The autonomic nervous system can change the rate of the heart by: Group of answer choices beta1 adrenergic receptor activation. Increases in cAMP lead to increased amounts of Na influx (though If channels) and Ca2 influx of the pacemaker cells. This increases the frequency of APs of the pacemaker, and increases the rate of contraction. beta2 adrenergic receptor activation. Increases in cAMP lead to increased amounts of Na influx (though If channels) and Ca2 influx of the pacemaker cells. This increases the frequency of APs of the pacemaker, and increases the rate of contraction. muscarinic ACh receptors activation. Activation leads to reduced activity of Ca2 channels, and increasing activation of K channels, hyperpolarizing cells and reducing the rate of contraction. alpha1 adrenergic receptor activation.

Over the past 60 years, many amphibian species have experienced significant population declines and some species have become extinct. scientists suspected that local human activities such as the destruction of wetlands, regional pollution, and deforestation were the main reasons for these losses. however, research over the past 20 years reveals significant amphibian population declines in protected areas of the world, such as nature preserves and parks. these global declines suggest widespread problems including increased ultraviolet radiation, acid rain, and disease. in switzerland, for example, 14 of the 20 native amphibian species are threatened with extinction. chytridiomycosis is a fungal disease first identified in 1998 as a cause of massive amphibian deaths. in some severely impacted populations, a few individuals have survived, perhaps because of some natural resistance. if these resistant individuals continue to survive and prosper, new resistant populations might emerge. this would be an example of the founder effect artificial selection genetic drift natural selection sexual selection

What molecules will be best used to compare different species with the exact same sequence of amino acids? why would two species have the same protein even if the molecules in question is different? (hint: transcription to translation to protein).

If the rna molecule in a human has the nucleotide sequence of guu, this would the amino acid valine would be needed to make the protein. how would this cha process was occurring in a mushroom?