Biology Test 8 (Part - I)

Filliform apparatus is found in synergid.

The aleurone layer is the proteinaceous outer layer of the endosperm in seeds like maize.

In angiosperms, pollen grains are typically released at either the 2-celled or 3-celled stage of development.

Seed viability can be assessed through various methods including germination tests and biochemical tests like the tetrazolium dye test (which uses triphenyl tetrazolium chloride).

Polygonatum species are known to require specific chilling treatments (stratification) to break seed dormancy.

The translator mechanism (or corpusculum-retinaculum complex) is a specialized structure found in the flowers of the family Apocynaceae, notably in Calotropis.

 The development of egg without fertilisation is called parthenogenesis.

Chilling treatment for breaking seed dormancy is typically conducted at low temperatures, generally in the range of 0 to 5 degrees Celsius.

The edible part of the litchi fruit is the fleshy aril, which is an outgrowth from the funicle that surrounds the seed. Mesoderm is a germ layer, cotyledons are seed leaves, and endosperm is the nutritive tissue.

A caruncle is a fleshy, outgrowth-like structure found on the seed coat, which is derived from the integuments of the ovule. It is commonly seen in seeds like castor.

Parthenocarpy is the development of fruit without fertilization. Banana is a classic example of a naturally occurring parthenocarpic fruit.

Pollen kit is a sticky, oily layer found on the surface of pollen grains in entomophilous (insect-pollinated) flowers. It helps the pollen adhere to the bodies of insects.

A typical mature female gametophyte (embryo sac) in angiosperms consists of 7 cells and 8 nuclei. These include the egg cell, two synergids, three antipodal cells, and one central cell with two polar nuclei.

Haploid callus is produced through anther or pollen culture because pollen grains are haploid. Culturing diploid tissues like leaves or embryos would result in diploid callus.

In grafting, the root system is provided by the stock (48 chromosomes, 2n = 48). The scion provides the reproductive parts; the egg is a haploid gamete (n = 12).

 The formation of embryo directly from nucellus and integument is called adventitive polyembryony.

Grafting requires the vascular cambium to align and fuse between the stock and scion. Monocots lack a vascular cambium, making successful grafting impossible.

Herkogamy (physical barriers), dichogamy (different maturation times), and self-sterility (genetic incompatibility) are all mechanisms plants use to prevent self-pollination.

Vallisneria is a classic example of hydrophily, where pollination occurs via water. The male flowers are released into the water and float to the female flowers.

 Double fertilisation refers to the fusion of one male gamete with an egg and another with 2 polar nuclei.The two central cell maternal nuclei (polar nuclei) that contribute to the endosperm arise by mitosis from the same single meiotic product that gave rise to the egg. The maternal contribution to the genetic constitution of the triploid endosperm is double that of the embryo.

In angiosperms like Maize, the endosperm is formed by double fertilization and is triploid (3n). In gymnosperms like Pinus, the endosperm is a haploid (n) tissue formed before fertilization.

Dicliny refers to the presence of unisexual flowers (staminate or pistillate) on the same or different plants. Cucurbita is a well-known example of a plant with unisexual flowers.

Seeds that require darkness for germination are called negatively photoblastic. The term 'photophobic' is generally not used in this context.