Living cells cannot use heat to provide the activation energy for biochemical reactions because ________. Which choice(s) complete the sentence correctly?

People have classified plants and animals for thousands of years.
a. True
b. False

A population of elephants becomes too large, and several members leave the population. What is this process called? death rate

Networks of blood vessels in bats' wings serve only to disperse heat generated in flight. This heat is generated only because bats flap their wings. Thus paleontologists' recent discovery that the winged dinosaur Sandactylus had similar networks of blood vessels in the skin of its wings provides evidence for the hypothesis that Sandactylus flew by flapping its wings, not just by gliding.The argument in the passage relies on which of the following assumptions?

(A) Sandactylus would not have had networks of blood vessels in the skin of its wings if these networks were of no use to Sandactylus.
(B) All creatures that fly by flapping their wings have networks of blood vessels in the skin of their wings.
(C) Winged dinosaurs that flapped their wings in flight would have been able to fly more effectively than winged dinosaurs that could only glide.
(D) If Sandactylus flew by flapping its wings, then paleontologists would certainly be able to find some evidence that it did so.
(E) Heat generated by Sandactylus in flapping its wings in flight could not have been dispersed by anything other than the blood vessels in its wings.

The heart, liver, and stomach are each examples ofA. a tissue.
B. an organ.
C. an organ system.
D. a nerve.

Which of the following chemical reactions proves the fact that the products of photosynthesis are reactants of respiration?Photosynthesis:
Respiration:



Photosynthesis:
Respiration:



Photosynthesis:
Respiration:

Antonym for Food Chain?