| Aim | To identify and examine the different parts of an embryo of a dicot seed, specifically the pea, gram, or red kidney bean. |
| Apparatus Required | Dicot seeds (pea, gram, or red kidney bean) Dissecting microscope Scalpel or razor blade Forceps Petri dishes Water Paper towels |
| Theory | Principle/Theory: After fertilization in plants, the ovary undergoes changes and forms a fruit. The mature ovule develops into a seed which consists of various parts such as the hilum, seed coat, endosperm, and embryo. The embryo is formed as a result of several divisions of the zygote and consists of the radicle, plumule, and cotyledons. Based on the number of cotyledons in the seed, angiosperms are classified as monocots or dicots. Germination is the process of the seed developing into a tiny embryonic plant under favorable conditions of water, light, temperature, and air. Germination involves the swelling of seeds, the emergence of the plumule into shoots, and the formation of roots from the radicle. What does a seed consist of? A seed is composed of the following parts: Hilum – a scar located on the seed coat, associated with the stalk of the plant. Seed coat – an outer covering that protects and provides nourishment to the seed inside. Endosperm – a tissue containing nutrients for the growth of the embryo. Embryo – a structure formed from the zygote division that develops into a new plant. What does the embryo consist of? The embryo consists of the following parts: Radicle – the embryonic root. Plumule – the embryonic shoot that will form the stem and leaves of the plant. Cotyledons – the first leaves of the plant that serve as a primary source of food for the growing seedling. How are seeds classified? Based on the number of cotyledons in the seed, angiosperms are classified into the following: Monocots – seeds with a single cotyledon. Dicots – seeds with two cotyledons. What is germination? Germination is the process of the seed developing into a tiny embryonic plant under favorable conditions of water, light, temperature, and air. Germination involves the swelling of seeds, the emergence of the plumule into shoots, and the formation of roots from the radicle. Additionally, in monocots, only one cotyledon forms during germination, while in dicots, two cotyledons develop. When a dicot seed (such as pea, gram, or red kidney bean) is germinated, the embryo contained within the seed gives rise to the new plant. The embryo is made up of several different parts, each with its own function in the growth and development of the plant. The cotyledons are the first leaves of the plant and serve as the primary source of food for the growing seedling. They also provide protection to the embryonic shoot and root as they emerge from the seed. The embryonic axis consists of the radicle, hypocotyl, and plumule. The radicle is the embryonic root and is the first part of the embryo to emerge from the seed. It anchors the seedling in the soil and absorbs water and nutrients from the soil. The hypocotyl is the part of the embryo between the radicle and the cotyledons, and it helps to lift the cotyledons above the soil surface during germination. The plumule is the embryonic shoot, which will develop into the stem and leaves of the plant. It is located at the top of the embryonic axis and contains the shoot tip and tiny leaves. By identifying and examining the different parts of the embryo of a dicot seed, we can gain a better understanding of the process of plant germination and the structures that are necessary for plant growth and development. The experiment can also help in distinguishing the different parts of the embryo in a dicot seed and their individual roles in the growth of the new plant. |
| Procedure | Take a dicot seed (pea, gram, or red kidney bean) and soak it in water for several hours until it swells and softens. Use a scalpel or razor blade to carefully cut through the seed coat and remove it, taking care not to damage the embryo inside. Place the embryo on a clean petri dish and gently rinse it with water. Use a dissecting microscope to observe the different parts of the embryo, including the cotyledons, embryonic axis, and plumule. Use forceps to carefully separate the cotyledons and examine them closely. Locate the embryonic axis, which includes the radicle and the hypocotyl. The radicle is the embryonic root, and the hypocotyl is the part of the embryo between the radicle and the cotyledons. Look for the plumule, which is the embryonic shoot. It will be found at the top of the embryonic axis and will have a small shoot tip and tiny leaves. Make sketches of the different parts of the embryo and label them accordingly. |
| Observation and Result | Observations: The dicot seed has two cotyledons, which are large and fleshy. The embryonic axis consists of the radicle, which is the embryonic root, and the hypocotyl, which is the part of the embryo between the radicle and the cotyledons. The plumule is the embryonic shoot and is located at the top of the embryonic axis. It consists of a shoot tip and tiny leaves. Results: The experiment successfully identified and examined the different parts of an embryo of a dicot seed. The cotyledons, embryonic axis, and plumule were observed and identified. The experiment demonstrated the importance of the different parts of the embryo in the growth and development of the plant. |
