AP Biology: Matter

How can you tell a biological molecule is a carbohydrate?

A biological molecule is a carbohydrate if it contains carbon, hydrogen, and oxygen in the molar ratio 1:2:1. The empirical formula for carbohydrates is CH2O. The monomers of carbohydrates are sugars. Carbohydrates are used for short term energy, storage, and structure.

Chemically, what is the difference between a saturated fat and an unsaturated fat? How does this difference affect the properties of the molecules?

A saturated fat has no double bonds between carbons. In a saturated fat, all of the carbons are bonded to two or more hydrogens (saturated with hydrogen). At room temperature, the molecules of a saturated fat are packed closely together forming a solid (butter). In an unsaturated fat, there is at least one double bond between carbons, meaning that one or more carbons are only bonded to 1 hydrogen (not saturated with hydrogen). Having double bonds changes the behavior of the molecule because free rotation cannot occur about a C=C double bond as it can with a C-C single bond. This mainly affects melting point. Unsaturated fats are liquid at room temperature because of kinks in some of their fatty acid hydrocarbon chains that do not allow them to pack closely together.

How is adhesion of water helpful

Adhesion helps water get to roots of plants and it also helps nutrients go into and through animals and plant bodies. Adhesion's job in transpiration is very important. The adhesiveness of the water helps the water climb up the xylem tissue to the leaves. Adhesion does this through capillary action, which is the movement of a liquid up or across the surface of a solid.

Adhesion

Adhesion, which is the clinging of one substance to another, coincides with cohesion. Adhesion works by the hydrogen bonds of water clinging or connecting with the substances directly surrounding it.

Why do atoms bond?

Atoms bond because valence electrons and holes in energy levels find each other and balance each other, forming a bond.

How is cohesion of water helpful

Cohesion helps waves and other water movements form and forms surface tension on top of the water. This surface tension allows bugs to walk on water and fish to eat the bugs that stay on the water surface. Another example of how cohesion is useful to living systems is through transpiration. Transpiration is the evaporation of water from plants. Cohesion holds the water together in a single molecule as water fills the xylem, transportation cells of the plant.

Cohesion

Cohesion is a property in water because of the hydrogen bonding between the hydrogen and oxygen elements. Cohesion from the hydrogen bonds make the water more structured and holds the substance together.

Explain the three major structural differences between RNA and DNA.

DNA has the bases tadenine, cytocine,gueanine, and thymine. RNA has the bases adenine, cytocine, gueanine, and uracil. DNA is a double helix. RNA is single stranded. DNA is long and thick. RNA is a short segment of DNA and thin.

Dissociation of Water

Dissociation of water is collisions between two water molecules to form hydroxide and hydronium ions. There is, however, a constant change; as one hydrogen ion reattaches to a hydroxide ion to form a water molecule, another water molecule dissociates to replace the hydrogen ion and the hydroxide ion in solution. The process is reversible. Water normally exists as a mixture of molecules, hydroxide ions and hydronium ions.

How is water's lower density as a solid helpful

Floating ice is less dense and so it floats on top of the non-frozen water. The frozen water floating on top serves to insulate the rest of the water below from freezing. This is important for aquatic organisms since it means that their habitat does not freeze solid. Example, fish that live below the frozen ice of a pond or a lake.

Why is water having good solvent properties important?

Good Solvent Properties of water give it the ability to dissolve anything that is charged/polar. It will not however dissolve non-polar ions such as oils. Mineral salts and organic materials such as oxygen, carbon, and nutrients dissolve in ocean giving ocean creatures needed materials for sustaining life.

How do herbivores solve the problem of cellulose digestion?

Herbivores are able to digest cellulose because they have evolved a mechanism to do just that. They have cellulose digesting prokaryotes in their digestive tracts. These prokaryotes hydrolyze the cellulose. This breaks the β linkages in cellulose, enabling access to energy released in breaking these bonds. This energy is used to nourish the herbivore.

How is the High Specific Heat of water helpful

High Specific Heat Capacity ensures resistance to sudden changes in temperature making water a better habitat for creatures. Our bodies are made up of lots of water which helps our body resist change in temperature = homeostasis. Cohesion through evaporation keeps plants from overheating.

Explain how the structure of water molecules account for Cohesion.

Hydrogen bonds hold and pull molecules towards each other.

Lower density as a solid (water)

Ice is the solid form of water and solidifies and floats when the temperature drops to 0 degrees Celsius. Ice floats because of the structure in water called hydrogen bonding. The water begins to freeze because molecules do not move fast enough to break the hydrogen bonds, then the water becomes locked because each molecule is hydrogen bonded to four other molecules. The bonds are placed far enough apart to make the ice ten percent less dense than the surrounding water which is the reason it floats on top of non frozen water.

How can you tell a biological molecule is a lipid?

Lipids are insoluble in water(hydrophobic) due to their high proportion of nonpolar carbon-hydrogen bonds. The most important types of lipids are: fats, phospholipids and steroids.

Why are living things mostly made of water?

Living things are mostly made up of water for many reasons. Molecules of water play a role in chemical reactions of living organisms. Water is made up of hydrogen and oxygen, elements that are essential to the life of most organisms. Living things require water more than any other substance and rely on its emergent properties to maintain their systems.

Explain the relationship between matter and energy.

Matter releases energy. In return, energy can change the form of matter.

Explain the relationship between monosaccharides, disaccharides, and polysaccharides.

