Cells<span> are </span>small<span> because the ratio of surface area to volume is the most efficient at their size. This is because when you have a lot of </span>small<span> objects </span>vs<span> a few </span>big<span> objects the surface area is much </span>larger<span> in relation to volume.</span>
The answer is a geyser on apex
Carbon dioxide—\text {CO}_2CO
2
start text, C, O, end text, start subscript, 2, end subscript—from the atmosphere is taken up by photosynthetic organisms and used to make organic molecules, which travel through food chains. In the end, the carbon atoms are released as \text {CO}_2CO
2
start text, C, O, end text, start subscript, 2, end subscript in respiration.
Slow geological processes, including the formation of sedimentary rock and fossil fuels, contribute to the carbon cycle over long timescales.
Some human activities, such as burning of fossil fuels and deforestation, increase atmospheric \text{CO}_2CO
2
start text, C, O, end text, start subscript, 2, end subscript and affect Earth's climate and oceans.
Answer: A penumbral lunar eclipse occurs when the Sun, Earth, and the Moon are imperfectly aligned.
Explanation: During this occurance the Earth comes between the Sun and moon and blocks the sunlight from falling on the moon.
The answer is <span>B. immune cells that are destroyed by HIV
CD4+ are immune cells (white blood cells) and are an important part of the immune system. Their name comes from the presence of CD4 glycoprotein on their surface. HIV uses CD4 glycoproteins on the surface of CD4+ cells to entry into the cells. The consequence is a reduced number of those cells. Therefore, CD4+ immune cells are destroyed by HIV.</span>
