Test: Sexual Reproduction In Flowering Plants 4 - From Past 28 Years Questions - NEET MCQ

Embryology is the study of an individual's life cycle after the fertilization takes place and till it develops into a new organism.

It is a Polygonum type ovule in which the body of ovule is straight i.e. funiculus, chalaza, embryo sac & micropyle lie in the same vertical axis.

Double fer tilization in a characteristic feature of angiosperms in which one male gamete fuses with egg (called syngamy) and other male gamete fuses with 2 polar nuclei (called triple fusion) to form endosperm.

200 seeds of pea would be produced from 200 pollen grains and 200 embryo sac. 200 pollen grains will be formed by 50 microspore mother cell while 200 embryo sac will be formed by 200 megaspore mother cell (because 3 will degenerate) so 250/500.

All other are diploid. Best method of haploid plant culture is pollen grain culture.

Pollination by insect is known as Entomophily. Among insects bees are the most common pollinators which pollinate about 80% of the total insect pollinated flowers.

Autogamy = Self Pollination Geitanogamy - (geiton = neighbour, gamos = marriage.) i.e. when pollen grains are transferred to the stigma of other flower of the same plant (i.e. neighboring flower).
Allogamy = Xenogamy – Cross pollination.

In angiosper ms the male gametes are carried by the pollen tube was discovered by Strasburger in 1884. The process is called Siphonogamy.

Each pollen has two layered wall. The outer layer is thick, tough, cuticularised called exine which is composed of a material called "sporopollenin". It is highly resistant to biological and physical decomposition, due to which pollens are preserved for a long time in fossils.

Each microspore mother cells undergoes meiosis to produce four pollen grains. 
Thus, 25 microspore mother cells are required to produce 100 pollen grains 

Polyembryony refers to the formation of more than one embryo within a seed of a flowering plant. e.g. Citrus.

Culture is the ter m generally used for artificial growth. The plant tissue culture actually refers to the growth of plant cells, tissues and organs on artificial nutrient media.

Each microspore mother cell gives rise to 4 microspores which develop into pollen grains.

In  angiosperms, one male gamete  fuses with the egg resulting in the formation of a diploid zygote. The other male gamete fuses with the two polar nuclei forming the primary endosperm nucleus . Thus type of  fertilization is  called double fertilization.

The male gamete will be haploid (n). 2 polar nuclei will be diploid (2n). Endosperm formed by fusion of male gamete with two polar nuclei will be pentaploid.

In gymnosperms the female gametophyte forming archegonia provides nourishment to the developing embryo. It later gets transformed into food-laden endosperm inside the seed. Endosperm provides nourishment for growth of seed at the time of seed germination. Triploid endosperm occurs in angiosperms.

Ornithophily is pollination by birds, characteristic is presence of colored flowers ( mostly red) with nectaries. The orientation of the stigma and anthers is to facilitate pollen transfer for cross pollination. 

So, the correct answer is 'Red sweet scented  flowers with nectaries at the base of the corolla tube'.

The second male gamete entering the ovary fuses with two haploid polar nuclei to form triploid primary endosperm nucleus which develops into endosperm. This fusion of two male gametes with two different structures (egg and secondary nucleus) in the same female gametophyte is called double fertilization. 

Megapore is a haploid structure which divides and gives rise to embryo sac which is also called as female gametophyte. Eight-nucleate embryo sacs may be monosporic (e.g.. Polygonum); or bisporic (e.g., Allium); or tetrasporic (e.g., Adoxa).

Vallisneria exhibits hydrophily and Salvia is pollinated by honey bee. In bottle brush pollination is carried out by birds.

The embryos arising from the maternal sporophyte tissues are called adventive embryos. In polyembryonate species the adventive embryo arises by the proliferation of the nucellus cells.

Antipodal cells occur at  the chalazal end of the ovule. Synergids are the helping cells. 

In orthotropous ovule micropyle is upward. This is the presentive type of ovule.

Commensalism is interaction between two individuals in which one is benefitted while the other is unaffected. In mutualism both individuals are beneficial for each other. The pollinating insect gets nectar from flower and in turn helps in pollination of flowers.

The deposition of callose starts in pollen mother cell as it enters meiosis and is complete by the end of first meiotic division. By the time tetrad are formed, the common callose wall dissolves; even then all the four micro-spores lie within a common callose wall.