Living systems are made of complex molecules including carbohydrates, fats, proteins, and nucleic acids. Even though there are more than 100 elements known to exist, these molecules are comprised of only a few elements. What are these elements?
carbon, hydrogen, nitrogen, oxygen, phosphorus, and sulfur
sodium, potassium, calcium, nitrogen, phosphorus, sulfur
fluorine, chlorine, iodine, nitrogen, phosphorus, sulfur
carbon, hydrogen, oxygen, fluorine, chlorine, iodine
Carbohydrates, such as glucose, are excellent sources of immediate energy for living organisms. More complex carbohydrates, such as glycogen and starch, can also be used for the long term storage of energy. However, carbohydrates play other vital roles, too. Which of the following describes another common use for carbohydrates?
Enzymes help speed up metabolic reactions.
Cellulose is used as a structural component in plant cell walls.
Keratin provides support in hair, nails, feathers, hooves, and some animal shells.
Collagen is a major component in cartilage and tendons.
Which of the following is true about nucleic acids?
Nucleic acids always consist of a five-carbon sugar, a nitrogenous base, and one or more phosphate groups.
Both DNA, which stores genetic information and encodes protein sequences, and RNA, which is involved in the direct production of proteins, are nucleic acids.
Nucleic acids are usually insoluble in water and are used for long term energy storage.
Glucose, cellulose, and starch are examples of nucleic acids found in most cells.
I and II only
I, III, and IV only
I, II, III, and IV
There are twenty standard amino acids that make up all proteins. What four elements are found in all amino acids?
carbon, hydrogen, oxygen, and nitrogen
oxygen, hydrogen, nitrogen, potassium
oxygen, hydrogen, sulfur, phosphorus
carbon, hydrogen, sulfur, phosphorus
Ribonucleic acids (RNA) consist of a five-carbon sugar,
a nitrogenous base, and one or more phosphate groups.
There are four nitrogenous bases that are found in RNA.
These four bases are
adenine, cytosine, guanine, and thymine.
adenine, guanine, thymine, and uracil.
cytosine, guanine, thymine, and uracil.
adenine, cytosine, guanine, and uracil.