Answer: A
Explanation:
Oxygen makes up another 20 to 21 percent of our atmosphere. It's essential for life on Earth, and interestingly enough, it is poisonous when highly concentrated. Our concentration of 20 to 21 percent seems just right.
By starch, I'm assuming you mean glycogen, or animal starch.
Similarities:
Both are polysaccharide molecules made from glucose molecules linked together in a long chain.
Both are storehouses of energy.
Differences:
Glycogen is made in animal cells and is the only form of starch animals can digest (unless they have certain microbes in their intestinal tracts to break down cellulose, which all herbivores need).
Cellulose is made in plant cells.
The bonds are a bit different; the molecules are isomers. Glycogen bonds with what is called an alpha 1,4 bond, meaning that the first carbon of one glucose molecule is bonded to the 4th carbon of the next glucose molecule, but in a way that puts the bonds in a shape that falls below the plane of the molecule, and allows branching.
Cellulose bonds with beta 1,4 bonds. The first and fourth carbons of adjoining glucose molecules are still connected, but the shape of the bond falls above the plane of the molecule and does not branch.
Since enzymes are specific to their substrates, the enzymes shaped to fit glycogen bonds do not fit on cellulose bonds, which is why animals cannot digest cellulose on their own. In herbivores, there are microbes in their digestive tracts which can produce enzymes to break these bonds so the glucose can be used. In carnivores and omnivores like humans, there is no enzyme to break down cellulose so it becomes 'roughage' in our diets. It passes through the digestive tract without being broken down.
The melting of the ice caps makes Earth warmer because less solar energy is reflected due to loss of Albedo
Answer:
Sexual reproduction is advantageous over asexual reproduction because it reduces the rate of mutation accumulation.
Explanation:
The main advantage of sexual reproduction is that it increases the genetic variation in the species by creating new combinations of alleles.
However, asexual reproduction produces more offspring, as it is usually a quicker method of reproduction. It also does not require the organisms to socialise to mate.
Sexual reproduction does not reduce the rate of mutation, which is influenced by environmental factors as well as the genome itself.
