Media of transportation - SS2 Biology Lesson Note

Living things employ various media or mechanisms for transportation within their bodies. Here are some examples of media of transportation in different living organisms:

1.       Fluid-based Transport:

·         Blood: In complex animals, including humans, blood acts as a fluid medium for transportation. It carries oxygen, nutrients, hormones, waste products, immune cells, and heat throughout the body via the circulatory system.

·         Hemolymph: In many invertebrates, such as insects and other arthropods, a fluid called hemolymph circulates through open circulatory systems, transporting nutrients, hormones, and waste products.

2.       Water-based Transport:

·         Xylem: In plants, xylem tissue transports water, dissolved minerals, and nutrients from the roots to the leaves and other aerial parts of the plant. This transport occurs through the passive process of transpiration and capillary action.

·         Phloem: The phloem tissue in plants transports sugars, amino acids, hormones, and other organic compounds from photosynthetic sources to other parts of the plant through a process called translocation.

3.       Air-based Transport:

·         Air Tubes: In insects, a network of air tubes called tracheae transports oxygen directly to the cells. These tubes branch throughout the insect's body, reaching even the deepest tissues, and enable efficient gas exchange.

4.       Diffusion:

·         Single-celled organisms: Some single-celled organisms, such as bacteria and protists, rely on diffusion for the transport of gases, nutrients, and waste products across their cell membranes. Diffusion occurs based on concentration gradients and molecular movement.

5.       Cell-to-Cell Transport:

·         Gap Junctions: In multicellular organisms, gap junctions allow direct communication and transport between neighboring cells. These small channels facilitate the exchange of ions, small molecules, and electrical signals.

·         Plasmodesmata: In plant cells, plasmodesmata are channels that connect adjacent cells, allowing for the transport of water, nutrients, and signals.

These media of transportation ensure the efficient distribution of essential substances, gases, nutrients, and signals within the living organisms, enabling their growth, metabolism, communication, and overall physiological functions.