# Biology EOC Practice Test #1

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• 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-hour 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 and accurate measurement for Chan's experiment.

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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 mere description of an invariable relationship and is not simply a speculation or guess. A scientific theory is also 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 correct answer is community because a community refers to all the different species that interact and live together in a particular area. In this scenario, the barnyard grass, other weeds, rice, and insects are all different species that exist and interact with each other in the same environment.

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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. She made sure they all received the same amount of light and water, and her boss informed her that they were all grown from the same seed variety. After testing the soil, 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 acidity of the soil, indicated by its pH level, affects 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
This 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. By testing 5 similar groups of cows with 5 different feed mixtures, the researchers can compare the weight gain of each group and determine which feed mixture leads to the greatest increase in lean muscle mass. This design controls for the variability in cow types and allows for a direct comparison between the different feed mixtures. Additionally, measuring weight gain at the end of a 6-week trial provides a consistent and measurable outcome for evaluating the effectiveness of each feed mixture.

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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 growth of Paramecium at different temperatures. By repeating the procedures described using 2 flasks and incubating one flask at 15oC and the other at 25oC, we can observe the population size of Paramecium under different temperature conditions. This will allow us to analyze the effects of temperature on the growth rate and population size of Paramecium.

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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.

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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 exercise increases both the pulse and the systolic pressure. The table shows that after running in place for 5 minutes, both Paul and Simon experienced an increase in their pulse rates and systolic pressures. This indicates that the heart is pumping more blood during exercise compared to when they are at 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 is 10. This can be calculated by summing up the number of eggs laid each day (5 + 10 + 25 + 50 = 90) and then dividing it by the number of days (90 / 5 = 18). Therefore, the average number of eggs laid per day is 18.

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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
Based on the graph, the elephant is approximately 1/3 as fast as the cheetah. The graph shows that the cheetah has the highest average fastest speed among the animals. By comparing the position of the elephant on the graph to the cheetah, it can be observed that the elephant's speed is approximately 1/3 of the cheetah's speed. Therefore, the elephant is the correct answer.

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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 basic assumption of science that Ella is operating under is that nature is orderly. This means that there is a consistent and predictable pattern to natural phenomena, such as the setting of the sun and the occurrence of a full moon. By stating that the sun will set at 6:30 p.m. and there will be a full moon on Thursday night, Ella is implying that these events follow a regular and predictable schedule, which aligns with the assumption that nature is orderly.

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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 it helps to eliminate bias and ensure that the groups are comparable. Random assignment helps to ensure that any differences observed between the two groups are due to the medication and not other factors. It helps to control for confounding variables and increases the internal validity of the study.

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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
The second test should be conducted with 1 mL of enzyme suspension incubated at 37oC for 20 min. This is because Edison wants to accurately test the effects of temperature on starch digestion. By increasing the temperature to 37oC, he is testing a higher temperature than the initial test at 25oC. By keeping the enzyme suspension volume and incubation time the same as the initial test, he is isolating the variable of temperature to determine its specific effect on starch digestion.

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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 information given in the question, where in both experiments, the 30-day old culture consistently shows more bacterial colonies compared to the new culture. This suggests that the older culture has a higher growth rate, 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
In order to determine whether temperature affects the rate at which mold grows on bread, it is important to have a control group that is subjected to the same conditions as the experimental group, except for the variable being tested (temperature in this case). Placing another piece of bread in a closed Petri dish on the countertop serves as the best comparison because it allows for the bread to be exposed to the same environmental conditions (such as humidity and air quality) as the bread in the refrigerator, but without the temperature difference. This will help to isolate the effect of temperature on mold growth.

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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 covalent bonds with other elements, including itself, to create a wide variety of complex molecules. This characteristic allows carbon-based compounds to have a vast array of structures and functions, making them essential for life processes. In contrast, inorganic compounds do not contain carbon and are typically simpler in structure. Therefore, the key factor that separates organic compounds from inorganic compounds is the presence of carbon.

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• 17.

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

• A.

ATP

• B.

Glucose

• C.

Lactic acid

• D.

Oxygen

B. Glucose
Explanation
Glucose is the correct answer because it undergoes hydrolysis in a process called glycolysis, which occurs in the cytoplasm of cells. During glycolysis, glucose is broken down into pyruvate, and this process releases energy in the form of ATP. The ATP generated from glycolysis is then used as a source of energy for muscle contraction. Therefore, the hydrolysis of glucose provides the necessary 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 contains smooth-sided channels called cisternae that help in modifying and sorting proteins and lipids received from the endoplasmic reticulum. This organelle plays a crucial role in the secretion of proteins, lipids, and other cellular materials to their appropriate destinations within and outside the cell.

