Biochemistry and Scientific Thinking

A complete set of review question-and-answer flashcards covering macromolecules, biological structures, enzyme activity, properties of water, pH, and scientific methodology based on the lecture slides.

What causes young flamingo feathers to change from gray or white to pink or orange?

Lipids from their food accumulate in the fats of the feathers.

Which element forms up to four covalent bonds with other atoms and is contained in all organic molecules?

Carbon

What general terms describe proteins, carbohydrates, and nucleic acids in relation to their building blocks?

They are polymers constructed of monomers.

Which of the following is not a macromolecule: lipids, carbohydrates, water, nucleic acids, or proteins?

Water

What is the primary function of carbohydrates in living organisms?

To provide energy

Why do carbohydrates function well as fuels?

Because of their bonds, which release energy when broken.

What monomers make up large, complex carbohydrates?

Monosaccharide monomers

In the provided diagram, which molecule's different fates in the blood are illustrated?

Glucose

What is the primary form of short-term energy storage in animals?

Glycogen

In the blood sugar level graph shown, which breakfast option produces a slow, sustained energy release as depicted by line 2?

A bowl of oatmeal

What is cellulose, a complex carbohydrate made by plants, commonly known as in a healthy diet?

Fiber

What structural characteristic is shared by all lipids despite their structural diversity?

They are hydrophobic.

Which major molecular categories belong to lipids?

Sterols, fats, triglycerides, and phospholipids.

Which molecule stores more energy: glucose, maltose, a triglyceride, ribose, or fructose?

A triglyceride

Which type of fat is solid at room temperature and can contribute to heart disease and strokes?

Saturated fat

In the provided image, which structure (A or B) depicts an unsaturated fat?

B

What process adds hydrogen atoms to unsaturated fats to make them more saturated?

Hydrogenation

Which group of lipids is important in regulating growth and development?

Sterols

"Roid rage" results from taking synthetic variants of which group of lipids?

Sterols

Which statement best describes the blue boxed portion (head region) of the phospholipid shown?

It is hydrophilic and is attracted to water.

What are four major biological functions of proteins?

Structure, protection, contraction, and transport.

How does the elemental composition of proteins differ from carbohydrates and lipids?

Proteins contain nitrogen.

What monomers make up protein polymers?

Amino acid monomers

Which labeled part of the amino acid structure determines its chemical properties?

The side chain

What is an essential amino acid?

An amino acid that cannot be synthesized by the body and must be obtained from food.

What level of protein structure is defined by the sequence of amino acids in a polypeptide chain?

Primary structure

What determines a protein's function?

Its shape, which arises from the number and sequence of amino acids that make up the protein.

How many levels of structure does hemoglobin have?

$$4$$

Why do the color and consistency of an egg change when cooked?

Because the proteins in the egg change shape at high temperature.

What happens to proteins when pH or temperature is too high or too low?

They may be denatured.

Which activity causes the protein denaturation process shown in this illustration?

Placing a raw egg in a hot fry pan.

In the diagram provided, which molecule functions as the enzyme?

Lactase

Why are people who are lactose intolerant unable to digest lactose?

Because their body does not make lactase.

How do enzymes catalyze chemical reactions?

By decreasing the energy of activation required to initiate the reaction.

How do competitive enzyme inhibitors interfere with enzyme activity?

By blocking the active site.

What monomers make up nucleic acids?

Nucleotide monomers

What is the primary function of nucleic acids?

To code for and build proteins.

In the red box of the provided DNA diagram, how are guanine (G) and thymine (T) linked along the backbone?

The sugar in guanine is attached to the phosphate group in thymine.

Which nitrogenous base is present in RNA but absent in DNA?

Uracil (RNA uses uracil whereas DNA uses thymine).

Why is scientific thinking better represented as a cycle rather than a linear step-by-step method?

Because science is a non-linear, flexible process where conclusions lead to new observations and revised hypotheses.

What is pseudoscience?

Claims that sound scientific but are not supported by trustworthy, methodical scientific studies.

What is a hypothesis?

A proposed explanation for an observed phenomenon.

What is a group of atoms held together by bonds called?

A molecule

What is a hydrogen bond?

A bond that forms between molecules.

Which property of water allows it to move from soil to leaves above ground in plants?

Cohesiveness

What structural feature of water gives it a high heat capacity?

Hydrogen bonds, which constrain the movement of individual water molecules.

Why does ice float in liquid water?

Because solid water is less dense than liquid water.

What property of water leads to hydrogen bonds and makes it an effective solvent?

Polarity

What does pH measure in a solution?

The amount of hydrogen ions in a solution.

According to the pH scale diagram, how much more acidic is stomach acid ($\text{pH } 2$) than coffee ($\text{pH } 5$)?

$$1,000\text{ times}$$