Flowers are the reproductive part of a plant. They are also objects of ornamental, cultural, religious and social significance. All the flowering plants undergo sexual reproduction. Here is a collection of all important questions from the part that are crucial for biology NEET 2023 preparations.

Select the option depicting the correct order of development in an anther.

(a) Pollen grain → Sporogenous Tissue → Microspore → Pollen mother cell

(b) Sporogenous tissue → Male gametes → Pollen mother cell → Pollen grain

(d) Sporogenous tissue → Pollen mother cell → microspore → pollen grains

Answer: (d)

Explanation: Sporogenous cells are specialised cells found in young anthers. These cells form microspore mother cells in a sac-like structure called microsporangium. These microspore mother cells undergo meiosis to form microspores. Microspores then absorb nutrition and develop to become pollen grains.

The pollen grain is made up of two types of cells – generative cell and vegetative cell. The generative cell forms the male gametes whereas the vegetative cell forms the pollen tube.

If the number of chromosomes present in pollen mother cells (PMC) is 48, then the number of chromosomes present in the microspore is ____

(a) 24

(b) 48

(d) 56

Answer: (a)

Explanation: The pollen mother cell is a diploid structure. It undergoes meiosis to produce microspores. If the pollen mother cell has 48 chromosomes then the microspores will contain 24 chromosomes after meiotic division.

Even after killing the generative cell with a laser beam, the pollen grain of a flowering plant germinates and produces normal pollen tube because

(a) laser beam stimulates pollen germination and pollen tube growth.

(b) the laser beam does not damage the region from which the pollen tube emerges.

(d) the vegetative cell has not been damaged.

Answer: (d)

Explanation: The microspore undergoes mitosis to form the pollen grains. The pollen grain is composed of two layers – exine and intine. Inside the pollen, two cells are found – a bigger vegetative cell and a smaller generative cell. The generative cells give rise to male gametes and the vegetative cell being nutritive in nature help in germination and growth of pollen tube. The laser beam only damages the generative cell, not the vegetative cell, hence normal pollen tube is produced.

Which of the following is not an advantage of apomixis?

(a) assured reproduction in the absence of pollinators

(b) maternal energy not wasted in unfit offspring

(d) superior ability to adapt to changing environments

Answer: (d)

Explanation: Apomixis is the process by which seeds are produced without fertilisation. Advantages of apomixis include:

It ensures the process of pollination even in the absence of pollinators.
Maternal energy is not wasted in eliminating the unfit offspring.
Paternal energy is also saved as there is no need to produce pollen grains in some plants.

Disadvantages of apomixis include:

There is a greater chance of harmful mutations taking place.
The plants do not have the ability to adapt to changing environments.

The inner wall of pollen grain is called ______ and it is made up of ________.

(a) exine, cellulose

(b) intine, pectin

(d) exine, sporopollenin

Answer: (c)

Explanation: The pollen grain is made up of two layers –

An outer exine that is made up of sporopollenin. It is a rough structure that is resistant to extreme temperatures, acids and strong alkalis and protects the pollen from the same.
An inner intine layer that is made up of pectin and cellulose.

How many cells and nuclei are present in a mature embryo sac?

(a) 8 cells, 16 nuclei

(b) 8 cells, 8 nuclei

(d) 7 cells, 8 nuclei

Answer: (d)

Explanation: A mature embryo sac consists of two synergids, one egg cell, three antipodals with one nucleus each and one central cell with two nuclei.

Embryo sac

What is the function of the filiform apparatus?

(a) To give rise to the seed.

(b) To guide the pollen tube into the synergids.

(d) All of the above

Answer: (b)

Explanation: Filiform apparatus are special cellular thickenings found in the synergids of the embryo sac at the micropylar end. The primary function of the filiform apparatus is to guide the pollen tube into the synergids.

Which of the following is not true about microsporogenesis and megasporogenesis?

I. All the cells in the microspore and megaspore tetrad give rise to microspore and megaspore, respectively.

II. Both the processes involve meiotic division.

III. One of them occurs in the ovule and the other occurs in the megasporangium.

IV. One of them results in the formation of a mature embryo sac and the other results in the formation of pollen grains.

(a) Only I and III are not true.

