Chapter 8: Respiration and Circulation
Q.1 Choose the correct alternative.
1. The muscular structure that separates the thoracic and abdominal cavity is _______.
2. What is the minimum number of the plasma membrane that oxygen has to diffuse across to pass from air in the alveolus to haemoglobin inside a RBC?
3. ________ is a sound-producing organ.
4. The maximum volume of gas that is inhaled during breathing in addition to T.V is _______.
5. _______ muscles contract when the external intercostal muscles contract.
6. Movement of cytoplasm in unicellular organisms is called __________.
7. Which of the following animals do not have closed circulation?
8. Diapedesis can be seen in _________ cell.
9. Pacemaker of heart is _________.
10. Which of the following is without a nucleus?
11. Cockroach shows which kind of circulatory system?
12. Opening of inferior vena cava is guarded by _______.
13. _______ wave in ECG represent atrial depolarization.
14. The fluid seen in the intercellular spaces in human is _________
Q.2 Match the Respiratory surface to the organism in which it is found.
| Respiratory Surface | Correct Organism (Matched) |
|---|---|
| Plasma membrane | Amoeba |
| Lungs | Bird / Salamander |
| External gills | Salamander |
| Internal gills | Fish |
| Trachea | Insect |
Q.3 Very Short Answer Questions.
1. Why does trachea have 'C' shaped rings of cartilage?
C-shaped cartilaginous rings reinforce the anterior and lateral sides of the trachea to protect and maintain the airway open. They also allow the trachea to collapse slightly to allow food to pass down the esophagus.
2. Why is respiration in insect called direct respiration?
Respiration in insects is called direct because tracheal tubes exchange \(O_2\)/\(CO_2\) directly with the haemocoel which then exchanges with tissues without the aid of blood.
3. Why is gas exchange very rapid at alveolar level?
Gas exchange is very rapid at the alveolar level because alveoli have a very large surface area and extremely thin walls (squamous epithelium), facilitating quick diffusion.
4. Name the organ which prevents the entry of food into the trachea while eating.
The Epiglottis prevents the entry of food into the trachea while eating.
