Seeds - structure and germination - class-IX

Pea and castor are dicots (2 cotyledons), while maize is a monocot (1 cotyledon). Thus, the sequence is 2, 2, and 1.

In monocot seeds, the coleorhiza protects the radicle, and the coleoptile protects the plumule during germination.

Dicotylodoneae is a group of angiosperms that are characterized by tap root system, vascular tissue present in columns, posses xylem vessels, leaves have reticulate venation, stem with open collateral vascular bundles arranged in a ring and seed are covered by fruits and show secondary growth.

Perisperm differs from endosperm in being a diploid tissue. 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. These are typically triploid but can vary widely from diploid. Endosperm that is diploid, resulting from the fusion of a pollen nucleus with one, rather than two, maternal nuclei.They are both nutritive layers in a seed. Perisperm develops from the nucellus of the seed and the endosperm develops when the sperm cell fuses with two haploid polar nuclei (contained in the central cell) in the centre of the embryo sac (or ovule). The resulting cell is triploid (3n). This triploid cell divides through mitosis and forms the endosperm, a nutrient-rich tissue, inside the seed. 

Seed coat is not thin in coconut. The fruit is an indehiscent fruit in which an outer fleshy part-exocarp or skin and mesocarp or flesh surrounds a shell of hardened endocarp with a seed inside. These fruits usually develop from a single carpel and mostly from flowers with superior ovaries. The definitive characteristic of a drupe is that the hard, lignified stone is derived from the ovary wall of the flower. The coconut is  a drupe, but the mesocarp is fibrous or dry, so this type of fruit is classified as a simple dry fruit, fibrous drupe. 
Therefore, the correct answer is option A.

Wheat grain is caryopsis. A caryopsis is a type of simple dry fruit that is monocarpellate and indehiscent and resembles an achene, except that in a caryopsis, the pericarp is fused with the thin seed coat. The caryopsis is popularly called as a grain and is the fruit typical of the family Poaceae (or Gramineae), which includes wheat, rice and corn. The term grain is also used in a more general sense as synonymous with cereal. Considering that the fruit wall and the seed are intimately fused into a single unit and the caryopsis or grain is a dry fruit, little concern is given to technically separating the terms fruit and seed in these plant structures. 
Thus, the correct answer is option C.

Cotyledonary node of embryo lies between epicotyl and hypocotyl. The epicotyl is the embryonic shoot above the cotyledons. In most plants the epicotyl will eventually develop into the leaves of the plant. In dicots, the hypocotyl is what appears to be the base stem under the spent withered cotyledons and the shoot just above that is the epicotyl.
In monocot plants, the first shoot that emerges from the ground or from the seed is the epicotyl, from which the first shoots and leaves emerge.
Therefore, the correct answer is option C.

The seed is endospermic in Ricinus. A characteristic of castor seed is the presenee of caruncle which develops from peduncle. The fruit is a spiny, greenish capsule containing large, oval, shiny, bean-like, highly poisonous seeds with variable brownish mottling.
A capsule is a type of simple, dry fruit produced by many species of flowering plants. A capsule is a structure composed of two or more carpels. Castor seeds have a warty appendage called as the caruncle, which is a type of elaiosome. The seeds are endospermic or albuminous where the embryo is embedded in the endosperm and nucellus, which the seedling will use upon germination. 
Therefore, the correct answer is option A.

In coconut, the fruit is a drupe, a thin embryo is inconspicuous and endosperm is edible. The coconut is a drupe, a multicarpellary ovary is not found  in coconut. The mesocarp is fibrous or dry, so this type of fruit is classified as a simple dry fruit, fibrous drupe. A drupe otherwise is an indehiscent fruit in which an outer fleshy part-exocarp, or skin and mesocarp or flesh surrounds a shell of hardened endocarp with a seed inside. These fruits usually develop from a single carpel and mostly from flowers with superior ovaries. The definitive characteristic of a drupe is that the hard, lignified stone  is derived from the ovary wall of the flower.
Therefore, the correct answer is option D.

