exchange surfaces

• What are specialized exchange surfaces?

  Parts for substance exchange
• In humans, the specialized exchange surfaces are the alveoli and the villi
• Where are alveoli found in the respiratory system?

  Ends of bronchioles
• Alveoli exchange oxygen and carbon dioxide between air and blood.
• What is the primary role of villi in the small intestine?

  Absorb nutrients
• Villi absorb nutrients like glucose and amino acids
• Plants use specialized exchange surfaces to absorb water and mineral ions.
• Which plant cells help absorb water and mineral ions from the soil?

  Root hair cells
• All specialized exchange surfaces in organisms share identical features.

  False
• Leaves in plants help absorb carbon dioxide
• A large surface area increases the rate of diffusion
• What is the first common feature of specialized exchange surfaces?

  Large surface area
• Villi have a long, thin shape to increase their surface area.
• Why are specialized exchange surfaces usually thin?

  Short diffusion distance
• Water in root hair cells diffuses across a thin cell wall and cell membrane
• Permeability of exchange surfaces allows substances to diffuse across.
• What does a good blood supply help maintain in exchange surfaces?

  Concentration gradient
• A good blood supply to villi ensures that glucose is quickly taken away, maintaining a concentration gradient
• A good supply of the external medium is essential for specialized exchange surfaces.
• What is the external medium for alveoli?

  Air
• Breathing in and out ensures a constant supply of oxygen to the alveoli
• Arrange the main features of specialized exchange surfaces in the correct order.

  1️⃣ Large surface area

  2️⃣ Thin surfaces

  3️⃣ Permeability to substances

  4️⃣ Good blood supply

  5️⃣ Good supply of external medium
• A good supply of external medium helps maintain a high concentration gradient.
• Larger organisms have more surface area compared to their volume than smaller organisms.

  False
• What is the surface area to volume ratio a measure of?

  Surface area compared to volume
• As organisms get larger, their surface area to volume ratio decreases
• The volume of a cube is calculated by multiplying its length, width, and height
• How do you calculate the surface area of a cube?

  Area of one face times six
• Match the cube size with its surface area to volume ratio:

  1x1x1 ↔️ 6:1

  2x2x2 ↔️ 3:1

  3x3x3 ↔️ 2:1
• The surface area of the smallest cube (1x1x1) is 6 square centimeters.
• Bacteria have a high surface area to volume ratio because they are tiny
• Humans rely on diffusion alone to exchange substances with their environment.

  False
• Why do larger organisms have a lower surface area to volume ratio?

  Volume increases faster than surface area
• What specialized exchange surfaces do humans use to increase their surface area to volume ratio?

  Lungs and intestines
• In the lungs, oxygen is absorbed across millions of tiny structures called alveoli
• Diffusion is faster over longer distances.

  False
• Steps for molecules to diffuse across a cell

  1️⃣ Molecules move from high concentration to low concentration

  2️⃣ Molecules cross the cell membrane

  3️⃣ Molecules reach the inside of the cell
• What is the primary function of the circulatory system in humans?

  Transport molecules around the body
• Molecules transported by the circulatory system only have to diffuse a very short distance
• Which tissues in plants are responsible for transporting substances?

  Phloem and xylem