Question

Valves are not present in
A. Capillaries
B. Veins
C. Arteries
D. Both A and C

Answer 1

Hint: Blood vessels are used to circulate the blood to the whole body. Small branches which collect the blood from the different organs or parts are called the venules and they are combined with each other to form a veins. It is used to return the blood to the heart. Three kinds of blood vessels are capillaries, veins and arteries. Arteries used to carry the oxygenated blood away from the heart. Valves are present only in the veins and not in the capillaries and arteries.

Complete answer:
Option A: Capillaries are the smallest blood vessels in the body. It is used to connect the veins and arteries for the exchange of certain elements between blood and tissues. It is very small compared to veins and arteries. Option A is incorrect.
Option B: Veins are used to return the deoxygenated blood from organs to the heart. It is important for blood circulation. The largest veins in the body are superior and inferior vena cava. It drains directly into the right atrium of the heart. Veins have valves called valvula venosa. It prevents back flow. Option B is incorrect.
Option C: Arteries used to transport the oxygen-rich blood from the heart to all parts of the body. It is a muscular tube surrounded by smooth tissue. It has four layers. Left coronary artery and right coronary arteries are the two types of arteries in the heart. It doesn't contain any vessels. Option C is incorrect.
Option D: Both capillaries and arteries don't have any vessels. Both A and C are the correct answer. Option D is correct.

Hence, Option D is the correct answer.

Note:
Valves are used to ensure blood flow towards the heart only. It prevents the backflow of blood. If the valves are not working properly then back flow occurs. Backflow causes blood leakage during blood flow into the heart chambers. It will cause pressure in the left atrium and lungs. Valves are located at each end of two ventricles. It acts as one way inlet or one way outlets. There are four valves in the heart.