In agriculture, the majority of the biomass produced comes from monocots. These include not only major grains (rice, wheat, maize, etc.), but also forage grasses, sugar cane, and the bamboos. Other economically important monocot crops include various palms (Arecaceae), bananas (Musaceae), gingers and their relatives, turmeric and cardamom (Zingiberaceae) and the onions and garlic family (Amaryllidaceae). Additionally, most of the horticultural bulbs, plants cultivated for their blooms, are monocots, such as lilies, daffodils, irises, amaryllis, cannas, bluebells and tulips. Maize is a flowering plant and not a dicot or pteridophyte. Almond is a dicot as it has  two cotyledons in their seeds. 

Radicle is the first part of a seedling to emerge from the seed during the process of germination. The radicle is the embryonic root of the plant and grows downward in the soil.
Plumule is the young shoot of  a plant embryo above the cotyledons, consisiting of the epicotyl and often of immature leaves.
Cotyledon is the significant part of the embryo within the seed of a plant. Upon germination, the cotyledon may become the embryonic first leaves of a seedling.
Ovule is the structure that gives rise to and contains female reproductive cells.
Thus, the correct answer is option (B), 'Plumule'.

Orchid seeds are small, light and contain little food reserves. A single seed capsule may contain1,500 to 3,000,000 seeds. Orchid seeds are small, dry, dusty and weighing as little as 0.004 mg.
So, the correct answer is 'small and light'

The coconut tree is in the family of palm trees, and palm trees are monocotyledons. Almonds, mango and sunflower are dicots. 

Seeds germinate in the presence of warmth, moisture and air. No light is needed for germination. Seeds generally contain starch as food supply. So, light is not needed for food production also during germination.

A seed contains the embryo (new generation) and the seed coat/endosperm (remnants of the parent plant/previous generation), effectively housing two generations.

If food is stored inside the endosperm then the cotyledons become small and thin. Such seeds are called as endospermic seeds or albuminous seeds. For example, maize, wheat and other cereals, castor bean seeds and coconut seeds.
So, the correct answer is 'Castor'

The pericarp of the maize is fused with the seed coat known caryopsis. The entire kernel is referred to as the seed.
Therefore, the correct answer is option A.

Viviparous plants produce seeds that germinate before they detach from the parent plant. In Rhizophora (mangroves), the seed germinates and develops into the seedling when it still attached to the parent plant
So, the correct answer is 'Rhizophora'

In monocot seeds like wheat or maize, the scutellum is a modified cotyledon that serves to absorb nutrients from the endosperm for the developing embryo.

 A. Cuscuta- Dodder is parasitic on a very wide variety of plants, including a number of agricultural and horticultural crop species, such as alfalfa, lespedeza. It has no cotyledons.

B. Santalum is a genus of woody flowering plants, the best known and commercially valuable of which is the Indian sandalwood tree. It has two cotyledons.

C. Lodoicea, commonly known as the sea coconut, it has one cotyledons.

So, the correct answer is 'Cuscuta'.

Monocots seed- one cotyledons.

Apogamy is the development of an embryo from a cell other than the egg cell (like synergids or antipodals) without fertilization. Parthenocarpy refers to fruit development without fertilization, and vivipary is seed germination while still attached to the parent plant.

Polyembryony refers to the phenomenon of having more than one embryo in the same seed. In Citrus, a seed has $2-40$ embryos, one normal embryo and the rest adventitive embryos(mostly nucellar). In adventitive embryony, an embryo develops directly from a diploid cell other than egg like that of nucellus and integument, e.g., Citrus, Opuntia.

Synthetic seeds are created by encapsulating somatic embryos in a protective, nutrient-rich hydrogel, such as sodium alginate, to facilitate handling and storage.

Endosperm represents the food storing tissue of a seed. It is produced as a result of double fertilisation in angiosperms. In most monocots and some dicot seeds, the food reserve remains in the endosperm. They are called endospermic or albuminous seeds, e.g., maize, wheat, castor bean, coconut, barley, rubber. However, in the majority of dicot seeds(e.g., orchids, Sagittaria), the endosperm is consumed during seed development and the food is stored in cotyledons and other regions. They are called non endospermic or exalbuminous seeds.

Stratification is a horticultural practice of exposing seeds to cold, moist conditions to simulate winter and break physiological dormancy, allowing them to germinate.

Castor seeds (Ricinus communis) are albuminous (endospermic) and possess a perisperm (remnant of nucellus) and a caruncle (a fleshy outgrowth near the hilum).

