Cellular Functions
Cystic fibrosis is caused by a defective protein that should normally be transported to the cell membrane. Instead, it gets misfolded and trapped inside the cell. The organelle most directly responsible for correctly folding and processing this protein before it reaches its destination is the:
Options:
Lysosome
Ribosome
Endoplasmic reticulum
Golgi apparatus
Mitochondrion
Endoplasmic reticulum
History:
22-year-old female presents with chronic fatigue despite adequate sleep. Reports shortness of breath during light exercise.
Physical Exam:
Pale skin, low endurance.
Lab Results:
Low red blood cell count
Normal liver enzymes
Cells show reduced ability to generate ATP
Elevated lactic acid levels
Defective mitochondria
What type of data does a bar graph typically display?
Categorical data
The allele associated with sickle cell anemia apparently reached a high frequency in some human populations due to:
Options:
1. random mating
2. superior fitness of heterozygotes in areas where malaria was present
3. migration of individuals with the allele into other populations
4. a high mutation rate at that specific gene
5. genetic drift
2. superior fitness of heterozygotes in areas where malaria was present
Question:
When the pH of a solution increases from 4 to 6, how has the hydrogen ion concentration changed?
Options:
It has increased by 2 times.
It has decreased by 2 times.
It has increased by 100 times.
It has decreased by 100 times.
It has not changed.
4) It has decreased by 100 times.
Question:
Which one of the following cell types would likely have the most extensive Golgi apparatus?
Options:
Red blood cells that transport oxygen
Pancreatic beta cells that secrete insulin
Skeletal muscle cells responsible for contraction
Adipose cells that store triglycerides
Neurons that transmit electrical signals
2) Pancreatic beta cells that secrete insulin
History:
35-year-old male presents with persistent respiratory infections and infertility.
Physical Exam:
Frequent coughing with mucus buildup
Reduced lung function
Infertility after 3 years of trying with partner
Lab Results:
Abnormal sperm motility
Bronchial cells show failure of ciliary movement
Defective cilia and flagella
A biology student is testing how different types of fertilizers affect the growth of tomato plants. She measures the average plant height after four weeks for three groups: plants given organic fertilizer, plants given chemical fertilizer, and plants given no fertilizer. Which type of graph should she use to display the results?
Options:
1. Line graph
2. Bar graph
3. Scatter plot
4. Pie chart
Bar graph
Which discovery supports the hypothesis that evolution of the lactase-persistence trait was driven by the selective pressure of the use of milk in sheep farming cultures?
Options:
1. People who are lactase persistent have a mutation in the switch region of the lactase gene.
2. The lactase gene is present in both humans and domesticated animals.
3. Ancient pots used to hold milk are about the same age as the lactase-persistence mutations.
4. Scientists have discovered different mutations for lactase persistence in different cultures.
3. Ancient pots used to hold milk are about the same age as the lactase-persistence mutations.
In the mid-20th century, researchers wanted to test whether a newly discovered antibiotic could effectively treat tuberculosis (TB). They infected a group of laboratory mice with Mycobacterium tuberculosis. Half the mice were given the antibiotic daily, while the other half received no treatment. At the end of the study, the researchers compared the severity of lung damage between the two groups.
What is the rationale for this experimental design?
Options:
The treated group tests whether the antibiotic reduces TB severity, while the untreated group provides a control to measure the natural course of the disease.
The untreated group represents all possible outcomes for tuberculosis infection in humans.
The treated group tests the antibiotic, while the untreated group tests whether tuberculosis is caused by bacteria.
The treated group measures the effect of antibiotics on lung tissue, while the untreated group measures the role of genetics in disease progression.
Both groups are simply for replication; no control is needed because the disease outcome is obvious.
1) The treated group tests whether the antibiotic reduces TB severity, while the untreated group provides a control to measure the natural course of the disease.
Question:
Nerve cells maintain a higher concentration of potassium (K⁺) inside the cell than outside. To restore this gradient after each action potential, the cell must use:
Options:
Facilitated diffusion to move K⁺ into the cell along its concentration gradient.
Active transport to move K⁺ into the cell against its concentration gradient.
Osmosis to balance K⁺ levels across the membrane.
Active transport to move K⁺ out of the cell against its concentration gradient.
Simple diffusion to move K⁺ into the cell.
2) Active transport to move K⁺ into the cell against its concentration gradient.
5-year-old child with developmental delay, seizures, and vision problems. Parents report child is missing developmental milestones.
Physical Exam:
Enlarged head circumference
Poor muscle tone
Retinal degeneration
Lab Results:
Accumulation of lipids in neurons
Cells show defective breakdown of macromolecules
High levels of undigested glycolipids in lysosomes
Defective lysosomes
Which best describes a control group in an experiment?
Options:
1. It is subjected to the condition that is being tested
2. It is a sample taken through all experimental steps except the one being tested
3. It is treated identically as the experimental group
4. It tests the dependent variable
5. All of the above
2. It is a sample taken through all experimental steps except the one being tested
A biologist is studying a population of rats living in a forest. Some rats have dark fur, while others have light fur. Predatory birds hunt the rats, and the forest floor is mostly dark soil with fallen leaves. The biologist wants to investigate whether fur color affects survival.
Which rats are most likely to survive predation in this environment?
1. Light-furred rats because they blend with the leaves
2. Dark-furred rats because they blend with the dark soil
3. Light-furred rats because predators prefer them
4. Fur color does not affect survival
2. Dark-furred rats because they blend with the dark soil
Question:
A patient presents with a severe bacterial infection. The physician orders a Gram stain. Under the microscope, the bacteria appear purple. Which of the following statements is most accurate about this organism?
Options:
It is Gram-negative and has a thin peptidoglycan layer surrounded by an outer membrane.
