Question Answers For All Chapters – General Science Class 7
Exercise
1. Fill in the blanks with the right word from the brackets.
(a) The process of digestion starts from the mouth. (stomach / mouth)
(b) Eyelids have involuntary muscles. (voluntary / involuntary)
(c) Production of blood cells is not a function of the muscular system. (Production of blood cells / Performing movements)
(d) Muscles of the heart are cardiac muscles. (ordinary muscles / cardiac muscles)
(e) Pushing forward the food that has been chewed is the function of the oesophagus. (stomach / oesophagus)
2. Find a match for me.
| Group A | Group B | Answer |
|---|---|---|
| (1) Cardiac muscles | (a) always function in pairs. | (b) we never feel tired. |
| (2) Are brought about by muscles | (b) we never feel tired. | (d) chewing movements of jaws. |
| (3) Pepsin | (c) uncontrolled and painful contraction of muscles. | (e) enzyme of the gastric juice. |
| (4) Cramps | (d) chewing movements of jaws. | (c) uncontrolled and painful contraction of muscles. |
| (5) Skeletal muscles | (e) enzyme of the gastric juice. | (a) always function in pairs. |
3. Who is telling a lie?
| Organ | Statement | Truth |
|---|---|---|
| 1. Tongue | “My taste buds can tell only a sweet taste.” | False – The tongue has taste buds for sweet, sour, salty, and bitter tastes. |
| 2. Liver | “I am the largest gland in the body.” | True – The liver is the largest gland in the human body. |
| 3. Large intestine | “I am 7.5 meters long.” | False – The large intestine is about 1.5 meters long, while the small intestine is 6 meters long. |
| 4. Appendix | “Digestion is impossible without me.” | False – The appendix has no role in digestion and is a vestigial organ. |
| 5. Lung | “I play an important role in excretion.” | True – The lungs help in excreting carbon dioxide from the body. |
4. Give reasons.
(1) Food becomes acidic in the stomach.
→ The stomach secretes hydrochloric acid, which helps in digesting proteins and killing harmful bacteria in food.
(2) Cardiac muscles are said to be involuntary muscles.
→ Cardiac muscles work continuously without our control, keeping the heart beating around 70 times per minute.
(3) Intoxicating substances should not be consumed.
→ Substances like tobacco and alcohol damage the liver, stomach, and intestines, leading to diseases like ulcers, cancer, and liver failure.
(4) Your muscles should be strong and efficient.
→ Strong muscles help in proper body movement, posture, and strength, preventing injuries and back problems.
5. Answer the following.
(a) How many types of muscles are there? Which are those types?
→ There are three types of muscles:
- Skeletal muscles – Control voluntary movements like walking and running.
- Cardiac muscles – Found in the heart, they contract and relax continuously.
- Smooth muscles – Found in internal organs like the stomach and intestines.
(b) What causes the problem of acidity? What is its effect on the body?
→ Excess secretion of hydrochloric acid in the stomach causes acidity. It leads to burning sensation, ulcers, and digestive problems.
(c) Name the different types of teeth. What is the function of each type?
→ There are four types of teeth:
- Incisors – Help in cutting food.
- Canines – Used for tearing food.
- Premolars – Help in crushing and grinding food.
- Molars – Used for chewing and grinding food completely.
6. Sketch and label a diagram of the digestive system and describe it in your own words.
Description of the Digestive System
- The digestive system includes the mouth, oesophagus, stomach, small intestine, large intestine, rectum, and anus.
- Salivary glands secrete saliva, which contains enzymes to break down food.
- The stomach produces gastric juice that helps digest proteins.
- The small intestine absorbs nutrients, and the large intestine absorbs water.
- Undigested food is removed as waste through the anus.
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