Test: Pinus - Class 11 MCQ

Pinus wallichiana is called 'blue pine' whereas Pinus ruxburgi is called 'chir pine'.

Pinus insularis is commonly called Khasi Palm in India.

Some fungi are found only in burnt areas, or at least have strong preferences for burnt areas only, and there are others which can do well in unburnt areas but get a boost from fire example, Morchella elata, and when pinus seedlings get fired then because of devoid of fungi it becomes difficult for the seeds to regrow.

The foliage leaves or needles in Pinus are borne by branches of limited and unlimited growth. 

Schizogenous cavities form by the sep- aration of glandular cell initials, resulting in a space lined by secretory epithelial cells. Lysigenous cavities form by the autolysis of glandular cells, with secretory cells releasing their secretion product into the enlarg- ing space as they degenerate (holocrine secretion).

The leaves of Pinus are dimorphic, that is it has two kinds of leaves-scale leaves and foliage leaves. Foliage leaves are present on dwarf shoots only and they are known as foliage spurs.

Sclerenchyma cells are thick walled, liginified and dead at maturity. These provide mechanical support to the Pinus needle. Sclerencyma may be fibres or sclereid.

The ground tissue system, the mesophyll, is divided into two regions: the palisade parenchyma, located beneath the upper epidermis and composed of columnar cells oriented perpendicular to the leaf surface, and spongy parenchyma, located in the lower part of the leaf and composed of irregularly shaped cells.

Pinus is a gymnosperm. The male plant bears male strobilus or male cone. It is formed by the aggregation of microsporophylls. The microsporophylls are arranged spirally and each microsporophyll has 2 microsporangia which are arranged abaxially (away from the stem or leaves).
So, the correct answer is 'Two microsporangia on abaxial side'.

The typical needle-shaped leaf is found in all species of the Pinaceae family and it is the arrangement of these needles in bundles or fascicles that is the most characteristic feature of the genus Pinus. The Collateral & open outer layer of the adult leaf is the waxy cuticle which protects the leaf from drying.

Foliar spur of a Pinus is called unifoliar if only one leaf is present at the apex of the dwarf shoot, bifoliar if two leaves are present, trifoliar if three leaves are present. And mostly Pinus shows bifoliar case.

Conjoint vascular bundles are seen in stem and leaves. A type of conjoint vascular bundle where xylem is arranged towards the interior (adaxial) and the phloem arranged towards the exterior (abaxial). A few resin-ducts are also present in the pith. Vascular bundles : These are collateral and open, and arranged in a ring, as in dicot stem. Each bundle consists of phloem, cambium and xylem.

P. armandii is penta foliar i.e, it has five needles. 

Xerophytes are the plants which grow in dry habitats i.e desert while hydrophytes are plants which grow in water.
Xerophytes have well developed root system while hydrophytes have poorly developed root system.
The water conducting tissue xylem is well developed in xerophytes while the same is poorly developed in hydrophytes.
Aerenchyma is absent in xerophytes while it is present in hydrophytes.
Sclerenchyma is present in xerophytes while it is absent in hydrophytes.
Xerophytes often have C4 and CAM pathway of photosynthesis while C4 and CAM pathway of photosynthesis are absent in hydrophytes.
Sunken stomata are present in the leaves of xerophytes while sunken stomata are absent in leaves of hydrophytes.
Phylloclade, cladode and phyllode types of modifications are found in xerophytes while they are absent in hydrophytes.

Male cones are modified dwarf shoots. They arise in clusters at the base of the long shoot. They arise in the axils of the scale leaves. A male conifer cone is homologous to a male flower of angiosperm.
Therefore, the correct answer is option B. 

Sulphur showers is a phenomenon related to pollination in Pine trees. Pines are naked seed- bearing plants, belonging to the group gymnosperms. Pines bear cones, they are called conifers. Pines have leaves in the form of needles. The cones are of two types, seed cones (female) and pollen cones (male) on the same plant. As the pollen cones mature, they discharge large quantities of pollen grains into the air and it appears as a yellow cloud of yellow of winged pollen grains. This is called Sulphur Shower and occurs during spring.

