What is the principal component of the thickest layer of the skin? a: collagen b: elastin c: mast cells d: phagocytes what is the tough protein that is one of the primary components of bones? e: collagen f: fibrinogen g: peptin h: periosteum what is the role of the proteins actin and myosin? i: attaching bones to bones j: attaching muscles to bone k: contacting the muscles l: storing energy

1. The correct answer is option A

The thickest layer is Dermis which is made up of two layers papillary and reticular. The reticular dermis is the lower layer of the dermis and is made up of dense irregular connective tissue featuring collagen fibers.

2. The correct answer is option  E

Bone is composed of fibrous and mineralized connective tissues which is enriched in collagen and calcium phosphate.

3. The correct answer is option C

Muscles are composed of two major protein filaments: a thick filament composed of the protein myosin and a thin filament composed of the protein actin. These two filaments slide over each other to repetitively contract the muscles.

the correct answer is option b

behavioral response need communication and thus co-ordination at several levels such as interaction among cells, organ system and the entire organism.

behavioral response produces both internal and environmental stimulus.

they fuse to form they have half as many chromosomes as a somatic cell of the same individual. b