Upon entering the thymus, thymocytes are classified as double with regard to coreceptors; before exiting as single-positive, naïve T cells, they pass through a period in which they are double . Question 7 options: positive; negative negative; positive Both "positive; negative" and "negative; positive" are correct. Neither "positive; negative" nor "negative; positive" are correct. Coreceptor expression state does not change in the thymus.

An organ system consists of a group of organs that performs specific functions necessary for the survival of an organism. humans have eleven different organ systems: integumentary, skeletal, muscular, nervous, endocrine, circulatory, lymphatic, respiratory, digestive, urinary, and reproductive. discuss the function of neurons, the brain and the spinal cord within the human nervous system while explaining the interrelationship of each organ.

The finches on the galapagos island were similar in form except for variations of their beaks. darwin observed that these variations were useful for: attracting a mate defending territory building nests gathering food

Restless tectonic plates move (shift) between one and fifteen centimeters per year month day minute