BIO 1107 Test 1 Openstax Questions

Why is it possible for humans to digest food that contains starch, but not cellulose?

Amylase can digest 1,4 linkage of glucose found in starch whereas it cannot digest the linkage of glucose found in cellulose.

Discuss how buffers help prevent drastic swings in pH.

Buffers absorb excess hydrogen and hydroxide ions to prevent increases or decrease in pH. An example is the bicarbonate system in human body.

What property of carbon makes it essential for organic life?

Carbon can form up to four covalent bonds, allowing it to form long chains.

How many neutrons do carbon-12 and carbon-13 have, respectively?

Carbon-12 contains 6 neutrons while carbon-13 contains 7 neutrons.

The unique properties of water are important in biological processes. For the following three properties of water, define the property and give one example of how the property affects living organisms:

Cohesion is the attraction between the water molecules, which helps create surface tension. Insects can walk on water because of cohesion. Adhesion is the attraction between water molecules and other molecules. Water moving up from the roots of plants to the leaves as a result of capillary action is because of adhesion. Heat of vaporization is the amount of energy required to convert liquid into gas. This property helps humans maintain homeostasis of body temperature by evaporation.

What are some reasons that DNA is double stranded and RNA is single stranded in plants and animals?

DNA encodes multiple genes and is stable. RNA codes for particular genes, is always functional, and can exit the nucleus.

How can an unsaturated fat be made to function like a saturated one?

Hydrogenation of unsaturated fats forms the trans fats.

What makes ionic bonds different from covalent bonds?

Ionic bond involves the transfer of electrons whereas covalent bond involves the sharing of electrons.

What is structurally different between starch and cellulose that gives them different physical properties?

Cellulose is formed by β-1,4 glycosidic linkages and crosslinks, making it rigid. Starch has α-1.4 and α-1.6 glycosidic linkages without the tight crosslinks of cellulose

What type of compound functions in hormone production, contributes to membrane flexibility, and is the starting molecule for bile salts?

Cholesterol, which is a lipid and also a steroid, functions here

The shape of hair proteins is maintained by a combination of hydrogen bonds and covalent, disulfide bonds. Heat is sufficient to break the hydrogen bonds, but harsh chemicals are required to break the disulfide bonds. Why is it harder to break the disulfide bonds than the hydrogen bonds?

Covalent bonds are stronger than hydrogen bonds.

Why are hydrogen bonds and van der Waals interactions necessary for cells?

Hydrogen bonds and van der Waals interactions form weak associations between molecules, providing the necessary shape and structure of DNA and proteins to function in the body.

Why can some insects walk on water?

Insects can walk on water because of its high surface tension.

With which cellular structure does the extracellular matrix interact?

cytoskeleton

Water takes up 333 million cubic miles on Earth, yet access to drinking water is a critical issue for many communities around the world. Explain why this is so.

Only 4 percent of the total water on earth is freshwater, out of which 68 percent is found in glaciers.

How do phospholipids contribute to cell membrane structure?

Phospholipids orient their heads towards the polar molecules and tails in the interior of the membrane, thus forming a bilayer.

Dehydration is a word usually used to mean the removal of water. How does this apply to macromolecules?

The hydroxyl groups of two monomers are used to form a bond by removing a hydrogen from one monomer and a hydroxyl group from the second forming a molecule of water.

What causes the changes in protein structure through the three or four levels of structure?

The primary chain forms secondary α-helix and β-pleated sheets which fold onto each other forming the tertiary structure.

What are the four types and functions of RNA?

mRNA is a single stranded transcript of DNA. rRNA is found in ribosomes. tRNA transfers specific amino acids to a developing protein strand. miRNA regulates the expression of mRNA strands.

