A Complete Walkthrough of Dicot Seed Embryo Identification for Class 10 Biology Students
Biology experiment - Identification of the Different Parts of an Embryo of a Dicot Seed
Seed is the product of sexual reproduction in plants. It contains all the necessary information and nutrients for the formation of the next generation of plants. Post fertilisation, a zygote is formed which divides multiple times to form an embryo. Embryo is protected inside a tough structure known as the seed which protects the small plant during unfavourable climatic and nutrient conditions.
Table of Contents
Aim
Requirements
Theory
Methodology
Observations
Conclusion
Summary
Aim
To identify various parts of an embryo, present inside a dicot seed.
Requirements
Kidney beans seeds soaked overnight, petridish, forceps, simple microscope, slide etc.
Theory
Fertilisation of male and female gametes in plants leads to the formation of a seed. Seeds are the matured ovules and the fruit is the matured ovary.
Seed - It is small and nutrient rich containing the embryo which forms the entire plant. It is made up of seed coat and embryo.
Seed coat - It is the outer covering which protects the tender embryo from adverse conditions. It prevents the drying out of the seeds.
Embryo - It is an immature plant and contains Cotyledons, Radical, Plumule, Epicotyl, and Hypocotyl.
Cotyledons - It is known as the seed leaf. There can either be two leaves, i.e., dicotyledon or single leaf, i.e., Monocotyledon. Based on this, angiosperms are divided into dicot and monocot plants.
Radical - It forms the embryonic root which later grows and develops the entire root system.
Plumule - It forms the embryonic shoot which later grows and develops the entire shoot system.
Epicotyl - It is the part of the embryonic stem which is present above the point of attachment in the cotyledons.
Hypocotyl - Area between radicle and place of origin seen in the cotyledons is known as hypocotyl.
Procedure
Soak seeds of red kidney beans overnight.
Take 8-10 soaked seeds and place in a petri dish.
Soaked seeds are soft and hence can open easily.
Remove the seed coat with the help of a forceps and dissect the seed in two halves.
Study the various regions of seed embryo.
Observe the embryo axis under a simple microscope.
Observe other parts of the seed, note down the observations, and draw diagrams.
Observations
Kidney shaped beans contain a concave and a convex side.
The concave side shows a dark scar like structure known as hilum.
Small pore below the hilum is known as micropyle.
The outer cover is the seed coat.
There are 2 cotyledons which are kidney shaped and red in colour.
Radical is seen near the micropylar end which is rod shapes and tapering at the tip. It is the future root.
Plumule is seen towards the upper end of the embryonal axis. It is the future shoot.
Hypocotyl is present between the radical and junction of the cotyledons.
Epicotyl is present between the plumule and the junction of the two cotyledons.
Result
In the dicot embryo experiment, various parts of the embryo of the dicot seed, i.e., radical, plumule, hypocotyl, epicotyl, and seed coat were observed and understood.
Different parts of an embryo of a dicot seed
Precautions
Select intact seeds for the experiment.
Dissect the seed carefully to prevent damage.
Use clean cloth and equipment for the experiment.
Be careful while removing the seed coat.
Lab Manual Questions
1. How can you differentiate between monocot and dicot seeds?
Ans: Dicot seeds upon dissection show two leaves of the cotyledons whereas monocot seeds will show single cotyledons.
2. In the dicot embryo experiment, why are the seeds soaked overnight?
Ans: When seeds are soaked overnight, the seed coat becomes soft and can be removed easily without damaging the inner seed and embryo.
3. In the dicot embryo, which part is known as small pore?
Ans: The small pore present in the dicot embryo is the micropyle. It is a small opening which allows the entry of water during the germination of the seed.
4. Describe the functions of cotyledons epicotyl.
Ans: Cotyledons are the two halves of the seeds which contain the reserve food material which helps in the growth of the plant. Epicotyl is the region present before plumule and is responsible for the formation of shoots.
Viva Questions
1. Differentiate between dry and soaked seeds.
Ans: Soaked seeds are soft and seed coats can be removed easily. Dry seeds have wrinkled seed coats, they are thick and cannot be removed easily.
2. Mention the two main parts of the embryo.
Ans: Radical and Plumule which forms the roots and shoots, respectively.
3. What happens when wet seeds are kept on moist cloth?
Ans: When wet seeds are kept on the moist cloth, they start germinating and form baby roots which is also known as sprouting.
4. What is the meaning of monocot seed?
Ans: These are seeds which contain only one cotyledon from which the entire plant is formed.
5. What happens when wet seeds are kept in a cool environment?
Ans: When moist seeds are kept in a cool environment such as a fridge, they do not germinate and do not form sprouts.
6. What is the function of a radicle?
Ans: Radical in the seed forms the baby root which then further forms the entire elaborate root system.
7. What are the requirements of a seed to convert into a full plant?
Ans: Following are the requirements to form a full-grown plant - water, carbon dioxide, sunlight, optimum temperature, and nutrient rich soil.
8. Give 5 examples of plants having dicot seeds.
Ans: Mango, Neem, Peepal, Banyan, Jack-fruit.
9. Give 5 examples of plants having monocot seeds.
Ans: Banana, Wheat, Rice, Maize, Jowar.
10. What type of venation and root system is present in a dicot plant?
Ans: A dicot plant will have reticulate leaf venation and tap root system.
Practical Based Questions
The structure of the seed does not contain:
Radical
Plumule
Seed coat
Root hair
Ans: Root hair
Find the odd one out.
Fibrous roots
Parallel venation
Reticulate venation
Single cotyledon
Ans: Reticulate venation
Seeds are located inside the:
Leaf
Fruit
Seed
Cotyledon
Ans: Fruit
The site where water moves inside the seed is_____
Hilum
Seed coat
Micropyle
Seed coat
Ans: Micropyle
The dark scar like structure on the seed is_____
Micropyle
Hilum
Radical
Plumule
Ans: Hilum
What is present between radical and the adjunct of cotyledons leaves?
