CUET UG Biology Booster Test 2 Male Gametophyte (Pollen) and Female Structures

According to NCERT, the outer layer of the pollen wall is called the exine, which is made of Sporopollenin (A). This substance is an incredibly tough polymer capable of tolerating hostile chemistry; it Withstands high temperature and alkali (II) as well as strong acids. It is a highly resistant Organic Material (C) for which there is No known enzyme degrades it (III). Due to this total resistance to biological and chemical breakdown, pollen grains are exceptionally well-preserved in the Fossil Record (D), specifically being Preserved due to sporopollenin (IV). To allow the growing pollen tube an avenue of escape during germination, Exine Pores (B) (germ pores) occur as small gaps where sporopollenin is uniquely Absent in germ pores (I). Combining these biological facts establishes the sequence: (A)-(II), (B)-(I), (C)-(III), (D)-(IV), matching Option A.

The microspore wall features several distinctive structural properties described in NCERT. The Exine (A) acts as the outer layer and displays Fascinating patterns and designs (II) that serve as a key diagnostic feature for identifying different plant families. The primary building material of this outer wall is Sporopollenin (B), which is classified as a highly Resistant organic material (III). The exine features small, uncovered Germ Pores (C), which are defined as Apertures called germ pores (I) where sporopollenin is absent to allow germination. The overall structural Hardness (D) of this specialized wall assembly serves an essential evolutionary purpose: Protecting the male gametophyte (IV) from drying out or suffering mechanical injury during dispersal. This generates the matching sequence: (A)-(II), (B)-(III), (C)-(I), (D)-(IV), matching Option A.

The Question asks to trace the layout of the pollen grain from the inside (innermost cytoplasm) outward to the environment. According to NCERT, the cytoplasm of the pollen grain is bounded by the Plasma membrane (III). Moving outward, the next layer is the inner cell wall, the Intine (II), which is thin and continuous. Further outward sits the tough exine layer, which features open gaps called Germ pores (I) that face the external environment. Tracing this pathway from the inside out follows the sequence: Plasma membrane $\rightarrow$ Intine $\rightarrow$ Germ pore, or III - II - I, which matches Option A.

To arrange these structures by their level of chemical resistance, we look at their biochemical makeup as outlined in NCERT: 1. Sporopollenin layer (II): The exine possesses unmatched chemical resistance; it withstands strong acids, alkalis, high temperatures, and resists all known enzymatic breakdown. 2. Cellulose-pectin layer (I): The intine is a standard organic plant cell wall; it offers moderate structural protection but can be easily broken down by standard enzymes like cellulase and pectinase. 3. Plasma membrane (III): This delicate lipid bilayer provides no chemical resistance or mechanical protection; it functions only as a semi-permeable cell boundary. Arranging these layers from highest resistance to lowest yields the sequence: II - I - III, matching Option A.

The vegetative cell is the larger cell produced during pollen maturation. According to NCERT, it is characterized by its Larger size than generative cell (D), its Abundant food reserve (A) that helps nourish the pollen tube, and its Large irregular nucleus (B). The vegetative cell itself remains a helper structure and never undergoes Mitotic division into gametes (C). Instead, that additional division is performed exclusively by the smaller generative cell to produce the two male gametes. Therefore, Option C is not involved in describing the function or features of the vegetative cell.

The generative cell is the smaller, reproductive cell within a mature pollen grain. NCERT states that it has a characteristic Spindle-shaped morphology (D), contains a compact nucleus with Dense cytoplasm (B), and is found Floating in vegetative cytoplasm (A). The generative cell is a free-floating unit and plays no role in Forming the pollen tube wall (C). The pollen tube wall is formed when the intine layer expands and grows out through a germ pore during germination. This makes Option C the incorrect statement.

In over 60% of angiosperms (including typical model plants like Hibiscus (A)), pollen is shed at the 2-celled stage. This stage consists of a Vegetative cell (D) and a Generative cell (B). At this point, the pollen grain does not contain fully formed Male gametes (C). Those two gametes are only produced later, when the generative cell undergoes an additional mitotic division inside the growing pollen tube. Therefore, the presence of separate male gametes is not associated with the 2-celled shedding stage, making Option C the correct choice.

The 3-celled stage is a reproductive phase found during pollen development in around 40% of angiosperms (B). This stage occurs when the generative cell undergoes a Mitotic division of generative cell (A) prior to shedding. This division splits the generative cell into Two male gametes (C), which exist alongside the large vegetative cell. In contrast, Pollen/nectar robbers (D) are insects or birds that feed on a flower's nectar or pollen without transferring it to a stigma, preventing pollination. This animal behavior is an ecological interaction that has nothing to do with the internal cell divisions of a pollen grain, making Option D the correct answer.

