# Biology End Of Course Practice Test #2

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35 questions; 45 minutes
This test will randomly select 35 questions from a test bank of EOC-type questions.

• 1.

### Chan wants to determine how much the mass of fungus growing on a nutrient agar plate changes over an 8 hr period. What is the most appropriate unit of measure for him to use?

• A.

Kilogram

• B.

Kilometer

• C.

Milligram

• D.

Millimeter

C. Milligram
Explanation
The most appropriate unit of measure for Chan to use in determining the mass of fungus growing on a nutrient agar plate over an 8 hr period would be milligram. Milligram is a smaller unit of measure compared to kilogram and kilometer, and it is commonly used to measure small masses. Since the mass of the fungus is expected to be relatively small, milligram would provide a more precise measurement for Chan's experiment. Millimeter, on the other hand, is a unit of measure for length and not mass, so it is not appropriate in this context.

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• 2.

### What is the best definition of a scientific theory?

• A.

An explanation of how and why a natural phenomenon behaves teh way it does

• B.

A description of an invariable relationship that exists in nature

• C.

A speculation or guess about how nature works

• D.

An unproven fact

A. An explanation of how and why a natural phenomenon behaves teh way it does
Explanation
A scientific theory is the best definition of a scientific theory because it provides an explanation of how and why a natural phenomenon behaves the way it does. It goes beyond a simple description of a relationship in nature and is not merely a speculation or guess. Additionally, a scientific theory is not an unproven fact, as it is based on extensive research, evidence, and experimentation.

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• 3.

### A scientist studies the effects that barnyard grass, a weed, has on the growth of rice, other weeds, and insects. The barnyard grass and other weeds, rice, and insects make up whihc level of biological organization?

• A.

Population

• B.

Community

• C.

Ecosystem

• D.

Biome

B. Community
Explanation
The scientist is studying the interactions between barnyard grass, other weeds, rice, and insects. These organisms are all living together in a specific area and are interacting with each other. This indicates that they make up a community, which is a group of different species living in the same area and interacting with each other.

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• 4.

### Lydia works in a flower shop after school. She notices that the hydrangeas in Container 1 have pink blossoms, while the hydrangeas in Container 2 have blue blossoms. She makes sure they all recieve the same amount of light and water. Her boss tells her that the flowers were all grown from the same seed variety. Lydia discovers, after testing the soil, that although the same type of soil was used, the soil in Container 1 has a pH of 6.0, and the soil in Container 2 has a pH of 5.0. Lydia most likely conducted her investigation to answer what question about hydrangeas?

• A.

How does the chemistry of the soil affect the color of hydrangea blossoms?

• B.

What role do genetic factors play in hydrangea color?

• C.

Do varying degrees of light affect hydrangea color?

• D.

What type of soil will produce a hydrangea with both pink and blue blossoms?

A. How does the chemistry of the soil affect the color of hydrangea blossoms?
Explanation
Lydia conducted her investigation to answer the question of how the chemistry of the soil affects the color of hydrangea blossoms. She noticed that the hydrangeas in Container 1 had pink blossoms while those in Container 2 had blue blossoms. Despite receiving the same amount of light and water, she discovered that the soil in Container 1 had a pH of 6.0 while the soil in Container 2 had a pH of 5.0. This suggests that the pH of the soil plays a role in determining the color of the hydrangea blossoms.

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• 5.

### Which experimental design would provide scientists with the best data for investigating which type of feed yields the greatest gain in lean muscle mass in cattle?

• A.

Test 5 different types of cows with the same feed mixture and measure their weight gain at the end of a 6-week trial.

• B.

Test 5 similar groups of cows with 5 different feed mixtures and measure their weight gain at the end of a 6-week trial.

• C.

Test 5 similar groups of cows with the same feed mixture, give each group varying amounts of feed, and measure their weight gain at the end of a 6-week trial.

• D.

Test 5 different types of cows with 5 different feed mixtures, give each group varying amounts of feed, and measure their weight gain at the end of a 6-week trial.

B. Test 5 similar groups of cows with 5 different feed mixtures and measure their weight gain at the end of a 6-week trial.
Explanation
Testing 5 similar groups of cows with 5 different feed mixtures and measuring their weight gain at the end of a 6-week trial would provide scientists with the best data for investigating which type of feed yields the greatest gain in lean muscle mass in cattle. This design allows for a comparison among different feed mixtures while controlling for other variables by using similar groups of cows. By measuring weight gain, scientists can directly assess the impact of each feed mixture on lean muscle mass in the cows.

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• 6.

### Shown below is a growth curve for Paramecium grown in a 1.0 L flask containing pond water at 20oC. The pond water is continually filtered to remove waste products, and nutrients are added at a constant rate. How could the experiment be modified to determine whether the temperature influences the population size of Paramecium?

