Two major sources of mutation are radiation and reactive oxygen species (ROS).The reactive oxygen species hypothesis for aging postulates that 

1) Senescence results from the accumulation of DNA, lipid, and protein damage inflicted by ROS of mitochondrial origin; and

2) Mitochondria of long-lived species should produce high ROS than do mitochondria of short-lived species.

3) the capacity of mitochondria to consume ROS might distinguish long-lived species from short-lived species, rather than differences in ROS generation. 

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#Question id: 12387

#Unit 7. System Physiology – Animal

An elderly patient complains of muscle weakness and lethargy. A urine specimen reveals a Na+ concentration of 600 mmol/L and an osmolarity of 1200 mOsm/L. Additional laboratory tests provide the following information: plasma Na+ concentration = 167 mmol/L, plasma renin activity = 4 ng angiotensin I/ml/hr (normal = 1), plasma antidiuretic hormone (ADH) = 60 pg/ml (normal = 3 pg/ml), and plasma aldosterone = 15 ng/dL (normal = 6 ng/dL). Which of the following is the most likely reason for this patient’s hypernatremia?

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#Question id: 12968

#Unit 10. Ecological Principles

Most terrestrial ecosystems have a pyramidal structure of where biomass of producers > primary consumers > secondary consumers > tertiary consumers. However, some aquatic ecosystems have an inverted pyramidal structure where the standing biomass of producers < primary consumers. An explanation for this is:

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#Question id: 2656

#Unit 2. Cellular Organization

In a cell as per the Operon Concept, the regulator gene governs the chemical reactions by

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#Question id: 2070

#Unit 2. Cellular Organization

The sodium-potassium pump is called an electrogenic pump because it:

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#Question id: 5025

#Unit 11. Evolution and Behavior

Which of these genetic processes may be most helpful in accounting for the Cambrian explosion?