In a flowering plant, archesporium gives rise to
In flowering plants, archesporium cells undergo periclinal (transverse) division to form outer primary parietal layer and inner sporogenous cells. Primary parietal wall after few more periclinal divisions form anther wall and sporogenous cells give rise to sporogenous tissue.
An ovule which becomes curved so that the nucellus and embryo sac lie at right angles to the funicle is
In campylotropous ovule, the body is curved but the embryosac is straight eg. Capsella. In Anatropous, the body of ovule is inverted and gets fused with funiculus along its whole length on one side (most of the angiosperms). In orthotropous condition the body of ovule lies straight and upright over the funicle. e.g. Piperaceae, Polygonaceae.
In oogamy, fertilization involves
In oogamy male and female gametes are morphologically as well as physiologically different. Female gametes are large and non-motile. Male gametes are small but motile.
Through which cell of the embryo sac, does the pollen tube enter the embryo sac?
After entering the ovule, the pollen tube is attracted towards the micropylar end of the embryosac. The attractants are secreted by synergids or help cells. The pollen tube pierces one of the two synergids and bursts open into it. The synergid is simultaneously destroyed.
Which one of the following represents an ovule, where the embryo sac becomes horseshoe shaped and the funiculus and micropyle are close to each other?
Circinotropous : The funicle is large and coiled around the ovule eg. Opuntia.
Amphitropous : Both body of ovule and embryo sac are curved. The embryo sac assumes horse-shoe shape. e.g. Papaveraceae.
Top-shaped multiciliate male gametes, and the mature seed which bears only one embryo with two cotyledons, are characteristic features of
Cycads is a group of gymnosperms which have top shaped multiciliated male gametes and each mature seed of these plants contain one embryo and two cotyledons e.g., Cycas.
In which one pair both the plants can be vegetatively propagated by leaf pieces?
Leaves of a number of plants develop or posses adventitious buds for vegetative propagation e.g., Broyophyllum, Kalanchoe, Adiantum caudatum.
Why is vivipary an undesirable character for annual crop plants?
Vivipar y is the condition when seeds germinate on the plant. It is an undesirable character for annual crop plants because germinated seeds can not be stored under normal conditions for the next season.
The arrangement of the nuclei in a normal embryo sac in the dicot plants is
In a dicot plant general arrangement of nuclei in the embryosac is that 3 nuclei in 3 cells of egg apparatus (one egg cell & 2 synergids) at micropylar end and 2 polar nuclei in almost middle region and 3 nuclei in the form of antipodals at the distal end from micropyle, towards nucellus. So total nuclei 3 + 2 + 3.
What would be the number of chromosomes in the cells of the aleuron layer in a plant species with 8 chromosomes in its synergids?
Aleurone layer is the layer formed by the endospermic tissue in the members of family Graminae eg. wheat, rice, maize etc. Obviously it will be a triploid tissue. So if synergids have 8 no. of chromosomes which are haploid than aleurone- layer must have 24 chromosomes.
Which one of the following is surrounded by a callose wall?
The wall of the pollen mother cell (microspore mother cell) is deposited by callose (β-1, 3-glucan). Callose plays a significant role in reproductive biology of angiosperms. It acts as a temporary wall to prevent the product of meiosis from cohesion and fusion and its dissolution results in the release of free spores.
Male gametes in angiosperms are formed by the division of
Generative cell which is a cell of the male gametophyte or pollen grain in seed plants that divides to give rise directly or indirectly two sperms.
Which one of the following pairs of plant structures has haploid number of chromosomes?
The egg cell is one of the haploid cell of egg apparatus present in the micropylar end of embryo sac in seeded plants. It is also cal led oosphere and represents the single female gamete of the embryo sac. Antipodal cells are the haploid cells, usually three in number, present in embryo sac at the opposite end of micropyle. Their function is unknown and at fertilization, they may disintegrate or multiply and enlarge.
Endosperm is consumed by developing embryo in the seed of
In pea, endosperm is consumed by developing embryo in the seed. The endosperm is completely absorbed by the growing embryo and the food reserve gets stored in the cotyledons. Such seeds are called non endospermic or exalbuminous.
Dry indehiscent single-seeded fruit formed from bicarpellary syncarpous inferior ovary is
Dry indehiscent single-seeded fruit formed from bicarpellary syncarpous inferior ovary is cypsela. Cypsela is also called inferior, false or pseudocarpic achene, the thin friut wall (developed from peri carp and thalamus)is attached to the seed at one point but the fruits develops from an inferior, unilocular and uniovuled ovary, e.g., sunflower, marigold. Some cypsela develop pappus for dispersal e.g. Soncus, Taraxacum.
The fleshy receptacle of syconus of fig encloses a number of:
The fleshy receptacle of syconus of fig encloses a number of Achenes. Achene is the thin dry pericarp is free from seed except at one point. The fruit develops from a monocarpellary pistil having superior unilocular and ovuled ovary.
Unisexuality of flowers prevents
Unisexuality of flowers prevents. autogamy, but not geitonogamy. In self fertilisation , the male and female gametes are derived from the same individual. Among plants, self fertilization also called autogamy is common in many cultivated species, eg., wheat and oats. However, self fertilization is a form of inbreeding and does not allow for the mixing of genetic material; if it occurs over a number of generations it will result in offspring being less vigorous and productive than those resulting from cross fertilization.
What does the filiform apparatus do at the entrance into ovule?
Filiform apparatus helps in the entry of pollen tube into a synergid in ovule. Filiform apparatus is in form of finger like projection comprising a core of micro fibrils enclosed in a sheath. The filiform apparatus resembles transfer cells" meant for short distance movement of metabolites. The filiform apparatus responsible for the absorption of food from the nucleus.
The fr uit is chambered, developed from inferior ovary and has seeds with succulent testa in
The fruit of pomegranate is chambered, developed from inferior ovary and has seeds with succulent testa. The fruit is Balausta. It is a special type of false or pseudocarpic berry in which the syncarpous pistil consists of two rows of fused carpels, one above the other.
Afruit developed from hypanthodium inflorescence is called
The fig (Syconus) is an aggregate fr uit, consisting of numerous seed-like pericarps inclosed within a hollow, fleshy receptacle where the flowers were attached. This fruit developed from hypanthodium inflorescence.
Cotyledons and testa respectively are edible parts in
Cotyledons and testa respectively are edible parts in groundnut and pomegranate. A cotyledon is a significant part of the embryo within the seed of a plant. Upon germination, the cotyledon may become the embryonic first leaves of a seedling. Testa is often thick or hard outer coat of a seed.
An example of a seed with endosperm, perisperm, and caruncle is
An example of a seed with endosperm, perisperm, and caruncle is castor. Castor seed is the source of castor oil, which has a wide variety of uses. The seeds contain between 40% and 60% oil that is rich in triglycerides.
Apomictic embryos in citrus arise from
Apomixis is an asexual type of reproduction in which the plant embryos grow from egg cells without being fertilized by pollen-the male part of the plant. In citrus, apomictic embryos arise from maternal sporophytic tissue like nucellus and integuments in ovule. This type of embryony is called adventive embryony.
Transfer of pollen grains from the anther to the stigma of another flower of the same plant is called
Geitonogamy is the process of transfer of pollen grains from the anther to the stigma of another flower of the same plant. Example, maize.
The scutellum observed in a grain of wheat or maize is comparable to which part of the seed in other monocotyledons?
Scutellum is the modified cotyledon observed in a grain of wheat or maize. It lies between embryo and the endosperm.