Question

Select the incorrect pair from the following: (a) Leucoplast-Carotene (b) Amyloplast-Starch (c) Elaioplast-Oils (d) Aleuroplasts-Proteins

Short answer

The incorrect pair is (a) Leucoplast-Carotene.

Step-by-step solution

Identify the Purpose of Each Plastid

Leucoplasts are colorless plastids that are associated with the synthesis and storage of non-pigmented compounds such as lipids, proteins, and starches. \n\nAmyloplasts specialize in the synthesis and storage of starch granules.\n\nElaioplasts are involved in storing oil and fats.\n\nAleuroplasts are specialized for protein storage.

Pair Each Plastid with Its Associated Substance

Based on their functions, the pairings are:\n\nLeucoplast - Starch, Proteins, Lipids\n\nAmyloplast - Starch\n\nElaioplast - Oils and fats\n\nAleuroplast - Proteins

Compare Pairings with Given Options

Leucoplast is listed with the substance Carotene, which is not typically associated with it. \n\n Amyloplast is correctly paired with Starch.\n\nElaioplast is correctly paired with Oils.\n\nAleuroplast is correctly paired with Proteins.

Key concepts

Leucoplast

Leucoplasts play an essential role in plant cells. As non-pigmented organelles, they are largely involved in the storage and synthesis of important biological molecules.

Primarily found in parts of plants that are not exposed to light, such as roots, tubers, and seeds, leucoplasts are integral in storing key nutrients. For instance, they may convert fatty acids into lipids for long-term energy reservation.

As a type of plastid, leucoplasts are often misconstrued as having a relationship with pigments like carotene. This is a common confusion, which was the focal point of the textbook exercise we're building upon. It is essential to note that carotene—a pigment responsible for yellow, orange, and red colors—is not synthesized in leucoplasts but in chromoplasts.

In summary, leucoplasts are versatile, primarily tasked with storing and converting energy in non-photosynthetic plant tissues.

Amyloplast

Amyloplasts are specialized leucoplasts dedicated to the storage of starch, a complex carbohydrate that plants utilize as an energy reserve.

These plastids are particularly abundant in plant tissues like potatoes, where they convert glucose units into starch and densely pack them into granular structures. Their presence is easily identified through the process of iodine staining, as amyloplasts will characteristically turn a dark blue or black color in the presence of iodine.

Amyloplasts not only serve storage purposes but also have a role in gravity sensing within plants, contributing to their ability to grow upright and navigate their growth direction.

Elaioplast

Elaioplasts are bound by a double membrane and can be frequently found in seeds and fruits that are rich in oils. Their primary function is to synthesize and store lipids, which include a variety of oils and fats.

This storage facility allows plants to have a reserve of energy-rich compounds that can later be mobilized during germination or used as energy sources for the development of new plant tissues.

Interestingly, these oils are also involved in creating fragrances and flavors in plants; hence, elaioplasts play a crucial part in the sensory characteristics of many fruits and flowers.

Aleuroplast

Aleuroplasts, sometimes referred to as proteinoplasts, are unique plastids focused on protein storage.

They are abundant in seeds, a critical feature because these proteins are later used to support the growth of the embryo within the seed during germination. The provision of these stored proteins to the developing plant is vital for the early stages of growth.

Due to their significance in germination, aleuroplasts ensure the continuation of plant species by supplying the necessary nutrients to sprouting seeds. This proper function of the aleuroplast was correctly represented in the textbook exercise, pairing it with the storage of proteins.