Explanation:
There are 12 pairs of ribs in the human body. Each rib is a thin flat bone connected dorsally to the vertebral column and ventrally to the sternum. It has two articulation surfaces on its dorsal end and is hence called bicephalic. First seven pairs of ribs are called true ribs. Dorsally, they are attached to the thoracic vertebrae and ventrally connected to the sternum with the help of hyaline cartilage. The 8th, 9th and 10th pairs of ribs do not articulate directly with the sternum but join the seventh rib with the help of hyaline cartilage. These are called vertebrochondral (false) ribs. Last 2 pairs (11th and 12th) of ribs are not connected ventrally and are therefore, called floating ribs. Thoracic vertebrae, ribs and sternum together form the rib cage.

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Reference: NCERT Biology Text, Class: XI, Unit V: Human Physiology, Chapter 20: Locomotion and Movement, Page no: 310.

Explanation:

Coconut milk represents the non-cellular endosperm of the coconut fruit. It is widely used in tissue culture because it is extremely rich in kinetin, a type of cytokinin. Cytokinins are plant growth hormones that promote cell division, and consequently they are widely used in tissue culture practices to rapidly promote cell growth and division.

Reference: NCERT Biology Text, Class: XI, Unit IV: Plant Physiology, Chapter 15: Plant Growth and Development & Advanced Biotechnology By R C Dubey, Page no: 837 & Molecular Embryology of Flowering Plants By Valayamghat Raghavan, Page no: 329.

Explanation:

Cheetah (Extinct big cat of India)
Cheetah or cheeta (Acinonyx jubatus) is the forest mammal, its initial burst of speed is amazing as it can attain a speed of 66 miles (110 Kms) per hour, faster than the fastest grey hound, for centuries cheetah was tamed and trained to hunt gazelles and other swift animals in india. Cheetah is now extinct in India, when it lived in india, it lived most commonly in low rugged hills. It was found in the parts of northern plains, hills of northern and Central India. Southwards upto Mysore.

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Reference: Riddles of Indian Rockshelter Paintings By Shiv Kumar Tiwari, Page no: 97, 98 and 99.