301. Assertion: Double fertilisation initiates both embryo formation and endosperm formation in the same ovule.
Reason: One male gamete fuses with the egg cell, while the other fuses with the polar nuclei.
ⓐ. Both Assertion and Reason are true, and the Reason correctly explains the Assertion.
ⓑ. Both Assertion and Reason are true, but the Reason does not correctly explain the Assertion.
ⓒ. Assertion is true, but Reason is false.
ⓓ. Assertion is false, but Reason is true.
Correct Answer: Both Assertion and Reason are true, and the Reason correctly explains the Assertion.
Explanation: The assertion is correct because double fertilisation gives rise to two distinct products in the same embryo sac. The reason is also correct and explains the assertion directly. Syngamy forms the zygote, which begins embryo development, while triple fusion forms the primary endosperm nucleus, which begins endosperm development. This is the core biological significance of double fertilisation.
302. Which statement best describes the fate of the two male gametes released by the pollen tube in angiosperms?
ⓐ. Both fuse with the egg cell one after the other.
ⓑ. Both fuse with the polar nuclei.
ⓒ. One forms the zygote and the other remains inactive.
ⓓ. One fuses with the egg and the other fuses with the central cell nuclei.
Correct Answer: One fuses with the egg and the other fuses with the central cell nuclei.
Explanation: The two male gametes do not perform the same role. One takes part in syngamy with the egg cell, while the other enters triple fusion with the polar nuclei in the central cell. This division of function is the basis of double fertilisation. It also explains why both embryo and endosperm begin developing after fertilisation.
303. After fertilisation, the ovule generally develops into the
ⓐ. fruit
ⓑ. seed
ⓒ. pericarp
ⓓ. stigma
Correct Answer: seed
Explanation: The ovule undergoes post-fertilisation changes and becomes the seed. Inside it, the zygote develops into the embryo, and other associated tissues also mature. This transformation is one of the most fundamental source-to-product relationships in flowering plants. The fruit, by contrast, develops from the ovary.
304. Which structure of the flower usually develops into the fruit after fertilisation?
ⓐ. Ovule
ⓑ. Placenta
ⓒ. Ovary
ⓓ. Embryo sac
Correct Answer: Ovary
Explanation: After fertilisation, the ovary enlarges and matures into the fruit. The ovules inside it develop into seeds, so ovary and ovule have different post-fertilisation outcomes.
305. The integuments of the ovule mainly give rise to the
ⓐ. endosperm
ⓑ. embryo
ⓒ. fruit wall
ⓓ. seed coat
Correct Answer: seed coat
Explanation: The integuments surround the ovule before fertilisation and later harden or mature into the seed coat. This coat protects the developing embryo and associated tissues within the seed. The endosperm and embryo arise from fertilisation products, not from integuments. So the seed coat is the correct post-fertilisation derivative of the integuments.
306. Which event generally begins before obvious embryo development in many angiosperms?
ⓐ. Formation of pericarp
ⓑ. Endosperm development
ⓒ. Dehiscence of anther
ⓓ. Pollination by agents
Correct Answer: Endosperm development
Explanation: In many flowering plants, endosperm development begins soon after triple fusion. The zygote may remain inactive for some time before starting active embryogenesis. This timing ensures that nutritive tissue becomes available for the developing embryo. The sequence therefore supports proper nourishment during early development.
307. Which sequence correctly matches post-fertilisation transformations in flowering plants?
ⓐ. ovule → fruit, ovary → seed, integuments → endosperm
ⓑ. ovary → seed, ovule → stigma, zygote → micropyle
ⓒ. ovule → seed, ovary → fruit, integuments → seed coat
ⓓ. zygote → endosperm, ovary → seed coat, ovule → fruit
Correct Answer: ovule → seed, ovary → fruit, integuments → seed coat
Explanation: These are the standard post-fertilisation changes in angiosperms: ovule to seed, ovary to fruit, and integuments to seed coat. The mapping links each mature structure with its floral origin.
308. If sepals, petals, or other floral parts remain attached even after fruit formation, they are described as
ⓐ. persistent
ⓑ. abortive
ⓒ. incompatible
ⓓ. tetrasporangiate
Correct Answer: persistent
Explanation: Some floral parts do not fall off after fertilisation and remain associated with the developing fruit. Such parts are called persistent floral parts. The term simply indicates retention after fertilisation, not reproductive failure. This concept belongs to the broader set of post-fertilisation changes in the flower.
309. In many flowering plants, the zygote does not begin active division immediately after fertilisation because
ⓐ. early endosperm development often begins first and helps support later embryo growth
ⓑ. the zygote must first undergo meiosis to become haploid
ⓒ. the zygote is expelled from the ovule before embryogenesis
ⓓ. the ovary must dehisce before any internal development starts
Correct Answer: early endosperm development often begins first and helps support later embryo growth
Explanation: In many angiosperms, the zygote may remain temporarily inactive after fertilisation. During this time, endosperm development often starts earlier and provides nutritive support for the future embryo. This sequence is biologically useful because the young embryo needs nourishment as it begins to develop. The delay is therefore coordinated, not abnormal.
310. The immediate product of triple fusion that later develops into endosperm is the
ⓐ. primary endosperm cell wall
ⓑ. secondary nucleus
ⓒ. primary endosperm nucleus
ⓓ. endothecium
Correct Answer: primary endosperm nucleus
Explanation: Triple fusion produces the primary endosperm nucleus in the central cell. This nucleus is the starting point of endosperm development in angiosperms. Since endosperm acts as nutritive tissue for the embryo, this product is one of the most important results of fertilisation. It should not be confused with the zygote, which arises from syngamy.