• A.

Repeat the procedures described using 1 flask, and increase the temperature to 25oC for Days 10-15.

• B.

Repeat the procedures described using 1 flask, and vary the temperature randomly during the entire incubation time.

• C.

Repeat the procedures described using 2 flasks; incubate 1 flask at 15oC and the other at 25oC.

• D.

Repeat the procedures described using 2 flasks; incubate both flasks at 20oC.

C. Repeat the procedures described using 2 flasks; incubate 1 flask at 15oC and the other at 25oC.
Explanation
To determine whether temperature influences the population size of Paramecium, it is necessary to compare the population growth at different temperatures. By repeating the procedures using 2 flasks and incubating one flask at 15oC and the other at 25oC, the experiment allows for a direct comparison of the population sizes under different temperature conditions. This will provide data to analyze the effect of temperature on the growth of Paramecium and determine if there is a correlation between temperature and population size.

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• 7.

### Scientists collected data on the height and weight of individuals in a population. They recorded their results in this scatterplot. What is the most accurate conclusion regarding the relationship between height and weight?

• A.

Tall individuals are always heavier than short individuals.

• B.

There is no relationship between height and weight.

• C.

There is a negative relationship between height and weight.

• D.

There us a positive relationship between height and weight.

D. There us a positive relationship between height and weight.
Explanation
The scatterplot shows a positive relationship between height and weight, indicating that as height increases, weight also tends to increase. This means that taller individuals are more likely to be heavier than shorter individuals.

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• 8.

### Paul and Simon want to determine who is more fit. They decide to run in place for 5 minutes and then measure their blood pressures to see whose returns to notrmal most quickly. They record the data in this table.   Paul told Simon that the heart pumps more blood during exercise than at rest. How do the experiment’s results support Paul’s statement?

• A.

Exercise increases only the pulse.

• B.

Exercise increases only the systolic pressure.

• C.

Exercise increases both the systolic and diastolic pressure.

• D.

Exercise increases both the pulse and the systolic pressure.

D. Exercise increases both the pulse and the systolic pressure.
Explanation
The experiment's results support Paul's statement because they show that exercise increases both the pulse and the systolic pressure. This indicates that the heart is pumping more blood during exercise, as the pulse measures the heart rate and the systolic pressure measures the force of blood against the artery walls when the heart beats. Therefore, the increase in both pulse and systolic pressure suggests that more blood is being pumped during exercise compared to rest.

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• 9.

### A researcher counted the number of eggs a single fruit fly laid in 24 hrs for 5 days and recorded the findings in this table. What is the average number of eggs laid per day over the 5 days?

• A.

5

• B.

10

• C.

25

• D.

50

B. 10
Explanation
The average number of eggs laid per day over the 5 days can be calculated by summing up the total number of eggs laid over the 5 days and then dividing it by 5 (the number of days). In this case, the total number of eggs laid over the 5 days is 50 (10 eggs per day * 5 days), and when we divide it by 5, we get the average of 10 eggs laid per day.

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• 10.

### The graph represents the average fastest speed of 5 animals recorded in one study. Based on the graph, which species is approximately 1/3 as fast as the cheetah?

• A.

Elephant

• B.

Kangaroo

• C.

Lion

• D.

Snake

A. Elephant
Explanation
According to the graph, the cheetah has the highest average fastest speed among the 5 animals. The graph does not provide specific values for the speeds of each animal, but it can be inferred that the elephant is approximately 1/3 as fast as the cheetah based on its position on the graph. The elephant is located significantly lower on the graph compared to the cheetah, indicating a much slower speed. Therefore, the elephant is the species that is approximately 1/3 as fast as the cheetah.

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• 11.

### Ella told her sister the sun would set at 6:30 p.m. and there would be a full moon on Thursday night. Under which basic assumption of science is she operating?

• A.

Nature is orderly.

• B.

Knowledge is superior to ignorance.

• C.

Nothing is self-evident.

• D.

All phenomena have natural causes.

A. Nature is orderly.
Explanation
The correct answer is "Nature is orderly." This assumption implies that there is a consistent pattern and order in the natural world, including the movement of celestial bodies like the sun and the moon. Ella's statement about the sun setting at 6:30 p.m. and there being a full moon on Thursday night suggests that she believes in the predictability and regularity of natural phenomena.

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• 12.

### Ming is having trouble sleeping and decides to participate in a study to determine whether a certain medication helps people sleep. There are 30 volunteers, each of whom is assigned to 1 of 2 groups. Volunteers in group 1 are given the medication, and volunters in group 2 are given a placebo (a pill with no medication). Which step is important in order to ensure scientifically valid results?

• A.

