The correct answer is: A. The hydrophilic head groups of the lipid molecules are exposed to the outside of the cell and the cytoplasm, which is a water-like environment. The hydrophobic tails form an oily layer inside the membrane that keeps water out of the cell.
Plasma membrane of the cell is arranged in a bilayer of phospholipids. Phospholipids are amphipathic molecules which means that they have both hydrophilic and hydrophobic regions. The hydrophilic heads of phospholipids that are faced outward and hydrophobic layer located in the interior of the bilayer together make a good barrier between the interior and exterior of the cell, so the water and other polar or charged substances cannot easily cross the hydrophobic core of the membrane.
If photosynthesis stopped, plants would stop converting carbon dioxide -- an air pollutant -- to organic material. ... Even if all the plants on Earth were to die, people would remain resourceful -- especially if their lives depended on it.
Explanation:
The Chandra X-ray observatory or CXC for its acronym in English, is an artificial satellite launched by NASA on July 23, 1999. It was named in honor of Indian physicist Subrahmanyan Chandrasekhar, one of the founders of astrophysics, who determined the boundary mass at which white dwarfs become a neutron star. In addition, Chandra means "moon" in Sanskrit.
The Chandra Observatory is the third of the Great Observatories of NASA. The first was the Hubble Space Telescope, the second was the Gamma Compton Ray Observatory, launched in 1991 and already disintegrated, and the last was the Spitzer Space Telescope. Before launching the Chandra Observatory was known as AXAF by the acronym in English of Advanced X-ray Astronomical Facility.
As the Earth's atmosphere absorbs most X-rays, conventional telescopes cannot detect them and a space telescope is necessary for their study.
In 1976 Riccardo Giacconi and Harvey Tananbaum proposed to NASA the idea of the Chandra Observatory, beginning preliminary work at the Marshall Space Flight Center. Meanwhile, in 1978, NASA launched the first X-ray space telescope, the Einstein (HEAO-2).
Despite this, work on the Chandra project continued during the 1980s and 1990s, but in 1992 the ship was redesigned to reduce costs. Four of the twenty mirrors that the observatory was going to dispose of were removed, and an elliptical orbit with which it would reach a third of the distance to the moon was calculated. This eliminated the possibility of being repaired by the space shuttle, but placed the observatory outside the influence of the earth's radiation belts most of its orbit.
