Tag: sexual reproduction in plants

Plumed seeds occur in Calotropis. The seeds are compressed, broadly ovoid, with a tufted micropylar coma of long silky hair. The crown of the hair on the seeds favouring anemochory give the plumed appearance.

Upon fertilization while ovule develops into seed. Pericarp develops from carpel. The pericarp is typically made up of three distinct layers, the epicarp, which is the outermost layer, the mesocarp, which is the middle layer and the endocarp, which is the inner layer surrounding the ovary or the seeds. In a citrus fruit, the epicarp and mesocarp make up the peel.
Therefore, the correct answer is option C.

Nelumbo nucifera, also known as Indian lotus, sacred lotus, bean of India, or simply lotus, is one of two species of aquatic plant in the family Nelumbonaceae. This plant is an aquatic perennial. Under favourable circumstances, its seeds may remain viable for many years, with the oldest recorded lotus germination being from that of seeds 1,300 years old recovered from a dry lake bed. 

Vivipary is a condition where plants produce seeds which germinate before they detach from the parent. 
Xerophytes are terrestrial plants which have adapted to survive in environment with little water, like desert or ice covered region. Seeds of such plants are modified to require more water before germination, so to make sure that there is sufficient supply of water for seedling survival. Hence, xerophytes do not show vivipary. 
Hydrophytes are plants which are adapted to survive in aquatic conditions.
Such plants show reproductive adaptation-
1. Production of buoyant seeds which can float on high flooded water and delay germination process.
2. Plants grow quickly after germination and form an extended shoot on water surface. 
Therefore, hydrophytes do not show vivipary. 
Epiphytes are plants which are not rooted in soil but grows on bodies of other plants. But they are not parasites, they produce their own food. Epiphytes show reproductive adaptations as,
1. They produce colorful flowers to attract many pollinators.
2. They also produce strong nectar to lure pollinators.
3. After pollination they produce large number of small seeds which can be dispersed by wind.
But epiphytes do not show vivipary.
Mangroves are various types of trees of medium height which are found in saline coastal habitat. Vivipary is a type of reproductive adaptation shown by mangroves. Mangroves show adaptation to survive in harsh, unstable, dynamic environment, low oxygen and varying salinity of soils. The salinity of the surrounding water and soil damage the seeds. The unstable flood can destroy the seeds. In such environment, if seeds are dispersed in water then their chances of survival are very less. Therefore, mangroves show vivipary.
Therefore, the correct answer is option C.

Many seeds are insensitive to light, but in a number of species, germination is stimulated or inhibited by exposure to continuous or short periods of illumination. So stimulated are many grasses, lettuce, fireweed, peppergrass, mullein, evening primrose, yellow dock, loosestrife, and Chinese lantern plant. Corn, the smaller cereals, and many legumes, such as beans and clover, germinate as well in light as in darkness.
Inhibition by light is found in chive, garlic, and several other species of the lily family, jimsonweed, fennel flower. Sometimes, imbibed (wet) seeds that do not germinate at all in darkness may be fully promoted by only a few seconds or minutes of exposure to white light or to karrikin. The best-studied case of this type, and one that is a milestone in plant physiology, concerns seeds of the Grand Rapids variety of lettuce, which is stimulated to germination by red light (wavelength about 660 nanometres) but inhibited by far-red light (wavelength about 730 nanometres). Red light inhibits stem elongation and lateral root formation but stimulates leaf expansion, chloroplast development, red flower coloration, and spore germination. Such stimulation by red light can be reversed by exposure to far-red light. So, red light is most effective in seed germination compared to green, blue and far red light. 
Therefore, the correct answer is option C.

Tetrazolium salt stains all living tissue in the seed embryo red. Thus, enabling trained analysts to determine the seeds viability or otherwise. The tetrazolium test is used to give a quick estimate of germination potential. The result of a tetrazolium test will generally predict the germination test result closely, however the tetrazolium test will not detect certain types of abnormalities nor will it give any indication of disease levels, chemical damage or dormancy. The viability of a seed is tested by tetrazolium salts. The viable seeds when respire reduce the colourless tetradyes into highly coloured compounds, i.e. 2, 3, 5 triphenyltetrazolium chloride is reduced to triphenylformazon which is red in colour. 
Therefore, the correct answer is option B.

Seed hairs of Gossypium are purely cellulosic and of commercial importance. Fibres grow from the seed coat to form a boll of cotton lint. The boll is a protective fruit and when the plant is grown commercially, it is stripped from the seed by ginning and the lint is then processed into cotton fibre. Cotton is a soft, fluffy staple fibre that grows in a boll or protective capsule, around the seeds of cotton plants of the genus Gossypium in the family of Malvaceae. The fibre is almost pure cellulose. So, pure cellulose is obtained from seed hairs and not from root hairs, stem hairs and leaf hairs. 
Thus, the correct answer is option D.

The plant is best known for its seeds, which are used as beads and in percussion instruments and which are toxic due to the presence of abrin. The plant is native to India and grows in tropical and subtropical areas of the world where it has been introduced. It has a tendency to become weedy and invasive where it has been introduced.
The seeds of Abrus precatorius are much valued in native jewellery for their bright colouration. Most beans are black and red, suggesting a ladybug, though other colours are available. Jewellery-making with jequirity seeds is dangerous and there have been cases of death by a finger-prick while boring the seeds for beadwork.
In Trinidad in the West Indies, the brightly coloured seeds are strung into bracelets and worn around the wrist or ankle to ward off jumbies or evil spirits and mal-yeux-, the evil eye. The Tamils use Abrus seeds of different colours. The red variety with black eye is the most common, but there are black, white and green varieties as well.
The seeds of Abrus precatorius are very consistent in weight. Formerly, Indians used these seeds to weigh gold using a measure called as Ratti, where 8 Ratti = 1 Masha. 12 Masha = 1 Tola (11.6 Grams). So, Abrus precatorius plant's seeds are used as jeweller's weight and not of Cajanus cajan (pigeon pea), Lens culinaris (lentil) and Glycine max (soya bean). 
Thus, the correct answer is option D.

After fertilization, zygote is formed which develops embryo, which forms the future plant. The endosperm cells serve as a source of nutrition for the developing embryo. The ovule becomes the seed. The ovary becomes the fruit. In most of the plants the antipodals and synergids disintegrate before, during or immediately after fertilization. The outer and inner integuments of the ovule become the testa or the seed coat of the seed.  Petals and sepals fall off. 
Thus, the correct answer is option (A), 'Seed.'