Biological death occurs when brain cells start to die due to lack of oxygen. Biological death follows clinical death (when a person stops breathing). Without oxygen brain damage can occur within minutes. 4-6 minutes of oxygen deprivation can cause minor brain damage. 6-10 minutes of oxygen deprivation will cause brain damage. After 10 minutes of no oxygen irreversible brain damage occurs.

Correct Option: C

Biological death occurs when brain cells start to die due to lack of oxygen. Biological death follows clinical death (when a person stops breathing). Without oxygen brain damage can occur within minutes. 4-6 minutes of oxygen deprivation can cause minor brain damage. 6-10 minutes of oxygen deprivation will cause brain damage. After 10 minutes of no oxygen irreversible brain damage occurs.

Discovery of DNA structure of genes: 25 April, 1953; Yuri Gagarin's feat of becoming the first man in space: 12 April, 1961; World's first human heart transplant: 3 December, 1967; and World's first test tube baby: 25 July, 1978.

Correct Option: A

Discovery of DNA structure of genes: 25 April, 1953; Yuri Gagarin's feat of becoming the first man in space: 12 April, 1961; World's first human heart transplant: 3 December, 1967; and World's first test tube baby: 25 July, 1978.

In the primary (growing) plant cell wall, the major carbohydrates are cellulose, hemicellulose and pectin. The cell wall in plants provides the most significant difference between plant cells and other eukaryotic cells. The cell wall is rigid (up to many micrometers in thickness) and gives plant cells a much defined shape.

Correct Option: A

In the primary (growing) plant cell wall, the major carbohydrates are cellulose, hemicellulose and pectin. The cell wall in plants provides the most significant difference between plant cells and other eukaryotic cells. The cell wall is rigid (up to many micrometers in thickness) and gives plant cells a much defined shape.

Sodium benzoate has the chemical formula NaC6H5CO2; it is a widely used food preservative, with E number E211. It is the sodium salt of benzoic acid and exists in this form when dissolved in water. It can be produced by reacting sodium hydroxide with benzoic acid.

Correct Option: A

Sodium benzoate has the chemical formula NaC6H5CO2; it is a widely used food preservative, with E number E211. It is the sodium salt of benzoic acid and exists in this form when dissolved in water. It can be produced by reacting sodium hydroxide with benzoic acid.

Carrot is an extremely rich source of vitamin A. The name carotene, which is a form of pro-vitamin, has been derived from carrot. The carotene is converted into vitamin A by the liver and it is also stored in our body.

Correct Option: A

Carrot is an extremely rich source of vitamin A. The name carotene, which is a form of pro-vitamin, has been derived from carrot. The carotene is converted into vitamin A by the liver and it is also stored in our body.