1.
There are two main subcategories of lipids. They are lipids with fatty acids and lipids without fatty acids.
Correct Answer
A. True
Explanation
Lipids are organic compounds that are insoluble in water but soluble in organic solvents. They can be categorized into two main subcategories based on the presence or absence of fatty acids. Lipids with fatty acids include triglycerides, phospholipids, and waxes, while lipids without fatty acids include steroids and terpenes. Therefore, the statement that there are two main subcategories of lipids, one with fatty acids and one without, is true.
2.
Which of the following are the main functions of lipids?
Correct Answer(s)
B. Energy storage
E. Energy source
Explanation
Lipids serve as a main source and storage of energy in the body. They can be broken down to release energy when needed, making them an important energy source. Additionally, lipids can also be stored in adipose tissue for long-term energy storage. Therefore, the main functions of lipids include energy storage and serving as an energy source.
3.
Lipids are polymers which are made up of many monomers.
Correct Answer
A. True
Explanation
Lipids are not polymers made up of many monomers like proteins or nucleic acids. Instead, lipids are a diverse group of molecules that are characterized by their hydrophobic nature. They are composed of fatty acids and other components, but they do not form long chains or repeating units like polymers do. Therefore, the statement that lipids are polymers made up of many monomers is false.
4.
A 5-year-old girl is presented with hepatosplenomegaly, abnormal bleeding, defects in long bone development, and neurological dysfunction. A liver biopsy reveals an accumulation of glucocerebroside. These symptoms indicate the child is suffering from:
Correct Answer
D. Gaucher's disease
Explanation
Gaucher’s disease, which comes in different degrees of severity, is caused by glucocerebrosidase deficiency.
5.
The alleles in the ABO blood group system code for:
Correct Answer
B. Glycosyl transferases
Explanation
The ABO antigens are oligosaccharide chains of membrane lipids. These oligosaccharides are synthesized by glycosyl transferases in the ER and Golgi.
6.
A pregnant woman mentions that 2 years ago, her first child died 2 weeks after birth because the newborn’s “lungs were immature” at birth. Since you are planning a C-section, you want to determine first whether there is a risk of respiratory problems for her current baby. Which of the following results from an analysis of her amniotic fluid would indicate a high risk?
Correct Answer
C. A low lecithin/shingomyelin ratio
Explanation
“Lecithin” includes dipalmitoyl-phosphatidylcholine, the major component of lung surfactant. Sphingomyelin is assessed to control for the overall lipid level.
7.
One in 30 Ashkenazi Jews carries a mutation for Tay-Sachs disease in the heterozygous state. The heterozygotes can be identified by measuring one of the following enzymes in cultured leucocytes:
Correct Answer
B. Hexosaminidase A
Explanation
Hexosaminidase A removes N-acetyl-galactosamine from ganglioside GM2.
8.
Excess cholesterol needs to be transported to the liver because it cannot be metabolized in most extrahepatic tissues. This 'reverse' transport of cholesterol requires a lipoprotein that is not required for other routes of cholesterol transport. This lipoprotein is:
Correct Answer
C. HDL
Explanation
HDL picks up free cholesterol from cells.
9.
Hypercholesterolemic patients taking HMG-CoA reductase inhibitors (statins) produce less cholesterol from endogenous synthesis. Lower intracellular cholesterol levels induce which of the following regulatory changes?
Correct Answer
E. An increased number of LDL receptors
Explanation
Cells acquire cholesterol according to their needs. If they cannot make it themselves, they have to get it from LDL. They do this by making more LDL receptors.
10.
Routine blood studies on an infant show turbid plasma with markedly elevated levels of triacylglycerol. A sample of plasma that has been left in the refrigerator overnight has cream-colored material floating on top. The underlying plasma is clear. Which type of hyperlipoproteinemia is most likely present in this infant?
Correct Answer
A. Type I
Explanation
Chylomicrons but not VLDL rise to the surface on prolonged standing.
11.
You culture fibroblasts from a patient in the laboratory. In order to up-regulate the low-density lipoprotein (LDL) receptors in these cells you should:
Correct Answer
C. Inhibit HMG-CoA reductase
Explanation
By inhibiting cholesterol synthesis, cellular free cholesterol is reduced and LDL receptors are upregulated.
12.
