Tag: growth and development in plants

In some seeds, the nucellus persists after fertilization and is referred to as perisperm (e.g., in black pepper and beet).

Fruit is a seed-bearing structure in flowering plants formed from the ovary after flowering. Fruits are the means by which angiosperms disseminate seeds.  A fruit results from maturation of one or more flowers, and the gynoecium of the flower forms all or part of the fruit. 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 from the edible portion. The pericarp may be described in three layers from outer to inner, the epicarp, mesocarp and endocarp. 

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.