It is Gram-positive and has a thick peptidoglycan layer that retains the crystal violet stain.
It is Gram-negative and contains lipopolysaccharides (LPS) in its cell wall.
It is Gram-positive and lacks peptidoglycan in its cell wall.
It is Gram-negative and resists staining due to the absence of a cell wall.
2) It is Gram-positive and has a thick peptidoglycan layer that retains the crystal violet stain.
Question:
A patient presents with difficulty breaking down cellular waste products. Laboratory analysis shows an accumulation of undigested macromolecules inside the cells, leading to swelling and eventual cell death. Which organelle is most likely malfunctioning?
Options:
Mitochondria
Rough ER
Lysosomes
Golgi apparatus
3) Lysosomes
History:
14-year-old male presents with stunted growth, premature graying of hair, and recurrent skin ulcers. Parents report he looks older than his peers and struggles with delayed wound healing.
Physical Exam:
Thin, fragile skin with multiple lesions
Joint stiffness
Small stature compared to peers
Evidence of early cataracts in both eyes
Laboratory Results:
Chromosomal analysis reveals abnormally shaped nuclei (“blebbed” nuclear envelopes)
Abnormal regulation of cell division (cells enter apoptosis prematurely)
Abnormal Nucleus
Which statement is NOT true about experimental design?
Options:
1. All conditions are held the same except for the condition being tested by the experiment.
2. It is best to use genetically identical mice to reduce the uncontrolled variables.
3. The condition being tested in an experiment is the control variable.
4. The dependent variable is observed at the end of the experiment when statistical comparisons are made between groups.
3. The condition being tested in an experiment is the control variable.
A population of island lizards lives in a tropical forest. The lizards vary in three traits:
Coloration: Green or brown, which affects camouflage in trees versus on the forest floor.
Tail length: Short or long, which influences balance and speed.
Disease resistance: Some lizards carry a genetic allele that provides resistance to a fungal skin infection common in humid areas.
Predatory birds hunt the lizards primarily from above. Ground-dwelling snakes prey on lizards on the forest floor. A recent increase in humidity has caused a rise in fungal infections. Scientists want to study which traits will become more common over multiple generations.
If the humidity continues to rise and fungal infections become deadly for susceptible lizards, which lizards are more likely to survive?
1. Lizards with the disease-resistance allele
2. Lizards without the allele
3. Tail length will determine survival
4. Coloration will determine survival
1. Lizards with the disease-resistance allele
Cells are small because as cell size increases, the
Options:
1. volume and surface area decrease.
2. volume increases faster than the surface area.
3. surface area and volume increase at the same rate.
4. surface area increases faster than the volume.
2. Volume increases faster than the surface area
Question:
A biology student is comparing three cell types:
Intestinal epithelial cells with finger-like projections that increase nutrient absorption.
Respiratory tract cells with short projections that move mucus.
Sperm cells with a long whip-like tail for motility.
Which pairing correctly matches the structure with its cytoskeletal component?
Microvilli – microtubules; Cilia – actin filaments; Flagella – microtubules
Microvilli – actin filaments; Cilia – microtubules; Flagella – microtubules
Microvilli – microtubules; Cilia – intermediate filaments; Flagella – actin filaments
Microvilli – actin filaments; Cilia – intermediate filaments; Flagella – actin filaments
2) Microvilli – actin filaments; Cilia – microtubules; Flagella – microtubules
History:
A 9-year-old boy is brought in with severe growth delays, recurrent infections, and easy bruising. His parents report frequent nosebleeds and unusual tiredness after minimal activity.
Physical Exam:
Short stature and underweight
Pallor and signs of anemia
Petechiae (small red/purple spots from bleeding under the skin)
Mild skeletal abnormalities in the hands and face
Laboratory Results:
Bone marrow biopsy shows reduced blood cell production (red cells, white cells, platelets all decreased)
Blood smear: abnormal-shaped red blood cells
Enzyme analysis: normal mitochondria, lysosomes, and ER function
Molecular testing reveals defective ribosomal RNA processing and reduced protein synthesis
Defective ribosomes
A biology student designs an experiment to test how pH affects the rate of the enzyme catalase breaking down hydrogen peroxide. She sets up five test tubes containing equal concentrations of catalase and hydrogen peroxide but adjusts each to a different pH (pH 3, 5, 7, 9, and 11). She measures the amount of oxygen gas released over 2 minutes.
In this experiment, the independent variable is:
1. The volume of oxygen gas released over 2 minutes
2. The pH levels of the solutions
3. The temperature at which the test tubes are kept constant
4. The control group with no enzyme added
3. The pH levels of the solutions
A population of beetles lives in a forest where the ground is covered with dark soil and fallen leaves. Some beetles are green, some are brown. Predatory birds feed on beetles that are easiest to see. Over several generations, scientists observe changes in the population.
Which statement best describes the selective pressure and expected outcome?
1. Predation by birds favors green beetles, so the proportion of green beetles will increase.
2. Predation by birds favors brown beetles, so the proportion of brown beetles will increase.
3. The color of beetles does not affect survival, so the population will remain the same.
4. Random mating will increase the number of green beetles regardless of predation.
2. Predation by birds favors brown beetles, so the proportion of brown beetles will increase.
A student looks at a sample of bacteria under the microscope after a Gram stain. The cells appear pink. Which of the following statements best describes these bacteria?
Options:
They are Gram-positive with a thick peptidoglycan cell wall.
They are Gram-negative with a thin peptidoglycan layer and an outer membrane.
They are Gram-positive and lack an outer membrane.
They are Gram-negative because they have no cell wall at all.
They are Gram-positive and contain teichoic acids in their walls.
2) They are Gram-negative with a thin peptidoglycan layer and an outer membrane.