Assigning the subjects to groups at random

• B.

Assigning all of the subjects with sleeping problems to the placebo group

• C.

Telling subjects if they are receiving the medicine or the placebo

• D.

Ensuring that the researchers can determine which subjects are getting the medicine

A. Assigning the subjects to groups at random
Explanation
Assigning the subjects to groups at random is important in order to ensure scientifically valid results because random assignment helps to eliminate potential biases and ensure that the groups are comparable. This helps to ensure that any observed differences between the groups can be attributed to the medication and not to other factors. Random assignment helps to increase the internal validity of the study and strengthens the ability to make causal inferences.

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• 13.

### Edison studies the effects of temperature on starch digestion in a test tube. He adds 2 g of starch and 1 mL of enzyme suspension to a test tube and incubates it at 25oC for 20 min. To accurately test the effects of temperature, Edison should begin a second test with 2 g of starch in a test tube and continue with which set of conditions?

• A.

1 mL of enzyme suspension incubated at 25oC for 10 min

• B.

1 mL of enzyme suspension incubated at 37oC for 20 min

• C.

2 mL of enzyme suspension incubated at 25oC for 20 min

• D.

2 mL of enzyme suspension incubated at 37oC for 10 min

B. 1 mL of enzyme suspension incubated at 37oC for 20 min
Explanation
In order to accurately test the effects of temperature on starch digestion, Edison should begin a second test with 2 g of starch in a test tube and continue with the set of conditions where 1 mL of enzyme suspension is incubated at 37oC for 20 min. This is because the first test was conducted at 25oC for 20 min, so in the second test, Edison needs to change the temperature to see the effects. Additionally, the amount of enzyme suspension should remain the same (1 mL) to maintain consistency between the two tests.

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• 14.

### Sunee and Jamila grow 2 distinct strains of E. coli bacteria following appropriate lab procedures. In Experiment 1, they use a new culture of Strain X and a 30-day old culture of Strain Y. In Experiment 2, they use a new culture of Strain Y and a 30-day old culture of Strain X. Sunee and Jamila measure the number of bacterial colonies and record the data in these graphs.What is the most accurate conclusion about the growth rate of the bacteria?

• A.

Strain X grows faster than Strain Y regardless of the culture's age.

• B.

Strain Y grows faster that Strain X regardless of the culture's age.

• C.

The 30-day old culture grows faster regardless of the strain.

• D.

The new culture grows faster regardless of the strain.

C. The 30-day old culture grows faster regardless of the strain.
Explanation
The most accurate conclusion about the growth rate of the bacteria is that the 30-day old culture grows faster regardless of the strain. This can be inferred from the data recorded in the graphs, where the number of bacterial colonies is consistently higher for the 30-day old culture compared to the new culture, regardless of the strain being used.

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• 15.

### A student wants to determine whether temperature affects the rate at which mold grows on bread. The student puts one piece of bread inside a Petri dish, closes the lid, and places the Petri dish in the refrigerator. Which treatment would be the best comparison for this experiment?

• A.

Placing another piece of bread in an open Petri dish in the same refrigerator

• B.

Placing another piece of bread in a closed Petri dish in the same refrigerator

• C.

Placing another piece of bread in an open Petri dish on the countertop

• D.

Placing another piece of bread in a closed Petri dish on the countertop

D. Placing another piece of bread in a closed Petri dish on the countertop
Explanation
The best comparison for this experiment would be placing another piece of bread in a closed Petri dish on the countertop. This is because the student wants to determine the effect of temperature on the rate of mold growth. By placing one piece of bread in the refrigerator and another on the countertop, both in closed Petri dishes, the only variable that differs between the two treatments is the temperature. This allows the student to isolate the effect of temperature on mold growth. Placing the bread in an open Petri dish in the same refrigerator or on the countertop would introduce additional variables (such as air circulation) that could confound the results.

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• 16.

### What key factor distinguishes organic compounds from inorganic compounds?

• A.

Organic compounds contain carbon.

• B.

Organic compounds contain hydrogen.

• C.

Organic compounds provide energy for cells.

• D.

Organic compounds are the building blocks of cells.

A. Organic compounds contain carbon.
Explanation
Organic compounds are distinguished from inorganic compounds by the presence of carbon. Carbon is a unique element that has the ability to form strong covalent bonds with other elements, including itself, to create a wide variety of complex molecules. This characteristic allows carbon to form the backbone of organic compounds, which are often associated with living organisms. In contrast, inorganic compounds may contain carbon, but they can also exist without it. Therefore, the presence of carbon is the key factor that sets organic compounds apart from inorganic compounds.

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• 17.

### The hydrolysis of which molecule provides energy for muscle contraction?

• A.

ATP

• B.

Glucose

• C.

