Questions

All living cells arise from pre-existing cells is one component of the cell theory.

The Cell Theory is one of the basic principles of biology.

The Cell Theory states:

1. All living organisms are composed of cells. They may be unicellular or multicellular.

2. The cell is the basic unit of life.

3. Cells arise from pre-existing cells.

During daylight hours, plants capture carbon dioxide from the atmosphere and use it to make carbohydrates which is stored as starch in the plant. Animals feed on the plants and extract the carbohydrates through their digestive system. The carbohydrates, namely glucose, are used by the animals for production of ATP through cellular respiration.

Cellar respiration in the animals produces carbon dioxide as a waste product. The carbon dioxide is released into the atmosphere, from where it is again captured by plants and the cycle is repeated.

Hence, option B) Plant ----> Animal ----> Atmosphere is the path possible in carbon cycle.

Goitre is characterized by the swelling of the neck region. This is due to the enlargement of the thyroid gland which secretes hormone thyroxine. Thyroxine has iodine as an integral part of it. If there is not sufficient iodine in one's  diet, the thyroid gland swells up.

In a nucleosome, the DNA is wrapped around histone octamer.