IGCSE Biology Paper-4: Specimen Questions with Answers 168 - 170 of 279

Passage

Shows the human gas exchange system. The functions of the parts of the gas exchange system are given in Table.

Human Gas Exchange System

Question 168 (2 of 2 Based on Passage)

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The gas exchange system contains cartilage.

Describe the function of cartilage in the gas exchange system.

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Explanation

Cartilage

  • Keeps the airways open and air resistance low, and prevents them from collapsing or bursting as the air pressure changes during breathing. The purpose of the hyaline cartilage C-rings in the respiratory system, or more specifically in the trachea is to allow for the expansion of the underlying esophagus when food or liquids pass through.
  • Cartilage present in Trachea and Bronchus.

Question 169

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Describe the treatment for human patients with Type 1 diabetes.

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Explanation

Treatment for Type 1 Diabetes Includes

  • Taking insulin
  • Carbohydrate, fat, and protein counting
  • Frequent blood sugar monitoring
  • Eating healthy foods
  • Exercising regularly and maintaining a healthy weight

Question 170

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Define the term excretion.

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Explanation

Excretion is the removal of metabolic waste (mainly) from the body.

Faecal matter is undigested waste, and not metabolic waste, so it is not considered as excretory product.

The excretory wastes are of two types:

Non-Nitrogenous Wastes

  • Carbon dioxide: It is removed through lungs (accessory excretory structure) .
  • Excess water and excess salts are removed through kidney (primary excretory structure) .

Nitrogenous Wastes

Such wastes are produced from the metabolism of proteins and nucleic acids.

Ammonia

The animals in which ammonia is the major excretory product are called Ammonotelics.

Urea
  • The animals in which urea is the major excretory product are called Ureotelics.
  • Urea is less toxic and requires less water for elimination.
Uric Acid
  • The animals in which uric acid is the major excretory product are called Uricotelics.
  • Uric acid is least soluble in water and can be stored as a solid waste.