Macromolecules EOC REVIEW DAY 1

Which of the following macromolecules serves as the primary source of energy in most living organisms?

• Proteins

• Lipids

• Carbohydrates

• Nucleic Acids

Answer explanation

Carbohydrates are the primary source of energy for most living organisms, as they are easily broken down into glucose, which fuels cellular processes. Proteins and lipids serve other functions, while nucleic acids are involved in genetic information.

Tags

NGSS.MS-LS1-7

Which macromolecule contains the elements carbon (C), hydrogen (H), and oxygen (O) in a ratio of approximately 1:2:1?

• Lipids

• Carbohydrates

• Nucleic Acids

• Proteins

Answer explanation

Carbohydrates are macromolecules that consist of carbon, hydrogen, and oxygen in a 1:2:1 ratio, making them distinct from lipids, nucleic acids, and proteins, which have different elemental compositions.

A molecule of DNA is made up of repeating subunits known as nucleotides. Which of the following components is NOT part of a nucleotide?

• A phosphate group

• A nitrogenous base

• A glycerol molecule

• A five-carbon sugar

Answer explanation

A nucleotide consists of a phosphate group, a nitrogenous base, and a five-carbon sugar. A glycerol molecule is not part of a nucleotide, making it the correct choice for this question.

Lipids are hydrophobic molecules. Which statement explains why this is the case?

• Lipids are nonpolar and cannot form hydrogen bonds with water.

• Lipids are composed primarily of carbohydrates, which repel water.

• Lipids dissolve easily in water due to their structure.

• Lipids have a high affinity for polar substances like water.

Answer explanation

Lipids are nonpolar molecules, meaning they do not have charged regions. This prevents them from forming hydrogen bonds with water, making them hydrophobic. Thus, the correct statement is that lipids cannot form hydrogen bonds with water.

Proteins are composed of amino acids. What is the bond that links amino acids together in a protein?

• Ionic bond

• Hydrogen bond

• Peptide bond

• Phosphodiester bond

Answer explanation

Amino acids are linked together in proteins by peptide bonds, which form through a dehydration reaction between the amino group of one amino acid and the carboxyl group of another. This is the correct bond type.

In a hypothetical scenario, a student isolates a macromolecule that contains the elements carbon, hydrogen, oxygen, nitrogen, and phosphorus. Which macromolecule could this be?

• Carbohydrate

• Protein

• Lipid

• Nucleic Acid

Answer explanation

The presence of carbon, hydrogen, oxygen, nitrogen, and phosphorus indicates a nucleic acid, as these elements are key components of DNA and RNA. Carbohydrates, proteins, and lipids do not contain phosphorus.

Which macromolecule is responsible for speeding up chemical reactions in cells by acting as a biological catalyst?

• Carbohydrates

• Nucleic Acids

• Enzymes (Proteins)

• Lipids

Answer explanation

Enzymes, which are proteins, act as biological catalysts that speed up chemical reactions in cells. They lower the activation energy required for reactions, making them essential for various cellular processes.

Which of the following best describes the primary function of nucleic acids in living organisms?

• Long-term energy storage

• Structural support

• Information storage and transmission

• Catalyzing biochemical reactions

Answer explanation

Nucleic acids, such as DNA and RNA, primarily function in information storage and transmission, encoding genetic information necessary for the development and functioning of living organisms.

Tags

NGSS.HS-LS3-1

Which of these best explains the relationship between monomers and polymers?

• Monomers are made up of several polymers linked together.

• Polymers are smaller units that combine to form monomers.

• None of the given options are correct.

Answer explanation

Monomers are the basic building blocks that link together to form polymers. The provided options incorrectly describe the relationship, making 'None of the given options are correct' the accurate choice.

Tags

NGSS.HS-LS1-1

A triglyceride is a type of lipid molecule. What are the components of a triglyceride?

• Glycerol and three amino acids

• Glycerol and three fatty acids

• Glycerol, phosphate, and two fatty acids

• Phosphate, sugar, and nitrogenous base

Answer explanation

A triglyceride consists of one glycerol molecule and three fatty acids. This structure is essential for energy storage in the body, distinguishing it from other lipid types that may include different components.