NCERT 7th Class (CBSE) Science: Nutrition in Animals

Question: How does a frog catch its prey?

Answer: The frog uses its long sticky tongue to catch insects. Frogs have well-developed digestive system in which food is digested with the help of digestive juices.

Question: How does a spider digests its food?

Answer: A spider weaves a sticky web in which small insects gets stuck. It then injects digestive juices into the body of the insects, which digest the body parts of the insects. Thus, the digestion of a spider’s food actually takes places outside the spider’s body. The spider then sucks up the digested food.

Question: What is the difference between milk teeth and permanent teeth?

Answer: A child has only 20 teeth – 10 in each jaw. These are known as milk teeth or temporary teeth. They fall off by the age of 10 and are replaced by larger permanent teeth. This set contains 4 incisors, 2 canines, 4 premolars and 6 molars in each jaw. There are total 32 teeth, 16 in each jaw of fully grown up adults.

Question: Name four types of teeth in your mouth. What are their functions?

Answer: Four types of teeth in our mouth are –

1. Incisors: Front teeth are known as incisors. These are chisel – shaped and are used for biting and cutting.
2. Canines: These are next to incisors. These are pointed and are used for piercing and tearing pieces of food such as meat.
3. Premolars: The teeth at the back of our mouth are broad with an almost flat surface. These crush and grind the food.
4. Molar: Molars are larger than premolars. There function is same as premolars.