CBSE Biology Experiment Identification of the Different Parts of an Embryo of a Dicot Seed

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

1. Soak seeds of red kidney beans overnight.

2. Take 8-10 soaked seeds and place in a petri dish.

3. Soaked seeds are soft and hence can open easily.

4. Remove the seed coat with the help of a forceps and dissect the seed in two halves.

5. Study the various regions of seed embryo.

6. Observe the embryo axis under a simple microscope. 

7. 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

1. The structure of the seed does not contain:

1. Radical

2. Plumule

3. Seed coat

4. Root hair

Ans: Root hair

2. Find the odd one out. 

1. Fibrous roots

2. Parallel venation

3. Reticulate venation

4. Single cotyledon

Ans:  Reticulate venation

3. Seeds are located inside the:

1. Leaf

2. Fruit

3. Seed

4. Cotyledon

Ans: Fruit

4. The site where water moves inside the seed is_____

1. Hilum

2. Seed coat

3. Micropyle

4. Seed coat

Ans: Micropyle

5. The dark scar like structure on the seed is_____

1. Micropyle

2. Hilum

3. Radical

4. Plumule

Ans: Hilum

6. What is present between radical and the adjunct of cotyledons leaves?

1. Hypocotyl

2. Epicotyl

3. Radical

4. Plumule

Ans: Hypocotyl

7. Red kidney beans are:

1. Seed coat

2. Seed

3. Flower

4. Root

Ans: Seed

8. The embryo axis contains___and ____

1. Hypocotyl, Epicotyl

2. Radical, Plumule

3. Hilum, Micropyle

4. Seed, seed coat

Ans: Radical, Plumule

9. Reserved store food in seed is____

1. Oils

2. Fats

3. Proteins

4. All of the above

Ans: All of the above

10.  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.