The correct option is 1 and 3 only.
Explanation
The mechanism of material exchange (food, oxygen, waste) between an organism and its environment depends heavily on the organism's body design, specifically the relationship between its surface area and volume. As complexity increases, simple physical processes like diffusion become insufficient.
Statement-wise Analysis:
- Statement 1 is Correct: In single-celled organisms, the entire surface of the organism is in direct contact with the environment. Therefore, simple diffusion across the cell membrane is sufficient to meet the requirements of food intake, gas exchange, and waste removal.
- Statement 2 is Incorrect: In multicellular organisms, not all cells are in direct contact with the surrounding environment. Simple diffusion is an extremely slow process and cannot deliver oxygen or nutrients to internal cells quickly enough to sustain life.
- Statement 3 is Correct: As body size and complexity increase, the volume of the organism increases much faster than its surface area. To overcome this, multicellular organisms develop specialized tissues and organs for specific functions (such as lungs for respiration or kidneys for excretion) and transport systems to carry materials to deep-seated cells.
Key Takeaway:
While single-celled organisms rely on the entire body surface for exchange via diffusion, multicellular organisms require specialized organs and transportation systems because simple diffusion is insufficient for their complex body designs.