Comprehension
Pollen pistil interaction involves all events from the landing of pollen grains on the stigma until the pollen tube enters the embryo sac (when the pollen is compatible). When a pollen tube grows through the style and enters into the ovules, it finally discharges two male gametes in one of the synergids. Syngamy and triple fusion are two fusion events that occur in angiosperms. Thus, angiosperms exhibit double fertilization. The products of these fusions are the diploid zygote and triploid primary endosperm nucleus. Zygote develops into embryo and primary endosperm cell forms the endosperm tissue. The developing embryo passes through different stages before maturation.
Question: 1

With reference to reproduction in flowering plants, which one of the following is incorrect?

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In flowering plants, the endosperm nourishes the developing embryo, but it does not directly develop into the seed. The seed is composed of the embryo, endosperm, and seed coat.
Updated On: Feb 12, 2026
  • Endosperm develops into seed
  • Ovary develops into fruit
  • Ploidy of PEN is 3n
  • Syngamy is the fusion of male and female gamete
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The Correct Option is A

Solution and Explanation

During angiosperm fertilization, pollen tubes deliver male gametes to the ovule. Two fusion events occur: syngamy (male gamete + female gamete) and triple fusion (second male gamete + two polar nuclei), forming a triploid endosperm nucleus.
Step 1: Option Analysis.
- Endosperm develops into seed (Option 1): Incorrect. Endosperm provides nourishment for the developing embryo. The seed comprises the embryo, seed coat, and endosperm.
- Ovary develops into fruit (Option 2): Correct. Post-fertilization, the ovary matures into a fruit containing seeds.
- Ploidy of PEN is 3n (Option 3): Correct. The primary endosperm nucleus (PEN) is triploid (3n) due to the fusion of a male gamete and two polar nuclei.
- Syngamy is the fusion of male and female gametes (Option 4): Correct. Syngamy is the fusion of male and female gametes, creating a diploid zygote.
Step 2: Conclusion.
The assertion that endosperm develops into seed is inaccurate. Endosperm functions as nutritive tissue, not the seed itself.
Final Answer: \[\boxed{\text{The incorrect statement is (1) Endosperm develops into seed.}}\]
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Question: 2

Which of the following is not a stage of growing embryo in dicotyledon plants?

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In dicotyledons, embryo development progresses through several stages: proembryo, globular, and heart-shaped, but not through an epiblast stage.
Updated On: Feb 12, 2026
  • Heart-shaped
  • Globular
  • Proembryo
  • Epiblast
Show Solution

The Correct Option is D

Solution and Explanation

In dicotyledon plants, embryo development proceeds through distinct stages. The correct stages are:
Stage 1: Evaluation of options.
- Heart-shaped (Option 1): A correct stage in dicotyledon embryo development, following the globular stage, characterized by the initial formation of cotyledons.
- Globular (Option 2): Another correct stage, where the embryo begins to differentiate into cotyledons and the stem axis.
- Proembryo (Option 3): Also a correct stage, representing the earliest phase post-fertilization with initial cell divisions leading to embryo formation.
- Epiblast (Option 4): This is an incorrect option. The epiblast is not a recognized stage of dicotyledon embryo development; it denotes an earlier, non-embryonic structure in certain plants.
Stage 2: Determination.
The epiblast does not represent a developmental stage of the growing embryo in dicotyledon plants.
Final Answer: \[\boxed{\text{The correct answer is (4) Epiblast.}}\]
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Question: 3

The coconut water from tender coconut, a good source of nutrition, is nothing but:

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Coconut water is the free-nuclear endosperm found in the coconut and provides essential nutrients during the early stages of coconut development.
Updated On: Feb 12, 2026
  • Free-nuclear endosperm
  • Synergids
  • Antipodal cells
  • Scutellum
Show Solution

The Correct Option is A

Solution and Explanation

Coconut water is the liquid endosperm found in coconuts during early development, primarily consisting of free-nuclear endosperm.
Step 1: Analyzing the options.
- Free-nuclear endosperm (Option 1): Correct. Coconut water is composed of free-nuclear endosperm, which develops internally as the embryo grows, providing nutrients, sugars, and other beneficial compounds.
- Synergids (Option 2): Synergids are ovule cells aiding fertilization by guiding pollen tubes; they are unrelated to coconut water.
- Antipodal cells (Option 3): Antipodal cells, located in the ovule, are involved in embryo sac development, not coconut water formation.
- Scutellum (Option 4): The scutellum is found in monocot seeds (e.g., corn) and aids nutrient absorption, but is not related to coconut water.
Step 2: Conclusion.
Coconut water is composed of free-nuclear endosperm and is a nutritious liquid.
Final Answer: \[\boxed{\text{The correct answer is (1) Free-nuclear endosperm.}}\]
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Question: 4

Formation of diploid zygote is a result of:

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Syngamy, the fusion of male and female gametes, is essential for forming the diploid zygote during fertilization.
Updated On: Feb 12, 2026
  • Emasculation
  • Triple fusion
  • Syngamy
  • Bagging
Show Solution

The Correct Option is C

Solution and Explanation

Fertilization culminates in the formation of a diploid zygote. In angiosperms, this involves two primary fusion events: syngamy and triple fusion.
Step 1: Option Analysis.
- Emasculation (Option 1): This procedure involves removing the anthers from a flower to prevent self-pollination; it is irrelevant to diploid zygote formation.
- Triple fusion (Option 2): In this process, one male gamete fuses with two polar nuclei, producing a triploid endosperm nucleus. While crucial for seed development, it does not yield the diploid zygote.
- Syngamy (Option 3): Syngamy is the union of the male gamete (sperm) and the female gamete (egg), resulting in the formation of a diploid zygote. This is the direct mechanism for diploid zygote creation.
- Bagging (Option 4): Bagging entails covering flowers to control pollination and is not directly linked to zygote formation.
Step 2: Determination.
The diploid zygote arises from syngamy, the fusion of male and female gametes.
Final Answer: \[\boxed{\text{Syngamy is the correct answer (3).}}\]
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Question: 5

If there are 38 chromosomes in the zygote, how many chromosomes will there be in its haploid egg cell?

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The diploid zygote is formed by the fusion of two haploid gametes, and the number of chromosomes in a haploid cell is half of the zygote's chromosome count.
Updated On: Feb 12, 2026
  • 38
  • 57
  • 19
  • 76
Show Solution

The Correct Option is C

Solution and Explanation

The fusion of two haploid cells, a male gamete and a female gamete, results in the formation of a zygote in sexually reproducing organisms. The zygote's chromosome count is the aggregate of the chromosomes from both contributing gametes.
Step 1: Clarification of Terminology.
- The zygote is characterized as diploid (2n), possessing two sets of chromosomes, one inherited from each parent.
- Haploid (n) gametes, exemplified by eggs and sperm, each contain half the number of chromosomes found in the diploid zygote.
Step 2: Calculation.
Given that a zygote contains 38 chromosomes, it is diploid. Consequently, each haploid gamete (egg or sperm) contributes half this amount: \[ \text{Number of chromosomes in egg} = \frac{38}{2} = 19 \] Step 3: Determination.
The haploid egg cell contains 19 chromosomes.
Final Answer: \[ \boxed{\text{The correct answer is (3) 19.}} \]
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