Tag: structure of monocot and dicot seed

A. Aleurone layer- In monocotyledonous endospermic seed, endosperm is surrounded by a special one- cell thick layer, called aleurone layer. The cells of aleurone layer are filled with proteinaceous aleurone grains which play an important role at the time of germination.

B. Coleorhiza- Protective sheath of radicle.

C. Scutellum- In monocotyledonous endospermic seed, the embryo consists of an upper shield shaped scutellum wich is actually a reduced cotyledon. The scutellum is closely pressed against the endosperm and helps in the translocation of nutrients from endosperm to the growing embryo at the time of germination and seedling growth.

D. Hilum- It is the point of attachment of the body of the ovule with the funiculus.

In monocots, particularly the grasses where the fruit is a caryopsis, the cotyledon forms a shield like structure the scutellum. Its function is to digest the endosperm and direct the nutrients to the developing embryo. It does not form green leaf like structures as in dicots.

Aleurone layer - a layer of protein storage cells,  present in cereal, maize seed, and is a  form of reserved food material.

In monocots, sieve tube first appears in leaves. The main function of the sieve tube is transport of carbohydrates, primarily sucrose, in the plant (e.g., from the leaves to the fruits and roots). Unlike the water-conducting xylem vessel elements that are dead when mature, sieve elements are living cells. They are unique in lacking a nucleus at maturity.

Long filamentous threads protruding at the end of a young cob of maize are styles. The apex of the stem ends in the tassel, an inflorescence of male flowers. When the tassel is mature and conditions are suitably warm and dry, anthers on the tassel dehisce and release pollen. Maize pollen is anemophilous and because of its large settling velocity, most pollen falls within a few meters of the tassel. Elongated stigmas, called as silks, emerge from the whorl of husk leaves at the end of the ear. They are often pale yellow and  like tufts of hair in appearance.
At the end of each is a carpel, which may develop into a kernel if fertilized by a pollen grain. The pericarp of the fruit is fused with the seed coat referred to as caryopsis, typical of the grasses and the entire kernel is often referred to as the seed. The cob is close to a multiple fruit in structure, except that the individual fruits never fuse into a single mass. 
Thus, the correct answer is option B.

Seeds of flowering plants are either dicotyledonous or monocotyledonous. While, the dicotyledons are characterized by two kidney shaped cotyledons, these are either non-endospermic exalbumnous or endospermic depending on the presence of endosperm and food storage areas. The monocotyledons with a single cotyledons are also differentiated as endospermic and non-endospermic based on the presence of endosperms. In case of Alisma and orchids, the seeds are extremely small with an undifferentiated embryo that lacks endosperm. They are referred to as acotyledons or exceptional monocots.
Thus, the correct answer is option C.

Monocot seeds are mostly endospermic, but Alisma is a monocot non -endospermic seed. In most monocotyledons the seeds are endospermic. The embryo is embedded in the endosperm which the seedling will use upon germination. In few they are non-endospermic seeds like that of dicotylednous plants where the endosperm is absorbed by the embryo as the latter grows within the developing seed and the cotyledons of the embryo become filled with stored food. 
Therefore, the correct answer is option C.

Cocos nucifera, the coconut palm, is a monocot perennial member of the Arecaceae, cultivated in tropical areas worldwide for its fruit and fiber. Coir, the fiber from the husk of the coconut is used in ropes, mats, door mats, brushes, sacks, caulking for boats, and as stuffing fiber for mattresses. It is used in horticulture in potting compost, especially in orchid mix. Thus, option A is correct. Corchorus, Clematis and Crotalaria are dicot plants. Thus, other options are wrong.

Sunflower is an oil seed plant (Helianthus annus L). The seeds of sunflower has 39 to 49% of oil.  It is the premium cooking oil because it has high level of unsaturated fatty acids.