Lactic acid

• D.

Oxygen

A. ATP
Explanation
ATP (adenosine triphosphate) is the molecule that provides energy for muscle contraction. When ATP is hydrolyzed (broken down) into ADP (adenosine diphosphate) and inorganic phosphate, energy is released. This energy is used by muscle cells to power the contraction process. Glucose is a source of energy for ATP production, but it is not directly involved in muscle contraction. Lactic acid and oxygen are not directly involved in providing energy for muscle contraction.

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• 18.

### Megan examines a liver cell and observes an organelle with many smooth-sided channels. Which activity would identify this organelle as the Golgi apparatus?

• A.

Digestion of macromolecules and old organelles

• B.

Detoxification of poisonous molecules within the cell

• C.

Harvesting of energy from organic molecules to make ATP

• D.

Processing and packaging of cellular materials prior to export

D. Processing and packaging of cellular materials prior to export
Explanation
The Golgi apparatus is responsible for processing and packaging cellular materials prior to export. It consists of smooth-sided channels that help in modifying, sorting, and packaging proteins and lipids into vesicles for transport to other parts of the cell or for secretion outside the cell. This activity is unique to the Golgi apparatus and distinguishes it from other organelles mentioned in the options.

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• 19.

### Which process generates most of the ATP produced during cellular respiration?

• A.

Electron transport chain

• B.

Fermentation

• C.

Glycolysis

• D.

Krebs cycle

A. Electron transport chain
Explanation
The electron transport chain is responsible for generating the majority of ATP during cellular respiration. This process occurs in the inner mitochondrial membrane and involves a series of electron carriers that transfer electrons from NADH and FADH2 to oxygen. As electrons are passed along the chain, energy is released and used to pump protons across the membrane, creating an electrochemical gradient. This gradient is then used by ATP synthase to produce ATP. Therefore, the electron transport chain is the main source of ATP production in cellular respiration.

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• 20.

### Which solution has the greatest concentration of hydroxide ions (OH-)?

• A.

Urine (pH 6.0)

• B.

Rainwater (pH 5.5)

• C.

Tomato juice (pH 2.0)

• D.

Gastric juice (pH 2.0)

A. Urine (pH 6.0)
Explanation
Urine has the greatest concentration of hydroxide ions (OH-) because it has a higher pH value (6.0) compared to the other solutions. pH is a measure of the concentration of hydrogen ions (H+), and a higher pH indicates a lower concentration of H+ ions. Since hydroxide ions (OH-) are formed when water (H2O) dissociates, a higher pH means a higher concentration of OH- ions. Therefore, urine with a pH of 6.0 has a greater concentration of hydroxide ions compared to rainwater (pH 5.5), tomato juice (pH 2.0), and gastric juice (pH 2.0).

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• 21.

### Which functional group found in amino acids is absent from monosaccharides, polysaccharides, fatty acids, and glycerol?

• A.

-COOH

• B.

-NH2

• C.

-OH

• D.

-PO4

B. -NH2
Explanation
The functional group -NH2, also known as the amino group, is absent from monosaccharides, polysaccharides, fatty acids, and glycerol. Amino acids contain this group, which is responsible for their role in protein synthesis and formation. Monosaccharides are simple sugars and do not have an amino group. Polysaccharides, such as starch and cellulose, are composed of monosaccharides and do not contain an amino group. Fatty acids and glycerol are components of lipids and lack an amino group. Therefore, the correct answer is -NH2.

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• 22.

### Jenna's favorite breakfast food, papaya, contains significant amounts of the enzyme papain (a protease). What substances does papain help digest?

• A.

Carbohydrates

• B.

Fatty acids

• C.

Nucleic acids

• D.

Proteins

D. Proteins
Explanation
Papain is a protease enzyme, which means it helps in breaking down proteins. Therefore, papain helps digest proteins.

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• 23.

### How do enzymes speed up chemical reactions?

• A.

By reducing activation energy

• B.

By reducing energy produced by the reaction

• C.

By increasing activation energy

• D.

By increasing energy produced by the reaction

A. By reducing activation energy
Explanation
Enzymes speed up chemical reactions by reducing the activation energy required for the reaction to occur. Activation energy is the energy needed to start a chemical reaction, and enzymes lower this energy barrier by providing an alternative pathway for the reaction to proceed. This alternative pathway has a lower activation energy, allowing the reaction to happen more easily and quickly. By reducing activation energy, enzymes increase the rate of the reaction without being consumed or permanently altered in the process.

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• 24.

### The presence of which structure indicates that cells are NOT photosynthetic bacteria?

• A.

Cell wall

• B.

Chloroplast

• C.

DNA

• D.