The male gametophyte has two prothallial cells in Coniferales and Ginkgoales while one in Cycadales. No prothallial cells are found in angiosperms. One stalk cell and two male gametes which are flagellated in Cycadales and Ginkgoales while non-flagellate in rest of gymnosperms like that of angiosperms.

The function of wing cells in pine pollen grains is to let the seeds be able to range over a larger area when they fall from the cones.  Pollen is a sticky powder that is produced by the male parts of flowering plants. It is an important part in the process of plant pollination and reproduction.

because after fertilization the endosperm spry d is 3n which is 3 X the ploidy of the megaspore mother cell's egg which is haploid and has 16 chromosomes.
answer 3 X 16 is 48. 

Dwarf Shoot/Branches of limited growth or Brachyblast :

- They develop in the axis of scaly leaves on the long shoot and bear both scaly and foliage leaves.

- They possess foliage leaves at their apex.

- These branches do not have apical bud and hence show only limited growth.

- A dwarf shoot with a group of needle like foliage leaves, called as foliar spur.

Megasporophyll : A leaf on which the megaspores are formed: corresponds to the carpel of a flowering plant. Compare microsporophyll. [C20: from mega- + sporophyll] The female or ovulate (seed) cone consists of a spiral series of overlapping ovuliferous scales each producing two ovules on the upper surface. Each scale is subtended by a small fused structure on its lower surface called a bract. The bracts in pine are microscopic and difficult to see.

The megaspore mother cell undergoes meiosis and the product of female meiosis is the linear tetrad of four megaspores. Multiple egg cells, each housed in its own archegonium, will form from the female gametophyte. This haploid female gametophyte in conifers is not a synonym for an endosperm.

Cleavage polyembryony has been reported from four genera in the Pinaceae family, Cedrus, Keteleeria, Pinus and Tsuga, (Dogra, 1967). Rarely does more than one proembryo develop further into an embryo.

During cleavage polyembryony, the four apical cells and the suspensor network in the proembryo separate into four filamentous embryos. The four embryos, which arise from the separated tiers, begin their development by apical cell growth (Buchholtz, 1920). The apical cell disappears as the embryonal mass starts to form. Initially the four embryos are of equal size, but successively the embryos start to compete for nutrition and space to grow and survive. It has been suggested that the embryo with the best physiological constitution situated in the most suitable environment becomes the dominant embryo, which usually develops to maturity (Buchholtz, 1926). The dominant embryo suppresses the growth and development of the subordinate embryos mechanically by means of its suspensor system, and thereby causes starvation.

Proembryo in a flowering plant denotes the series of cells that are formed after fertilization within the ovule of a plant, before formation of the embryo.

Meroblastic embryogeny is common in gymnosperms. When the part of zygote is involved in the development of embryo, this type of embryo development is called meroblastic embryogeny. In these plants embryo is developed from a portion of oospores and in such case more than two embryos can be developed(polyembryony)

Gymnosperm seeds develop either on the surface of scales or leaves, which are often modified to form cones, or solitary as in Yew, Torreya, Ginkgo. The gymnosperms and angiosperms together compose the spermatophytes or seed plants.

Seed of Pinus contain several embryos with a compound suspensor which helps in pushing the embryo into the endosperm. They are developed through cleavage polyembryony in which splitting of an embryo into several identical parts, each of which is capable of developing into a mature embryo. And usually, only one embryo develops to maturity.

Sperm motility refers to how well the sperm in a given semen sample are moving and it is one of the parameters looked at in a semen analysis. As long as at least 40% of the sperm in a sample are moving, this is considered normal sperm motility.

Megaspore represents the first cell of the female gametophyte produced by reduction division from magaspore mother cell. The megaspore develops into female prothallus or endosperm.

The ovules of gymnosperms and other extinct seed plants is orthotropous as they typically have only one coat or integument and the body of the ovule sits erect on the stalk. 

Gymnosperms typically have one integument (unitegmic) ovule.