Case Based Questions Test: Sexual Reproduction in Flowering Plants - NEET MCQ

- A at the micropylar end.
- B being the megaspore mother cell, C representing the megaspore dyad, and D signifying the megaspore tetrad are correct placements in the diagram.
Therefore, the correct answer is D Statement I is incorrect, Statement II is incorrect
Diagram from NCERT

A diagrammatic view of a typical anatropous ovule

Topic in NCERT: The section name from which the line "d) A diagrammatic view of a typical anatropous ovule" is given is: The Megasporangium (Ovule)
Line in NCERT: "d) A diagrammatic view of a typical anatropous ovule"

The prominent pollen grain aperture called germ pore is present in exine, it is decay-resistant outer coating of a pollen grain or spore.

Topic in NCERT: Pollen Grain Structure

Line in NCERT: "The exine is made up of sporopollenin and has germ pores."

Parthenium is a invasive species in India, and its is also known as carrot grass or congress grass which is the major cause of allergy in India, the parthenium weed produces as much as 3,000 million pollen grains per square meter during the flowering season.

Topic in NCERT: Pollen Allergy and Its Causes

Line in NCERT: "It may be mentioned that Parthenium or carrot grass that came into India as a contaminant with imported wheat, has become ubiquitous in occurrence and causes pollen allergy."

Mango possess a single ovule in each ovary and orchids, watermelon, and papaya have multiple ovules present in each ovary.

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)."

Central cell form binucleate endosperm mother cell upon fertilization with one of the two sperm cells, forms triploid endosperm to nourish embryo development.

Topic in NCERT: nucleate embryo sac

Line in NCERT: "The large central cell, as mentioned earlier, has two polar nuclei."

Let's analyze the Assertion (A) and Reason (R) based on the provided text:
Assertion (A): The innermost layer of microsporangium is called tapetum.

• This statement is true. In the structure of a microsporangium, the tapetum is indeed the innermost layer, surrounding the developing pollen grains.

Reason (R): Tapetum nourishes the develop into pollen grains.

• This statement is true. The function of the tapetum is to provide nutrients and support to the developing pollen grains.

Both assertion (A) and reason (R) are true but reason (R) is not the correct explanation of assertion
Topic in NCERT: Tapetum
Line in NCERT: "The innermost wall layer is the tapetum. It nourishes the developing pollen grains."

The integuments are the outer layer(s) of the ovule and develop into a seed coat as the ovule matures following fertilization.

Topic in NCERT: Structure of microsporangium

Line in NCERT: "Four wall layers, the epidermis, endothecium, middle layers and the tapetum surround the microsporangium."

Androecium is the male part and gynoecium is the female part, and in those flower have both of these they are called bisexual flower.

Topic in NCERT: SEXUAL REPRODUCTION IN FLOWERING PLANTS

Line in NCERT: "the androecium consists of a whorl of stamens representing the male reproductive organ and the gynoecium represents the female reproductive organ."

To store pollens for years in liquid nitrogen, the correct temperature is -196°C (C: -196°C). Here's why:
- Liquid nitrogen is  ideal for long-term storage of biological samples.
- At this temperature, biological activities are significantly slowed down, preserving the integrity of the stored material.
- Extreme cold like -196°C prevents degradation and maintains the viability of the stored pollens for an extended period.
Topic in NCERT: Pollen Storage and Viability
Line in NCERT: "it is possible to store pollen grains of a large number of species for years in liquid nitrogen (-196°C)."