The assertion is correct but the reason for the assertion is not right. Maize is an albuminous seed. The seeds are endospermic or albuminous where the embryo is embedded in the endosperm and nucellus, which the seedling will use upon germination. In maize the pericarp of the fruit is fused with the seed coat referred to as caryopsis. The cob is close to a multiple fruit in structure, except that the individual fruits -the kernels never fuse into a single mass. The grains are about the size of peas, and adhere in regular rows around a white, pithy substance, which forms the ear.
Therefore, the correct answer is option C.

Seeds that possess a special food storage tissue called as the endosperm are said to be albuminous and those which have no such tissue for storage are said to be exalbuminous or non-endospermic. In albuminous seeds, food is being stored in endosperm the cotyledons are small and thin while on exalbuminous seeds cotyledon store up food and become thick and fleshy. When germination of seed takes place then food is used by embryo whether it is stored in endosperm or in cotyledon. Epigeal germination implies that the cotyledons are pushed above ground. The hypocotyl (part of the stem below the cotyledon) grows, while the epicotyl (part of the stem above the cotyledon) stays the same length. In this way, the hypocotyl pushes the cotyledon upward. Hypogeal germination implies that the cotyledons stay below the ground. The epicotyl grows, while the hypocotyl stays the same length. In this way, the epicotyl pushes the plumule above the ground. 

Rosary pea (Abrus precatorius) is a slender, perennial climber, that twines around trees, shrubs, and hedges. It is a legume with alternate compound leaves, 2 to 5 inches long, with 5 to 15 pairs of oblong leaflets. 

The edible parts of the seeds mentioned are as follows,
French Bean- cotyledons, Coconut - endosperm, testa, cotyledon and embryo
cashew nut - cotyledon, litchi - juicy aril,
groundnut - seeds, pomegranate - testa,
walnut - cotyledons, tamarind - mesocarp,
Therefore, the correct answer is option A.

The aleurone cells are characterized by the presence of thick walls and
non-vacuolated cytoplasm interconnected by plasmodesmata. The most
prominent organelles of these cells are aleurone grains, followed by
sphaerosomes. Aleurone grains are surrounded by a single unit membrane
which is closely associated with sphaerosomes. Aleurone grains possess
two kinds of inclusion, besides the ground substance: (i) Globoids,
present within the globoidal cavities, contain phytic and lipids; (ii)
Protein-carbohydrate bodies, which are $1-1.5\mu$m in diameter. The
ground substance also contains high concentration of protein, but it is
less than that in the protein-carbohydrate bodies.

Cotton taken for commercial purpose is a soft, fluffy staple fibre growing in a boll from trichomes on the seed coat of the plants of the genus Gossypium  of the family Malvaceae. The cotton fibre is pure cellulose and under natural conditions, these bolls tend to increase the dispersal of the seeds.
Thus, the correct answer is option B.

Seeds are the dispersal and propagation units of the all seed plants which includes gymnosperms and angiosperms. Seeds which develop from an ovule after fertilization consists of a coat or testa that encloses an embryo made up of a plumule, a
radicle and one or two cotyledons.
The testa which needs to split open by the radicle for germination to proceed  protects the seed from fungi, bacteria and insects. The cotyledons which are fleshy in groundnut are edible and in case of pomegranate, the fleshy testa is edible.
Thus, the correct answer is option B.

1. Endosperm the white fleshy part commonly called as meat is the edible part of the coconut.
   
2. Cotyledons are the edible part in walnut and cashew nuts.
3. Mesocarp is the edible part of mango.
4. Aril is the edible part of litchi.
5. Cotyledon and testa are edible in groundnut and pomegranate.

Sorghum is a genus of plants in the grass family. Most species are native to Australia, with some extending to Africa, Asia, Mesoamerica and certain islands in the Indian and Pacific Oceans. One species is grown for grain and many of which are used as fodder plants, either cultivated or as part of pasture. The plants are cultivated in warm climates worldwide and naturalized in many places.
Sorghum is in the subfamily Panicoideae and the tribe Andropogoneae. Sorghum vulgare is the botanical name of jawar. Oryza sativa, commonly known as Asian rice, is the plant species most commonly referred to in English as rice.