What problem may occur if veins do not have valves?
Answer and explanation
Correct answer: Blood may flow backward
Veins return blood to the heart at relatively low pressure, especially from the lower parts of the body. Valves open toward the heart and close when blood tends to reverse direction. Without these one-way valves, gravity and muscle relaxation could allow pooling or backward flow, making venous return less efficient. Therefore option A is correct; the other options confuse circulation with unrelated processes.
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What is the correct answer to this question?
Blood may flow backward
Why is this the correct answer?
Veins return blood to the heart at relatively low pressure, especially from the lower parts of the body. Valves open toward the heart and close when blood tends to reverse direction. Without these one-way valves, gravity and muscle relaxation could allow pooling or backward flow, making venous return less efficient. Therefore option A is correct; the other options confuse circulation with unrelated processes.
Which subject and chapter does this question cover?
This is a Class 10 Science question. Chapter: World of Living. Topic: Life Processes.
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