Class 7 Science Chapter 3 MCQ

Australia is the highest wool producing country in the world. It is responsible for the production of 25% of the world’s wool.

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.

For obtaining wool, sheep are reared. Their hair is cut and processed into wool. The quality and texture of the fibres obtained from them. Certain breeds of sheep have thick coat of hair on their body which yields good quality wool in large quantities.

For obtaining silk, moths are reared and their cocoons are collected to get silk threads. A female silk moth lays hundreds of eggs at a time. The eggs are stored carefully on strips of cloth or paper.

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.

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”.

Cocoon is one of the stages of life cycle of silkworm. Fleece of sheep gives wool, cotton ball gives cotton and jute stalk gives jute fibre.

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.

Sericulture is the rearing of silkworm to obtain silk fibre. Sericulture means “Silk farming”.

Silk is a protein fibre and usually burns readily, not necessarily with a steady flame, and smells like burning hair. The ash is easily crumbled. Silk samples are not as easily extinguished as cotton or linen.

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.

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.

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.

Apiculture is the scientific method of rearing of honeybees. All the rest are correct. Hence, your answer will be option [C].

The maximum length of continuous silk that can be obtained from a cocoon is measured at 900 metres. This is the highest observed, however the length may vary in most cases as different cocoons are of different size and shape therefore having varied amount of silk within them.

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”.

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

Reeling of silk is the process of taking out threads from the cocoon for use as silk.

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.