Answer:
The early Earth was very different from our Earth today.
Explanation:
Earth's first atmosphere had lots of water vapor but had almost no oxygen. Later, frequent volcanic eruptions put several different gases into the air (Figure 12.13). These gases created a new type of atmosphere for Earth.
The greater the speed of two identical masses, the greater the kinetic energy. So, the mass that is traveling twice as fast as the other has much more kinetic energy. The formula for kinetic energy is KE=m*v^2 (kinetic energy equals mass times velocity squared), and velocity is the same as speed in this case because it is squared. So, the mass traveling twice as fast has 4 times the kinetic energy, because 2 squared=2*2=4.
Answer: The mass traveling twice as fast has four times the kinetic energy.
Answer: Option C) The arrangement of atoms allows precise hydrogen bonding.
Explanation:
The individual hydrogen bonds between the base pairs confer stability to double helix of DNA.
The bases atoms take SPECIFIC POSITIONS or better still ARRANGEMENT, with Guanine pairing with Cytosine base atoms by three hydrogen bonds, while Adenine pair Thymine base atoms by two hydrogen bonds.
So, the arrangement of base atoms allows precise hydrogen bonding and hence STABILITY of DNA double helix.
Proteins are polymers composed of repeating units of amino acids, linked via peptide bonds (bonds between the amine and carboxyl groups of the adjacent amino acids). All proteins have a primary, secondary and tertiary structure and some, such as haemoglobin, have a quaternary structure.
Primary structure of the proteins are the sequence of amino acids and their order. The "R" regions of the amino acids determine the proteins secondary tertiary and quaternary structures.
In the secondary structure, the protein folds into either an alpha helix or a beta pleated sheet. This occurs due to hydrogen bonding between the "R" group of the amino acids.
The tertiary structure gives the protein its 3D shape. Here it is folded further and more bonds (such as disulphide bonds) also form.
In the quaternary structure, prosthetic groups (e.g. a haem group for haemoglobin) is added. If the protein has more than one protein chains, here the chains join to form the final protein.
