The answer is C is b/c sun exposure is completely natural unlike the followin answers.
Answer:
Muscle contraction is defined at the molecular level by myosin molecules bringing actin filaments together.
Explanation:
Researchers at Osaka University have created new electron cryomicroscopy images with remarkable resolution that reveal unusually substantial conformational changes in the myosin molecule during the pull.
Answer:
Varicose veins can best be described as veins cannot prevent the backflow of blood.
Explanation:
Varicose veins are a manifestation of venous insufficiency or peripheral vascular insufficiency.
Veins are blood vessels that, unlike arteries, are not able to contract, so they depend on gravity, muscle contractions and a system of valves to be able to carry blood to the heart.
<u>When the venous valves do not work, the blood is not transported properly, backflow occurs and is retained, producing dilation of the vein walls, which is characteristic of varicose veins</u>. In this case, veins cannot prevent the backflow of blood.
The other options are not correct because:
- <em>Varicose veins do not lose their ability to transport blood.
</em>
- <em>Veins cannot be used to transport blood from the heart.
</em>
- <em>Failure to adequately transport waste to the heart does not apply in this case.</em>