Ribosome

B. Chloroplast
Explanation
The presence of chloroplast indicates that cells are photosynthetic bacteria, as chloroplasts are the organelles responsible for photosynthesis. Therefore, the absence of chloroplasts suggests that the cells are not photosynthetic bacteria.

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• 25.

### Naomi adds cyclohexamide to cells grown in a test tube. Within minutes, she identifies short incomplete segments of proteins in the cells. On which organelle does cyclohexamide act?

• A.

Endoplasmic reticulum

• B.

Golgi apparatus

• C.

Nucleus

• D.

Ribosome

D. Ribosome
Explanation
Cyclohexamide acts on the ribosome. The ribosome is responsible for protein synthesis in cells. By adding cyclohexamide to the cells, Naomi is able to identify short incomplete segments of proteins. This suggests that cyclohexamide is inhibiting the ribosome's ability to complete protein synthesis, resulting in the formation of incomplete protein segments.

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• 26.

### A scientist places a cell in a solution, and over time the cell gains mass and swells. What is the most likely explanation for the cell's gain in mass?

• A.

The solution is hypertonic to the cell.

• B.

The solution is hypotonic to the cell.

• C.

The solution and the cell have equal concentrations of solutes.

• D.

The solution and the cell have equal concentrations of water.

B. The solution is hypotonic to the cell.
Explanation
The most likely explanation for the cell's gain in mass is that the solution is hypotonic to the cell. In a hypotonic solution, the concentration of solutes is lower outside the cell compared to inside the cell. As a result, water moves into the cell through osmosis, causing the cell to swell and gain mass.

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• 27.

### The diagram shows a cell membrane composed of a phospholipid bilayer with a channel protein. Each X represents the same type of molecule inside or outside the cell. Facilitated diffusion moves these molecules across the cell membrane. In what direction do these molecules move and through which structure?

• A.

Into the cell through the channel protein

• B.

Into the cell through the phospholipid bilayer

• C.

Out of the cell through the channel protein

• D.

Out of the cell through the phospholipid bilayer

A. Into the cell through the channel protein
Explanation
The molecules move into the cell through the channel protein. This is because facilitated diffusion is a passive process that allows molecules to move across the cell membrane with the help of specific proteins. In this case, the channel protein acts as a tunnel or pathway for the molecules to pass through, allowing them to move into the cell. The phospholipid bilayer, on the other hand, does not directly facilitate the movement of molecules in this scenario.

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• 28.

### The areobic and anaerobic pathways of cellular respiration REQUIRE which products of glycolysis?

• A.

• B.

Pyruvate and ATP

• C.

• D.

Explanation
The aerobic and anaerobic pathways of cellular respiration require pyruvate and NADH as products of glycolysis. Pyruvate is the end product of glycolysis and is further broken down in the presence of oxygen during aerobic respiration. NADH is an electron carrier that is produced during glycolysis and is used in the electron transport chain to generate ATP. Therefore, both pyruvate and NADH are essential for the continuation of cellular respiration in both aerobic and anaerobic conditions.

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• 29.

### While investigating yeast respiration, a researcher detects ethanol in the yeast culture. Which molecules does the yeast culture also contain?

• A.

Lactic acid and ATP

• B.

Oxygen and lactic acid

• C.

Carbon dioxide and ATP

• D.

Oxygen and carbon dioxide

C. Carbon dioxide and ATP
Explanation
When yeast undergoes respiration, it produces carbon dioxide and ATP. Carbon dioxide is a byproduct of cellular respiration and is released into the environment. ATP, on the other hand, is the energy currency of the cell and is produced during the process of respiration. Therefore, if ethanol is detected in the yeast culture, it suggests that the yeast is undergoing respiration and producing carbon dioxide and ATP as well.

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• 30.

### These diagrams represent different stages of animal cell division. From start to finish, what is the correct order of the stages?

• A.

2, 4, 3, 1

• B.

2, 3, 4, 1

• C.

3, 2, 1, 4

• D.

3, 1, 2, 4

A. 2, 4, 3, 1
Explanation
Prophase (chromosomes condense & nuclear membrane disappears)
Metaphase (chromosomes line up in the MIDDLE)
Anaphase (chromosomes are pulled APART)
Telophase (2 nuclear membranes form & cytokinesis occurs

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• 31.

### When the pH in a stomach increases from 2 to 4, how does the hydrogen ion concentration change?

• A.

It increases by a factor of 2.

• B.

It increases by a factor of 100.

• C.

It decreases by a factor of 2.

• D.

It decreases by a factor of 100.

D. It decreases by a factor of 100.
Explanation
When the pH in a stomach increases from 2 to 4, it means that the stomach becomes less acidic. pH is a logarithmic scale that measures the concentration of hydrogen ions (H+) in a solution. As the pH increases by 2 units, it indicates a decrease in the hydrogen ion concentration by a factor of 100. This is because each unit on the pH scale represents a tenfold change in the concentration of hydrogen ions. Therefore, when the pH increases from 2 to 4, the hydrogen ion concentration decreases by a factor of 100.

