201. Which floral feature most effectively ensures self-pollination without requiring any external pollinating agent?
ⓐ. Cleistogamy
ⓑ. Herkogamy
ⓒ. Dichogamy
ⓓ. Self-incompatibility
Correct Answer: Cleistogamy
Explanation: Cleistogamous flowers remain closed, so pollen is transferred within the same flower itself. Because the reproductive parts are enclosed together, pollinating agents are not needed. This makes self-pollination highly certain. Among the listed conditions, it is the strongest direct device promoting autogamy.
202. Which statement about cleistogamous flowers is correct?
ⓐ. They do not open and therefore can set seed by assured self-pollination.
ⓑ. They are always dependent on insects for pollination.
ⓒ. They always promote xenogamy more than autogamy.
ⓓ. They prevent pollen from reaching the stigma of the same flower.
Correct Answer: They do not open and therefore can set seed by assured self-pollination.
Explanation: A cleistogamous flower remains closed even at maturity. Since the anthers and stigma remain enclosed together, self-pollination can occur reliably. This is why such flowers can produce seeds even when pollinating agents are absent. Their closure favors autogamy rather than cross-pollination.
203. Which statement best describes a chasmogamous flower?
ⓐ. It never opens and always remains self-pollinated.
ⓑ. It lacks both stamens and carpels.
ⓒ. It opens at maturity and may undergo self- or cross-pollination.
ⓓ. It always rejects pollen from the same plant.
Correct Answer: It opens at maturity and may undergo self- or cross-pollination.
Explanation: Chasmogamous flowers open at maturity and expose their reproductive organs. Because of this exposure, they may undergo self-pollination or cross-pollination depending on floral structure and pollinating conditions. They are therefore less restrictive than cleistogamous flowers. Opening increases reproductive possibilities rather than fixing only one outcome.
204. A viable pollen grain reaches the stigma of the same plant but fails to bring about fertilisation because the pistil rejects it genetically. This is an example of
ⓐ. homogamy
ⓑ. herkogamy
ⓒ. dichogamy
ⓓ. self-incompatibility
Correct Answer: self-incompatibility
Explanation: Self-incompatibility is a genetic mechanism that prevents self-pollen from successfully effecting fertilisation. The pollen may be viable and may even germinate partially, but the pistil recognizes and rejects it. This is different from sterility, where the pollen itself is defective. The mechanism serves as an outbreeding device.
205. Which statement correctly distinguishes self-incompatibility from pollen sterility?
ⓐ. In self-incompatibility, pollen may be viable but is rejected by the pistil.
ⓑ. In self-incompatibility, pollen grains are never formed in the anther.
ⓒ. In self-incompatibility, the flower must remain closed at maturity.
ⓓ. In self-incompatibility, the stigma is always absent.
Correct Answer: In self-incompatibility, pollen may be viable but is rejected by the pistil.
Explanation: Self-incompatibility does not mean that the pollen is dead or malformed. Instead, the pollen may be perfectly viable but is prevented from completing fertilisation because of genetic recognition by the pistil. This makes it very different from sterility. The distinction is important because both conditions can prevent seed formation, but for different reasons.
206. In a bisexual flower, the anthers shed pollen before the stigma becomes receptive. This condition is best described as
ⓐ. homogamy
ⓑ. dichogamy
ⓒ. cleistogamy
ⓓ. geitonogamy
Correct Answer: dichogamy
Explanation: Dichogamy refers to the maturation of male and female organs at different times. If pollen is shed before the stigma becomes receptive, self-pollination is reduced. This separation in timing encourages cross-pollination. It is therefore one of the classic outbreeding devices.
207. Which of the following conditions would most strongly reduce the chance of autogamy in a bisexual flower without removing either reproductive organ?
ⓐ. Homogamy
ⓑ. Cleistogamy
ⓒ. Herkogamy
ⓓ. Closed corolla
Correct Answer: Herkogamy
Explanation: Herkogamy is a spatial separation between anthers and stigma in the same flower. Because the two organs are positioned apart, self-pollen is less likely to reach the stigma. This reduces the probability of autogamy while still allowing both reproductive organs to remain present. The barrier is positional rather than temporal or genetic.
208. Which combination most strongly favors self-pollination in a flower?
ⓐ. Unisexuality and dichogamy
ⓑ. Herkogamy and self-incompatibility
ⓒ. Dichogamy and herkogamy
ⓓ. Bisexuality and homogamy
Correct Answer: Bisexuality and homogamy
Explanation: Bisexuality provides both stamens and carpels in the same flower, and homogamy ensures that they mature at the same time. Together, these two conditions create a favorable situation for self-pollination. In contrast, dichogamy, herkogamy, and self-incompatibility act against selfing. So this combination supports autogamy rather than outbreeding.
209. Which floral feature directly prevents a single flower from showing true autogamy?
ⓐ. Unisexuality
ⓑ. Homogamy
ⓒ. Cleistogamy
ⓓ. Closed anther wall
Correct Answer: Unisexuality
Explanation: True autogamy requires that a single flower contain both male and female reproductive organs. A unisexual flower lacks either stamens or carpels, so self-pollination within that same flower cannot occur. The flower may still participate in other pollination types, but not autogamy. This makes unisexuality a structural barrier to selfing within one flower.
210. Which statement is correct regarding cleistogamous and chasmogamous flowers?
ⓐ. Both always require pollinating agents.
ⓑ. Cleistogamous flowers assure self-pollination, whereas chasmogamous flowers may allow cross-pollination.
ⓒ. Chasmogamous flowers never open in response to maturity.
ⓓ. Cleistogamous flowers always show greater genetic variation than chasmogamous flowers.
Correct Answer: Cleistogamous flowers assure self-pollination, whereas chasmogamous flowers may allow cross-pollination.
