Chapter 2 - Nutrition in Animals
1. Choose the correct option. (R)
a) Butterflies suck nectar from flowers with a long tube called ____________
i) pseudopodia ii) mouth
iii) omasum iv) proboscis
b) The partially digested solid part of food that is sent back to the mouth by ruminants is called ___________.
(a) plaque (b) bolus
(c) cud (d) chyme
c) The _________________ is a muscular organ found at the base of the mouth. (a) tongue (b) throat
(c) pancreas (d) pharynx
2. Name the following: (An) 1. An enzyme present in gastric juice.
ans: Pepsin
2. The upper part of the tooth that is visible above the gums. ans: Crown
3. The finger-like projections lining the inside of the small intestine. ans: Villi
3. State whether the following statements are true or false. Correct the false statements by changing the underlined words. (An)
1. The mouth is a cone-shaped passage way for both food and air. ans: False
The pharynx is a cone-shaped passage way for both food and air.
2. Enzymes are biological catalysts which speed up chemical reactions inside our body.
ans: True
3. There are 14 molars in adult humans.
ans: False
There are 12 molars in adult humans.
IV.In the following questions, two statements are given- one labelled Assertion (A) and the other labelled Reason (R). Read the statements carefully and choose the correct alternative (A), (B), (C) and (D) as given below. (An)
(A) Both A and R are true and R is the correct explanation of the assertion. (B) Both A and R are true but R is not the correct explanation of the assertion. (C) A is true but R is false.
(D) A is false but R is true.
(i)Assertion:Camelsare carnivores.
Reason: Carnivores feed only on the flesh of other animals.
ans: (D) A is false but R is true.
(ii)Assertion:The small intestine is the longest organ of the digestive tract. Reason:The small intestine is 6-7 m long with a diameter of about 3-4cm. ans: (A) Both A and R are true and R is correct explanation of theassertion.
V. Answer the following in one sentence. (U) 1. Name the four chambers of the ruminant stomach.
ans: Rumen, Reticulum, Omasum and Abomasum.
2. List the accessory digestive organs in humans.
ans: The accessory digestive organs include the liver, the pancreas and the salivary glands.
3. What is mastication?
ans: Mastication is the mechanical grinding of food into smaller pieces by teeth. VI.State one function of the following. (R)
1. Pseudopodia in amoeba
ans: •Capturing of food
•Locomotion
2. Cilia in Paramecium
ans: Cilia that push the food into the cell.
3. Omasum in ruminants
ans: It is responsible for the absorption of excess water. VII. Give reasons for the following statements. (An) 1. Mucus is present in saliva
ans: The mucus is present in saliva to make food slimy and slippery so that it can be easily swallowed.
2. Stomach produces hydrochloric acid.
ans:
∙ Hydrochloric acid mixes with the partially digested food from themouth and provides the acidic environment necessary for digestion of the food. ∙ It also helps to control the bacteria and other microorganisms present in the food.
VIII. (Ap)
Shipra is studying in grade 7. Her younger brother wanted to learn about how our teeth decay. She created a flow chart to explain the steps involved in tooth decay. Can you help her to complete the flowchart?
Bacteria are naturally present in the mouth
They act on the food particles present in the gaps between our teeth and form a sticky yellowish layer on the teeth called as plaque.
The sugars and starch in the food items are converted to acids by the plaque.
These acids corrode the enamel and may cause tooth decay and cavities.
VIII. State the functions of the labelled parts of the teeth.(R)
Canine – Help is tearing the
food
Premolars- Help to crush,
grind and move food from
the front teeth to the molars
for chewing
Molars- To chew the food into
small, easily consumable pieces
Incisors- Help to bite and cut food into small chewable pieces
IX. Kevin counted his permanent teeth in a mirror and made an observation table as shown below. He however made some mistakes while filling the table. Help Kevin to correct the observation table.(Ap)
Types of teeth Number of teeth
Incisors 14
Canines 4
Premolars 8
Molars 8
Types of teeth Number of teeth
Incisors 8
Canines 4
Premolars 8
Molars 12
1. The process of digestion involves mechanical as well as chemical breakdown offood. Identify the organs, the actions, and the enzymes that break down foodusing mechanical, chemical or both methods and accordingly fill the words inthe Venn diagram. (Ap)
(stomach, biting, pepsin, peristalsis, chyme, mouth, chewing, amylase)
amylase pepsin
chyme mouth stomach
biting
peristalsis chewing
2. Higher Order Thinking Skills (HOTS)
What could happen if there was no epiglottis in the pharynx region? ans: Epiglottis helps to prevent the food from entering into the wind pipe. When we swallow food, the epiglottis closes to prevent the food from entering the wind
pipe. If epiglottis is not present, the food will enter in the wind pipe, which can lead to choking and further leads to death.
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