Hypocotyl
Epicotyl
Radical
Plumule
Ans: Hypocotyl
Red kidney beans are:
Seed coat
Seed
Flower
Root
Ans: Seed
The embryo axis contains___and ____
Hypocotyl, Epicotyl
Radical, Plumule
Hilum, Micropyle
Seed, seed coat
Ans: Radical, Plumule
Reserved store food in seed is____
Oils
Fats
Proteins
All of the above
Ans: All of the above
Monocots and Dicots contain______and_____respectively
A) Reticulate venation and one cotyledons
B) Parallel venation and two cotyledons
C) Parallel venation and one cotyledons
D) Reticulate venation and two cotyledons
Ans: Parallel venation and two cotyledons
Summary
Seeds are small progenies of the plant. They contain the genetic information and the resources which are necessary to form an entire plant. After fertilisation of the male and female gametes, a single-celled zygote is formed which later develops into a plant embryo which remains dormant and is enclosed within a protective covering called the seed. On the onset of favourable conditions, the dormancy is broken and the seed germinates forming an entirely new plant.
FAQs on Embryo Parts of a Dicot Seed: CBSE Class 10 Biology Experiment 2025-26
1. What are the most important parts of a dicot seed's embryo that are frequently asked in CBSE Class 10 exams for the 2025-26 session?
For the Class 10 Biology syllabus, the embryo is the most critical part of a dicot seed. Its key components are:
- Embryonal Axis: This is the main axis of the embryo, which includes the plumule and radicle.
- Cotyledons: These are the two fleshy 'seed leaves' attached to the embryonal axis. They store food reserves for the embryo.
- Plumule: This is the embryonic shoot, which develops into the future shoot system (stem and leaves) of the plant after germination.
- Radicle: This is the embryonic root, which grows downwards to form the root system of the new plant.
2. For a 3-mark question, explain the function of the plumule and radicle in a dicot seed embryo.
The plumule and radicle are the two developmental poles of the embryonal axis, each with a vital function for the establishment of a new plant:
- The plumule is the part of the embryo that develops into the shoot upon germination. It grows upwards, emerging from the soil to form the stem, leaves, and eventually, flowers of the plant.
- The radicle is the embryonic root that develops into the primary root system. It is usually the first part to emerge from the seed, growing downwards to anchor the seedling and absorb essential water and nutrients from the soil.
3. What is the primary role of cotyledons in a dicot seed like a gram or pea, and why is this an important concept for exams?
In non-endospermic dicot seeds such as gram and pea, the cotyledons serve as the primary food storage organs. This is an important concept because it's a key adaptation. During the seed's development, the food material from the endosperm is transferred to the cotyledons, making them thick and fleshy. During germination, these cotyledons provide the critical nourishment (like proteins and carbohydrates) required by the growing plumule and radicle until the seedling develops leaves and can perform photosynthesis on its own.
4. Describe the protective layers of a dicot seed and explain their importance for the survival of the embryo.
A dicot seed is protected by a tough outer covering known as the seed coat. This is a crucial feature for the embryo's survival and is composed of two distinct layers:
- Testa: The thick, hard, outermost layer. Its primary function is to protect the delicate embryo from mechanical injuries, dehydration, and attacks by microbes.
- Tegmen: The thin, membranous inner layer located just beneath the testa, providing a secondary layer of protection.
5. Why are the hilum and micropyle significant for a dicot seed, even though they are not parts of the embryo itself?
While the hilum and micropyle are features of the seed coat, they play indispensable roles in the embryo's life cycle.
- The hilum is a scar indicating the point where the seed was attached to the fruit wall. It is a structural landmark.
- The micropyle is a tiny pore near the hilum that is critically important. It allows for the entry of water, which is the primary trigger for initiating the germination process and activating the embryo. It also facilitates the exchange of respiratory gases.
6. From an evolutionary perspective, why is a seed with an embryo considered a more advanced method of reproduction than a spore?
A seed containing an embryo is considered more advanced than a spore due to several key survival advantages:
- Stored Food Supply: The embryo has a dedicated food source (the cotyledons or endosperm), providing energy for germination and early growth. Spores lack this extensive reserve.
- Enhanced Protection: The embryo is protected by a durable, multi-layered seed coat, which offers superior defence against harsh environmental conditions compared to the simpler wall of a spore.
- Prolonged Dormancy: A seed can remain dormant for extended periods, waiting for favourable conditions (water, temperature) to germinate. This strategic waiting greatly increases the chances of the seedling's survival.
7. How can you differentiate between a dicot embryo and a monocot embryo based on their structure?
You can differentiate between dicot and monocot embryos based on a few distinct structural features, which is a common higher-order thinking question:
- Number of Cotyledons: This is the most fundamental difference. A dicot embryo has two cotyledons, whereas a monocot embryo has only one (called a scutellum).
- Protective Sheaths: Monocot embryos possess specialized protective sheaths that are absent in dicots. The coleoptile covers the plumule (embryonic shoot), and the coleorhiza covers the radicle (embryonic root).
8. Why do some dicot seeds like castor retain their endosperm, while others like pea or bean do not? What does this imply?
This difference reveals two distinct strategies for nourishing the embryo.
- In non-albuminous (or exalbuminous) seeds like pea and bean, the developing embryo completely consumes the endosperm. The food reserves are then transferred and stored in the fleshy cotyledons.
- In albuminous seeds like castor, the endosperm is not fully used up during embryo development. It persists in the mature seed and acts as the main nutritive tissue for the embryo during germination.
