Plant Reproduction Archives

21. Gametophytes of sexually reproducing flowering plants are A) Haploid B

Gametophytes of sexually reproducing flowering plants are
A) Haploid
B) Diploid
C) Tetraploid
D) Polyploid

Haploid

Diploid

Tetraploid

Polyploid

This question was previously asked in

UPSC NDA-1 – 2015

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In the life cycle of sexually reproducing flowering plants (angiosperms), the dominant generation is the sporophyte, which is diploid (2n). This sporophyte produces spores through meiosis. These spores develop into the gametophytes (male gametophyte or pollen grain, and female gametophyte or embryo sac). The gametophytes are haploid (n). They produce gametes (sperm and egg) through mitosis.

The gametophyte generation in plants is haploid, producing gametes by mitosis. The sporophyte generation is diploid, producing spores by meiosis.

In flowering plants, the gametophyte generation is significantly reduced and dependent on the sporophyte. The male gametophyte is the pollen grain, and the female gametophyte is the embryo sac within the ovule.

22. Many fruits burst with a sudden jerk because of which the seeds are sc

Many fruits burst with a sudden jerk because of which the seeds are scattered a few yards from the parent plant. This type of dispersal of seeds is known as :

Anemochory

Hydrochory

Autochory

Zoochory

This question was previously asked in

UPSC Geoscientist – 2024

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The dispersal of seeds by the plant itself through mechanisms like sudden bursting of fruits is known as Autochory.

Autochory refers to seed dispersal that is achieved by the plant itself, without reliance on external agents like wind, water, or animals. This can happen through various mechanisms, including explosive dehiscence of fruits or pods, where tension builds up in the drying fruit wall leading to a sudden burst that ejects the seeds.

Anemochory is dispersal by wind (e.g., dandelion seeds). Hydrochory is dispersal by water (e.g., coconut). Zoochory is dispersal by animals (e.g., seeds consumed and excreted, or seeds attached to fur). The description provided clearly matches the definition of autochory via an explosive mechanism.

23. Which one of the following is the technique of joining parts of two pl

Which one of the following is the technique of joining parts of two plants to form a composite plant ?

Layering

Grafting

Cutting

Budding

This question was previously asked in

UPSC Geoscientist – 2024

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Grafting is an asexual propagation technique where tissues of one plant (the scion) are joined to those of another (the rootstock) so that they unite and continue to grow as one plant. This allows combining desirable traits from two different plants.

Grafting involves joining parts of two plants (scion and rootstock) to grow together.

Layering is a method where a portion of an aerial stem grows roots while still attached to the parent plant. Cutting involves taking a piece of a plant (stem, root, or leaf) and rooting it to form a new independent plant. Budding is a type of grafting where a single bud is used as the scion.

24. Which one of the following is a ‘drupe’?

Which one of the following is a ‘drupe’?

Orange

Brinjal

Coconut

Tomato

This question was previously asked in

UPSC Geoscientist – 2023

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A drupe is a type of fleshy fruit characterized by a hard, stony layer (the endocarp) surrounding the seed, enclosed within a fleshy outer part (mesocarp) and skin (exocarp). A coconut fits this definition: the fibrous husk is the mesocarp, the hard shell surrounding the “meat” and water is the stony endocarp, and the seed is inside.

– A drupe has three layers: exocarp (skin), fleshy mesocarp, and stony endocarp surrounding the seed.
– Coconut is classified botanically as a fibrous drupe.
– Orange is a hesperidium (a type of berry).
– Brinjal (Eggplant) and Tomato are berries.

Other examples of drupes include peaches, plums, cherries, apricots, olives, and mangoes. The definition can be sometimes confusing for multi-seeded fruits or those with dry pericarps, but the presence of the stony endocarp is key for a drupe.

25. Which one of the following is a ‘false fruit’?

Which one of the following is a ‘false fruit’?

Peach

Banana

Apple

Apricot

This question was previously asked in

UPSC Geoscientist – 2023

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A true fruit develops exclusively from the ovary of a flower after fertilization. A false fruit, or accessory fruit, develops from the ovary along with other parts of the flower, such as the thalamus (receptacle), petals, sepals, or calyx. In the case of an apple, the main edible, fleshy part is derived from the greatly enlarged and fleshy thalamus, which surrounds the core (developed from the ovary). Peach, banana, and apricot are considered true fruits as their fleshy, edible parts develop directly from the ovary wall.

– True fruit develops from the ovary.
– False fruit develops from the ovary plus other floral parts (like thalamus).
– Apple’s edible part is derived from the thalamus.
– Peach, Banana, and Apricot develop primarily from the ovary.

Other examples of false fruits include strawberries (fleshy receptacle) and figs (inverted inflorescence/syconium). The concept of “true” vs. “false” fruit is primarily a botanical classification based on floral origin, and all are commonly referred to as fruits in everyday language. Bananas are parthenocarpic fruits, meaning they develop without fertilization, but they are derived solely from the ovary, classifying them as true fruits botanically.

26. Dispersal of species by the agent of wind is termed as

Dispersal of species by the agent of wind is termed as

thalassochore

hydrochore

anemochore

anemohydrochore

This question was previously asked in

UPSC Geoscientist – 2022

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Anemochory is the term used to describe the dispersal of plant seeds, spores, or fruits by wind. This method relies on wind currents to carry the propagules away from the parent plant.