Monosaccharides are simple sugars(one). Disaccharides are molecules that consist of two covalently bonded simple sugars. Polysaccharides are molecules that consist of hundreds or thousands (many) of simple sugars covalently bonded. Monosaccharides are simple sugars and are composed of one sugar. They are often used to form larger molecules. Disaccharides are formed by linking two monosaccharides together. Polysaccharides are made up of three or more monosaccharides(longer polymers) that have been joined together through dehydration synthesis. All three of these(monosaccharides, disaccharides, and polysaccharides) are carbohydrates used for energy or energy support and are made of sugars.

Explain how the structure of water molecules account for High Specific Heat.

One calorie of heat is released or absorbed before an increase or decrease in temperature.

Why are proteins the most complex biological molecules?

Proteins are the most complex biological molecules because they are made of five different elements: carbon, hydrogen, oxygen, nitrogen, and sulfur. Compared to other biological molecules, which may only contain up to three or four other elements.

How do the properties of a compound like H2O or NaCl illustrate the concept of emergent properties?

Separately, the things that make those compounds are not fit for our consumption, but together, they're helpful.

Why are starch and glycogen useful as energy storage molecules, while cellulose is useful for structure and support? Why isn't cellulose easily broken down?

Starch and glycogen are useful for energy storage because they are easily digested by organisms. Their structure and shape allows them to be easily digested. The bonds between the α-glucose units are broken and energy is released. These bonds are broken with the help of starch-hydrolyzing enzymes. The structure of cellulose makes it good for structure and support because they have β-glucose units. The β-glucose units that make up cellulose are not easily digested by most organisms because they do not have enzymes that can break the bonds between two β-glucose units because they only recognize α linkages. The β-glucose bonds in cellulose make tough fibers when linked.

What is the cause of molecular polarity?

The charged atoms are displaced in molecules.

Why is dissociation of water important?

The dissociation of water molecules leads to acidic and basic conditions that can affect life. The pH balance in the body is important to sustain life and to ward off certain diseases and bacteria.

How common are the elements that living systems are made out of?

The elements living things are made of are abundant, so we don't run out and have to have an important aspect of us missing.

Explain how the structure of water molecules account for Adhesion.

The molecules are attracted the surface of other substances.

How does the type of bonds present in a substance influence the chemical and physical properties of that substance?

The strength of bonds often determine properties such as flexibility, strength, a melting point, or a boiling point.

How does the structure of the 'R' group affect the properties of a particular amino acid?

The structure of the R group can determine whether the amino acid is polar, non-polar, or electrically charged. Electrically charged amino acids will have their charge written in their tail (R group). Nonpolar will have no oxygen. Polar will have oxygen or sullfer

Why are radioactive elements useful for the study of biological systems?

They can be traced as they travel through the body. For example, they can concentrate around a tumor, and with our technology, we can detect where the concentration is.

How are triglycerides, phospholipids, and steroids similar? How do they differ?

Triglycerides, phospholipids, and steroids are all types of lipids. They are made of carbon, hydrogen, and oxygen with no polymers. They are all insoluble in water. Triglycerides are made of glycerol and three fatty acids and are connected by ester linkages. (saturated and unsaturated fats) Phospholipids are modified triglycerides having only two fatty acids attached per one glycerol. The third hydroxyl group joins with a phosphate group instead of a third fatty acid which happens in triglycerides. Phospholipids have hydrophobic tails and hydrophyllic heads. (phospholipid bilayer) Steroids are lipids composed of a skeleton of 4 carbon rings. Cholesterol is the precursor from which other steroids are sythesized. Steroids serve as hormones which are crucial molecules in animals. Triglycerides, phospholipids, and steroids differ in their structures and in their functions. Triglycerides are molecules with 3 fatty acids bonded to a glycerol backbone. Their main function is long term energy storage. Phospholipids are molecules with 2 fatty acids and a phosphate attached to a glycerol backbone. They are important for cell membranes with their polar head + nonpolar tails. They form a phospholipid bilayer. Steroids have a notable structure of four fused rings. Steroids in the form of hormones help regulate body functions.

High specific heat (Water)

Water has a high specific heat capacity which means the amount of heat that must be absorbed or released to change the temperature by 1 degree Celsius is greater than other substances. This is due to hydrogen bonding because heat must be absorbed to break hydrogen bonds and heat is released when they form. The hydrogen bonds cause much of this heat to be used before the water molecules can move faster from the energy.

Water as a good solvent

Water is a very good solvent because of the polarity of the molecule and sometimes the formation of hydrogen bonds. With table salt, the hydrogen and positive regions attract the negatively charged chloride ions in salt. The negatively charged oxygen regions are attracted to the positive sodium ions in salt. Both of these attractions separate the sodium and chloride ions and shield them from bonding with each other. Both of these attractions separate the sodium and chloride ions. The water molecules surrounding the different molecules happens in hydrogen bonding too, with nonionic compounds.

If the breaking of bonds requires an input of energy (which it always does), how is it possible that some chemical reactions (like the burning of gasoline, for instance) can release energy into the environment?

While such reactions require energy, the energy they release is greater.

Explain the relationship between the dissociation of water and the pH of a particular aqueous solution.

pH is a measure of the concentration of hydrogen ions. Hydrogen ions are produced by the dissociation of water. So, the pH is an indirect measurement of the degree of dissociation of water. Low pH represents an acidic substance/solution where H+ (the hydrogen ion) is greater than the OH- (the hydronium ion) or dissociation of water is the other source that creates a low pH. High pH represents the bases, which come from substances that reduce the hydrogen ion concentration. Some substances reduce the concentration by accepting hydrogen ions (i.e. ammonia becoming ammonium ion, NH4+), while other bases reduce the H+ concentration by dissociating to form hydroxide ions that combine with hydrogen ions and form water.