A 5-year-old boy develops severe stomach pain after eating a big piece of fatty cheesecake. Serum amylase is found to be mildly elevated. The plasma triglyceride level is 1200 mg/dL, and the total cholesterol is 220 mg/dL. The parents mention that the child does not like fatty foods at all, but this was the first time he tasted cheesecake. Which apolipoprotein might be deficient in this patient to account for his fat intolerance?
Correct Answer
B. C-II
Explanation
The boy has type I hyperlipoproteinemia. Some cases are caused by a deficiency of apoC-II, which is a required activator of lipoprotein lipase. Conditioned taste aversions are common in all metabolic diseases that lead to sickness after eating certain foods.
13.
A 33-year-old man is found to have tendon xanthomas. When questioned about his lifestyle he says that he exercises regularly, eats balanced meals and is not in any physical distress. A blood analysis reveals plasma total cholesterol of 350 mg/dL and triglycerides of 70 mg/dL. He is treated with cholestyramine and a statin and sent for further analysis. His hyperlipidemia is best classified as:
Correct Answer
E. Type IIa
Explanation
This looks like familial hypercholesterolemia.
14.
Statins are the most important type of cholesterol-lowering drug, and they lower specifically LDL rather than HDL cholesterol. How do the statins lower LDL cholesterol?
Correct Answer
D. By inhibiting HMG-CoA reductase, thereby preventing cholesterol synthesis and forcing the cells to obtain their cholesterol from LDL
Explanation
When the cells cannot make their own cholesterol, they have to snatch it from circulating LDL. To that end, they increase their synthesis of LDL receptors.
15.
On physical examination you notice that a patient has tendon xanthomas. A blood analysis reveals a total cholesterol level of 350 mg/dL, which is due mainly to raised levels of LDL, and normal levels of triglyceride. What other investigation would be helpful in this patient?
Correct Answer
C. Isolate the patient's lympHocytes and look for the number of LDL receptors
Explanation
This looks like familial hypercholesterolemia. In that case you expect a reduction of functional LDL receptors to 50% of normal.
16.
Cholestyramine can be used for the treatment of hypercholesterolemia, either alone or in combination with a statin. Which enzyme is most immediately affected by cholestyramine tratment?
Correct Answer
C. 7a-hydroxylase
Explanation
Cholestyramine is a non-absorbed ion exchanger that binds bile acids in the small intestine, thus interrupting their enterohepatic circulation. 7a-hydroxylase is disinhibited by the lack of bile acids, and converts excess cholesterol to bile acids.
17.
There are two main subcategories of lipids. They are lipids with fatty acids and lipids without fatty acids.
Correct Answer
A. True
Explanation
The statement is true because lipids can be classified into two main subcategories based on the presence or absence of fatty acids. Lipids with fatty acids include triglycerides, phospholipids, and waxes, while lipids without fatty acids include steroids and prostaglandins. This classification helps in understanding the different structures and functions of lipids in living organisms.
18.
Most of your blood cholesterol is produced by:
Correct Answer
A. Your Liver
Explanation
Your liver produces about 1,000mg of cholesterol daily, pretty much all your body needs. Approximately 200 – 500mg more comes from the foods we consume.
19.
Only adults need to have their cholesterol checked. Children can't have high cholesterol.
Correct Answer
B. False
Explanation
False – Studies have shown the buildup of fatty plaque in the arteries can start at an early age. Hereditary health issues can contribute to this as well. And considering the poor eating habits and how overweight many of today’s children are, don’t take anything for granted.
20.
High cholesterol levels put me at risk for:
Correct Answer
C. Atherosclerosis
Explanation
Atherosclerosis – High cholesterol levels can put you at risk for plaque buildup in the arterial walls which indicates an increased risk of heart attack and stroke.
21.
Which of the following is a major risk factor for heart disease and stroke?
Correct Answer
D. All of the above
Explanation
All of the above – This was your easy question!
22.
What is Hypercholesterolemia?
Correct Answer
D. High cholesterol in the blood
Explanation
Hypercholesterolemia refers to the condition of having high levels of cholesterol in the blood. Cholesterol is a waxy substance that is found in the body and is necessary for various bodily functions. However, when there is an excessive amount of cholesterol in the blood, it can lead to the formation of plaque in the arteries, increasing the risk of heart disease and other cardiovascular problems. Therefore, high cholesterol in the blood is the correct answer as it accurately describes the condition of hypercholesterolemia.
23.