(b) Only III is not true.

(d) I and II are not true.

Answer: (c)

Explanation: During megasporogenesis, only one cell from the megaspore tetrad moves forward to make the mature embryo sac, whereas the other three degenerate. Microsporogenesis and megasporogenesis both involve meiotic divisions. While microsporogenesis takes place in the microsporangium of the anther, megasporogenesis takes place in the megasporangium of the ovule. The result of megasporogenesis and microsporogenesis are megaspores and microspores, respectively. Embryo sac and pollen grains are produced by the process of megagametogenesis and microgametogenesis.

Match the following columns and choose the correct option.

Column 1	Column 2
A	Autogamy	i	Transfer of pollen grains from anther to the stigma of different plants.
B	Xenogamy	ii	Transfer of pollen grains from anther to the stigma of another flower of the same plant.
C	Geitonogamy	iii	Transfer of pollen grains from the anther to the stigma of the same flower.

(a) A-i, B-ii, C-iii

(b) A-iii, B-i, C-ii

(d) A-ii, B-iii, C-i

Answer: (b)

Explanation: There are three types of pollination –

Autogamy: The transfer of pollen grains from anther to the stigma of the same flower is known as autogamy. It is a type of self pollination.
Geitonogamy: The transfer of pollen grains from anther to the stigma of another flower in the same plant is known as geitonogamy. It is also a type of self pollination.
Xenogamy: It is a cross pollination between the pollen grain from anther of one plant to the stigma of another plant.

Fertilisation is of different types based on the route of entry of the pollen tube. Choose the correct option according to the following figure.

(a) A-Mesogamy, B-Chalazogamy, C-Porogamy

(b) A-Porogamy, B-Chalazogamy, C-Mesogamy

(d) A-Chalazogamy, B-Mesogamy, C-Porogamy

Answer: (b)

Explanation:

Fertilisation that takes place when the pollen tube enters the embryo sac through the micropylar end is known as porogamy. Example – Lily
Fertilisation that takes place when the pollen tube enters the embryo sac through the chalazal end is known as chalazogamy. Example – Casuarina
Fertilisation that takes place when the pollen tube enters the embryo sac through the integuments is known as mesogamy. Example – Cucurbita

Which of the following will not decrease inbreeding depression?

(a) Cross-pollination

(b) Producing unisexual flowers

(d) Anther and stigma growing up to same height in a bisexual flower

Answer: (d)

Explanation: The phenomena of repeated self pollination creates a condition called inbreeding depression. Inbreeding depression is the reduction in the biological fitness of an organism. When the anther and stigma grow up to a same height in a bisexual flower, there are high chances of pollen landing on the stigma and hence self pollination will occur. This will lead to an increase in inbreeding depression. Certain outbreeding devices have been adapted by plants to promote cross pollination and hence decrease inbreeding depression.

The devices include dioecious plants that prevent both autogamy and geitonogamy. E.g – apaya.
Dichogamy is another device where either the male or frame reproductive part matures before the other one of the flower. Protandry is when the anther develops first (E.g – Salvia, sunflower) and protogyny is when the stigma develops first (E.g – Mirabilis jalapa, Gloriosa).
Self incompatibility is when the pollen grains are not able to germinate on the stigma of the same flower. E.g – Potato, tobacco and crucifers.
Heterostyly is a device where the anther and stigma are placed at different locations so as to avoid self pollination. E.g – jasmine, primrose, Lythrum.

Pollen-pistil interaction refers to all the events starting from

(a) Pollen deposition on the stigma until male gamete fuses with the egg cell.

(b) Pollen deposition on the stigma until the pollen tube enters the ovule.

(d) Pollen deposition on stigma until the germination of pollen grains.

Answer: (b)

Explanation: The pollen-pistil interaction is not a momentary interaction between the pollen and the pistil but it is a continuous dialogue between the pollen grains and female reproductive organs until the pollen tube enters the ovule. The pistil checks if the incoming pollen is compatible to its type and then only the pollen is allowed to go further.

Which of the following options describes the correct steps in artificial hybridisation?

