Question 1

Which of the following best explains why water is considered an excellent solvent for biological systems?

Accepted Answer

Because water is a polar molecule, allowing it to surround and separate charged and polar solutes through hydrogen bonding.

Question 2

A patient is given an intravenous solution that is hypotonic relative to their blood plasma. What is the most likely effect on their red blood cells?

Accepted Answer

The red blood cells will swell and may burst as water enters the cells by osmosis.

Question 3

Which of the following best describes the role of ATP in cellular metabolism?

Accepted Answer

ATP provides energy for cellular processes by releasing a phosphate group through hydrolysis: $$ \mathrm{ATP} ightarrow \mathrm{ADP} + \mathrm{P_i} + 	ext{energy} $$

Question 4

A mutation causes a cell to produce a non-functional sodium-potassium pump. Which of the following is a likely consequence?

Accepted Answer

The cell will lose the ability to regulate its internal ion concentrations, leading to swelling or shrinking due to osmotic imbalance.

Question 5

Which of the following statements about enzymes is correct?

Accepted Answer

Enzymes lower the activation energy of biochemical reactions, increasing the reaction rate without being permanently changed.

Question 6

A person with a genetic defect in the gene coding for the LDL receptor is at increased risk for which of the following conditions, and why?

Accepted Answer

Atherosclerosis, because LDL cholesterol cannot be efficiently removed from the blood, leading to plaque formation in arteries.

Question 7

Which of the following best explains why a deficiency in vitamin D can lead to bone demineralization?

Accepted Answer

Vitamin D is required for the absorption of calcium ions ($$ \mathrm{Ca$$^{2+}$$} ) $$from the digestive tract into the bloodstream.

Question 8

During vigorous exercise, muscle cells may rely on anaerobic metabolism. What is the primary product of glycolysis under anaerobic conditions, and what is its physiological consequence?

Accepted Answer

Lactic acid, which can accumulate and contribute to muscle fatigue and soreness.

Question 9

Which of the following best describes the function of the rough endoplasmic reticulum (RER) in eukaryotic cells?

Accepted Answer

The RER is the site of protein synthesis for proteins destined for secretion or insertion into membranes, due to the presence of ribosomes.

Question 10

A patient is diagnosed with sickle cell anemia, a disease caused by a single nucleotide substitution in the gene for beta-globin. Which of the following best describes the molecular consequence of this mutation?

Accepted Answer

The mutation causes a single amino acid change in the hemoglobin protein, altering its structure and function.

Question 11

Which of the following best explains the difference between passive and active transport across the plasma membrane?

Accepted Answer

Passive transport moves substances down their concentration gradient without energy input, while active transport moves substances against their concentration gradient using energy, often from ATP hydrolysis.

Question 12

Which of the following best describes the function of the hormone insulin?

Accepted Answer

Insulin decreases blood glucose levels by promoting glucose uptake into cells and stimulating glycogen synthesis.

Question 13

A patient with a deficiency in the enzyme lactase will most likely experience which of the following after consuming dairy products?

Accepted Answer

Symptoms such as bloating, gas, and diarrhea due to undigested lactose reaching the large intestine.

Question 14

Which of the following best describes the role of the major histocompatibility complex (MHC) proteins in the immune system?

Accepted Answer

MHC proteins present antigen fragments on the cell surface, allowing T cells to recognize self from non-self.

Question 15

Which of the following best explains why antibiotics are ineffective against viral infections?

Accepted Answer

Viruses lack the cellular structures and metabolic pathways targeted by antibiotics, such as cell walls and ribosomes.

Question 16

A patient is found to have a tumor that is classified as 'malignant.' Which of the following characteristics is most likely present?

Accepted Answer

The tumor cells invade surrounding tissues and may metastasize to distant sites.

Question 17

Which of the following best describes the process of translation in protein synthesis?

Accepted Answer

Translation is the process by which mRNA is decoded by ribosomes to assemble a specific sequence of amino acids into a polypeptide chain.

Question 18

Which of the following best explains why a person with type O negative blood is considered a universal donor for red blood cell transfusions?

Accepted Answer

Type O negative blood lacks A, B, and Rh antigens, so it does not trigger an immune response in recipients of any blood type.

Comprehensive Study Notes: Human Biology and Disease

Study Guide - Practice Questions

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