7. The swallowed food moves downwards in the alimentary canal because of (a) force provided by the muscular tongue
(b) the flow of water taken with the food
(c) gravitational pull
(d) the contraction of muscles in the wall of food pipe

Explanation:

d is the answer because of peristalsis

due to the contraction of the muscles in the wall of food pipe,the canal movement takes place and move downwards in the alimentary canal.

This always includes a support and swallows food that should be moved downwards.

The muscles always try to move downwards that gives proper food contraction in the canal movement.

Explanation:

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the backbone of the dna and rna compound is sugar phosphate.

answer : haversian

[explanation: -(compact bone is organized as parallel columns, known as haversian systems, which run lengthwise down the axis of long bones. these columns are composed of lamellae, concentric rings of bone, surrounding a central channel, or haversian canal, that contains the nerves, blood vessels, and lymphatic system of the bone)]