HIV is an RNA virus that affects CD4 cells, also known as T cells, in the human body. Which mechanism is most likely responsible for the fast rate at which HIV can spread?

mutation

Why can water be a good insulator within the body of endothermic (warm-blooded) animals?

specific heat capacity

Use the periodic table to describe what a Bohr model of Fluorine (F) would look like and explain why the Bohr model is not an accurate representation of the electron orbitals in fluorine.

A Bohr model would have 2 electron rings, and a Bohr model would not show the sub-shell of second ring

Limestone is a naturally occurring mineral rich in calcium carbonate ( CaCO3). In water, calcium carbonate dissolves to form carbonate (CO32−) (CO32−), a weak base that acts as a buffer. Which would you expect to be more affected by acid rain, an environment rich in limestone or an environment poor in limestone?

An environment poor in limestone would be more affected by acid rain.

imestone ​is a naturally occurring mineral rich in calcium carbonate ( CaCO3 ). In water, calcium carbonate dissolves to form carbonate (CO32−)(CO32−) , a weak base that acts as a buffer. Which would you expect to be more affected by acid rain, an environment rich in limestone or an environment poor in limestone?

An environment poor in limestone would be more affected by acid rain.

Most organisms carry their hereditary genetic information as DNA. However, some viruses use RNA instead. The HIV virus has RNA, but its genetic information is found in host DNA. How does this happen?

An enzyme reverses the usual process, producing DNA from the viral RNA.

The protein sequence of cytochrome c from chimpanzees and humans is identical. The protein sequence of cytochrome c from rhesus monkeys differs from the human sequence by one amino acid. What do these comparisons suggest?

Chimpanzees are more closely related to humans than rhesus monkeys.

How do the differences in amino acid sequence lead to different protein functions?

Different amino acids provide different geometric configurations and thus varied functions.

Why can water be a good insulator within the body of endothermic (warm-blooded) animals?

Specific heat capacity

Which of these describe some of the similarities and differences between glycogen and starch?

Starch is less branched than glycogen and is found in plant

How do the nucleus and the endomembrane system work together for protein synthesis?

The endomembrane system processes and ships proteins specified by the nucleus. In the nucleus, DNA is used to make RNA which exits the nucleus and enters the cytoplasm of the cell. The ribosomes on the rough ER use the RNA to create the different types of protein needed by the body.

Fiber is not really a nutrient, because it passes through our body undigested. Why can't fiber be digested and why is it important to our diet?

The enzymes required to digest cellulose are not produced in human body; undigested fiber adds bulk to the food easing bowel movements.

List the mass number and atomic number of carbon-12 and carbon-13, respectively.

The mass number and atomic number of carbon-13 is 13 and 6, while that of carbon-12 is 12 and 6, respectively.

Is the nuclear membrane part of the endomembrane system? Why or why not?

The nuclear membrane is part of the endomembrane system as it is continuous with the rough endoplasmic reticulum.

Describe the pH scale and how it relates to living systems. Give an example of how drastic pH changes are prevented in living systems.

The pH scale ranges from 0 to 14, where anything below 7 is acidic and above 7 is alkaline. The bicarbonate system in the human body buffers the blood.

How do phospholipids contribute flexibility to cell membrane structure?

The phospholipids containing unsaturated fatty acids cannot be tightly packed which provides membrane flexibility.

Which of the following bodily process would most likely be hindered by a lack of water in the body?

digestion

What are three examples of how the characteristics of water are important in maintaining life?

First, the lower density of water as a solid versus a liquid allows ice to float, forming an insulating surface layer for aquatic life. Second, the high specific heat capacity of water insulates aquatic life or bodily fluids from temperature changes. Third, the high heat of vaporization of water allows animals to cool themselves by sweating.

Identify each sugar as an aldose or ketose.

Glucose and galactose are aldoses. Fructose is a ketose

Looking at the above figure, can you infer which two groups together will form a strong ionic bond?

Group 1 and Group 17

What role do electrons play in dehydration synthesis and hydrolysis?

H+ and OH−ions share electrons with the respective monomers in hydrolysis

What role do electrons play in dehydration synthesis and hydrolysis?