The hardening of arteries due to a build up of plaque is called
Correct Answer
A. Atherosclerosis
Explanation
Atherosclerosis is the correct answer because it refers to the hardening of arteries caused by the accumulation of plaque. This condition occurs when fatty substances, cholesterol, cellular waste products, calcium, and fibrin build up in the inner lining of the arteries, forming plaques. Over time, these plaques can narrow and harden the arteries, leading to reduced blood flow and potential complications such as heart attacks or strokes. Sickle Cell Anemia, High blood pressure, and Hypercholesterolemia are unrelated conditions and not specifically related to the hardening of arteries due to plaque build-up.
24.
Which of the following is TRUE about saturated fats?
Correct Answer
C. Considered a 'bad' fat
Explanation
Saturated fats are considered a 'bad' fat because they are known to raise levels of LDL cholesterol in the blood, which can increase the risk of heart disease. Unlike unsaturated fats, saturated fats do not have double bonds in their chemical structure. Additionally, saturated fats are typically solid at room temperature, unlike unsaturated fats which are liquid.
25.
Which best describes Linoleic acid?
Correct Answer
B. A polyunsaturated fat
Explanation
Linoleic acid is classified as a polyunsaturated fat because it contains multiple double bonds in its chemical structure. This means that it has more than one unsaturated carbon-carbon bond. Polyunsaturated fats are typically liquid at room temperature and are considered to be healthier than saturated fats. They are found in various plant-based oils and have been associated with several health benefits, including reducing the risk of heart disease.
26.
What does PCR stand for?
Correct Answer
D. Polymerase Chain Reaction
Explanation
PCR stands for Polymerase Chain Reaction. It is a laboratory technique used to amplify a specific DNA sequence. The process involves repeated cycles of heating and cooling to denature, anneal, and extend the DNA strands. This allows for the production of multiple copies of the targeted DNA region, which can then be analyzed and studied further. PCR is widely used in various fields of research, diagnostics, forensic analysis, and genetic testing.
27.
Which best describes the purpose of PCR?
Correct Answer
A. Synthesize large amounts of DNA
Explanation
PCR (Polymerase Chain Reaction) is a laboratory technique used to amplify small amounts of DNA into large quantities. It involves a series of temperature changes that allow DNA replication to occur in a test tube. By using specific primers and DNA polymerase, PCR can synthesize large amounts of DNA from a small starting sample. This technique is widely used in various fields of research, diagnostics, and forensic science to study and analyze DNA sequences, detect genetic diseases, identify pathogens, and perform genetic fingerprinting. Therefore, synthesizing large amounts of DNA accurately describes the purpose of PCR.
28.
If a PCR reaction started with 2 strands of DNA, how many strands of DNA would be created after 30 cycles. Assume one cycle completes each minute.
Correct Answer
D. 2,147,483,648
Explanation
During each cycle of PCR, the DNA strands undergo a process of denaturation, annealing, and extension. In the denaturation step, the double-stranded DNA is separated into two single strands. In the annealing step, primers bind to the single strands. In the extension step, DNA polymerase synthesizes new DNA strands using the primers as a template. After each cycle, the number of DNA strands doubles. Therefore, after 30 cycles, the number of DNA strands would be 2^30, which equals 2,147,483,648.
29.
Which type of cholesterol is considered 'bad'?
Correct Answer
B. LDL
Explanation
LDL cholesterol is considered 'bad' because it can build up in the walls of the arteries, leading to the formation of plaque. This plaque can narrow the arteries and restrict blood flow, increasing the risk of heart disease and stroke. High levels of LDL cholesterol are associated with an increased risk of cardiovascular problems, while low levels of LDL cholesterol are generally considered beneficial for heart health. HDL cholesterol, on the other hand, is considered 'good' because it helps remove LDL cholesterol from the bloodstream, reducing the risk of plaque buildup. Triglycerides are another type of fat found in the blood, and high levels can also contribute to heart disease.
30.
What is the normal (or optimal) range for 'good' cholesterol?
Correct Answer
C. 60 or above mg/dL
Explanation
The normal or optimal range for 'good' cholesterol is 60 mg/dL or above. This means that having a level of 'good' cholesterol equal to or above 60 mg/dL is considered healthy. It is important to maintain a sufficient level of 'good' cholesterol as it helps to remove harmful cholesterol from the bloodstream and reduce the risk of heart disease.
