Question

1. when oxygen is lost from blood the colour of the blood without the oxygen changes

a. from pink to red
a. from red to blue
b. from red to pink
e. from blue to red
c. from pink to blue

1. which of the following is not true

a. mammalian heart has four chambers
b. amphibian heart has 3 chambers
c. aves heart have four chambers
d. pisces heart have three chambers
e. all of them are correct

1. which structure is used at the mouth of aorta

a. tricuspid valve
d. bicuspid
b. semilunar valve
e. pulmonary
c. s - a node

1. which part of the heart is thicker

a. left atrium
b. left ventricle
c. right atrium
d. right ventricle
e. all of them are same

1. which of the following is not found in the thoracic cavity of man.

a. heart
d. superior vena cava
b. lungs
e. stomach
c. bronchi

Explanation:

• Question 6: Oxygenated blood is bright red due to oxy - hemoglobin. Deoxygenated blood is darker (often described as a bluish - red in the body, but when exposed, it can appear more of a deep red - purple. However, in the context of basic biology teaching, it is often simplified as changing from red (oxygenated) to blue (deoxygenated) without considering the exact chemical - optical interactions in detail.
• Question 7: Pisces (fish) have a two - chambered heart (an atrium and a ventricle).
• Question 8: The semilunar valve is located at the mouth of the aorta to prevent back - flow of blood from the aorta to the left ventricle.
• Question 9: The left ventricle has to pump blood to the entire body (systemic circulation), so its walls are thicker compared to other heart chambers.
• Question 10: The stomach is located in the abdominal cavity, while the heart, lungs, bronchi, and superior vena cava are in the thoracic cavity.

Answer:

1. A. from red to blue
2. D. Pisces heart have three Chambers
3. B. Semilunar valve
4. B. Left ventricle
5. E. stomach