2

Q1. How is digested food absorbed in the small intestine?

Solution

The inner walls of the small intestine bear numerous finger-like outgrowths called villi which increase the surface area for absorption of digested food. The digested food is then transported to the different organs in the body by the blood vessels. 

Q2. Write the functions of hydrochloric acid secreted by the inner lining of the stomach.

Solution

Functions of hydrochloric acid: i. It kills many bacteria that enter along with the food. ii. It makes the medium in the inner stomach acidic and helping the digestive juices to act.

Q3. How the food captured in food vacuole is digested in Amoeba?

Solution

Digestive juices secreted into the food vacuole act on the food and break it down into simpler substances.

Q4. Describe different types of teeth and state their functions.

Solution

There are four types of teeth in human beings. They are incisors, canines, premolars and molars. (i) Incisors are the chisel shaped teeth at the front of the mouth. The incisors are for biting and cutting the food. (ii) Canines are the large, pointed teeth just behind the incisors. The canines are for piercing and tearing the food. (iii) Premolars are the large teeth just behind the canines on each side. Premolars have large, flat surfaces. The premolars are for crushing the food. (iv) Molars are very large teeth which are present just behind the premolars, towards the back of our mouth. The molars have a larger surface area than premolars. The molars help in chewing and grinding the food.

Q5. Which gland secretes bile juice and where it gets stored? What is its function?

Solution

Liver secretes bile juice which is stored in a sac called the gall bladder. Bile juice helps in the digestion of fats.

Q6. What are the final products of digestion?

Solution

The carbohydrates get broken into simple sugars such as glucose, fats into fatty acids and glycerol, and proteins into amino acids.

Q7. After the absorption of the nutrients in the small intestine, the food is then passed to the large intestine. What happens to the food in the large intestine?

Solution

The undigested food is passed onto the large intestine. Here, some salts and water are absorbed from the food and the rest is sent to the rectum, from where the undigested food goes to the anus and is removed from the body.

Q8. Why cellulose is digested in cow but not in human?

Solution

Cow has certain bacteria which digests cellulose but human beings do not have such bacteria or enzymes that can digest cellulose.

Q9. For what are the absorbed nutrients in amoeba used?

Solution

The absorbed substances are used for growth, maintenance and multiplication. 

Q10. What happens to the undigested food in amoeba?

Solution

After the digested food gets absorbed, the undigested food is expelled by the vacuole.

Q11. What is the function of pseudopodia in Amoeba?

Solution

Finger-like projections called pseudopodia in Amoeba help to capture food and provide movement to it.

Q12. Discuss the feeding mechanism in starfish.

Solution

Starfish feeds on animals covered by a hard shell. After opening the shell, the starfish pops out its stomach through its mouth to eat the soft animal flesh. The stomach then goes back into the body and the food is digested. 

Q13. How the food pipe helps in the process of digestion?

Solution

Digestion does not take place in food pipe. It only helps to push the food downwards to the stomach by the peristalsis movement of the walls of food pipe.

Q14. How the food is trapped in food vacuole in Amoeba?

Solution

When Amoeba senses food, it pushes out pseudopodia around the food particle and engulfs it. The food becomes trapped in a food vacuole.

Q15. How is energy released in the body cells?

Solution

In the cells, glucose breaks down with the help of oxygen into carbon dioxide and water, and energy is released.

Q16. Mention the important functions of the tongue.

Solution

i. It is used for talking. ii. It helps in mixing of saliva with food during chewing. iii. It helps in swallowing of the food. iv. It helps to taste food.

Q17. What is Caecum?

Solution

Ruminants have a large sac like structure between the small intestine and large intestine called caecum.

Q18. Why do grass-eating animals keep chewing continuously even when they are not eating? What is this process called?

Solution

Grass-eating animals quickly swallow the grass and store it in the rumen. Here, the food gets partially digested and returns to the mouth in small lumps. So, grass eating animals keep chewing continuously even when they are not eating. This process is called rumination.

Q19. How Amoeba constantly changes its shape and position?

Solution

Amoeba constantly changes its shape and position by pushing out one or more finger-like projections, called pseudopodia or false feet.

Q20. Inside the throat, air and food share a common passage. How is food prevented from entering the windpipe?

Solution

During the act of swallowing, a flap-like valve closes the passage of the windpipe and guides the food into the foodpipe.