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CBSE Class 12 · Biology

Sexual Reproduction in Flowering Plants

Official NCERT chapter from Biology (book code lebo1). ExamMaster notes are original teaching at CBSE Class 12 depth.

This lesson follows the official chapter “Sexual Reproduction in Flowering Plants” in Biology. The words below are ExamMaster’s teaching, not a paste from the book. Use the NCERT chapter for the classroom sequence; use these notes to hold the idea without copying exercises or figures.

  • CBSE Class 12
  • Medium level
  • 8 concepts

1Flower — A Fascinating Organ of Angiosperms

A flower is the angiosperm reproductive shoot as taught — the four-whorl map you already met, now as the organ that holds the later events. Fascinating here means a job-map, not a pretty-slogan. One typical flower is enough.

A leaf-rosette as a flower because it is colourful is a miss.

Figure. A flower is four whorls, each named for a job — not a pretty list of parts.

How it works

  1. Name the flower as the reproductive shootThe organ.
  2. Keep the whorl-map as the startThe look.
  3. Refuse pretty as the testA job-map.

2Pre-fertilisation: Structures and Events

Pre-fertilisation: pollen in the anther, embryo sac in the ovule as taught — the two sides before the join. Events are stage-names (microspore, megaspore as framed). One honest pair is enough.

A fruit as a pre-fertilisation look is a miss — that is later.

Figure. Before fertilisation the female side is a seven-celled embryo sac; pollen must still reach the stigma.

How it works

  1. Name pollen-side and ovule-sideThe two looks.
  2. Keep the taught stage-namesThe events.
  3. Refuse a join-word hereNot yet.

3Double Fertilisation

Double fertilisation: two joins in the embryo sac as taught — one makes the zygote, one makes the endosperm-start as framed. Double is two joins, not two flowers. Stage-names only.

A single animal-style join as the whole angiosperm story is a miss.

Figure. Two male gametes, two fusions: egg to zygote, polar nuclei to PEN. That pair is double fertilisation.

How it works

  1. Name two joins as taughtDouble.
  2. Keep zygote and endosperm as the two leftoversThe jobs.
  3. Stay on stage-namesThis class.

4Post-fertilisation: Structures and Events

Post-fertilisation: ovule to seed, ovary to fruit as taught. Events are develop-looks. A seed is the next plant in a coat; a fruit holds it. One path-sentence is enough.

A flower-whorl as the leftover fruit is a miss.

Figure. After the two fusions, each product has one named fate. Fruit is the ovary, not a new organ.

How it works

  1. Name ovule→seed and ovary→fruitThe path.
  2. Keep seed and fruit as two wordsThe leftovers.
  3. Refuse a market-sweet as the testA develop-word.

5Apomixis and Polyembryony

Apomixis and polyembryony: a seed without the usual join, or more than one embryo, as taught. These are named extras, not the default path. One sentence each is enough.

Calling every seed apomictic is a steal.

Figure. Apomixis skips fusion yet still makes a seed. Polyembryony is more than one embryo inside one seed.

How it works

  1. Name the taught extra (no usual join, or many embryos)The word.
  2. Keep it an extra, not the defaultHonest.
  3. Refuse a slogan as the testA named leftover.

6A pollen grain is a male gametophyte

A pollen grain is a male gametophyte as taught — a small stage that carries the male bits. Pollen is that stage-name, not “yellow dust”. One grain-sentence is enough.

A spore from a fern labelled pollen is a miss.

Figure. The pollen grain is already the male gametophyte: coats outside, two cells inside.

How it works

  1. Name pollen as the male gametophyteThe stage.
  2. Keep it a flower-side lookThis chapter.
  3. Refuse dust as the scienceA stage-name.

7Keep the claim at the step you can name

Keep the claim at the step you can name: pre, double join, or post. A “flowers do everything” claim is a mute bag.

A pretty bouquet with no step-word is not a claim.

Figure. Name only the step you can point to. Pollen on a stigma is pollination, not fertilisation.

How it works

  1. Name the stepThe claim-size.
  2. Attach the job of that stepWhat happens.
  3. Refuse a nameless posterThis class.

8A miss: treating a fruit as only a sweet object

A miss: treating a fruit as only a sweet object. A fruit is a ripened ovary that holds seeds as taught. Sweet is a market-glance.

A candy as “the fruit science” is the miss.

Figure. A fruit is the ovary after fertilisation. Sweet taste is not the definition.

How it works

  1. Keep sweet as a glanceNot the test.
  2. Name ovary-to-fruit and the seedsThe science.
  3. Refuse sweet-only as the chapterThe miss named.
Double fertilisation means
  1. Two joins in the embryo sac as taught
  2. Two flowers always
  3. A fruit is sweet

Two leftovers.

Notes

  • Mapped to the official NCERT chapter “Sexual Reproduction in Flowering Plants”. Original teaching only — no textbook sentences.
  • Science here is Physics, Chemistry and Biology ideas at this class, never a language or social-science chapter.

Recap

Hold these pegs from the official chapter “Sexual Reproduction in Flowering Plants”. The wording is ExamMaster’s teaching, not a textbook recap.

Flower — A Fascinating Organ of Angiosperms
A flower is the angiosperm reproductive shoot as taught — the four-whorl map you already met, now as the organ that holds the later events.
Pre-fertilisation: Structures and Events
Pre-fertilisation: pollen in the anther, embryo sac in the ovule as taught — the two sides before the join.
Double Fertilisation
Double fertilisation: two joins in the embryo sac as taught — one makes the zygote, one makes the endosperm-start as framed.
Post-fertilisation: Structures and Events
Post-fertilisation: ovule to seed, ovary to fruit as taught.
Apomixis and Polyembryony
Apomixis and polyembryony: a seed without the usual join, or more than one embryo, as taught.
A pollen grain is a male gametophyte
A pollen grain is a male gametophyte as taught — a small stage that carries the male bits.

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