Page 1 - 1. Transportation of substances in animals

SAI International School

Subject- Biology, Class-VII
Topic- Transportation and Excretion
Subtopic- Transportation of substances in organisms
Lesson Notes

Transportation in Unicellular Organisms:
• In unicellular organisms such as Amoeba and Paramecium, transportation of substances
happens through diffusion and osmosis.
• No specialised transportation system is present in such organisms.

Transportation in Multicellular Organisms:
• Special transport system to carry oxygen, carbon dioxide, nutrients, waste products,
food, and various other substances from one part of the body to the other.

Know more:

Diffusion: Diffusion is the process by which particles move from a region of higher concentration
to a region of lower concentration until they are evenly spread out.

Osmosis: Osmosis is the movement of water molecules from a region of higher water

concentration to a region of lower water concentration through a semi-permeable membrane.

Circulatory system in Human Beings:
• The circulatory system in humans is composed of three main components, viz.
heart, blood vessels and blood.
• Help in transportation of nutrients, respiratory gases, various enzymes and
hormones to body cells.
• Transportation of wastes from body cells to excretory organs.
Blood:

1. PLASMA:
• Plasma makes the liquid part of the blood.
• It is 90% water and rest 10% salts, digested food, proteins, waste materials etc.
2. BLOOD CELLS:
a) Red Blood Cells or Red Blood Corpuscles (RBC):
• biconcave disc-like structures
• lifespan: 120 days
• contains haemoglobin that gives blood red colour and binds with oxygen to form
oxyhaemoglobin