Explanation: Cleistogamous flowers remain closed and therefore strongly favor self-pollination. Chasmogamous flowers open, which allows the possibility of cross-pollination as well as self-pollination. Their reproductive options are broader because pollinating agents can interact with them. The two flower types thus differ mainly in openness and pollination opportunity.
211. A flower is bisexual and opens normally, but self-pollen rarely reaches the stigma because the stigma lies well away from the anthers. Which outbreeding device is operating here?
ⓐ. Cleistogamy
ⓑ. Homogamy
ⓒ. Herkogamy
ⓓ. Autogamy
Correct Answer: Herkogamy
Explanation: The clue here is the physical separation between anthers and stigma within the same flower. That condition is called herkogamy. It reduces the chance that self-pollen will contact the stigma even though both organs are present together. This promotes cross-pollination by making self-pollination mechanically difficult.
212. Choose the correct completion.
When anthers and stigma mature at different times, the condition is called ______; when self-pollen is genetically rejected by the pistil, the condition is called ______.
ⓐ. homogamy; geitonogamy
ⓑ. herkogamy; cleistogamy
ⓒ. autogamy; xenogamy
ⓓ. dichogamy; self-incompatibility
Correct Answer: dichogamy; self-incompatibility
Explanation: Dichogamy refers to a difference in timing between pollen release and stigma receptivity. Self-incompatibility is a genetic mechanism that prevents self-pollen from achieving fertilisation even if it reaches the stigma. Both conditions reduce selfing, but they do so in different ways. One acts through timing, while the other acts through recognition and rejection.
213. A flower remains closed throughout its life cycle and still sets seed regularly even when pollinating insects are absent. This most strongly indicates
ⓐ. cleistogamy
ⓑ. herkogamy
ⓒ. dichogamy
ⓓ. self-incompatibility
Correct Answer: cleistogamy
Explanation: Cleistogamous flowers do not open, so pollen transfer occurs within the closed flower itself. Because of this, they can set seed even when pollinating agents are absent. This condition assures self-pollination in a very reliable way. The other listed conditions reduce selfing rather than ensuring it.
214. Which of the following does not promote autogamy?
ⓐ. Bisexuality
ⓑ. Self-incompatibility
ⓒ. Homogamy
ⓓ. Cleistogamy
Correct Answer: Self-incompatibility
Explanation: Self-incompatibility prevents self-pollen from successfully effecting fertilisation. Even if pollen from the same plant reaches the stigma, it may be rejected. In contrast, bisexuality, homogamy, and cleistogamy all favor self-pollination under suitable conditions. So self-incompatibility acts against autogamy rather than promoting it.
215. Which floral condition would make autogamy most likely in an open flower?
ⓐ. Unisexuality with dichogamy
ⓑ. Herkogamy with self-incompatibility
ⓒ. Bisexuality with homogamy
ⓓ. Feathery stigma with abundant pollen
Correct Answer: Bisexuality with homogamy
Explanation: For autogamy in an open flower, both sexes must be present in the same flower and must mature at the same time. Bisexuality provides stamens and carpels together, and homogamy ensures synchrony of their maturity. This combination creates favorable conditions for self-pollination. The other options either hinder selfing or are associated with other pollination modes.
216. Which event is impossible in a pistillate flower?
ⓐ. Xenogamy
ⓑ. Geitonogamy
ⓒ. Cross-pollination
ⓓ. Autogamy
Correct Answer: Autogamy
Explanation: A pistillate flower has only carpels and lacks stamens. Since autogamy requires pollen from the same flower to reach its own stigma, both male and female organs must be present in that flower. Therefore true autogamy cannot occur in a pistillate flower. However, pollen may still come from another flower of the same plant or a different plant.
217. Which floral feature is most characteristic of wind pollination?
ⓐ. Production of abundant, light pollen
ⓑ. Presence of nectaries and sweet fragrance
ⓒ. Large, brightly coloured petals
ⓓ. Sticky pollen with heavy ornamentation
Correct Answer: Production of abundant, light pollen
Explanation: Wind-pollinated flowers usually produce large quantities of light pollen because dispersal by air is uncertain and inefficient. Such pollen is easily carried by moving air currents. In contrast, showy petals, fragrance, and nectar are more closely associated with animal pollination. Wind pollination therefore depends more on quantity and dispersibility than on attraction.
218. Vallisneria is a standard example of
ⓐ. anemophily
ⓑ. hydrophily
ⓒ. entomophily
ⓓ. cleistogamy
Correct Answer: hydrophily
Explanation: Hydrophily is pollination by water, and Vallisneria is a classic example. In this plant, pollination occurs with the help of water currents at the surface.
219. Pollination by water is commonly seen in some
ⓐ. legumes
ⓑ. grasses
ⓒ. orchids
ⓓ. sea grasses
Correct Answer: sea grasses
Explanation: Sea grasses are among the well-known examples of hydrophily in angiosperms. Their pollen is transported by water in the marine environment. This makes them an important contrast to the more common wind- and insect-pollinated flowers. Textbook examples such as sea grasses help anchor the concept of water pollination.
220. Which adaptation is most likely to be associated with insect pollination?
ⓐ. Exposed stamens and feathery stigma
ⓑ. Very large output of dry, non-sticky pollen
ⓒ. Colourful petals and floral rewards
ⓓ. Absence of nectar and fragrance
Correct Answer: Colourful petals and floral rewards
Explanation: Insect-pollinated flowers often attract pollinators using bright petals, fragrance, nectar, or edible pollen. These features help bring insects repeatedly to the flower. By contrast, exposed stamens, feathery stigmas, and large amounts of dry pollen are typical of wind pollination. Attraction and reward are therefore major clues to entomophily.
