BSC1006 ADVANCED BIOLOGY EXAM Q & A 2024, Exams of Biology

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BSC100 6

Advanced Biology

Q & A w/ Rationales

1. What is the process by which DNA is duplicated during the S phase of the cell cycle? a. Transcription b. Translation c. Replication d. Transduction Answer: c. Replication Rationale: DNA replication occurs during the S phase of the cell cycle. During this process, the DNA helix unwinds and each strand serves as a template for the synthesis of a new strand, resulting in two identical DNA molecules.
2. Which of the following cell organelles is responsible for producing ATP through aerobic respiration? a. Golgi apparatus b. Endoplasmic reticulum c. Mitochondria d. Ribosomes Answer: c. Mitochondria Rationale: Mitochondria are known as the powerhouse of the cell as they generate energy through aerobic respiration. This process occurs in the mitochondria's inner membrane, using nutrients to produce ATP (adenosine triphosphate).
3. What is the primary function of red blood cells in the

a. Allele frequencies remain constant over generations in a large population. b. Genetic mutations always increase population fitness. c. Natural selection leads to the elimination of deleterious alleles. d. Genetic drift occurs only in small populations. Answer: a. Allele frequencies remain constant over generations in a large population. Rationale: According to the Hardy-Weinberg equilibrium, allele frequencies in a population will remain constant if the population is large, mating is random, no mutations occur, no migration occurs, and natural selection does not act upon the population.

6. What is the function of the Golgi apparatus in eukaryotic cells? a. Protein synthesis b. DNA replication c. Lipid synthesis d. Protein modification and packaging Answer: d. Protein modification and packaging Rationale: The Golgi apparatus is responsible for modifying, sorting, and packaging proteins and lipids for transport to their final destinations within or outside the cell. It receives proteins from the endoplasmic reticulum and modifies them by adding sugar molecules or other

modifications.

7. Which of the following is an example of a post-zygotic reproductive barrier? a. Geographic isolation b. Temporal isolation c. Hybrid inviability d. Behavioral isolation Answer: c. Hybrid inviability Rationale: Post-zygotic barriers occur after the formation of a zygote. In the case of hybrid inviability, the hybrid offspring may not develop properly or survive to reproductive age, therefore preventing gene flow between different species.
8. What is the function of restriction enzymes in DNA technology? a. Amplifying specific DNA sequences b. Ligating DNA fragments together c. Cutting DNA at specific recognition sites d. Sequencing DNA molecules Answer: c. Cutting DNA at specific recognition sites Rationale: Restriction enzymes are used in DNA technology to cut DNA molecules at specific nucleotide sequences called recognition sites. These enzymes are naturally found in bacteria and provide a defense

11. Which of the following is an example of an endothermic reaction in living organisms? a. Photosynthesis b. Respiration c. Fermentation d. Glycolysis Answer: b. Respiration Rationale: Respiration is an endothermic reaction in living organisms, as it requires the input of energy in the form of glucose to produce ATP. This process occurs in all living cells and involves the breakdown of glucose to release energy for cellular activities.
12. What is the role of the hypothalamus in the human body? a. Maintaining body temperature and hunger regulation b. Producing and releasing hormones c. Filtering waste products from the blood d. Pumping oxygenated blood to the body Answer: a. Maintaining body temperature and hunger regulation Rationale: The hypothalamus is a small region in the brain that plays a crucial role in maintaining homeostasis. It regulates body temperature, hunger, thirst, sleep, and various other physiological processes.

