Test: Sexual Reproduction in Flowering Plants - 4 - NEET MCQ

Albuminous seeds are the seeds which have food stored in the special nourishing tissue called as endosperm that remains persistent till maturity. Cotyledons only act as food sucking organs and not food storage organs e.g., Castor seed. Non-albuminous seeds are the seeds which have the stored food and the cotyledons in a special structure called as a kernel. It does not remain until the embryo is mature. e.g. Pea seed.

Topic in NCERT: Seed

Line in NCERT: "Albuminous seeds retain a part of endosperm as it is not completely used up during embryo development (e.g., wheat, maize, barley, castor). Non-albuminous seeds have no residual endosperm as it is completely consumed during embryo development (e.g., pea, groundnut)."

To determine the correct statements regarding the structure of a monocot seed:
- Statement I: A is pericarp.
- The pericarp is the outermost layer of a fruit formed from the ovary wall, and A represents this layer in the seed.
- Statement II: B is the cotyledon of the monocot seed.
- This is incorrect; B represents the endosperm, not the cotyledon.
- Statement III: C is triploid in nature and develops before B.
- This is incorrect; C is the scutellum, which is diploid.
Therefore, only Statement I is correct.

In the embryo sac or the female gametophyte, two synergids and an egg form the egg apparatus at the micropylar end. The synergids have specialized thickenings called the filiform apparaus that guides the pollen tube into the embryo sac for fertilization and degenerate. After fertilization the egg forms the zygote and the polar cell forms the PEN.

Topic in NCERT: POST-FERTILISATION: STRUCTURES AND EVENTS

Line in NCERT: "Degenerating synergids" "Degenerating antipodal cells"

Each anther lobe develops two pollen sacs. Thus, a two-lobed anther develops four pollen sacs situated at four corners of the anther. The wall layers from the periphery to centre consist of:

• A single layer of epidermis
• A single layer of endothecium
• One to three middle layers
• A single layer of tapetum

Topic in NCERT: Structure of microsporangium
Line in NCERT: "four wall layers, the epidermis, endothecium, middle layers and the tapetum surround the microsporangium."

- False fruits develop not only from the ovary, as the thalamus also contributes to fruit formation in false fruits. 

- In the given diagram, A represents the thalamus and B represents the achene.
- Therefore, Statement I is incorrect, and Statement II is correct.
- The correct answer is option B Statement I is incorrect, Statement II is correct.

Topic in NCERT: FALSE FRUITS
Line in NCERT: "However, in a few species such as apple, strawberry, cashew, etc., the thalamus also contributes to fruit formation. Such fruits are called false fruits."
Diagram from NCERT: 

A fruit is the seed- bearing structure in flowering plants also referred to as angiosperms produced from the ovary after flowering. Rather, in some fruits, it is not the ovary that produces the fruit. In fact, other parts of the flower, just like the thalamus, inflorescence, and calyx are modified to become an area of the fruit.
Topic in NCERT: False Fruits
Line in NCERT: "In a few species such as apple, strawberry, cashew, etc., the thalamus also contributes to fruit formation. Such fruits are called false fruits."

Meiosis occurs in:

• Spore mother cells: Meiosis is a type of cell division that occurs in spore mother cells. These cells undergo meiosis to produce haploid spores, which will later develop into gametes.

Topic in NCERT: MEGASPOROGENESIS
Line in NCERT: "The MMC undergoes meiotic division."

It is the ovule which develops into a seed, so number of seeds is equal to the number of ovules.

Topic in NCERT: The Megasporangium (Ovule)

Line in NCERT: "The number of ovules in an ovary may be one (wheat, paddy, mango) to many (papaya, water melon, orchids)."

The correct option is A Both assertion and reason are true and reason is a correct explanation of the assertion.
In angiosperm, triploid endosperm is formed by fusion of secondary nucleus and second male gamete. This tissue is used by developing embryo.
Topic in NCERT: Endosperm
Line in NCERT: "Endosperm development precedes embryo development. The primary endosperm cell divides repeatedly and forms a triploid endosperm tissue. The cells of this tissue are filled with reserve food materials and are used for the nutrition of the developing embryo. "

• The tapetum which is present along with the embryo to provide nourishment for the growing embryo. It is found in sporangium, particularly within the anther of flowering plants. It is important for the development of pollen grains. The cells are usually bigger and normally have more than one nucleus per cell.
• Sporogenous tissues are diploid in nature.
• Endothecium - secretes materials essential for the proper maturation of the pollen grains.
• Intine is the inner layer; outer tough layer of pollen is called as exine.

Topic in NCERT: Tapetum

Line in NCERT: "The innermost wall layer is the tapetum. It nourishes the developing pollen grains."

Topic in NCERT: Embryo
Line in NCERT: "A typical dicotyledonous embryo , consists of an embryonal axis and two cotyledons. The portion of Figure : A typical dicot embryonal axis above the level of cotyledons is the epicotyl, which terminates with the plumule or stem tip. The cylindrical portion below the level of cotyledons is hypocotyl that terminates at its lower end in the radicle or root tip. The root tip is covered with a root cap."
Diagram in NCERT:

• Statement in option [A] is incorrect and can be corrected as Embryo sac is not the post-fertilisation product.
• Following are the post-fertilisation changes Ovule converted into seed.
• Ovary converted into fruit. Zygote converted into embryo. Central cell converted into endosperm.

Topic in NCERT: POST-FERTILISATION: STRUCTURES AND EVENTS

Line in NCERT: "After fertilisation, ovary develops into fruit and ovules develop into seeds."

Endospermic seeds are those that have an endosperm in the mature seed. It is fleshy, oily, surrounds the embryo, and functions as the sole food storage organ. Inside the seed coat, a thin and papery cotyledon is present. Monocot plants have endospermic seeds.

Topic in NCERT: Seed

Line in NCERT: "Albuminous seeds retain a part of endosperm as it is not completely used up during embryo development (e.g., wheat, maize, barley, castor)."

Tranverse section of a young anther

Making hybrid crops into apomicts ensures that the hybrid characters are maintained in the progeny without segregation. This means that farmers can use the same hybrid seeds year after year without needing to buy new seeds, as the hybrid traits will remain stable. This is a significant advantage as it reduces the cost of hybrid seeds for farmers.
Line from ncert:- One of the problems of hybrids is that hybrid seeds have
to be produced every year. If the seeds collected from hybrids are sown,
the plants in the progeny will segregate and do not maintain hybrid
characters.

Topic in NCERT: HYBRID SEED PRODUCTION AND APOMIXIS

Line in NCERT: "There is no segregation of characters in the hybrid progeny."