Scientists measured the pressure in the xylem of redwood trees at different heights and found that the higher they made their measurements, the lower the pressure. They extrapolated this to a pressure of zero, and concluded that the tallest a tree could grow is 122–130 meters. The tallest known tree on Earth is 112.7 meters. Which of the following most likely limits the height of trees?
A. amount of transpiration in leaves
B. ability to take up CO2
C. strength of water cohesion
D. amount of energy needed to pump water to the tops of the trees
E. amount of photosynthesis in leaves
C. strength of water cohesion
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Motor proteins require energy in the form of ATP. ATP hydrolysis results in a conformational change that allows the protein to move along microtubular tracks (pathways). What structural component of the motor protein contains the ATP binding site
and, therefore, changes shape to enable movement? A) the portion of the molecule that binds to the vesicle being transported B) the stalk C) the portion of the molecule that binds to the microtubular track along which the vesicle is being transported D) a location midway between the vesicle binding site and the portion of the molecule that binds to microtubular tracks
Which most completely describes the circumstances under which yarrow will alter its phenotype?
a. temperature, soil conditions and water conditions b. soil conditions only c. being produced by sexual versus asexual reproduction d. water conditions only e. asexual reproduction, soil conditions, and water conditions
The Cenozoic is often referred to the age of all of the following EXCEPT:a
insects. b. mammals. c. flowering plants. d. birds. e. reptiles
In the process of DNA replication, adenine will pair with
A. guanine. B. cytosine. C. thymine. D. uracil.