Answer:
Chemical weathering changes the molecular structure of rocks and soil. For instance, carbon dioxide from the air or soil sometimes combines with water in a process called carbonation. This produces a weak acid, called carbonic acid, that can dissolve rock.
Explanation:
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Answer:
Explanation:
An element only has <u>one</u> type of atom and cannot be broken down by chemical means.
Let's analyze the answer choices.
1. This has two types of atoms, so it cannot be an element. It has more than one type of atom.
2. This has two types of atoms that are bonded together. It cannot be an element because there is more than one type of atom and the bonds can be broken.
3. This has one type of atoms, so it is an element.
Therefore the best answer choice is 3.
Answer:
A point mutation can be described as a mutation in which changes occur in a single nucleotide. A nucleotide may get changed, deleted or inserted from the sequence of DNA. Point mutations can be harmless or harmful depending on the nucleotide in which the changes occur.
A change in just one nucleotide can result in the formation of wrong amino acid and hence changed or wrong proteins can be formed. If the original protein was involved in cellular reproduction, then the entire process of reproduction can be affected by a point mutation.
Sickle- cell anaemia is a disease in which the body fails to produce enough healthy red blood cells. This disease occurs due to point mutation. Point mutation occurs where glutamine (GAG) of the β-globin gets changed into valine (GUG). This change causes the haemoglobin to get a deformed structure due to which it is not able to carry out oxygen.
Vertebrates developed about 550 million years ago. The oldest vertebrate fossils are those of FISH with no jaws. These e<span>arly jawless fish did not have paired fins and their bodies were covered with heavy, bony scaled, but their skeletons were made of cartilage. For the next 50 million years, they were the only vertebrates.</span>
