Ch 1Reproduction in Lower and Higher Plants — Class 12 Biology, concept-first.

Reproduction is the process by which living organisms produce young ones of their own kind. It is essential for every species: it carries the species forward from one generation to the next and so kee…

Asexual reproduction does not involve the union of two compatible sex cells (gametes). A single parent organism gives rise to offspring that are genetically identical to itself and to one another; suc…

Because plants reproducing through their vegetative parts produce offspring genetically identical to the parent, agriculture and horticulture deliberately harness this property to multiply superior or…

Sexual reproduction involves the fusion of two compatible gametes (sex cells), one contributed by each parent, and every organism must first reach reproductive maturity before it can reproduce this wa…

The androecium is the male reproductive whorl of the flower; each individual member of this whorl is called a stamen.

Microsporogenesis is the process by which the diploid microspore mother cells contained in the sporogenous tissue of the anther undergo meiotic division to produce a tetrad of four haploid microspores…

The pollen grain itself represents the very first cell of the male gametophyte generation. Immediately after (or shortly before) its release from the anther, the pollen grain undergoes its first mitot…

The gynoecium (pistil) is the female reproductive whorl of the flower, and each individual unit of the gynoecium is called a carpel, or megasporophyll.

Megasporogenesis is the process by which a diploid megaspore mother cell (MMC), which differentiates within the nucellus roughly at its centre but displaced toward the micropylar end of the ovule, und…

Because both the male gametes (locked inside non-motile pollen grains) and the female gamete (locked inside an embedded embryo sac) are themselves non-motile, and because they are produced at two phys…

Continued, generation-after-generation self-pollination tends to reduce genetic diversity and can lead to inbreeding depression, a decline in vigour and fitness in the offspring.

Pollen-pistil interaction is the entire sequence of physiological events that begins the moment a pollen grain lands on the stigma (a sporophytic tissue) and continues until the pollen tube finally en…

Double fertilization is a fertilization mechanism unique to flowering (angiospermic) plants, first discovered by the Russian botanist Nawaschin in liliaceous plants such as Lilium and Fritillaria.

Following triple fusion, the resulting triploid primary endosperm nucleus divides repeatedly by mitosis to build up a nutritive tissue called the endosperm, which develops within the ovule alongside,…

Embryogenesis, the development of the zygote into a fully formed embryo, begins only after a certain amount of endosperm has already formed around it, ensuring the developing embryo has a nutritive ti…

The ultimate goal of reproduction in any organism, plants included, is the production of offspring for the next generation, and seed formation is the principal route by which flowering plants achieve…

Apomixis is a form of reproduction in which an embryo forms through an essentially asexual route, without the formation of true gametes and without the act of fertilization, even though it occurs with…

Parthenocarpy, a term coined by the botanist Noll in 1902, is the phenomenon in which a fruit develops without the ovary having undergone fertilization at all.

Polyembryony is the occurrence of more than one embryo developing within a single seed, a phenomenon first recorded by the early microscopist Antonie van Leeuwenhoek in 1719, in seeds of the citrus ge…

The textbook's exercise opens (Q. 1, printed page 16) with seven multiple-choice questions on pollination adaptations, meiosis in the ovule, ploidy, geitonogamy, chromosome numbers, endosperm formatio…

Q. 2 of the exercise (printed page 16): ten very-short-answer questions, from the part of the gynoecium that screens pollen to the function of the filiform apparatus.

Q. 3 of the exercise (printed page 16): four short-answer questions on the commercial use of polyembryony, why pollination and seed formation matter for fruit formation, incompatibility as a barrier,…

Q. 4 of the exercise (printed pages 16-17): four long-answer questions, on double fertilization, the maturation of the microspore into the male gametophyte, dicot embryo development, and a labelled an…

Q. 5 of the exercise (printed page 17) prints seven fill-in-the-blank sentences arranged around a sectional flower diagram; each sentence points to one part of the flower, and the diagram itself shows…

Q. 6 of the exercise (printed page 17): label the parts of a seed, from the book's drawing of a bean seed, whole and opened.

Q. 7 of the exercise (printed page 17): match each structure before seed formation with the structure it becomes after seed formation.

The chapter closes (printed page 17) with a project: natural vegetative propagation by leaves only, in different vascular plants.

Sample papers and previous-year board questions for this subject.