Reproduction - class-X

The movement of pollen tube towards embryosac though style is chemotactic as it secrets pectinases and other hydrolytic enzymes to create a passage for its entry into style .

12, 36, 24; because pollen grains are haploid while endosperm has triploid chromosome number and integument is diploid in nature.

In porogamy, filiform apparatus of synergids secretes, some chemotropically active sunstances, which direct the pollen tube towards micropyle of ovule.

The pollen grain wall consists of an outer exine (sporopollenin) and an inner intine. The intine is composed of pecto-cellulose.

This type of tapetum can be seen easily in Alisma, Butomus, Tradescantia, and Typha, etc. The tapetal cells fuse among themselves for forming a tapetal plasmodium. The protoplast of the fused tapetal cells then moves into the locule, where they surround the pollen mother cells or pollen grains. This protoplast movement into the locule is taking place during meiotic prophase. 

Thus the correct answer is option D.

The pollen wall actually is the multi-layered structure that includes an intine, which is composed mainly of polysaccharide, and an exine, which consists mainly of sporopollenin. The exine can be further divided into the sexine and nexine. Sexine is the single layer of bacula which is covered by a layer of the tectum.

So the correct answer is C.

The anther is responsible for the production of microspores (pollen grains), the production of Ubisch bodies (which contribute to exine formation), and the protection/storage of developing pollen.

In the development of the ovule, the archesporial cell typically differentiates from the nucellar tissue in the hypodermal region at the micropylar end.

Embryology is the branch of biology that studies the formation, growth, and development of an embryo from an egg (zygote).

Abundant occurrence and preservation of the fossil pollen grains result from the extremely resistant nature of the outer wall of the pollen grains. This wall is the exine and composed of a compound commonly known as sporopollenin. It originates from the polymerization of carotenoids and carotenoid esters.

Thus the correct answer is B. 

Antipodal cells are part of the mature embryo sac and are haploid (n). The egg cell is also haploid (n). Nucellus and megaspore mother cells are diploid (2n).

A pollen grain is the male gametophyte in seed plants. At the time of release, it is considered an immature male gametophyte.

Nucellus, embryo sac, and micropyle are all parts of the ovule. A pollen grain is a separate structure (the male gametophyte) that is not part of the ovule itself.

Asphodelus is known to have a tritegmic ovule, meaning it has three integuments. Most angiosperms are bitegmic or unitegmic.

The pollen is having two layers. The tough outer layer is referred to as the exine. This sophisticated and complex outer layer is having a compound known as sporopollenin. It is waterproof, resistant to the deterioration and very stiff as well. This shell is actually one of nature's most advanced polymers. It ensures that the tender cells must have a strong chance of survival.

Thus the correct answer is option D.

A crassinucellate ovule is characterized by a well-developed nucellus, where the primary parietal cell divides to form a layer of parietal tissue between the epidermis and the megaspore mother cell.

Each microsporocyte (microspore mother cell) undergoes meiosis to produce 4 microspores (pollen grains). Therefore, 4 microsporocytes produce 4 * 4 = 16 pollen grains.

In an amphitropous ovule, the embryo sac is curved into a horseshoe shape, and the micropyle, chalaza, and funicle are brought close together.

The root of a flowering plant is diploid (2n = 24). Gametes are haploid (n), so they contain half the number of chromosomes, which is 12.

In angiosperms, pollen grains are typically shed at either the 2-celled stage (vegetative and generative cell) or the 3-celled stage (vegetative cell and two male gametes).

Endosperm is triploid (3n). Pisum sativum (2n=14, 3n=21), Oryza sativa (2n=24, 3n=36), Nicotiana tabacum (2n=48, 3n=72), Allium cepa (2n=16, 3n=24). Matching: a-v, b-iv, c-i, d-ii.

The exine of a pollen grain is composed of sporopollenin, which is one of the most resistant organic materials known, protecting the pollen from degradation.

The nucellus is a diploid tissue (2n). The microspore mother cell (MMC) is also a diploid cell derived from the sporophytic tissue, so it has the same chromosome number.

