Which of the following explains why fossils of some extinct organisms have been found while others have not? A.
Fossils only exist for organisms that lived over 3 million years ago.

B.
Fossils only exist for organisms that had shells or hard outer body coverings.

C.
Most organisms die and decompose without leaving any fossil remains.

D. Only very large organisms have enough body mass to result in fossil formation.

Now it's your turn to investigate human impact around the world. grab your virtual lab coat and put on your environmental science hat. you will be taking a trip around the globe to explore three locations. at each location, you will investigate the cause and effect relationships of deforestation, desertification, and urbanization. you will also gather evidence of how these factors have impacted the environment over time

Choose the incorrect statement (a) the motor end plate membrane is only capable of generating graded potentials, but it is contiguous with the skeletal muscle sarcolemma, which can generate action potentials. (b) propagation of an action potential through the t-tubules into the sarcoplasmic reticulum triggers the release of ca++ into the cytoplasm of a skeletal muscle fiber. (c) the generation of suprathreshold endplate potentials in multiple muscle fibers could be due to the increased frequency of action potential generation at the axon hillock of a single motor neuron. (d) a greater amount of ach would be found in the presynaptic vesicles of a motor unit that fired several action potentials after exposure to botulinum toxin, than in a motor unit that fired several action potentials after exposure to the venom of the krait snake (which contains α-bungarotoxin).

In 1859, the english naturalist charles darwin published a book entitled on the origin of the species. one of the major ideas that was presented in his book was the theory of natural selection. what was another idea that was presented in his book?