Tag: sexual reproduction in plants

Germination is the process by which a plant grows from a seed. A series of changes in the reproductive biology among the heterosporous plants led to the evolution of seed plants. In seed plants, the megaspore is retained in the megasporangium and the microspore is taken to a pollen chamber at the tip of this organ. The development and fertilization of gametophyte occur within a protected environment. A pattern that showcases evolution of seed is found among the vascular plants. In homosporous vascular plants (plants that produce only one type of spore) have exosporic gametophytesthat is, the gametophyte develops outside of the spore wall. In addition, these exosporic gametophytes are normally bisexual (produce both sperm and eggs). In heterosporous vascular plants (presence of both microspores and megaspores), development of gametophyte is endoscopic and gametophytes are unisex, producing either sperm or eggs.
Therefore, the correct answer is option B.

Lathyrism is a disease caused by eating seeds of species of Lathyrus (the grass pea), mainly L. sativus (the chickpea or khesari), L. cicera (flat-podded vetch) and L. clymenum (Spanish vetchling). It affects mostly people in Bangladesh, India, Pakistan, Nepal and Algeria but is sometimes found in France, Italy, Spain and Australia. This disease affects horses and cattle as well as in man.
Beta-Oxalyl-amino-L-alanine acid (BOAA), an excitatory neurotoxin and glutamate agonist, has been identified as the constituent of the chick pea responsible for the disease. BOAA appears to exert its effects through mitochondrial toxicity.
Prolonged use of seeds of Lathyrus sativus causes a debilitating disorder is not due to presence of glucodsinolates, amygdalin and cyanogenic glucosides. 
Therefore, the correct answer is option C.

Endosperm is a tissue produced inside the seeds of most flowering plants around the time of fertilization. It surrounds the embryo and provides nutrition in the form of starch, though it can also contain oils and protein.
Thus, the correct answer is option (B), 'Endosperm'.

• During fertilisation, there is a fusion of the male and the female gametes. 
• In the case of angiosperms, there is a phenomenon called as double fertilisation. 
• There is a formation of zygote and endosperm after triple fusion. The zygote gets transformed to form the embryo. 
• The ovule gets converted to seed and the ovary develops to form the fruit. the integuments form the seed coat. 

The outer and inner integument of the ovule are of dermal derivation. The endothelium develops from the inner layer of integument. It is also called as  integumentary tapetum. At maturity, it becomes about 14-cell layers thick. The middle layers give the shape of the ripe seed. 

A dormant seed contains only 10-15% of water and is essentially dehydrated. The seed has to absorb water in order to become active. Plants grow by absorbing nutrients from the soil and all the nutrients have to be in the dissolved form.
Irrigation does not always improve soil texture. Irrigation does not protect the crops from frost. Irrigation is the artificial application of water to the land or soil. It is used to assist in the growing of agricultural crops, maintenance of landscapes, and revegetation of disturbed soils in dry areas and during periods of inadequate rainfall.

A fruit is the seed-bearing structure in flowering plants (also known as angiosperms) formed from the ovary after flowering. Fruits are the means by which angiosperms disseminate seeds. The outer, often edible layer, is the pericarp, formed from the ovary and surrounding the seeds, although in some species other tissues contribute to or form the edible portion. The pericarp may be described in three layers from outer to inner, the epicarp, mesocarp and endocarp. A fruit results from maturation of one or more flowers, and the gynoecium of the flower(s) forms all or part of the fruit

Fertilization occurs when one of the sperm cells fuses with the egg inside of an ovule. After fertilization occurs, each ovule develops into a seed. Each seed contains a tiny, undeveloped plant called an embryo. The ovary surrounding the ovules develops into a fruit that contains one or more seeds.

After fertilization process, the different cells in the embryo sac develops to form several parts of the embryo. For instance, the outer integument forms testa, inner integument forms tegmen and ovary wall forms pericarp.

The haploid sperm and haploid egg combine to form a diploid zygote, while the other sperm and the two haploid polar nuclei of the large central cell of the megagametophyte form a triploid nucleus. It will later develop into the endosperm, nutrient tissue which provides nourishment to the developing embryo.