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• 32.

### Pepsin is a protein-digesting enzyme in the human stomach. Antacids cause the pH of the stomach to increase and protein digestion becomes less efficient. What occurs to reduce the efficiency of protein digestion?

• A.

Antacids break the covalent bonds within pepsin.

• B.

Pepsin dissolves antacids in the gastric juice.

• C.

The active site of pepsin changes shape.

• D.

The concentration of pepsin increases.

C. The active site of pepsin changes shape.
Explanation
When the pH of the stomach increases due to the intake of antacids, it causes the active site of pepsin to change shape. This change in shape makes it difficult for pepsin to bind with and break down proteins effectively. As a result, the efficiency of protein digestion is reduced.

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• 33.

### During aerobic cellular respiration, where do ATP molecules form?

• A.

Cytoplasm only

• B.

Mitochondrial matrix only

• C.

Mitochondrial matrix and inner mitochondrial membrane only

• D.

Cytoplasm, mitochondrial matrix, and outer mitochondrial membrane

C. Mitochondrial matrix and inner mitochondrial membrane only
Explanation
During aerobic cellular respiration, ATP molecules form in the mitochondrial matrix and inner mitochondrial membrane only. This is because the process of aerobic respiration occurs in the mitochondria, specifically in the inner membrane and matrix. The inner mitochondrial membrane contains the electron transport chain, which plays a crucial role in generating ATP through oxidative phosphorylation. The matrix, on the other hand, is where the Krebs cycle occurs, producing high-energy molecules that are used in the electron transport chain to generate ATP. Therefore, ATP synthesis primarily occurs in the mitochondrial matrix and inner mitochondrial membrane.

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• 34.

### A science teacher performs an experiment to measure the CO2 uptake of the green algae Chlorella under light conditions. He prepares a suspension of Chlorella and places it in a growth chamber near a lamp. A student disrupts the experiment by turning off the lamp, creating dark conditions. Why is there a negative uptake (release) of CO2 under dark conditions?

• A.

CO2 production requires light.

• B.

Cellular respiration is taking place.

• C.

Chlorella is actively photosynthesizing.

• D.

Glucose production in the dark requires less CO2.

B. Cellular respiration is taking place.
Explanation
In the absence of light, the green algae Chlorella cannot perform photosynthesis to convert CO2 into glucose. Instead, it undergoes cellular respiration, which is the process of breaking down glucose to release energy. During cellular respiration, CO2 is produced as a byproduct. Therefore, under dark conditions, Chlorella exhibits a negative uptake (release) of CO2 as it is actively undergoing cellular respiration.

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• 35.

### DNA and RNA have many structural similarities. Which structure in DNA and RNA is similar?

• A.

Purine bases

• B.

Pyrimidine bases

• C.

Type of sugar

• D.

Attached proteins

A. Purine bases
Explanation
DNA and RNA both contain purine bases, which are adenine (A) and guanine (G). These purine bases are responsible for the genetic information and coding in both DNA and RNA molecules. They play a crucial role in the formation of the complementary base pairs, where adenine pairs with thymine (in DNA) or uracil (in RNA), and guanine pairs with cytosine. Therefore, the similarity in the structure of purine bases is a significant characteristic shared by DNA and RNA.

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• 36.

### What occurs during metaphase I of meiosis?

• A.

Centromeres of replicated chromosomes line up along the cellâ€™s equator.

• B.

Centromeres divide as sister chromatids move toward opposite poles of the cell.

• C.

Homologous chromosome pairs line up along the cellâ€™s equator.

• D.

Homologous chromosomes move toward opposite poles of the cell.

C. Homologous chromosome pairs line up along the cellâ€™s equator.
Explanation
Metaphase I = homologous chromosomes are pulled to the middle of the cell

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• 37.

### When comparing 2 populations of animals, which statement most likely indicates that they are the same species?

• A.

They produce fertile offspring.

• B.

They inhabit the same general area.

• C.

Their outward appearance is similar.

• D.

They consume the same type of diet.

A. They produce fertile offspring.
Explanation
The statement "They produce fertile offspring" most likely indicates that the two populations of animals are the same species. This is because the ability to produce fertile offspring is a key characteristic of members of the same species. If two populations can successfully reproduce and their offspring are capable of reproducing as well, it suggests that they share enough genetic similarity to be considered the same species.

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• 38.

### Persons A and B have similar mRNA sequences with the exception of 1 nucleotide.         Person A: AUGGUUACUAAGGGCUGA         Person B: AUGGUUACUGAGGGCUGA The genetic code chart to determine how this difference affects the sequence of amino acids in the resulting protein.

