Question 1

Differentiate between microsporogenesis and megasporogenesis. Which type of cell division occurs during these events? Name the structures formed at the end of these two events.

Accepted Answer

Microsporogensis involves meiosis in microspore/pollen mother cells to produce microspores/pollen grains tetrads that remain suspended in central of each microsporangium. Pollen mother cells are present in each microsporangium of anther. Megasporogenesis includes meiosis in megaspore mother cell of ovule to form megaspore tetrad out of which one megapore is functional. Meiosis occurs during both megasporogenesis and microsporogenesis to prodduce haploid male and female gametes. Microsporogenesis forms haploid microspores while megasporogenesis forms haploid megaspores.

Question 2

Which is the most common type of embryo sac in angiosperms?

Accepted Answer

The most common type of female gametophyte (embryo sac) in angiosperms is the monosporic embryo sac in which the embryo sac develops from a single functional megaspore (n), while the other three megasproes degenerate.The functional megaspore undergoes three sequential mitotic divisions and gives rise to the 8-nucleate and 7-celled mature embryo sac.

Question 3

Identify the type of Pistil in the diagram.

Accepted Answer

(b) The diagram represents the multicarpellary, syncarpous pistil of Papaver. The gynoecium of this plant consists of more than one pistil, showing multicarpellary condition. These pistils are fused together and hence are called syncarpous.

Question 4

The cells in embryo sac which act as haustoria are

Accepted Answer

Antipodal cells take part in nourishing the embryo. For this, the antipodal cells often develop haustoria.

Question 5

(i) Draw a labelled sketch of a mature 7-celled, 8-nucleate embryo sac. (ii) Which one of the cell in an embryo-sac produce endosperm after double fertilization ?

Accepted Answer

(i) A diagrammatic view of the mature embryo sac-(ii) Central cell-  After double fertilization the Primary Endosperm Nucleus (PEN) formed as a result of triple fusion (fusion of one male gamete (n) with a diploid secondary nucleus (2n) or with two haploid polar nuclei) produces endosperm.

Question 6

Exine of pollen grain is made up of

Accepted Answer

Exine is the outermost layer of the pollen grain made up of sporopollenin. Sporopollenin is a highly resistant polymer made up of phenolics, carotenoids, phenylpropanoids and fatty acids.

Question 7

Filiform apparatus are

Accepted Answer

Filiform apparatus are the special thickening of synergid cells for guiding the pollen tube and male gametes, so that the fusion takes place properly.

Question 8

Egg apparatus of angiosperms consist of

Accepted Answer

In embryo sac of angiosperm, egg apparatus occurs towards micropylar pole and generally organizes by two synergids and one egg cell. Egg cell has a large vacuole at its upper and a prominent nucleus near its lower end. Synergids show a filiform apparatus attached to their upper wall. It is known to attract and guide the pollen tube. Each of the synergids has a vacuole at its lower end and the nucleus at its upper end.

Question 9

Plumule is produced from the

Accepted Answer

Apical octant gives rise to plumule region while basal octant gives rise to radicle region during embryonic development of seed.

Question 10

Number of chromosomes in an angiospermic plant is 14, then the number of chromosomes in synergid cells will be

Accepted Answer

The pollen tube ultimately enters an ovule through the micropyle and penetrates one of the sterile cells on either side of the egg ( synergids). These synergids begin to degenerate immediately after pollination. Synergids are haploid in nature. Thus, if the angiosperms plant cell has 2n = 14, synergids will have n = 7.

Question 11

Which of the following statement is correct for the pollen tube?

Accepted Answer

The movement of pollen tube towards embryo sac though style is chemotactic as it secretes pectinase and other hydrolytic enzymes to create a passage for its entry into style

Question 12

Which of the following is a mismatched pair?

Accepted Answer

Male reproductive organ is called androecium and their unit is called stamen. Stamen is also known as microsporophyll. A typical stamen differentiates into three parts- filament, anther and connective tissue. The anther is bilobed and the lobe encloses 4 pollen sacs or microsporangia. The integumented nucellus or megasporangium is called ovule.

Question 13

Which one of the following is not related to other three?

Accepted Answer

Antheridium is a male structure and the other three archegonium, oogonium & ovule are female parts. An antheridium is a haploid male reproductive structure producing gametes, occurring in ferns, mosses, fungi and algae. Archegonium is the female, egg-producing reproductive structure on the gametophytes of non-flowering land plants. The archegonium is comprised of an oogonium surrounded by protective layers of thick-walled pigmented cells. In seed plants, ovule is the structure that gives rise to female reproductive cells.

Question 14

Point out the odd one from the given options

Accepted Answer

Nucellus, embryo sac & micropyle are all found in ovule while pollen grain is a male gametophyte.

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