In gymnosperms, the female gametophyte tissue that nourishes the embryo is:
A. Endosperm (angiosperm term)
B. Megagametophyte (haploid tissue of gymnosperm seed)
C. Cotyledon
D. Seed coat only
Answer: B — Megagametophyte.
Explanations:
A. Endosperm is angiosperm; gymnosperms have nutritive megagametophyte tissue (haploid).
B. Correct.
C/D. Cotyledons are embryonic leaves; seed coat is integument derivative, not nutritive tissue.

93. Which feature is common to both gymnosperms and pteridophytes (but not bryophytes)?
A. Vascular tissues (xylem and phloem) in sporophyte stage
B. Dominant gametophyte generation
C. Seeds and pollen
D. Flowers
Answer: A.
Explanations:
A. Correct: both pteridophytes and gymnosperms have vascular sporophytes.
B. Dominant gametophyte is bryophytes.
C. Seeds and pollen are gymnosperms only.
D. Flowers are angiosperms.

94. Which of the following is a key adaptation of gymnosperms to terrestrial life?
A. Presence of stomata only in gametophyte
B. Evolution of seed which protects embryo and aids dispersal
C. Lack of vascular tissue
D. Exclusive aquatic habitat
Answer: B.
Explanations:
A. Stomata present in sporophytes; not restricted to gametophyte.
B. Correct: seeds protect embryos, allow dormancy and dispersal — major evolutionary advance for land habit.
C/D. Incorrect.

95. Which statement about gymnosperm wood is correct?
A. It lacks tracheids and is composed solely of vessels.
B. Gymnosperm xylem mainly consists of tracheids with few or absent vessels (unlike many angiosperms).
C. Gymnosperms form secondary growth via diffuse porous vessels.
D. Gymnosperm wood has fibrous cortical layers only.
Answer: B.
Explanations:
A. False — gymnosperm wood lacks vessels typically.
B. Correct: conifers/ gymnosperms primarily have tracheids for conduction and support; vessels are uncommon.
C/D. Incorrect.

96. Which genus is an example of a gymnosperm with broad leaves and deciduous habit representing a “living fossil”?
A. Pinus
B. Ginkgo (Ginkgo biloba)
C. Cycas
D. Welwitschia
Answer: B — Ginkgo.
Explanations:
A. Pinus — evergreen coniferous.
B. Ginkgo — correct: Ginkgo biloba has fan-shaped leaves, deciduous habit, and ancient lineage.
C/D. Cycas and Welwitschia are gymnosperms but not described as broad-leaved deciduous living fossil in the same way.

97. Which of the following statements about pollen grains of gymnosperms is FALSE?
A. Pollen grains are the male gametophytes or contain them.
B. Pollen eliminates need for external water for fertilization in some gymnosperms.
C. Pollen grains develop within the microspore mother cell directly without meiosis.
D. Pollination may be followed by delayed fertilization in some gymnosperms (pollination-fertilization interval).
Answer: C — False.
Explanations:
A. True: pollen grains represent or contain male gametophyte.
B. True: pollen allows transport of male gametophyte by wind or pollinators, reducing reliance on water.
C. False: pollen arises from microspores produced by meiosis of microspore mother cells; pollen does not develop without meiosis.
D. True: in some Pinus species, pollination and fertilization are separated temporally.

98. Which of the following describes megasporophyll in gymnosperms?
A. A leaf-like scale bearing ovules in female cones
B. A pollen-bearing structure
C. A root-like structure
D. A photosynthetic lamina only in gametophyte
Answer: A.
Explanations:
A. Correct: megasporophylls are modified leaves or scales bearing megasporangia/ovules in female cones.
B. Pollen-bearing are microsporophylls.
C/D. Not correct.

99. Which one of the following pairs is correctly matched?
A. Pinus — cycad
B. Cycas — cycad
C. Gnetum — bryophyte
D. Welwitschia — angiosperm
Answer: B — Cycas is a cycad.
Explanations:
A. Pinus is a conifer (not cycad).
B. Correct.
C. Gnetum — is a gymnosperm (Gnetales), not bryophyte.
D. Welwitschia is a gymnosperm (Gnetales), not angiosperm.

100. In gymnosperms, which tissue develops from integuments and forms the seed coat?
A. Nucellus
B. Endosperm
C. Testa and tegmen (seed coat layers derived from integument)
D. Embryo
Answer: C.
Explanations:
A. Nucellus persists as nutritive tissue in many gymnosperms (megagametophyte derived tissues), not seed coat.
B. Endosperm — angiosperm nutritive tissue, not gymnosperm (which uses megagametophyte).
C. Correct: integuments give rise to seed coat layers (testa, sometimes tegmen).
D. Embryo forms from zygote. (more…)