Questions

Mixed heart means the heart in which the oxygenated and the deoxygenated blood is mixed. Reptiles and amphibians have mixed heart.

The dermis is a layer of the skin of the integumentary system. The dermis lies deep to the superficial epidermis which is also the most superficial layer of the skin. The dermis lies superficial to the underlying hypodermis which is also referred to as subcutaneous tissue.

Among the components of the dermis are: sweat glands, hair follicles, collagen fibers, sensory- nerve endings and arrestor pill muscles.

The given puzzle follows a pattern that,

Number - <last digit> <sum of all digits>.

111 - 13

112 - 24

113 - 35

So 

117 - 79

If some action has started in the past and is still continuing, then present perfect continuous tense should be used instead of present continuous tense. So, the phrase ‘am waiting’ needs to be replaced with ‘have been waiting’ to make the sentence contextually correct. Thus, the correct formation would be, ‘I have been waiting for three –quarters of an hour’.

The second pointer is of char type and not a good pointer.