In situations where the distance between roots and leaves is significant, a proper transportation system becomes essential because diffusion alone cannot efficiently provide raw materials to leaves and transport energy to roots.

The soil serves as a rich source of raw materials like nitrogen and phosphorus for plants. Roots are the plant organs primarily responsible for absorbing these substances from the soil.

Short distances between soil-contacting organs (roots) and chlorophyll-containing organs (leaves) allow easy diffusion of energy and raw materials throughout the plant body. However, if these distances increase due to changes in plant body design, diffusion becomes insufficient.

Lymphatic capillaries collect tissue fluid or lymph from intercellular spaces, and larger lymph vessels drain into veins. This process helps regulate fluid balance by returning excess fluid from the extracellular space back into the blood, ensuring efficient circulation.

Lymph or tissue fluid is formed when plasma, proteins, and blood cells escape through capillary walls into intercellular spaces. It serves as a colorless fluid similar to blood plasma, with fewer proteins. Lymph drains excess fluid and carries digested fats ...

Platelet cells circulate in the blood to plug leaks in the circulatory system, helping to clot blood at points of injury. This response minimizes blood loss and maintains the efficiency of the pumping system.

Capillaries, with walls one-cell thick, allow for efficient exchange of materials between the blood and surrounding cells. This thin barrier facilitates the diffusion of substances like oxygen and nutrients into tissues and the removal of waste products.

Veins have thinner walls compared to arteries as they carry blood back to the heart at lower pressure. Veins have valves to ensure one-directional blood flow, preventing backflow.

Arteries have thick, elastic walls because they carry blood away from the heart under high pressure, helping to withstand and accommodate the force generated by the pumping action of the heart.

Fish have a two-chambered heart, and blood is oxygenated in the gills before directly circulating through the body, resulting in a single passage through the heart per cycle, unlike other vertebrates with double circulation.