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medium difficulty6 min

Stamen, Microsporangium and Pollen Grain

A stamen is the male reproductive unit of a flower, consisting of filament and anther; each anther contains microsporangia where microspore mother cells undergo meiosis to form pollen grains.

In one line: MMC to meiosis to microspores; pollen tube starts from the intine through a germ pore.

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Understand it

  • The anther is usually bilobed and each lobe contains microsporangia.
  • Inside a microsporangium, sporogenous tissue gives rise to microspore mother cells, which undergo meiosis to form haploid microspores.
  • This process is called microsporogenesis.
  • Each microspore develops into a pollen grain with a tough exine and inner intine.
  • Exine contains germ pores through which the pollen tube can emerge, while intine contributes to pollen tube formation.
  • Mature pollen commonly has a vegetative cell and a generative cell.
  • Exam questions often combine anther structure, meiosis, pollen wall features, and pollen viability.

Example

In many angiosperms, a mature pollen grain is two-celled at the time of shedding, with a larger vegetative cell and a smaller generative cell that later forms two male gametes.

Rule to remember

Biological sequence rule: microspore mother cell, meiosis, tetrad of haploid microspores, separation of microspores, pollen grain formation.

See it worked out

Follow the example line by line, then use the same method on new questions.

Worked example

  1. 1If an anther cell with chromosome number 2n undergoes meiosis during microsporogenesis, the resulting microspores are n.
  2. 2These haploid microspores form the male gametophyte.

Method you can reuse

  1. 1Start with a young anther containing microsporangia.
  2. 2Sporogenous tissue differentiates into microspore mother cells.
  3. 3Each microspore mother cell undergoes meiosis.
  4. 4A tetrad of four haploid microspores forms.
  5. 5Microspores separate and develop into pollen grains.
  6. 6The generative cell later gives rise to male gametes, and the vegetative cell supports pollen tube growth.

Sketch it in your answer

Label anther lobe, connective, pollen sacs or microsporangia, epidermis, endothecium, middle layers, tapetum, sporogenous tissue, exine, intine, germ pore, vegetative cell, and generative cell.

Check yourself

Answer the question in your head before opening the answer.

Try it yourself

Why is microsporogenesis called a reductional process?

Think first, then show answer
Microsporogenesis is reductional because diploid microspore mother cells undergo meiosis to produce haploid microspores, which later develop into pollen grains.

Common wrong answer

Writing that mitosis forms microspores is wrong; microspores arise by meiosis from microspore mother cells.

Don't mix this up

Students often write that pollen grains are male gametes. A pollen grain is the male gametophyte; the male gametes are formed inside it from the generative cell.

Exam tip

Use the sequence microspore mother cell, meiosis, microspore tetrad, pollen grain when writing microsporogenesis.

Write it in the exam

Each point is worth about one mark. Write point 1 for a 1-mark question and keep adding points as the marks go up.

How CBSE asks it

Questions may ask students to draw a transverse section of an anther, label pollen wall layers, explain microsporogenesis, or justify why pollen grains are resistant due to exine.

Answer plan

Define stamen and anther, describe microsporangium layers briefly, write the microsporogenesis sequence with meiosis, explain pollen wall and cells, then add the role of germ pore in pollen tube emergence.
  1. 1

    Enough for 1 mark

    A stamen is the male reproductive unit of a flower, consisting of filament and anther; each anther contains microsporangia where microspore mother cells undergo meiosis to form pollen grains.

  2. 2

    Add for 2 marks

    Example: In many angiosperms, a mature pollen grain is two-celled at the time of shedding, with a larger vegetative cell and a smaller generative cell that later forms two male gametes.

  3. 3

    Add for 3 marks

    The anther is usually bilobed and each lobe contains microsporangia.

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