PPSCFPSCNTSPakistan govt jobs
- Subject
- Biology Mcqsbiology-mcqs
- Published
- 22 Jan 2020
- Last updated
- 28 May 2026
Explanation
The "lub" sound, also known as the first heart sound, is caused by the sudden closure of the bicuspid (mitral) and tricuspid valves as the ventricles contract, preventing backflow into the atria.
More Biology Mcqs
Practice related questions from the same subject.
- 1.Which field of study focuses on the cultivation of crops and the management of soil?
- 2.What does pedology focus on studying?
- 3.What is another name for mitochondria?
- 4.Which field focuses on examining the interactions between antigens and antibodies present in the blood?
- 5.Which scientific discipline focuses on organizing and categorizing living organisms?
- 6.In the scientific name Homo sapiens, which two taxonomic categories are represented by the Latin terms?
- 7.Which virus is responsible for causing rabies?
- 8.Which of the following conditions is commonly associated with multiple opportunistic infections?