General Science/Everyday Science MCQs
Topic Notes: General Science/Everyday Science
MCQs and preparation resources for competitive exams, covering important concepts, past papers, and detailed explanations.
Plato
- Biography: Ancient Greek philosopher (427–347 BCE), student of Socrates and teacher of Aristotle, founder of the Academy in Athens.
- Important Ideas:
- Theory of Forms
- Philosopher-King
- Ideal State
1
What is the primary function of the stomach in the digestive system?
Answer:
Store food and begin protein digestion
The stomach is a muscular sac that churns food into a liquid called chyme. It secretes hydrochloric acid and pepsin to begin breaking down protein molecules into smaller chains.
2
Which valve prevents blood from flowing back into the left ventricle from the aorta?
Answer:
Aortic semilunar valve
The aortic semilunar valve opens during ventricular systole to let blood out and snaps shut during diastole to ensure that blood remains in the systemic circulation.
3
The structural and functional unit of the skeletal system is the:
Answer:
Osteon (Haversian System)
In compact bone, osteons are cylindrical structures that contain mineral matrix and living osteocytes arranged around a central canal, providing maximum strength with minimal weight.
4
Which hormone is secreted by the pineal gland to induce sleepiness?
Answer:
Melatonin
Melatonin production increases in the evening as light levels drop, helping to regulate the body's circadian rhythm and prepare the brain for sleep.
5
The 'white' part of the eye that provides structure and protection is the:
Answer:
Sclera
The sclera is the opaque, fibrous, protective outer layer of the eye. It helps maintain the eye's shape and serves as an attachment point for the extrinsic eye muscles.
6
Which organ system is responsible for removing carbon dioxide from the body and bringing in oxygen?
Answer:
Respiratory
The respiratory system includes the nose, pharynx, larynx, trachea, bronchi, and lungs. Its primary role is to facilitate the exchange of vital gases between the air and the blood.
7
What is the function of the myelin sheath that covers many axons in the nervous system?
Answer:
Increase the speed of signal transmission
The myelin sheath is a fatty, insulating layer produced by glial cells (Schwann cells or oligodendrocytes). It allows electrical impulses to jump between nodes (saltatory conduction), greatly increasing speed.
8
The 'pacemaker' of the heart, which initiates the electrical impulse for a heartbeat, is the:
Answer:
SA (Sinoatrial) node
The SA node, located in the right atrium, generates spontaneous electrical signals that travel through the heart muscle, causing the atria and then the ventricles to contract in a coordinated rhythm.
9
Which part of the tooth is the hardest substance in the human body?
Answer:
Enamel
Tooth enamel is a highly mineralized tissue consisting mostly of hydroxyapatite. It protects the tooth from wear, tear, and decay during chewing.
10
The 'functional unit' of the lungs, where gas exchange occurs, is the:
Answer:
Alveolus
Alveoli are microscopic air sacs arranged in clusters at the end of terminal bronchioles. Their extremely thin walls allow for the efficient exchange of oxygen and carbon dioxide by diffusion.