First, human body systems form a core part of biology in many competitive exams. Moreover, this article gives you 20 original MCQs on digestion, circulation, breathing, excretion, bones, muscles, hormones and immunity. Also, RRB NTPC, SSC and UPSC aspirants can use these questions to test their basics. Next, each question has four options, one correct answer and an Extra Information note. In addition, these notes teach useful facts that exam setters often ask. Therefore, you should read each question, pick an answer and then check the note. Besides, you can attempt the questions in timed rounds to build speed. As a result, you will remember key biology facts for a longer time. Finally, begin with your weakest section and move ahead step by step.
Digestive System MCQs for Competitive Exams
Q1
Which organ produces bile in the human body?
Show Answer & Explanation
Answer: B) Liver
First, the liver is the largest gland in the human body. Moreover, it makes bile, which helps break down fats. As a result, the small intestine absorbs fats more easily. However, the gall bladder only stores bile and does not make it. Lastly, the liver also stores glycogen and removes harmful substances.
Q2
Which part of the digestive tract absorbs most nutrients?
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Answer: D) Small intestine
In fact, the small intestine measures about six metres in an adult. Besides, tiny finger-like villi cover its inner wall. Because of this, the surface area for absorption grows very large. For example, villi absorb glucose and amino acids into the blood. Overall, this organ completes most digestion and absorption.
Q3
Which enzyme in saliva starts the digestion of starch?
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Answer: A) Salivary amylase
Initially, salivary amylase begins breaking starch in the mouth. Also, it turns starch into maltose, a simple sugar. Hence, bread tastes slightly sweet after long chewing. In contrast, pepsin works in the stomach and digests proteins. In short, each enzyme has its own place and job.
Q4
Which acid do the stomach glands release to kill germs?
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Answer: C) Hydrochloric acid
Next, gastric glands release hydrochloric acid into the stomach. Furthermore, this acid kills many germs in the food. Therefore, it also protects the body from infection. Still, a mucus layer shields the stomach wall from the acid. To sum up, acid and mucus work as a balanced team.
Q5
Which chamber of the human heart pumps oxygen-rich blood to the whole body?
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Answer: C) Left ventricle
First, the left ventricle has the thickest wall of all four chambers. Moreover, it must push blood through the aorta to the whole body. As a result, its muscle grows strong and heavy. In contrast, the right ventricle only sends blood to the lungs. Finally, a normal human heart has four chambers in total.
Q6
Which tiny cell fragments help blood clot after a cut?
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Answer: A) Platelets
In fact, platelets have another name, thrombocytes. Additionally, they gather at a wound and form a plug. For this reason, bleeding slows down quickly. For example, a small cut stops bleeding within minutes. Overall, a low platelet count can cause serious bleeding.
Q7
What is the normal blood pressure of a healthy adult?
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Answer: D) 120/80 mm Hg
To begin, the top number shows the systolic pressure. Also, the bottom number shows the diastolic pressure. Consequently, doctors read both numbers together. However, a reading above 140/90 mm Hg often signals high blood pressure. Thus, a sphygmomanometer helps people check this pressure at clinics.
Q8
Which scientist first described blood circulation in 1628?
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Answer: B) William Harvey
First, William Harvey was an English physician. Moreover, he published his findings on circulation in 1628. Therefore, people honour him as a pioneer of modern physiology. Meanwhile, Edward Jenner developed the first smallpox vaccine in 1796. In summary, Harvey showed that blood moves around the body in a circle.
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Respiratory and Excretory System MCQs
Q9
Which tiny air sacs in the lungs exchange oxygen and carbon dioxide with blood?
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Answer: D) Alveoli
Initially, alveoli have very thin walls and a rich blood supply. Also, a human lung holds hundreds of millions of them. As a result, gas exchange happens fast and smoothly. For example, oxygen moves into blood while carbon dioxide moves out. Thus, scientists name this process diffusion.
Q10
Which muscle below the lungs drives normal breathing?
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Answer: B) Diaphragm
First, the diaphragm is a dome-shaped muscle under the lungs. Next, it contracts and moves downward during inhalation. As a result, the chest cavity grows larger and air rushes in. In contrast, it relaxes during exhalation and moves upward. Finally, this steady motion lets an adult breathe about 12 to 20 times each minute.