H+and OH−ions share electrons with the respective monomers in hydrolysis.

Which molecule carries information in a form that is inherited from one generation to another?

Hereditary information is stored in DNA.

Vegans are people who do not consume any animal products in their diet. Why do vegans need to pay special attention to the protein they eat?

It is more difficult to obtain all essential amino acids from single plant sources.

K-41 is one of the naturally occurring isotopes of potassium. Use the periodic table to explain how the structure of K-41 differs from the normal K atom.

K-41 has a total of 22 neutrons and normal K atom has 20 neutrons

What are three functions that lipids serve in plants and/or animals?

Lipids serve in the storage of energy, as a structural component of hormones, and also as signaling molecules

Which categories of amino acid would you expect to find on the surface of a soluble protein, and which would you expect to find in the interior?

Polar and charged amino acids will be found on the surface. Non-polar amino acids will be found in the interior.

The word hydrolysis is defined as the lysis of water. How does this apply to polymers?

Polymers break by separating water into hydrogen and hydroxyl group that are added to the monomers.

Why is the process of protein synthesis critical to life?

Protein is required for tissue formation and constitutes hormones and enzymes.

What is a difference between saturated and unsaturated fats?

Saturated fats are solid at room temperature and unsaturated fats are liquid at room temperature

Compare and contrast saturated and unsaturated triglycerides.

Saturated triglycerides contain single bonds and are solids at room temperature, while unsaturated triglycerides contain double bonds and are liquids at room temperature.

What property of carboxyl makes carboxyl containing molecules hydrophilic? Which macromolecules contain carboxyl?

Carboxyl groups release H+, making its parent molecule hydrophilic. It is found amino acids and fatty acids.

A change in DNA on a chromosome affects all proteins made from that gene for the life of the cell. A change in the RNA involved in protein production is short lived. What is the difference between the effects of the changes in the two types of nucleic acids?

DNA is the genetic material that is passed from parent cells to daughter cells and to future generations.

One of the risks for people with diabetes is diabetic ketoacidosis, a build-up of acid in the blood stream. Explain why this is dangerous to humans.

Diabetic ketoacidosis decreases normal pH (7.35-7.45) to a lower value.

How do the differences in amino acid sequences lead to different protein functions?

Different amino acids produce different proteins based on the bonds formed between them

How do the differences in amino acid sequences lead to different protein functions?

Different amino acids produce different proteins based on the bonds formed between them.

A mutation occurs, and cytosine is replaced with adenine. What impact do you think this will have on the DNA structure?

The DNA will bulge in the places where cytosine is replaced by adenine.

What would happen if even one amino acid is substituted for another in a polypeptide? What would be an example?

The amino acid may not show any significant effect the protein structure and function or it may have a significant effect, as in the case of hemoglobin in individuals with sickle cell trait.

What happens to the proteins that are synthesized on free ribosomes in the cytoplasm? Do they go through the Golgi apparatus?

The proteins do not go through the Golgi apparatus and remain free in the cytosol.

Based on carbon dating, scientists estimate this pygmy mammoth died 11,000years ago. How would the ratio of 14C to 12C in a living elephant compare to the 14C to 12C ratio found in the mammoth?

The ratio would be higher in the elephant than the mammoth.

Why have trans fats been banned from some restaurants? How are they created?

Trans fat is produced by the hydrogenation of oil that makes it more saturated and isomerized. It increases LDL amounts.

Using the DNA from the previous question, ATC/GTT/GTA/CTG/TAG/GAT/AAA what mRNA would be made from this DNA fragment?

UAG/CAA/CAU/GAC/AUC/CUA/UUU

The fatty acids of triglycerides are classified as saturated, unsaturated, or trans fats. What is it about the structure of these compounds that gives them their physical characteristics?

Unsaturated fats and trans fats have some double bonded carbon atoms, while saturated fats do not.