C
CraftExam
medium difficulty7 min

Apomixis and Polyembryony

Apomixis is seed formation without fertilisation, while polyembryony is the occurrence of more than one embryo in a single seed.

In one line: Apomixis asks how the seed formed; polyembryony asks how many embryos are inside.

Concept Practice Coming Soon

Understand it

  • Apomixis produces seeds without the normal fusion of gametes, so the offspring can remain genetically similar to the parent plant.
  • It is important in agriculture because it can help maintain desirable hybrid traits across generations if used effectively.
  • Polyembryony means multiple embryos develop within one seed; these may arise from different sources, such as more than one egg or cells of the nucellus in some plants.
  • The two terms are related to seed formation but are not identical.
  • Board questions usually test definitions, examples, and the usefulness of apomixis in preserving hybrid vigour.

Example

Citrus seeds may show polyembryony, where more than one embryo can occur in a seed. Apomixis is discussed in relation to maintaining hybrid characters without repeated hybrid seed production.

Rule to remember

Key rule: apomixis concerns absence of fertilisation during seed formation; polyembryony concerns presence of multiple embryos in one seed.

See it worked out

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

Worked example

  1. 1If a seed develops without fertilisation but gives rise to a plant similar to the parent, identify the phenomenon as apomixis.
  2. 2If one seed contains several embryos, identify it as polyembryony.

Method you can reuse

  1. 1Check whether fertilisation has occurred.
  2. 2If seed formation occurs without fertilisation, identify apomixis.
  3. 3Check the number of embryos inside one seed.
  4. 4If more than one embryo is present, identify polyembryony.
  5. 5For significance, connect apomixis with preservation of hybrid traits.

Visual tip

A diagram is not usually essential, but a seed outline showing more than one embryo can help visualise polyembryony. Labels may include seed coat, embryos, and nutritive tissue.

Check yourself

Answer the question in your head before opening the answer.

Try it yourself

How is apomixis useful in hybrid seed production?

Think first, then show answer
Apomixis can be useful because it allows seeds to form without fertilisation, helping maintain desirable hybrid characters in the offspring instead of losing them through segregation.

Common wrong answer

Apomixis always means many embryos.

Why it loses marks: Apomixis can produce a seed without fertilisation even when only one embryo is present.

Don't mix this up

Students often treat apomixis and polyembryony as the same process. Apomixis refers to seed formation without fertilisation, while polyembryony refers to the number of embryos in a seed.

Exam tip

In short answers, define both terms separately and then add agricultural significance for apomixis.

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

This concept is asked in short-answer questions on definitions, differences, examples, and why apomixis has practical value in agriculture.

Answer plan

Define apomixis, define polyembryony, state one example or occurrence, distinguish the two clearly, and add that apomixis can help maintain hybrid vigour in crop improvement.
  1. 1

    Enough for 1 mark

    Apomixis is seed formation without fertilisation, while polyembryony is the occurrence of more than one embryo in a single seed.

  2. 2

    Add for 2 marks

    Example: Citrus seeds may show polyembryony, where more than one embryo can occur in a seed. Apomixis is discussed in relation to maintaining hybrid characters without repeated hybrid seed production.

  3. 3

    Add for 3 marks

    Apomixis produces seeds without the normal fusion of gametes, so the offspring can remain genetically similar to the parent plant.

Practice

Concept practice is coming soon

Login to access concept-level MCQs and weak-concept practice as they become available.

10 MCQs5 MinutesInstant Results
Login

Help improve this page

Found something confusing, incorrect, or missing?

Open Learning Map