Flower & its Parts

1 Mark Questions

1.Name the part of the flower which the tassels of corn cob represent.[All Indian 2014] Ans. The part of the flower that represent the tassels of corn cob are stamens or male reproductive parts.

2.Draw a diagram of a matured microspore of an angiosperm. Label its cellular components only.[Foreign 2014]

Ans. The labelled diagram of a mature microspore of an angiosperm with its cellular components is given below:

Vegetative Exine cell Intine

Generative cell Germ pore

1. State the function of filiform apparatus found in mature embryo sac of an angiosperm.

[Foreign 2014]

Ans. The special cellular thickenings at the micropylar tip called filiform apparatus, found in mature embryo sac of an angiosperm helps in guiding the pollen tubes up to the synergids.

1. Abilobed, dithecous anther has 100 microspore mother cells per microsporangium. How

many male gametophytes this anther can produce? [HOTS; Delhi 2010]

Ans. An anther is a four-sided (tetragonal) structure consisting of four microsporangia located at the corners, two in each lobe. Total microsporangium = <math>4 \times 100 = 400</math>. So, anther produces 400 male gametes

5.An anther with malfunctioning tapetum often fails to produce viable male gametophytes. Give one reason. [Delhi 2010]

Ans. The anther with malfunctioning tapetum cannot provide complete nutrition to the developing microspores or male gametophytes. So, it fails to produce viable male gametophyte.

2 Marks Questions

1. Name the organic materials of which exine and intine of an angiosperm pollen grains are

made up of. Explain the role of exine. [Delhi 2014]

Ans. The angiosperm pollen grains comprises of outer exine made up of resistant organic material sporopollenin, while inner thin layer of intine is made up of cellulose and pectin. Since, the outer hard layer of exine is made up of sporopollenin which is one of the most resistant organic substance, it helps the pollen grains to resist high temperatures, strong acids and alkali and it also protects them from enzyme degradation.

7.Differentiate between the two cells enclosed in a mature male gametophyte of an angiosperm.[All India 2013]

Ans. Haploid pollen grain represents the male gametophyte. It contains two cells, i.e. vegetative cell and generative cell. The vegetative or tube cell is larger in size as with prominent nuclei that gives rise to two male gametes, while vegetative cell does not.

compare to generative cell and have vacuolated cytoplasm. The generative cell on the other hand have thin dense cytoplasm

1. Name all the haploid cells present in an unfertilised mature embryo sac of a flowering

plant. Write the total number of cells in it.[HOTS; All India 2013] or

How many haploid cells are present in mature female gametophyte of a flowering plant? Name them.[Delhi 2013 C]

Ans. An unfertilised embryo sac of angiosperm is composed of 7 cells, i.e. 7-celled and 8- nucleated. Among 8-nuclei, 6 are enclosed by cell walls and organised into cells, which are haploid in number (3 antipodal, 2 synergids and 1 egg cell) and a large central cell with 2 pollen nuclei.

1. Where is sporopollenin present in plants? State its significance with reference to its chemical nature.[Delhi 2012]

Ans. Sporopollenin is present in exine of pollen grains in plants. It is one of the most resistant organic substances and can withstand high temperatures, strong acids and alkalis. It protect the pollen grains from enzymes and helps them to be well preserved.

10.In the TS of a mature anther given below, identify A and B and mention their functions. [Foreign 2009]

Ans. A-Sporogenous tissue

Function Its cells are potential mother cells and form pollen grains.

1. Tapetum

Function It nourishes the developing pollen grains.

11.(i) Draw a schematic diagram of TS of a mature anther. Label only the layers that help in dehiscence of the anther to release pollen grains.

1. Why is exine of the pollen grain not a continuous layer? [Delhi 2009]

Ans.(i) Diagram of TS of a mature anther: Anther is a bilobed structure with each lobe having