Q11
Which structure acts as the basic filtering unit of the kidney?
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Answer: A) Nephron
In fact, each kidney contains about one million nephrons. Moreover, every nephron has a filter, the glomerulus. Because of this, blood loses waste and extra water here. However, the body takes back useful substances such as glucose. Overall, the nephron cleans blood and makes urine.
Q12
Which main nitrogenous waste do humans release in urine?
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Answer: C) Urea
First, the liver makes urea from harmful ammonia. Then, the blood carries urea to the kidneys. Consequently, the kidneys remove it through urine. In contrast, birds and reptiles mainly release uric acid. Finally, this difference helps those animals save water in dry places.
Skeletal and Muscular System MCQs
Q13
How many bones does a healthy adult human skeleton have?
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Answer: B) 206
To begin, a newborn baby has about 270 to 300 bones. Moreover, many of these bones fuse as the child grows. Therefore, an adult has 206 bones. For example, the skull bones join together in adults. In conclusion, the skeleton protects organs and supports the body.
Q14
Which bone is the longest in the human body?
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Answer: C) Femur
In fact, the femur is the longest and strongest bone. Besides, it forms the main bone of the thigh. Because of this, it bears most of the body’s weight. In contrast, the stapes in the ear is the smallest bone. Finally, the stapes measures only about three millimetres.
Q15
Which muscle type forms the wall of the heart?
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Answer: D) Cardiac muscle
First, cardiac muscle has striped fibres like skeletal muscle. However, it works without conscious control. Therefore, the heart beats without any thought from us. In addition, branched fibres help the muscle contract together. Meanwhile, smooth muscle lines organs such as the intestine and blood vessels.
Q16
Which joint allows movement in almost all directions?
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Answer: A) Ball and socket joint
For example, the shoulder and the hip have ball and socket joints. Also, these joints let limbs rotate in many directions. As a result, people can swing their arms in a full circle. In contrast, the knee and elbow have hinge joints that move in one plane. Finally, pivot joints in the neck let the head turn side to side.
Endocrine and Immune System MCQs
Q17
Which gland do teachers often call the master gland?
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Answer: A) Pituitary gland
In fact, the pituitary gland is only about the size of a pea. Moreover, it sits at the base of the brain. Because of this, it works closely with the hypothalamus. For example, it releases growth hormone and controls other glands. Overall, it guides growth, metabolism and reproduction.
Q18
Which disease arises when the body lacks enough insulin?
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Answer: D) Diabetes mellitus
First, the pancreas makes insulin to control blood sugar. Next, insulin helps cells take in glucose. As a result, blood sugar stays in a safe range. However, low insulin raises sugar levels and harms organs over time. Thus, doctors advise healthy food and exercise to lower the risk.
Q19
Which white blood cells make antibodies against germs?
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Answer: C) Lymphocytes
Initially, B lymphocytes make antibodies after they meet a germ. Then, antibodies stick to the germ and mark it for destruction. Therefore, other immune cells destroy it quickly. In contrast, T lymphocytes attack infected cells directly. Finally, memory cells help the body respond faster next time.
Q20
Which organ is the largest organ of the human body?
Show Answer & Explanation
Answer: B) Skin
To begin, skin covers the whole body and protects it from germs. Also, it controls body temperature through sweat. Because of this, the body stays cool in hot weather. For example, skin also makes vitamin D in sunlight. In short, skin works as a sense organ too.
Final Thoughts on Human Body Systems MCQs
Overall, these MCQs cover the key facts about human body systems. Moreover, you studied digestion, blood circulation, breathing, excretion, bones, muscles, hormones and immunity. For example, you learned about the liver, the heart, the alveoli and the nephron. Therefore, you should now revise each Extra Information note once more. Next, practise the MCQs again and take timed tests to check your speed. Also, write down the facts you missed and review them every week. In addition, aspirants of RRB NTPC, SSC and UPSC exams can mix these questions with other biology topics. However, avoid rushing, because steady practice gives better results than last-minute study. Finally, keep practising with a calm mind, and you will grow more confident every day.