13. Which of the following statements is true regarding meiosis? a. It results in the formation of identical daughter cells. b. It only occurs in somatic cells. c. It involves two rounds of cell division. d. It results in the formation of haploid cells. Answer: d. It results in the formation of haploid cells. Rationale: Meiosis is a specialized type of cell division that occurs in reproductive cells. It involves two rounds of cell division and results in the formation of haploid cells (containing half the number of chromosomes) which are essential for sexual reproduction.
14. What is the role of transfer RNA (tRNA) during translation? a. Carrying the genetic code from the DNA to the ribosomes b. Synthesizing proteins based on the genetic code c. Transporting amino acids to the ribosomes d. Replicating DNA strands Answer: c. Transporting amino acids to the ribosomes Rationale: Transfer RNA (tRNA) molecules play a crucial role in protein synthesis by transferring specific amino acids to the ribosomes. Each tRNA carries a specific amino acid and binds to the corresponding codon on the mRNA molecule.

species benefit from the interaction, leading to coevolutionary adaptations. Question 2: What is the primary function of the Golgi apparatus in a cell? A. Protein synthesis B. Lipid synthesis C. Cellular respiration D. Protein modification and packaging Answer: D. Protein modification and packaging Rationale: The Golgi apparatus is responsible for modifying, sorting, and packaging proteins and lipids into vesicles for transportation to their final destination within the cell or for secretion. Question 3: Which of the following is a characteristic of prokaryotic cells? A. Presence of a nucleus B. Membrane-bound organelles C. Circular DNA D. Multicellularity Answer: C. Circular DNA Rationale: Prokaryotic cells lack a true nucleus and membrane-bound organelles. Instead, their genetic material is organized in a circular DNA molecule located in the nucleoid region of the cell. Question 4:

In which phase of the cell cycle does DNA replication occur? A. G1 phase B. S phase C. G2 phase D. M phase Answer: B. S phase Rationale: DNA replication takes place during the synthesis (S) phase of the cell cycle, where the genetic material is duplicated to ensure that each daughter cell receives a complete set of chromosomes. Question 5: What is the role of the enzyme RNA polymerase in gene expression? A. DNA replication B. Translation C. Transcription D. Post-translational modification Answer: C. Transcription Rationale: RNA polymerase is responsible for catalyzing the synthesis of an RNA strand complementary to a DNA template, a process known as transcription, which is the first step in gene expression. Question 6: Which of the following is an example of a polysaccharide? A. Glucose B. Fructose C. Starch

chitin, not calcium carbonate. Question 9: What is the function of the hypothalamus in the endocrine system? A. Production of hormones B. Regulation of body temperature C. Storage of hormones D. Secretion of digestive enzymes Answer: B. Regulation of body temperature Rationale: The hypothalamus plays a crucial role in maintaining homeostasis by regulating body temperature, hunger, thirst, and other essential physiological processes. Question 10: Which of the following is a defining characteristic of angiosperms? A. Seeds enclosed within fruit B. Vascular tissue C. Spores for reproduction D. Naked seeds Answer: A. Seeds enclosed within fruit Rationale: Angiosperms are flowering plants that produce seeds enclosed within a fruit, a unique feature that distinguishes them from gymnosperms. Question 11: What is the function of the medulla oblongata in the human brain? A. Regulation of heart rate and breathing

B. Higher cognitive functions C. Visual processing D. Motor coordination Answer: A. Regulation of heart rate and breathing Rationale: The medulla oblongata is responsible for controlling vital autonomic functions such as heart rate, breathing, and blood pressure. Question 12: Which of the following is a characteristic of a secondary immune response? A. Slower and weaker compared to the primary response B. Production of IgM antibodies C. Memory B cells rapidly differentiate into plasma cells D. Short-lived protection against the antigen Answer: C. Memory B cells rapidly differentiate into plasma cells Rationale: During a secondary immune response, memory B cells generated from the primary response quickly differentiate into plasma cells, leading to a faster and more robust production of antibodies. Question 13: What is the function of the kidneys in the excretory system? A. Regulation of blood sugar levels B. Filtration of metabolic waste products C. Production of digestive enzymes D. Synthesis of red blood cells Answer: B. Filtration of metabolic waste products

C:

