Transportation in Animals and Plants

• Understand the human circulatory system: heart, blood vessels, and blood.
• Understand how water and minerals move in plants (via xylem) and how food moves (via phloem).
• Understand basic excretion in humans (role of kidneys).

1. Blood is made of plasma, red blood cells (carry oxygen), white blood cells (fight infection), and platelets (clotting).
2. The heart pumps blood through arteries (away from heart) and veins (towards heart); capillaries connect them at tissues.
3. In plants, xylem transports water and minerals upward from roots; phloem transports food (made in leaves) to other parts.
4. Excretion removes waste from the body; in humans, the kidneys filter blood to remove waste as urine.

Why do arteries have thicker walls than veins?

Arteries carry blood at high pressure directly from the pumping heart,
so they need thick, elastic walls to withstand that pressure.
Veins carry blood at lower pressure back to the heart.

• Confusing xylem (water/minerals, upward) with phloem (food, both directions).
• Assuming all blood vessels carry oxygen-rich blood (pulmonary artery carries oxygen-poor blood to the lungs).
• Thinking excretion and digestion are the same process (they are different).

• Which blood vessels carry blood away from the heart?
• Which plant tissue transports food made by leaves?

Open the Practice tab for graded questions on Transportation in Animals and Plants.