Paheli Boojho Fibre to Fabric Class 7 Answers

Paheli Boojho Fibre to Fabric Class 7 Answers Chapter 3:

1. Boojho is wondering why it hurts when someone pulls his hair but not when he goes for a haircut.

Answer:

Our body has numerous sensors which detect senses like touch, pull, heat, cold etc. When someone pulls our hair it sends responses to our brain and we feel the pain. Hairs do not contain any sensors. They are just our outgrowths and are not even alive. As a result, when someone cut our hair we do not feel pain.

2. Boojho is wondering why a cotton garment cannot keep us as warm in winter as a woollen sweater does.

Answer: Our body continuously emits heat from its surface. This heat is lost in the surroinding. If a garment can keep this heat and do not lose it to nature we feel warm.

Woollen garments are light and thick. In its pores, there are empty spaces that contain air. Air is a bad conductor of heat. As a result, our body heat is trapped inside the garment and we feel the warmth.

Cotton garments are thin and with fewer empty spaces, so they do not trap air. As a result, they are good when there is more heat outside like in summer.

3. Paheli wants to know if the cotton thread and silk thread are spun and woven in the same manner?

No, cotton threads are strong and long. Numerous cotton fibres are joined and twisted to form cotton fibre and make yarn. These yarn on spinning yield fabric.

Silk fibres are smaller and fragile. They are mixed up with rayon to add strength and then woven to get fabric.

4. Paheli wants to know the maximum length of continuous silk thread that can be obtained from a cocoon.

Answer:

Silkmoth larvae eat a lot of mulberry leaves and become larger in size. Now it shakes the mouth in a circular fashion and forms raw silk around its body. The length of this fibre is on average 800 meters. 900m of maximum length has been reported till now.

5. Boojho wants to know why caterpillars need to shed their skin when they grow bigger but we humans do not

Caterpillar skin does not grow like its own body. As a result, its body does not fit into its skin. As a result, they shed their skin and become larger.

The human body and the skin grow together and there is no need for shedding the skin. As a result, humans do not shed their skin.

6. Boojho wants to know why caterpillars should not be collected with bare hands.

Silkworms in the caterpillar phase are spines and hairs. These spines and hairs may be allergic to us. Some caterpillar hairs are found poisonous also. Moreover, the touch of bare hands to caterpillars is harmful to the caterpillar as well, as they may die as well. So, they should not be touched with bare hands.

Read also: 

Science Class 7 Chapter 3 Fibre to Fabric Activity Answers

Nutrition in AnimalsPaheli Boojho Answer

Nutrition in Animals Exercise solution

Class 7 Science Solutions

Leave a Comment Cancel reply