31.
Which of the following is FALSE about triglycerides?
Correct Answer
A. Triglycerides are not considered when assessing cholesterol levels
Explanation
Triglycerides are indeed considered when assessing cholesterol levels. Triglycerides are a type of fat found in the blood, and they are often measured along with other cholesterol levels during a lipid profile test. High levels of triglycerides are associated with increased risk of heart disease and can contribute to the development of high cholesterol. Therefore, it is important to assess triglyceride levels when evaluating overall cholesterol levels.
32.
Which direction will DNA travel on an electrophoresis gel?
Correct Answer
C. Negative to positive
Explanation
DNA will travel from the negative electrode (cathode) to the positive electrode (anode) on an electrophoresis gel. This is because DNA is negatively charged due to the phosphate groups in its backbone. When an electric current is applied, the negatively charged DNA molecules are attracted towards the positive electrode and move towards it through the gel matrix.
33.
The kink or bend that a double bond causes in a fats results in what phase at room temperature?
Correct Answer
B. Liquid
Explanation
The kink or bend in a double bond prevents the fat molecules from packing closely together, resulting in a less ordered arrangement. This leads to a weaker intermolecular force and a lower melting point, causing the fat to be in a liquid phase at room temperature.
34.
Why are trans fats considered "double trouble"?
Correct Answer
A. They raise LDL cholesterol in the blood
Explanation
Trans fats are considered "double trouble" because they raise LDL cholesterol in the blood. LDL cholesterol is often referred to as "bad" cholesterol because high levels of it can lead to the buildup of plaque in the arteries, increasing the risk of heart disease and stroke. Therefore, trans fats, which raise LDL cholesterol, pose a significant risk to cardiovascular health.
35.
3-hydroxy, 3-methylglutaryl-CoA (HMG-CoA) is not only the substrate for the rate-limiting enzyme of cholesterol synthesis, but also an intermediate in the synthesis of:
Correct Answer
D. Ketone bodies
Explanation
HMG-CoA in the cytoplasm is a precursor for cholesterol. In the mitochondria it forms ketones.
36.
What is this?
Correct Answer
B. Amino acid
Explanation
An amino acid is a molecule that is the building block of proteins. It contains an amino group, a carboxyl group, and a side chain. Proteins are made up of chains of amino acids, known as polypeptides. Disaccharides are carbohydrates composed of two monosaccharide units. Therefore, the correct answer is amino acid, as it is the only option that relates to proteins and their structure.
37.
What is this?
Correct Answer
D. Disaccharide
Explanation
A disaccharide is a type of carbohydrate composed of two sugar molecules joined together. It is formed through a process called dehydration synthesis, where a molecule of water is removed to form a covalent bond between the two sugar molecules. Examples of disaccharides include sucrose (table sugar), lactose (milk sugar), and maltose (found in grains). This answer is correct because it accurately identifies disaccharide as a type of molecule, distinct from polysaccharides (composed of many sugar molecules), polypeptides (chains of amino acids), and amino acids (the building blocks of proteins).
38.
What is this?
Correct Answer
B. Saturated fatty acid
Explanation
A saturated fatty acid is a type of fatty acid that contains only single bonds between carbon atoms, meaning that it is "saturated" with hydrogen atoms. This type of fatty acid is typically solid at room temperature and is commonly found in animal fats and tropical oils. It is called a saturated fatty acid because it is saturated with hydrogen atoms and does not contain any double bonds between carbon atoms.
39.
Lipids are polymers which are made up of many monomers.
Correct Answer
A. True
Explanation
Lipids are not polymers made up of many monomers. Instead, they are macromolecules composed of fatty acids and glycerol. Therefore, the correct answer is False.
40.
Use the gel above, which samples seem most related? A is the size standard or 'ladder'.
Correct Answer
D. B and C
Explanation
The gel above shows multiple samples, including a size standard or 'ladder' labeled as A. The question asks which samples are most related to each other. Based on the gel, it can be observed that samples B and C have similar band patterns, indicating a high degree of similarity. Therefore, the most related samples are B and C.
41.
Using the gel, what is the estimated base pair length of the shortest fragment from sample D?
Correct Answer
B. 18,500
Explanation
The estimated base pair length of the shortest fragment from sample D is 18,500. This means that the smallest fragment of DNA in sample D is approximately 18,500 base pairs long when visualized using the gel.