3.3.2 Gas exchange in single celled organisms and insects

Front

Primary function of gas exchange surfaces in single-celled organisms?

Back

To facilitate gas exchange

Answer explanation

The primary function of gas exchange surfaces in single-celled organisms is to facilitate gas exchange, allowing them to take in oxygen and expel carbon dioxide efficiently, which is vital for their survival.

Front

Which structure in the insect tracheal system is responsible for opening and closing to regulate air flow?

Back

Spiracles

Answer explanation

Spiracles are the openings in the insect tracheal system that regulate air flow by opening and closing. They control the entry of air into the tracheae, making them essential for respiration in insects.

Front

How do single-celled organisms primarily achieve gas exchange?

Back

Across their body surface

Answer explanation

Single-celled organisms primarily achieve gas exchange across their body surface. This process allows for the diffusion of gases directly through their cell membranes, as they lack specialized structures like lungs or gills.

Front

What is the main compromise terrestrial insects face between gas exchange and water loss?

Back

Efficient gas exchange with minimal water loss

Answer explanation

Terrestrial insects must balance gas exchange for respiration with the need to conserve water. The correct choice, 'Efficient gas exchange with minimal water loss', highlights their adaptation to optimize both processes.

Front

Role of tracheoles in the tracheal system of insects?

Back

To facilitate direct gas exchange with tissues

Answer explanation

Tracheoles are fine tubes in the tracheal system of insects that facilitate direct gas exchange with tissues, allowing oxygen to diffuse directly to cells and carbon dioxide to be expelled, which is essential for respiration.

Front

Which of the following is NOT a feature of gas exchange surfaces in single-celled organisms?

• Large surface area
• Thin membrane
• High metabolic rate
• Moist surface

Back

High metabolic rate

Answer explanation

Single-celled organisms have gas exchange surfaces that are large, thin, and moist to facilitate diffusion. A high metabolic rate is not a feature of their gas exchange surfaces, as it refers to the overall activity level of the organism.

Front

What adaptation helps insects minimise water loss during gas exchange?

Back

Spiracles that can close

Answer explanation

Spiracles that can close help insects minimize water loss during gas exchange by regulating airflow and reducing evaporation, making them crucial for survival in dry environments.

Front

Why is a large surface area important for gas exchange in single-celled organisms?

Back

It enhances the rate of gas exchange

Answer explanation

A large surface area in single-celled organisms allows for more efficient gas exchange. This is crucial for their survival, as it enhances the rate at which oxygen enters and carbon dioxide exits the cell.

Front

Structural feature of the insect tracheal system?

Back

Tracheae

Answer explanation

The tracheal system of insects consists of a network of tubes called tracheae, which transport oxygen directly to tissues. Alveoli and bronchi are features of the mammalian respiratory system, while a diaphragm is not present in insects.

Front

How do spiracles contribute to the efficiency of the insect tracheal system?

Back

By allowing selective opening and closing to control air flow

Answer explanation

Spiracles allow insects to control air flow by selectively opening and closing, which helps regulate gas exchange efficiently. This adaptation is crucial for maintaining oxygen levels and minimizing water loss.