311. Which statement about post-fertilisation changes in a flower is correct?
ⓐ. The ovary becomes the seed coat, while the ovule becomes the fruit.
ⓑ. The zygote directly forms the fruit wall, while the nucellus forms the embryo.
ⓒ. The stigma develops into endosperm, while the style forms the micropyle.
ⓓ. The ovule forms the seed, and the ovary forms the fruit.
Correct Answer: The ovule forms the seed, and the ovary forms the fruit.
Explanation: After fertilisation, different floral structures undergo specific transformations. The ovule becomes the seed, while the ovary develops into the fruit. The integuments form the seed coat, and the zygote develops into the embryo. These source-to-product mappings are fundamental to post-fertilisation development.
312. Floral parts that wither and fall off after fertilisation are described as
ⓐ. persistent
ⓑ. non-persistent
ⓒ. syncarpous
ⓓ. nucellar
Correct Answer: non-persistent
Explanation: Not all floral parts remain attached after fertilisation. Those that dry up and fall away are described as non-persistent floral parts. This contrasts with persistent floral parts, which remain associated with the developing fruit. The distinction is useful in describing post-fertilisation changes in flowers.
313. Which sequence correctly traces the major post-fertilisation transformation in a flowering plant?
ⓐ. fertilisation → seed and fruit development
ⓑ. dehiscence → meiosis → embryo sac formation
ⓒ. pollination → microsporogenesis → anther formation
ⓓ. autogamy → pollen release → tapetum formation
Correct Answer: fertilisation → seed and fruit development
Explanation: Fertilisation marks the beginning of major structural changes in the ovule and ovary. After this event, the ovule develops into a seed and the ovary into a fruit. Embryo and endosperm development also proceed within the seed. Thus, seed and fruit formation are direct post-fertilisation outcomes.
314. If the integuments of an ovule fail to develop properly after fertilisation, which seed structure would be most directly affected?
ⓐ. Embryo
ⓑ. Endosperm
ⓒ. Seed coat
ⓓ. Cotyledon
Correct Answer: Seed coat
Explanation: The integuments of the ovule mature into the seed coat. Therefore, abnormal development of integuments would most directly affect the protective covering of the seed. Embryo and endosperm arise from fertilisation products, not from integuments. This makes seed coat the most direct derivative involved.
315. Endosperm in angiosperms is mainly important because it
ⓐ. produces pollen tubes for the male gametophyte
ⓑ. nourishes the developing embryo
ⓒ. forms the seed coat around the embryo
ⓓ. develops into the fruit wall after germination
Correct Answer: nourishes the developing embryo
Explanation: Endosperm is the nutritive tissue formed after triple fusion in flowering plants. Its main role is to support the growth and development of the embryo. In many seeds it stores food, and in some it persists even at maturity. This nutritive function is the key reason endosperm is biologically important.
316. The endosperm of angiosperms is generally
ⓐ. haploid
ⓑ. diploid
ⓒ. tetraploid
ⓓ. triploid
Correct Answer: triploid
Explanation: Endosperm usually originates from the primary endosperm nucleus formed by triple fusion. Since one male gamete fuses with two polar nuclei, the resulting nucleus is triploid. The tissue developing from it therefore has a triploid nature in most angiosperms. This ploidy distinguishes endosperm from the diploid embryo.
317. Which statement correctly describes free nuclear endosperm?
ⓐ. Nuclear divisions occur without immediate wall formation.
ⓑ. It develops only after the seed coat is fully mature.
ⓒ. It is formed directly from the zygote by repeated mitosis.
ⓓ. It always remains absent in mature seeds.
Correct Answer: Nuclear divisions occur without immediate wall formation.
Explanation: In free nuclear endosperm development, the nucleus divides repeatedly while the cytoplasm remains initially undivided by cell walls. This leads to a multinucleate condition at an early stage. Cell walls may form later in some cases. The type is identified mainly by the absence of immediate cytokinesis after nuclear division.
318. The white edible kernel of coconut represents
ⓐ. a persistent nucellus
ⓑ. a diploid embryo
ⓒ. cellular endosperm tissue
ⓓ. a mature ovary wall
Correct Answer: cellular endosperm tissue
Explanation: Coconut is a standard example used to explain endosperm development. The liquid coconut water corresponds to free nuclear endosperm, while the white kernel represents the later cellularized tissue. Both belong to endosperm, not to embryo or fruit wall. This example is widely used because it clearly shows different physical states of endosperm.
319. A seed that retains endosperm in the mature state is called
ⓐ. non-albuminous
ⓑ. albuminous
ⓒ. apocarpous
ⓓ. parthenocarpic
Correct Answer: albuminous
Explanation: Albuminous seeds are those in which endosperm persists up to seed maturity. In such seeds, the endosperm remains available as stored food. By contrast, non-albuminous seeds use up the endosperm during development. The distinction depends on endosperm persistence, not on cotyledon number.
320. Which type of endosperm is characterized by an initial division that creates a large micropylar chamber and a smaller chalazal chamber?
ⓐ. free nuclear
ⓑ. cellular
ⓒ. albuminous
ⓓ. helobial
Correct Answer: helobial
Explanation: Helobial endosperm shows a characteristic early partition into two unequal chambers. One chamber lies toward the micropylar end and the other toward the chalazal end. This makes it distinct from free nuclear and cellular types. The classification is based on the pattern of endosperm development after triple fusion.
