All organisms have a barrier that separates their internal environment from the outside world. Which of the following organ systems forms a barrier between the internal and external environments for humans?
A.
excretory system
B.
circulatory system
C.
integumentary system
D.
nervous system

Sydney drew a flow chart to illustrate the nitrogen cycle.which labels best complete the flow chart? x: producers undergo photosynthesis.y: nitrogen compounds are released into the air.x: nitrogen compounds are released into the air.y: producers undergo photosynthesis.x: free nitrogen is in the atmosphere.y: producers absorb nitrogen compounds through their roots.x: producers absorb nitrogen compounds through their roots.y: free nitrogen is in the atmosphere.

Part a - prefixes, roots, and suffixes match these prefixes, suffixes and roots to their meanings. phospho- angio- -uria -tropic -phag- a. the word root means blood or lymph vessels. b. the word root means urine. c. the word root means feeding or eating. d. the word root means phosphate or phosphorus. e. the word root means attracted specifically to the specified organ or tissue. part b – match these vocabulary terms to their meanings. gonadotropic polyuria angiotensin ii polyphagia phosphodiesterase upon the release of renin, is produced and stimulates vasoconstriction and the release of aldosterone. fsh and lh are examples of hormones, which target the ovaries or testes. an enzyme that degrades second messengers like camp or cgmp is . overproduction of urine, or , is a sign of diabetes mellitus. overeating, or , is a sign associated with diabetes mellitus.

Red flowered snapdragons are crossed with white flowered snapdragons, producing all pink snapdragons in the f1 generation. what would you expect if you crossed pink with pink? 3/4, 1/4, 1/2 red, 3/4,/1/2,/1/4 pink,1/2, 3/4, 1/4 white