Class 7 Science Chapter 3 MCQ

The female silk moth lays eggs, from which hatch larvae which are called caterpillars or silkworms.

The Wool mark certification trademark is one of the world’s best-known textile fibre quality brands, providing consumers with guaranteed fibre content and an assurance of quality.

Rest of the option given here are obtained by killing animals, but wool is produced from shearing of skin of sheep.

There are some famous breeds of sheep which found in India. Such as, Lohi is famous for “Good quality of wool”. Marwadi is famous for “Coarse wool”. Nali is famous for “Carpet wool” and pathanwadi is famous for “Hosiery”.

Generally, when we burn a fibre of wool, it produces a sizzling noise, smells like burning hair with curls away from the flame. Here, all the options are correct. Hence, your answer will be option [D].

India is the second largest producer of silk in the world after China. Silk Industry provides employment to 7.9 million people in India. China is the world’s single biggest producer and chief supplier of silk to the world markets. India is the world’s second largest producer. About 97% of the raw mulberry silk comes from some Indian states.

Removal of fleece is called sheep shearing, separating hair of different textures is called shorting, washing wool to remove grease is called scouring and rolling of sheep fibre into yarn is called rolling.

Here, all the options are correct. Hence, your answer will be option [D].

After brushing, filaments from four to eight cocoons are joined and twisted. About 48 such twisted filament are joined to make a thread that is wound on a real. This is called “raw silk”.

About 90% of “Mulberry Silk” comes from Karnataka, Andhra Pradesh and Tamil Nadu. States like Assam, Madhya Pradesh and Orissa are also producer of silk.

Among the natural fibres, jute ranks next to cotton in terms of production. Jute is a cellulosic fibre, under the category of bast fibres and its cultivation is almost as old as human civilization. Jute leaves are rich in iron, eating them regularly can help to improve the condition. Jute, an annual herbaceous plant, is mainly cultivated in South and South East Asia.

The best wool producing countries are Australia, New Zealand, South Africa, China and Argentina. Australia is the world’s largest producer of wool and contributes 25% of total world supply.

Silk protein consists of “Sericin” and “Fibroin” mainly. Fat and cellulose are not present in silk. Nylon is a synthetic fibre.

In India, mostly sheep are reared for getting wool. And rest of the statements are correct.

When certain desired traits (properties) of parents are considered before breeding, it is called selective breeding.

Sericulture is a practice of rearing of silkworms for obtaining silk while silviculture is a practice of developing and caring forests.

The woolen industry in India is small and is located in the states of Jammu and Kashmir, Himachal Pradesh, Arunachal Pradesh, Uttarakhand, Sikkim, Haryana, Punjab, Rajasthan and Gujarat.

Moth is the silkworm under development inside a cocoon. Mulberry, Tassar and Mooga are varities of silk produced by different rearing practices.

Caterpillar must shed their skin in order to grow, unlike us insects have an exo-skeleton which means that they are pretty much “encased” inside their skin. The skin does not grow with the animals. Caterpillars shed their skin three to five times while the grow. And this process is called “molting”. There is skin never grow as skin of human does. So, while growing they have to crawl out of their skin when their skin becomes too tight. Each skin is called an “instar”.

The rearing of silkworms for obtaining silk and their rearing, breeding is called “Sericulture” while “Silviculture” is a practice of developing and caring forests.

Angora wool is used to make baby blanket. Camel wool is used to make woollen carpet. Sheep wool is used to make woollen sweater.

The woolen industry in India is small and is located in the states of Jammu and Kashmir, Himachal Pradesh, Arunachal Pradesh, Uttarakhand, Sikkim, Haryana, Punjab, Rajasthan and Gujarat.

Generally, bleaching and dyeing of silk fibres (adding colours) are usually done, before the yarns are made into fibres.

The woolen industry in India is small and is located in the states of Jammu and Kashmir, Himachal Pradesh, Arunachal Pradesh, Uttarakhand, Sikkim, Haryana, Punjab, Rajasthan and Gujarat.

Wool comes from sheep, goat, yak and some other animals. In India, mostly sheep are reared for getting wool.