• A.

Lys in Person A is replaced with Glu in Person B.

• B.

Phe in Person A is replaced with Leu in Person B.

• C.

Persons A and B have identical amino acid sequences.

• D.

A stop codon is generated in Person B and not in Person A.

A. Lys in Person A is replaced with Glu in Person B.
Explanation
The given mRNA sequences differ by only 1 nucleotide, specifically at the 9th position. In Person A, the nucleotide is "A" while in Person B, it is "C". According to the genetic code chart, this change results in the substitution of the amino acid Lysine (Lys) in Person A with Glutamic acid (Glu) in Person B. Therefore, the correct answer is that Lys in Person A is replaced with Glu in Person B.

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• 39.

### Which example best illustrates Mendel's law of independent assortment?

• A.

Two short-haired cats produce a litter of 4 kittens including 1 long-haired and 3 shot-haired.

• B.

A color-blind man and a woman with normal vision produce a son with normal vision and a color-blind daughter.

• C.

A tall prurple-flowered pea plant and a short white-flowered pea plant are crossed, producing offspring including tall white-flowered pea plants.

• D.

A red-flowered snapdragon and a white-flowered snapdragon are crossed, producing offspring with pink flowers.

C. A tall prurple-flowered pea plant and a short white-flowered pea plant are crossed, producing offspring including tall white-flowered pea plants.
Explanation
This example best illustrates Mendel's law of independent assortment because it shows the inheritance of two different traits (height and flower color) that are not linked or dependent on each other. The fact that tall and white-flowered pea plants are produced in the offspring indicates that the alleles for these traits have segregated independently during the formation of gametes. This supports the principle of independent assortment, which states that different genes for different traits segregate independently of each other during the formation of gametes.

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• 40.

### How does the regulation of gene expression lead to cell specialization?

• A.

• B.

Methylation of some regions of DNA prevents transcription.

• C.

Mutations change certain RNA sequences.

• D.

Removal of exons from RNA prevents translation into protein.

B. Methylation of some regions of DNA prevents transcription.
Explanation
The regulation of gene expression leads to cell specialization by methylation of some regions of DNA preventing transcription. Methylation is a process where methyl groups are added to specific regions of DNA, which can inhibit the binding of transcription factors and RNA polymerase to the DNA, thus preventing the transcription of genes in those regions. This selective methylation allows different genes to be expressed in different cell types, leading to the specialization and differentiation of cells in multicellular organisms.

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• 41.

### In humans, pigmented skin is dominant to non-pigmented skin (albinism). What is the genotype of an individual with albinism?

• A.

Carrier

• B.

Heterozygous

• C.

Homozygous dominant

• D.

Homozygous recessive

D. Homozygous recessive
Explanation
An individual with albinism has a genotype of homozygous recessive. This means that both of their alleles for the pigmentation gene are recessive, resulting in the absence of pigmentation in their skin. Since pigmented skin is dominant to non-pigmented skin, individuals with albinism must have two copies of the recessive allele.

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• 42.

### Two black guinea pigs bred and produced 3 black offspring and 2 albino offspring. Assuming no mutations, which guinea pigs must be heterozygous?

• A.

All 3 black offspring

• B.

Exactly 2 of the black offspring Exactly 2 of the black offspring Exactly 2 of the black offspring Exactly 2 of the black offspring

• C.

Both albino offspring

• D.

Both parents

D. Both parents
Explanation
Both parents must be heterozygous. This is because in order for the offspring to have both black and albino phenotypes, the parents must have both black and albino alleles. Heterozygous individuals have two different alleles for a particular gene, in this case, one allele for black and one allele for albino.

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• 43.

### Jeanine inherited 2 alleles for round eye shape and has round eye shape. Her brother inherited 1 allele for round eye shape and 1 allele for almond eye shape and has almond eye shape. What type of trait is round eye shape?

• A.

Co-dominant

• B.

Dominant

• C.

Recessive

• D.

C. Recessive
Explanation
Round eye shape is a recessive trait. This is indicated by the fact that Jeanine inherited 2 alleles for round eye shape and has round eye shape, while her brother inherited 1 allele for round eye shape and 1 allele for almond eye shape and has almond eye shape. In genetics, a recessive trait is only expressed when an individual has two copies of the recessive allele. Since Jeanine has round eye shape, it means that both of her alleles for eye shape are round, indicating that round eye shape is a recessive trait.

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• 44.

### In humans, red-green color blindness is a recessive, sex-linked trait. The chromosomes and alleles associated with color blindness are represented in this chart. Which child could NOT be born to these parents; a female (XBXb) and a male (XBY)?

