Embryo of Dicot Seed (Identification) MCQs Quiz | Class 10

Class: X, Subject: Science (Code 086), Unit: Practicals (Unit II), Topic: Embryo of Dicot Seed (Identification) MCQs Quiz | Class 10. This quiz covers the parts of a dicot embryo and its identification in common seeds like pea, gram, and rajma. Test your knowledge by attempting all questions and then download your answer sheet as a PDF.

Understanding the Dicot Seed Embryo

A dicotyledonous (dicot) seed, like those of pea, gram, or rajma, contains an embryo with two cotyledons. The embryo is the miniature plant within the seed, comprising an embryonic axis and cotyledons. Understanding its structure is crucial for comprehending plant development.

Key Parts of a Dicot Embryo:

  • Embryonic Axis: The central axis of the embryo from which the future plant parts develop. It has two ends:
    • Plumule: The part of the embryonic axis that develops into the shoot system (stem, leaves, flowers). It is located at the upper end of the axis.
    • Radicle: The part of the embryonic axis that develops into the root system. It is located at the lower end of the axis.
  • Cotyledons: These are seed leaves. In dicots, there are two cotyledons. They are typically thick and fleshy, storing food reserves (like starch, proteins, and fats) for the developing embryo until it can photosynthesize independently.
  • Epicotyl: The portion of the embryonic axis above the point of attachment of the cotyledons and below the plumule. It elongates during germination, pushing the plumule upwards.
  • Hypocotyl: The portion of the embryonic axis below the point of attachment of the cotyledons and above the radicle. It also elongates during germination, pushing the cotyledons and plumule above the soil (epigeal germination) or remaining below the soil (hypogeal germination).

Identification in Common Dicot Seeds (Pea, Gram, Rajma):

When you soak and split common dicot seeds like pea, gram (chickpea), or rajma (kidney bean), you can easily observe their embryonic structure:

  1. Seed Coat: The outer protective layer.
  2. Hilum: A scar on the seed coat, representing the point where the ovule was attached to the ovary wall.
  3. Micropyle: A small pore located near the hilum. It allows water absorption and gaseous exchange during germination.
  4. Cotyledons: Two large, fleshy structures that make up the bulk of the seed, storing food.
  5. Embryonic Axis: Found tucked between the two cotyledons. You can carefully separate the cotyledons to expose the plumule and radicle.

Structure of a Dicot Embryo at a Glance

Part of Embryo Description / Function
Cotyledons Two seed leaves; store food for the embryo.
Plumule Future shoot system (stem, leaves).
Radicle Future root system.
Epicotyl Axis above cotyledon attachment, below plumule.
Hypocotyl Axis below cotyledon attachment, above radicle.

Quick Revision:

  • Dicot seeds have two cotyledons.
  • The embryo consists of an embryonic axis and cotyledons.
  • Plumule forms the shoot; radicle forms the root.
  • Cotyledons store food for the developing embryo.
  • Hilum and micropyle are key external features for identification.

Extra Practice Questions:

  1. What is the primary function of cotyledons in a dicot seed?
  2. Name the part of the embryonic axis that gives rise to the shoot system.
  3. Which part of the seed allows for water absorption during germination?
  4. Provide two examples of common dicot seeds where the embryo can be easily identified.
  5. What is the scar on the seed coat called, indicating the point of attachment to the fruit?