Q45. What are the major culprits of tooth decay?
sweets, soft drinks and other sugar products are the major culprits of tooth
Q46. Why do we get instant energy from glucose?
In the cells, glucose breaks down easily with the help of oxygen into carbon
dioxide and water, and energy is released.
Q47. What are the main parts of the alimentary canal?
The canal can be divided into various compartments: (1) the buccal cavity, (2)
foodpipe or oesophagus, (3) stomach, (4) small intestine, (5) large intestine
ending in the rectum and (6) the anus.
Q48. How is food prevented from entering the windpipe?
During the act of swallowing a flap-like valve closes the passage of the
windpipe and guides the food into the foodpipe. If, by chance, food particles
enter the windpipe, we feel choked, get hiccups or cough.
Q49. What is small intestine?
The small intestine is highly coiled and is about 7.5 metres long. It receives secretions
from the liver and the pancreas. Besides, its wall also secretes juices.
Q50. Why we cannot digest cellulose like the cattle do?
Ruminants have a large sac-like structure called rumen between the oesophagus
and the small intestine. The cellulose of the food is digested here by the
action of certain bacteria which are not present in humans.
Q51. Can we survive only on raw, leafy vegetables/grass?
No, human cannot survive only on raw, leafy vegetables, or grass because they are
rich in cellulose, which is a type of carbohydrate that humans are not able to
digest due to the absence of cellulose-digesting enzymes.
Q52. Explain the process of digestion in grass eating animals.
eating animals quickly swallow the grass and store it in a part of the stomach
called rumen. Here the food gets partially digested and is
called cud. But later the cud returns to the mouth in small lumps and the
animal chews it.
Q53. Write a short note on digestion in starfish.
Starfish feeds on animals covered by hard shells of calcium carbonate. After
opening the shell, the starfish pops out its stomach through its mouth to eat
the soft animal inside the shell. The stomach then goes back into the body and
the food is slowly digested.
Q54. Write a short note on large intestine.
large intestine is wider and shorter than small intestine. It is about 1.5
metre in length. Its function is to absorb water and some salts from the
undigested food material. The remaining waste passes into the rectum and
remains there as semi-solid faeces.
Q55. How can we prevent tooth decay?
can prevent tooth decay in the following manner:
By cleaning the teeth with a brush or datun
and dental floss at least twice a day and rinse the mouth after every meal.
By not putting dirty fingers or any
unwashed object in the mouth.
Q56. What are villi? What is their location and function?
The inner walls of the small intestine have thousands of finger-like
outgrowths. These are called villi (singular villus). These are found in small
The villi increase the surface area for
absorption of the digested food.
The surface of the villi absorbs the
digested food materials.
Q57. What are the functions of the tongue in human body?
Functions of the tongue in human body
It helps in talking.
It mixes saliva with the food during
chewing and helps in swallowing food.
It has taste buds that detect different
tastes of food.