• A.

Color-blind daughter

• B.

Color-blind son

• C.

Daughter with normal color vision

• D.

Son with normal color vision

A. Color-blind daughter
Explanation
Since red-green color blindness is a recessive trait, it can only be expressed in individuals who have two copies of the color blindness allele (Xb). The father (XBY) does not have the color blindness allele, so he cannot pass it on to any of his children. Therefore, a color-blind daughter cannot be born to these parents.

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• 45.

### What characteristic of early autotrophs gave them an advantage over early heterotrophs?

• A.

They ate heterotrophs.

• B.

They produced spores.

• C.

• D.

They reproduced asexually.

C. They made their own food.
Explanation
Early autotrophs had an advantage over early heterotrophs because they were able to produce their own food. Autotrophs, such as plants, algae, and some bacteria, are capable of photosynthesis or chemosynthesis, which allows them to convert sunlight or inorganic compounds into energy-rich organic molecules. This ability to produce their own food gave autotrophs a sustainable source of energy, while heterotrophs relied on consuming other organisms for their nutritional needs. By being self-sufficient in their food production, autotrophs had a greater advantage in surviving and thriving in their environment.

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• 46.

### The genotype of F1 individuals from a dihybrid cross is AaBb x AaBB. What is the expected ratio of AaBb individuals in the F2 generation?

• A.

8/16

• B.

4/16

• C.

2/16

• D.

1/16

B. 4/16
Explanation
In a dihybrid cross, the F1 generation is produced by crossing two heterozygous individuals for two different traits. In this case, the F1 individuals have the genotype AaBb x AaBB. When these individuals are crossed in the F2 generation, the expected ratio of AaBb individuals can be determined using the Punnett square. The possible genotypes of the offspring are AaBB, AaBb, AABb, and AABb. Out of these four possible genotypes, only one is AaBb. Therefore, the expected ratio of AaBb individuals in the F2 generation is 1 out of 4, which is equivalent to 4/16.

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• 47.

### Alkaptonuria is a genetic disorder of protein metabolism. The disorder is determined by 2 alleles at 1 locus. What is the genotype for Individual 1 in the diagram?

• A.

AA or Aa

• B.

AA

• C.

Aa

• D.

Aa

C. Aa
Explanation
The genotype for Individual 1 in the diagram is Aa. This is because the disorder is determined by 2 alleles at 1 locus, meaning that there are two possible forms of the gene for this disorder. Individual 1 has a combination of both alleles, which is represented by the genotype Aa.

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• 48.

### Which example best illustrates the process of natural selection?

• A.

Giraffe necks varied in length, and all offspring had an equal chance of survival.

• B.

Giraffe necks varied in length, and the shorter-necked giraffes were at a disadvantage.

• C.

Giraffes with short necks migrated to locations best suited for their neck lengths.

• D.

Giraffes stretched their necks to reach for food, and resulting offspring had longer necks.

B. Giraffe necks varied in length, and the shorter-necked giraffes were at a disadvantage.
Explanation
In natural selection, certain traits become more or less common in a population over time based on their advantage or disadvantage in the environment. In this example, the fact that giraffe necks vary in length suggests genetic variation within the population. The shorter-necked giraffes being at a disadvantage indicates that their trait is less favorable for survival, which means they are less likely to pass on their genes to the next generation. This process of differential survival and reproduction leads to the gradual increase in the frequency of longer-necked giraffes in the population, illustrating natural selection.

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• 49.

### Most male crickets produce a mating song by rubbing together their curved wings. In a certain geographic area, parasitic flies detected male crickets singing and deposited their larvae into them, which killed the crickets. Eighteen generations later, the number of males with flat wings has increased to 90%. The flat-winged crickets do not sing, but are still able to mate with females, and parasitic flies cannot detect them. Which type of selection is occurring in this cricket population?

• A.

Artificial

• B.

Directional

• C.

Disruptive

• D.

Stabilizing

B. Directional
Explanation
In this cricket population, there is a clear shift towards the trait of flat wings over curved wings. This indicates that there is a directional selection occurring, where one extreme of the trait (flat wings) is favored over the other extreme (curved wings). The selection pressure is caused by the parasitic flies, as they target and kill the male crickets with curved wings who produce mating songs. The flat-winged crickets, on the other hand, are able to mate with females and avoid detection by the flies, allowing them to survive and pass on their genes.

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• 50.

### Horse skeleton fossils indicate that the size of horses increased over time. Which statement best explains this fossil record?

• A.

Smaller horses bred with larger horses, creating hybrids.

• B.

Smaller horses were infected by a fatal virus early in their history.

• C.

Larger horses consumed the food supply of the smaller horses.

• D.

Larger horses produced a slightly greater number of surviving offspring.