Multicellular Organisms - Absorption of Materials

Question 1

Describe the 3 features that surfaces involved in the absorption of materials have in common

Answer 1

• a large surface area
• thin walls
• extensive blood supply

These features increase the efficiency of absorption

Question 2

• Why must carbon dioxide be removed from the body?
• Describe the movement of oxygen and carbon dioxide through the lung lining

Answer 2

• Makes the blood dangerously acidic
• Oxygen and carbon dioxide enter and leave the blood by diffusion through the lining of the lungs

Question 3

• Describe the 3 features of the lungs

Answer 3

THIN LINING: Lining of the alveoli is very thin so gases can quickly diffuse through it.
LARGE SURFACE AREA: Speeds up diffusion because gases have more area to diffuse.
GOOD BLOOD SUPPLY: The alveoli have a dense capillary network so large volumes of gases can be exchanged.

Question 4

Explain the process of gas exchange in the lungs

Answer 4

The lungs facilitate gas exchange by swapping oxygen for carbon dioxide. Oxygen diffuses from high conc. in the alveolus to low conc. in the blood, while carbon dioxide moves from high conc. in the blood to low conc. in the alveolus.

Question 5

What is an alveolus?

Answer 5

Small sac-like structure in the lung that provides surface area for gas exchange to occur.

Question 6

Describe the role and adaptation of the small intestine

Answer 6

Role: Rapid absorption of small soluble food molecules
Adaptation: lining of the small intestine is folded into millions of villi, which provides a very large surface area, which increases the speed of absorption.

Question 7

Describe the 3 features of villus

Answer 7

• Its lining is only one cell thick, which increases speed of absorption.
• Capillaries in each villus to provide a good blood supply to transport glucose and amino acids.
• A lacteal to transport products of fat digestion.

Question 8

What is a lacteal?

Answer 8

Central vessel in the villi responsible for the absorption of fats.

Question 9

Describe the process of digestion

Answer 9

Food is broken down by enzymes into small, soluble molecules for absorption. Digestion occurs in the mouth, stomach, and small intestine, with nutrients absorbed into the blood through the small intestine lining.