AP BIO TEST

What is a hydrogen bond?

A hydrogen bond is the partially positive hydrogen atom in one polar covalent molecule will be attracted to an electronegative atom in another polar covalent molecule

Using the properties of water, describe how water can move up a capillary tube to move from the roots to the leaves in a plant.

Water can move up a capillary tube to move from the roots to leaves in a plant by Adhesion of water to the walls of a vessel will cause an upward force on the liquid at the edges and result in a meniscus which turns upward. Capillary action occurs when the adhesion to the walls is stronger than the cohesive forces between the liquid molecules.

Describe why water is considered a polar molecule.

Water is considered a polar molecule because oxygen has a higher electronegativity than hydrogen, the electrons of the molecules tend to group closer to the oxygen than to the hydrogen atoms.

Using the properties of water, describe how a water strider can walk on water.

Water striders can walk on water by a combination of several factors. Water striders use the high surface tension of water and long, hydrophobic legs to help them stay above water. Water striders use this surface tension to their advantage through their highly adapted legs and distributed weight.

How did hydrogen bonding allow for each property?

Hydrogen bonding allows for each property by Water molecules are polar, so they form hydrogen bonds. This gives water unique properties, such as a relatively high boiling point, high specific heat, cohesion, adhesion and density.

Where are hydrogen bonds found in water?

Hydrogen bonds are found between neighboring hydrogen and oxygen atoms of adjacent water molecules

Where are hydrogen bonds found in DNA?

Hydrogen bonds are found between the nucleotide bases in the middle of the DNA

b. For each R group option, describe the polarity and justify your response.

The polarity of each R group is polar folds out because it is hydrophilic and is attracted to the water, nonpolar folds in because it is hydrophobic and is "afraid" of the water, and charged folds out because it is hydrophilic and is attracted to the water.

What is the structure of an amino acid?

The structure of an amino acid is a carboxyl group, an amino group, a hydrogen, and an R-group side chain that are all covalently bonded to a central carbon atom.

a. What are the three options for the R group?

The three options for the R group are charged, polar, and nonpolar.

5. What are three properties of water?

The three properties of water are high specific heat, cohesion, and adhesion.

How many hydrogen bonds are found between each complementary base pairing?

There are 2 hydrogen bonds between Thymine and adenine and 2 hydrogen bonds between cytosine and guanine.