(a) Bagging, emasculation, pollination, rebagging

(b) Emasculation, bagging, pollination, rebagging

(d) Emasculation, pollination, bagging

Answer: (b)

Explanation: A technique that has been employed to develop superior varieties of plants is known as artificial hybridisation. Plants with desirable characteristics are chosen and crossed to obtain a hybrid progeny. This process has four steps:

Emasculation: The process of removal of anthers before its dehiscence is known as emasculation.
Bagging: The process of covering the stigma so that no other pollen can land on it is known as bagging.
Pollination: The stigma reaches its receptivity and then the desired pollen grains are brushed over the stigma for pollination.
Rebagging: The stigma is bagged again to avoid any contamination.

Which of the following statements regarding post-fertilisation development in flowering plants is incorrect?

(a) Ovary develops into a fruit

(b) Ovules develop into an embryo sac

(d) PEC forms the endosperm

Answer: (b)

Explanation: Events that occur after fertilisation are called post-fertilisation events. Here, the zygote develops into an embryo by the process of embryogeny. Primary endosperm cells divide repeatedly to form the triploid and nutritive endosperm. The ovary develops into a fruit and the ovule forms seeds. The embryo sac is formed much before fertilisation.

Which among the following transforms into a seed?

(a) Ovary

(b) Integumented megasporangium

(d) Both a and b

Answer: (b)

Explanation: Ovule, also called as integumented megasporangium, develops into seed after fertilisation.

Non-albuminous seed is produced in

(a) maize

(b) castor

(d) pea

Answer: (d)

Explanation: The seeds that do not contain endosperm are called non-albuminous seeds. In the majority of dicot seeds and some of the monocot seeds, the endosperm is fully consumed during seed development, hence the food is stored in other organs like cotyledons. Examples of albuminous seeds include wheat, castor, barley and maize. Pea and groundnut seeds are examples of non-albuminous seeds.

Number of meiotic divisions required to produce 200/400 seeds of pea would be

(a) 200/400

(b) 400/800

(d) 250/500

Answer: (d)

Explanation: The pollen mother cells undergo meiotic divisions to produce a tetrad of microspores. Hence, 200 pollen grains will be produced from 50 meiotic divisions. Similarly, 100 eggs are produced from 100 divisions of megaspores, thus 200 eggs will be produced by 200 divisions of megaspores. Thus, 200 pollen grains (50 divisions) and 200 egg cells (200 divisions) will produce 200 pea seeds (a total of 250 divisions). Similarly, 400 pea seeds will be produced by 500 divisions.

Which of the following can be termed as false fruits?

(a) Fruits that develop only from the ovary.

(b) Parthenocarpic fruits

(d) Fruits that have no seeds

Answer: (c)

Explanation: There are three types of fruits:

True Fruits: Fruits that develop from mature ovaries. E.g., pea, grapes, mango, coconut
False Fruits: Fruits that develop from other parts of the flower other than ovary. E.g., apple, pear
Parthenocarpic Fruits: Fruits that develop without the fertilisation of ovules. E.g., banana, seedless watermelon and grapes

The layer of the fruit wall surrounding the outer wall of the seed is called

(a) testa

(b) epicarp

(d) tegmen

Answer: (a)

Explanation: The wall of the fruit is called pericarp. It is divided into three layers – epicarp (the outer skin), mesocarp (tissue between epicarp and endocarp) and endocarp (innermost layer of the fruit that surrounds the seed). The outer seed coat is called the testa and the inner seed coat is called the tegmen.

Which among the following show true polyembryony?

1. Opuntia

2. Mangifera

3. Saxifraga

4. Bergenia

(a) 1 only

(b) 2 only

(d) 2,3 and 4 only

Answer: (c)

Explanation: The occurrence of more than one seed in an embryo is called polyembryony. There are two types –

True Polyembryony: In this type, the embryo is formed inside the embryo sac, polyembryony arises due to the projection of dividing nucellus inside the embryo sac. E.g., Opuntia, Mangifera
False Polyembryony: In this type, two or more nuclei fuse and more than two embryo sacs are formed inside the nucellus. E.g., Saxifraga, Bergenia

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