Introduction - SS2 Biology Lesson Note

In biology, the transport system refers to the specialized structures and processes that allow for the movement of substances, such as nutrients, gases, hormones, and waste products, throughout an organism's body. It ensures that essential materials are delivered to cells and metabolic waste products are removed efficiently.

Different organisms have evolved various transport systems to meet their specific needs. Here are some examples of transport systems in biology:

1.       Circulatory System (in animals):

·         In animals, including humans, the circulatory system consists of the heart, blood vessels (arteries, veins, and capillaries), and blood.

·         The heart pumps blood, which carries oxygen, nutrients, hormones, and other substances, throughout the body.

·         Arteries carry oxygenated blood away from the heart, while veins carry deoxygenated blood back to the heart.

·         Capillaries are tiny, thin-walled vessels that allow for the exchange of substances between the blood and body tissues.

2.       Xylem and Phloem (in plants):

·         In plants, the transport system involves the xylem and phloem tissues.

·         Xylem transports water, dissolved minerals, and nutrients from the roots to the rest of the plant. It consists of specialized cells called tracheids and vessel elements.

·         Phloem transports organic compounds, such as sugars and hormones, from the leaves (source) to other parts of the plant (sink). It consists of sieve tube elements and companion cells.

3.       Vascular Tissue (in lower plants):

·         Lower plants, such as mosses and ferns, possess a simple vascular tissue system.

·         The vascular tissue consists of specialized cells called hydroids that transport water and leptoids that transport organic compounds.

4.       Diffusion (in single-celled organisms):

·         Some single-celled organisms, such as bacteria and protists, rely on diffusion for the transport of substances.

·         Diffusion is the passive movement of molecules from an area of higher concentration to an area of lower concentration, driven by random molecular motion.

1.       Air Tubes (in insects):

·         In insects, a network of air tubes called tracheae delivers oxygen directly to cells and removes carbon dioxide.

·         The tracheal system branches throughout the body and connects to tiny openings called spiracles on the insect's exoskeleton.