– Anemochore refers specifically to dispersal by wind.
– Thalassochore refers to dispersal by seawater.
– Hydrochore refers to dispersal by water (generally, including fresh and salt water).
– Anemohydrochore refers to dispersal by both wind and water.

Wind dispersal is common among species that produce small, light propagules, or those with adaptations like wings or tufts of hair (e.g., dandelions, maple seeds) that aid in catching the wind. The effectiveness of anemochory depends on wind speed, propagule structure, and height of release.

27. Which one of the following about anemophilous plants is correct?

Which one of the following about anemophilous plants is correct?

Bright coloured flowers

Sweet smelling flowers

No nectar

Dwarf stigmata

This question was previously asked in

UPSC Geoscientist – 2020

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Anemophilous plants are pollinated by wind. Since they do not rely on attracting animal pollinators, their flowers typically lack features like bright colours, sweet scents, and nectar, which are adaptations for attracting insects or birds.

The absence of nectar, bright petals, and strong scents is a characteristic adaptation of wind-pollinated (anemophilous) flowers because they do not need to bribe or lure pollinators.

Other characteristics of anemophilous flowers include small, inconspicuous flowers, large production of light, smooth pollen grains that are easily carried by wind, and often exposed stamens and large, feathery or branched stigmas to efficiently capture airborne pollen. Examples include grasses, oaks, ragweed, and pine trees.

28. In ovules of Angiosperms, which one of the following is not a haploid

In ovules of Angiosperms, which one of the following is not a haploid cell?

Nucellus

Synergid

Egg

Antipodal

This question was previously asked in

UPSC CDS-2 – 2023

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The Nucellus in the ovule of Angiosperms is diploid.

The Angiosperm ovule contains the female gametophyte (embryo sac) surrounded by parental diploid tissue. The nucellus is the mass of parenchyma cells that makes up the body of the ovule, enclosing the embryo sac. It is derived from the sporophyte generation and is therefore diploid (2n). The embryo sac itself contains haploid cells like the egg cell, synergids, and antipodal cells, as well as a central cell which is typically diploid (formed by the fusion of two haploid polar nuclei).

The embryo sac develops from a haploid megaspore through mitosis. The egg cell, synergids (usually two), and antipodal cells (usually three) are all haploid (n). The central cell contains two polar nuclei, which fuse to form a diploid (2n) or polyploid nucleus depending on the species.

29. Which one of the following agents does not contribute to propagation o

Which one of the following agents does not contribute to propagation of plants through seed dispersal?

Wind

Fungus

Animal

Water

This question was previously asked in

UPSC CDS-2 – 2018

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The correct answer is B) Fungus.

Seed dispersal is the movement or transport of seeds away from the parent plant. Common agents of seed dispersal include wind (anemochory), water (hydrochory), animals (zoochory), and mechanical means (autochory). Fungi are typically decomposers or pathogens and do not act as agents for the propagation of plants through seed dispersal; they are usually involved in the decay of organic matter or infecting plants.

Animal dispersal can involve seeds sticking to fur/feathers, being ingested and passed through the digestive tract, or being collected and stored by animals. Water dispersal is common for plants near water bodies, with seeds floating away. Wind dispersal often involves lightweight seeds or seeds with wings/parachutes. Fungi play crucial roles in ecosystems, such as nutrient cycling and symbiotic relationships (like mycorrhizae), but not seed dispersal.

30. Which one of the following denotes a ‘true’ fruit?

Which one of the following denotes a ‘true’ fruit?

When only the thalamus of the flower grows and develops into a fruit

When only the receptacle of the flower develops into a fruit

When fruit originates only from the calyx of a flower

When only the ovary of the flower grows into a fruit

This question was previously asked in

UPSC CDS-2 – 2018

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In botany, a ‘true’ fruit develops exclusively from the ovary of a flower after fertilization. The ovary wall matures into the pericarp (fruit wall), and the ovules inside the ovary develop into seeds.
A) When only the thalamus…: If the thalamus develops into the edible part of the fruit, it is considered a false fruit or accessory fruit (e.g., apple, pear).
B) When only the receptacle…: Similar to the thalamus, if the receptacle contributes significantly to the fruit structure, it’s an accessory fruit (e.g., strawberry, where the receptacle becomes the fleshy part).
C) When fruit originates only from the calyx…: The calyx (sepals) can sometimes persist or even enlarge in the fruit (e.g., in strawberry where persistent calyx is present, or ground cherry where it encloses the fruit), but the fruit itself develops from the ovary. If the calyx formed the primary fruit structure, it would not be a true fruit originating *only* from the ovary.
D) When only the ovary of the flower grows into a fruit: This is the definition of a true fruit. The fruit wall (pericarp) is derived from the ovary wall.

– A true fruit develops solely from the ovary.
– False fruits (accessory fruits) involve other floral parts besides the ovary in their formation (e.g., thalamus, receptacle, calyx).
– The ovary contains ovules, which develop into seeds after fertilization.

Examples of true fruits include tomato, mango, peach, cherry, and grape. Examples of false fruits include apple, pear, strawberry, fig, and pineapple. Parthenocarpic fruits develop from an unfertilized ovary and are typically seedless (e.g., some varieties of bananas and grapes), and are still considered true fruits as they originate from the ovary.