Answer: b
Explanation: b best fits how the transmission of hiv works
3.8 billion – 2.5 billion years ago
The Archean is the name of the age which started with the shaping Earth. This time of Earth's history endured quite a while, over 2.5 billion years. When the archean age ended the earth was just coming alive.
The target cells of FSH are the Sertoli cells of the testes and the granulosa cells of the ovary.
Answer:
At an occluded front, the cold air mass from the cold front meets the cool air that was ahead of the warm front. The warm air rises as these air masses come together. ... The temperature may warm or cool. After the front passes, the sky is usually clearer and the air is drier.
link: https://www.windows2universe.org/earth/Atmosphere/tstorm/occl_front.html
Answer:
D) In case 1, both PS I and PS II completely lose function; in case 2, a proton gradient is still produced.
Explanation:
The light dependent reaction of photosynthesis, which produces the ATP and NADPH needed in the light independent stage of the process, includes complexes of proteins and pigments called PHOTOSYSTEMS. These photosystems (I and II) are key to the functionality of the light dependent reactions in the thylakoid.
The major pigment present in both photosystems is CHLOROPHYLL A, which absorbs light energy and transfers electrons to the reaction center. Chlorophyll B is only an accessory pigment meaning it can be done without. Hence, if all of the chlorophyll A is inactivated in the algae but leaves chlorophyll B intact as in case 1, both PS I and PS II will lose their function because Chlorophyll A is the major pigment that absorbs light energy in both photosystems.
In case 2, if PS I is inhibited and PS II is unaffected, a PROTON GRADIENT WILL STILL BE PRODUCED because the splitting of water into protons (H+) and electrons (e-) occurs in PSII. Hence, H+ ions can still be pumped into the inner membrane of the thylakoid in order to build a proton gradient even without the occurrence of PS I.