In angiosperms, the female gamete is the egg cell, which is located within the embryo sac inside the ovule.

Palynology is the scientific study of pollen grains and spores, both living and fossilized.

An orthotropous ovule is one where the micropyle, chalaza, and funiculus lie in a straight vertical line.

Microspore mother cells undergo meiosis to produce microspores, which then develop into pollen grains.

Option B is incorrect because multiple pollen tubes can grow into the style, although only one typically enters the ovule to effect fertilization.

The most common type of ovule in angiosperms is the anatropous ovule, not the orthotropous one.

Root cells are diploid (2n = 14). Synergids are part of the embryo sac and are haploid (n). Thus, n = 7.

After arriving at the wall of the ovary, the pollen tube enters the ovule either through the micropyle or by some other route. The entrance of the pollen tube through the micropyle is the normal condition and is known as porogamy. In some cases the pollen tube enters the ovule through the chalaza(chalazogamy e.g., Casuarina), or through integuments (mesogamy e.g. Cucurbita).

In the given figure A-central cell, B-egg nucleus, C-plasma membrane, D-synergid, E-filiform apparatus, F-male gametes, G-vegetative nucleus.

The body of the ovule consists of a mass of parenchymatous cells named nucellus. It is equivalent to megasporangium $(2n)$. Megaspore mother cell or megasporocyte is a diploid$(2n)$ cell which undergoes meiosis to form a linear tetrad of four haploid megaspores (n). Normally, the chalazal megaspore is the functional megaspore while the other three degenerate.

In many aquatic plants with emergent flowers, pollination occurs by wind or insects, e.g., lotus, water lily, water hyacinth.

One Microspore mother cell after meiosis produce 4 pollen grains.

The microspore or pollen grain is the first cell of male gametophyte. The microspore starts dividing and it is known as precocious. 

In tenuinucellate ovules, the nucellus is thin and often disappears. The endothelium (a specialized layer of the inner integument) then provides nourishment to the developing embryo sac.

The given statement is absolutely true. People lack proper knowledge about Sexually Transmitted Diseases and their aetiology. People also do not know the importance of using contraception, the importance of having protected intercourse and avoiding intercourse with unknown partners. So, creating awareness through seminars and school education camps among adolescence will do the needful.

Saheli is a new kind of oral contraceptive for females. It was developed by the Central Drug Research Institute (CDRI) in Lucknow, India. It was commercialized in 1991. So the correct option is 'Central Drug Research Institute(CDRI)'.

Reproductive health means the ability of a woman to reproduce and regulate her fertility. It also means safe pregnancy, childbirth, contraceptives, and sex. It also includes avoidance of sexually transmitted diseases (STDs). 

India was amongst the first countries in the world to initiate action plans and programs at a national level to attain total reproductive health as a social goal. These programs called family planning were initiated in 1951 and were periodically assessed over the past decades. Thus option D is the correct answer. 

IUD is the most common and effective method of contraception in India. It is cheap and is easily available. It doesn't affect the sexual activity of the user and can be fitted at home.  

Reproductive health as a total well being in physical, emotional, behavioral and social aspects of reproduction.

 In early marriage , since the age of the female partner is low , so as to give birth to a healthy child . Therefore the IMR & MMR are high in early marriages. Also in some parts of the rural India, there still exist some sex related taboos So, the correct answer is 'Both A and B'

India was the first country in the world to establish a government family planning programme way back in 1951 . This programme not only benefits the parents , but also the nation's health . This programme created a awareness among the people about the use of contraceptives , avoiding forced abortions & various types of sexually transmitted diseases . 

Sex education at a proper age is very important so as to maintain a healthy reproductive society. Also we need proper medical facilities & good knowledge of birth control devices to maintain the same 

The total number of children born or likely to be born to a woman in her lifetime if she were subject to the prevailing rate of age-specific fertility in the population is called as Total fertility rate.

IMR & MMR refer to the infant mortality rate & the maternal mortality rate respectively. While the BMR is the is the basal metabolic rate, which is the rate of energy expenditure by the body . In early marriage, since the age of the female partner is low, IMR and MMR is high