1)which structure regulates breathing rate in humans?
a)diaphragm
b)lungs
c)hypothalamus
d)medulla

2)the first forms of life on earth
a)appeared about 10,000 years ago
b)could easily maintain a stable internal environment
c)were single-celled
d)depended on the hypothalamus for thermo regulation .

in an embryo , the tissues that receive a nerve produce sprouting factor, which encourages nerves to grow and branch , while the nerve produces anti sprouting factor ,which inhibits grow.

a. positive feedback
b. negative feedback
c. thermoreglation
d. homeostasis

Choose the molecule that is described by each phrase. energy used during long activities:

Asolution of an enzyme and a substrate was placed in a water bath and the temperature of the reaction was raised gradually. the graph shown was plotted at the end of the experiment. what can be concluded from the graph? a) temperature has no effect on the activity of the enzyme. b) the effect of temperature on the enzyme is unpredictable. c) the enzyme shows increased activity up to a certain temperature. d) the activity of the enzyme is inversely proportional to the temperature.

18. determine whether each stateme blank space given. ach statement is true (t) or false (f). place your answer in the 8. when a cell is put into an isotonic solution, individual wat put into an isotonic solution, individual water molecules cannot move back and forth across the cell membrane. d. when a cell is put into a hypertonic solution, there is a net movement of water molecules across the cell membrane into the cell. c. when a cell is put into a hypotonic solution, there is a net movement of water molecules across the cell membrane out of the cell. d. the movement of any solvent across a semi-permeable membrane is called osmosis. e. carrier proteins have the ability to change shape and physically move molecules across the cell membrane. f. in facilitated diffusion, the concentration of the molecules to be moved across the cell membrane is higher inside the cell.