According to NCERT, Parthenium (carrot grass) (A) became a widespread weed in India after entering the country accidentally as a Imported wheat contaminant (A). The weed spreads rapidly and produces large amounts of airborne pollen that acts as a severe allergen, causing widespread Pollen allergy (B) and chronic Bronchial afflictions (C) like asthma and bronchitis. Parthenium is toxic to both humans and livestock, and it is never used for Deliberate cultivation for food (D). This makes Option D the correct answer.

Pollen grains are rich in nutrients, which has led to their widespread use as dietary health products. In western markets, these nutrients are sold commercially as Tablets and syrups (D). These products are used as a Food supplement for athletes (B) and are given to improve the Increased performance of race horses (A) by boosting energy and stamina. However, pollen does not act as a Cure for chronic respiratory disorders (C). In fact, inhaling airborne pollen is a primary cause of respiratory illnesses like asthma and bronchitis. This makes Option C the incorrect association.

This Question evaluates how environmental factors and plant physiology affect agricultural practices based on the provided Passage:: "In some cereals such as rice and wheat, pollen grains lose viability within 30 minutes of their release..." Because these pollen grains lose their ability to fertilize so quickly, successful pollination depends entirely on timing. The pollen must land on a receptive stigma almost immediately after being released from the anther (Option B). If weather conditions or poor timing delay this contact past the 30-minute window, the pollen dies, preventing fertilization and reducing crop yields.

According to the Passage:, pollen grains can be stored for years in liquid nitrogen (-196°C) to create pollen banks. In agricultural breeding programs, this long-term storage provides a major advantage: it breaks the limitations of natural flowering schedules. Breeders can harvest pollen from a plant that flowers in the spring, store it in a pollen bank, and use it months later to fertilize a plant that flowers in the autumn. This allows for the hybridization of crops across different seasons (Option B), giving breeders greater flexibility.

Anatomical classification uses precise terms to describe both the number and the physical arrangement of a flower's reproductive organs. Because the botanist observes "many" separate pistils, the gynoecium must be classified as Multicarpellary. Furthermore, because these multiple pistils are completely "separate and distinct" from base to tip rather than being joined together, the structure must be described as Apocarpous (as seen in the separate carpels of Michelia). Combining these observations gives the complete anatomical description: Multicarpellary apocarpous (C).

This Question evaluates the terminology used to describe the configuration of a flower's female reproductive organs. Because the gynoecium contains "many" individual pistils, it belongs to the broad category of Multicarpellary systems. Additionally, because these multiple pistils are "fused into a single structure" rather than growing independently, the condition is defined as Syncarpous (as seen in the fused carpels of Papaver). Combining these two structural descriptions gives the complete classification: Multicarpellary syncarpous (B).

NCERT uses specific plant examples to illustrate the different types of pistil fusion. The genus Papaver (the poppy plant) is explicitly used to demonstrate a multicarpellary, syncarpous gynoecium. In a Papaver flower, multiple individual carpels develop, but their walls fuse together completely during growth to form a single, unified ovary topped by a shared stigmatic disc. This structural layout is defined by the presence of Fused carpels (B), making Option B the correct choice.

NCERT uses the genus Michelia (a member of the Magnolia family) to illustrate the apocarpous condition. In a Michelia flower, the gynoecium contains multiple carpels arranged along an elongated central axis. Because these carpels do not fuse during development and instead remain completely Free from each other (B), the structure is classified as apocarpous. This independent arrangement allows each separate carpel to develop into its own individual fruitlet, confirming Option B as the correct answer.

NCERT states that a typical pistil is divided into three parts: the stigma, style, and ovary. The stigma is located at the very top of this assembly and acts as a specialized target area. It is described as a "landing platform" because its primary function is to Receive pollen grains during pollination (B). The surface of the stigma often develops a sticky texture or microscopic hairs to trap these incoming grains, holding them securely so they can begin germination. This makes Option B the correct functional description.

A individual pistil is organized into three connected sections: the top stigma, the narrow middle style, and the swollen base. This swollen base is the ovary, which houses the plant's female reproductive structures. Internally, the walls of the ovary form an open chamber known as the Ovarian cavity (C) or locule. This open space contains the placenta tissue and provides the room needed for the ovules to grow and develop securely, confirming Option C as the correct anatomical structure.

To understand this structural relationship, we look at the internal anatomy of the ovary as described in NCERT: the swollen base of the pistil contains an internal space called the ovarian cavity or locule. Along the inner walls of this cavity lies the placenta, a specialized ridge of tissue that acts as an anchor point. The individual ovules grow from this placenta layer, meaning the placenta sits securely inside the locule (B). This makes Option B the correct description of their relationship.

The total number of ovules inside an ovary is a fixed genetic trait that varies between different plant families. NCERT explicitly states that the number of ovules in an ovary may be One (A) (as seen in grass and cereal crops like wheat, paddy, and mango) or it may be many (as seen in papaya, watermelon, and orchids). Because wheat and paddy produce single-seeded grain fruits, their ovaries are structurally limited to housing a single ovule per flower. This confirms Option A as the correct choice.