1）Oxygen began to enter the atmosphere of the early Earth as a result of
1. bubbles bursting at the surface of the oceans.
2. photosynthesis by cyanobacteria.
3. volcanic eruptions.
4. endosymbiosis of prokaryotes and eukaryotes.
5. respiration by microspheres.
2）An abundance of which of the following was conspicuously absent from the Earth’s atmosphere 4 billion years ago?
1. nitrogen
2. free oxygen
3. carbon dioxide
4. carbon monoxide
5. hydrogen
3）Risk factors for heart disease include all of the following EXCEPT
1. high blood pressure.
2. cigarette smoking.
3. regular exercise.
4. high cholesterol levels.
5. obesity.
4）Which of the following serves as the cardiac pacemaker ?
1. diaphragm
2. AV bundle
3. Purkinje fibers
4. AV node
5. SA node
5）All of the following have nerve cells EXCEPT
1. sponges.
2. butterflies.
3. hydras.
4. jellyfish
6）Which of the following divisions of the autonomic nervous system causes heart rate to
increase, pupils to dilate, and blood vessels to dilate?
1. sympathetic division
2. somatic division
3. parasympathetic division
4. sensory division
7）Which of the following is the usual resting potential of a neuron?
I) positive II) negative III) neutral
1. Either I or II
2. I only
3. II only
4. III only
8）Gene mutations can be caused by all of the following except
1. insertion or deletion of nucleotide bases in a DNA sequence.
2. mutagenic agents such as X-rays, free radicals and chemicals.
3. a single nucleotide base being replaced by a different base.
4. by the fertilization of an egg cell by a sperm cell
THANKS…………so much <3
1. bubbles bursting at the surface of the oceans.
2. photosynthesis by cyanobacteria.
3. volcanic eruptions.
4. endosymbiosis of prokaryotes and eukaryotes.
5. respiration by microspheres.
2）An abundance of which of the following was conspicuously absent from the Earth’s atmosphere 4 billion years ago?
1. nitrogen
2. free oxygen
3. carbon dioxide
4. carbon monoxide
5. hydrogen
3）Risk factors for heart disease include all of the following EXCEPT
1. high blood pressure.
2. cigarette smoking.
3. regular exercise.
4. high cholesterol levels.
5. obesity.
4）Which of the following serves as the cardiac pacemaker ?
1. diaphragm
2. AV bundle
3. Purkinje fibers
4. AV node
5. SA node
5）All of the following have nerve cells EXCEPT
1. sponges.
2. butterflies.
3. hydras.
4. jellyfish
6）Which of the following divisions of the autonomic nervous system causes heart rate to
increase, pupils to dilate, and blood vessels to dilate?
1. sympathetic division
2. somatic division
3. parasympathetic division
4. sensory division
7）Which of the following is the usual resting potential of a neuron?
I) positive II) negative III) neutral
1. Either I or II
2. I only
3. II only
4. III only
8）Gene mutations can be caused by all of the following except
1. insertion or deletion of nucleotide bases in a DNA sequence.
2. mutagenic agents such as X-rays, free radicals and chemicals.
3. a single nucleotide base being replaced by a different base.
4. by the fertilization of an egg cell by a sperm cell
THANKS…………so much <3
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answers are 2, 2, 3, 5, 1, 1, 3, 4 in order