1. A patient with cystic fibrosis (CF) has a mutation in the CFTR gene that causes a defective chloride channel protein. How does this mutation affect the function of the respiratory epithelium? a) It increases the secretion of mucus and reduces the clearance of bacteria. b) It decreases the secretion of mucus and increases the clearance of bacteria. c) It increases the secretion of bicarbonate and reduces the pH of the airway surface liquid. d) It decreases the secretion of bicarbonate and increases the pH of the airway surface liquid. Answer: a) It increases the secretion of mucus and reduces the clearance of bacteria. Rationale: The defective chloride channel protein in CF patients prevents the movement of chloride ions out of the epithelial cells, which leads to a reduced osmotic gradient and less water secretion. This results in thick and sticky mucus that accumulates on the airway surface and impairs the ciliary action that normally clears bacteria and debris.
2. A researcher is studying the role of microRNAs (miRNAs) in gene regulation. She introduces a synthetic miRNA into a cell culture and observes that it binds to a specific mRNA and inhibits its translation. What is the most likely mechanism by which this miRNA exerts its effect? a) It recruits an RNA-induced silencing complex (RISC)

that cleaves the mRNA. b) It recruits an RNA-induced transcriptional silencing complex (RITS) that methylates the mRNA. c) It forms a double-stranded RNA (dsRNA) with the mRNA that triggers RNA interference (RNAi). d) It forms a stem-loop structure with the mRNA that blocks the ribosome binding site. Answer: a) It recruits an RNA-induced silencing complex (RISC) that cleaves the mRNA. Rationale: MiRNAs are small non-coding RNAs that regulate gene expression by binding to complementary sequences on target mRNAs and inhibiting their translation or stability. One of the main mechanisms by which miRNAs achieve this is by recruiting RISC, a protein complex that contains an endonuclease called Argonaute that cleaves the mRNA.

3. A student is conducting an experiment to measure the rate of photosynthesis in a plant. He uses a spectrophotometer to measure the absorbance of light by chlorophyll at different wavelengths. He obtains the following data: | Wavelength (nm) | Absorbance | |-----------------|------------| | 400 | 0.85 | | 450 | 0.65 | | 500 | 0.35 | | 550 | 0.15 | | 600 | 0.25 |

a genetic variant (LCT-13910T) that is associated with lactose tolerance in different populations. He obtains the following data:

Population	Frequency of LCT-13910T (%)
Northern Europe	77
Southern Europe	35
East Africa	28
West Africa	5
East Asia	2
Native America	1

Based on these data, what can he conclude about his hypothesis? a) It is supported by the data, as the frequency of LCT- 13910T is highest in regions where dairy farming originated and spread. b) It is contradicted by the data, as the frequency of LCT- 13910T is highest in regions where dairy farming is rare or absent. c) It is partially supported by the data, as the frequency of LCT-13910T is high in some regions where dairy farming originated and spread, but low in others. d) It is not supported or contradicted by the data, as the frequency of LCT-13910T is influenced by other factors besides dairy farming, such as migration, genetic drift, or mutation. *Answer: c) It is partially supported by the data, as the frequency of LCT-13910T is high in some regions where

dairy farming originated and spread, but low in others.* Rationale: The hypothesis that lactose tolerance is a result of natural selection driven by dairy farming practices predicts that the frequency of LCT-13910T should be high in populations that have a long history of consuming milk and dairy products, and low in populations that do not. The data show that this is true for some populations, such as Northern Europe and East Africa, where dairy farming originated and spread. However, the data also show that this is not true for other populations, such as Southern Europe and West Africa, where dairy farming also originated and spread, but the frequency of LCT-13910T is low. Therefore, the hypothesis is only partially supported by the data, and other factors may also play a role in determining the frequency of LCT-13910T.

5. A biochemist is studying the structure and function of hemoglobin, a protein that transports oxygen in the blood. He uses X-ray crystallography to determine the three- dimensional shape of hemoglobin and finds that it consists of four polypeptide chains: two alpha chains and two beta chains. Each chain has a heme group that contains an iron atom that can bind to an oxygen molecule. He also measures the oxygen-binding affinity of hemoglobin at different concentrations of oxygen and obtains a sigmoidal curve. What does this curve indicate about the mechanism of oxygen binding by hemoglobin? a) It indicates that hemoglobin has a positive cooperativity mechanism, meaning that the binding of one oxygen molecule increases the affinity for another oxygen