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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 membrane of the mitochondria and involves the transfer of electrons through a series of protein complexes. As the electrons move through the chain, they create a proton gradient, which is used to generate ATP through oxidative phosphorylation. This process is highly efficient and produces a large amount of ATP compared to glycolysis and the Krebs cycle. Fermentation, on the other hand, does not generate ATP through the electron transport chain but rather through substrate-level phosphorylation.

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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 a pH of 6.0, which indicates that it is slightly acidic. However, compared to the other options given, urine has the highest pH value. Rainwater has a pH of 5.5, indicating that it is slightly more acidic than urine. Tomato juice and gastric juice both have a pH of 2.0, indicating that they are highly acidic. Therefore, among the given options, urine has the greatest concentration of hydroxide ions (OH-).

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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. This group is characteristic of amino acids, which are the building blocks of proteins. Monosaccharides, polysaccharides, fatty acids, and glycerol do not contain the amino group and are not involved in protein synthesis.

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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 the digestion of proteins. It breaks down proteins into smaller peptides and amino acids, making them easier to absorb and utilize by the body. Therefore, papain aids in the digestion of proteins present in Jenna's favorite breakfast food, papaya.

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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 activation energy. Activation energy is the energy required to start a chemical reaction. Enzymes lower this energy barrier, allowing reactions to occur more easily and quickly. They do this by binding to the reactant molecules and bringing them closer together, facilitating the formation of new bonds and the breaking of existing bonds. By reducing activation energy, enzymes increase the rate at which reactions proceed, making them essential for biological processes.

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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
Chloroplasts are the organelles responsible for photosynthesis in plants and algae. Therefore, their presence indicates that cells are capable of photosynthesis. Since the question asks for the structure that indicates cells are NOT photosynthetic bacteria, the correct answer is chloroplast.

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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 is a protein synthesis inhibitor that specifically targets the ribosomes, the organelles responsible for protein synthesis. By adding cyclohexamide to the cells and observing the formation of short incomplete protein segments, Naomi can conclude that the drug is interfering with the ribosomes' ability to synthesize proteins. Therefore, the correct answer is ribosome.

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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 because facilitated diffusion is a passive process that allows molecules to move across the cell membrane with the help of specific channel proteins. These channel proteins create a pathway for the molecules to pass through the hydrophobic phospholipid bilayer, which would otherwise be impermeable to them. Therefore, the molecules move into the cell through the channel protein.

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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
During glycolysis, glucose is broken down into two molecules of pyruvate. Pyruvate is then further processed in the aerobic pathway of cellular respiration, specifically in the Krebs cycle. NADH is also produced during glycolysis as a result of the oxidation of glucose. Both pyruvate and NADH are essential for the subsequent steps of cellular respiration, making them necessary products of glycolysis. The other options, NADPH and ATP, are not directly produced during glycolysis but have other roles in cellular processes.

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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
During yeast respiration, glucose is broken down in the absence of oxygen, leading to the production of ethanol, carbon dioxide, and ATP. The presence of ethanol in the yeast culture indicates that fermentation has occurred. Fermentation is an anaerobic process that converts glucose into ethanol and carbon dioxide, while ATP is produced as an energy source for the yeast cells. Therefore, the yeast culture also contains carbon dioxide and ATP.

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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. The pH scale is logarithmic, which means that each unit change in pH represents a tenfold change in acidity or alkalinity. Therefore, an increase in pH from 2 to 4 indicates a decrease in hydrogen ion concentration 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.
• 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, where the majority of ATP synthesis takes place. The mitochondrial matrix is the innermost compartment of the mitochondria, where the citric acid cycle occurs, leading to the production of ATP. The inner mitochondrial membrane contains the electron transport chain, which generates a proton gradient that drives the synthesis of ATP through the process of oxidative phosphorylation. Therefore, ATP molecules do not form in the cytoplasm or the outer mitochondrial membrane during aerobic cellular respiration.

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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 dark conditions, Chlorella is unable to perform photosynthesis due to the absence of light. As a result, it relies on cellular respiration for energy production. During cellular respiration, organic compounds, including glucose, are broken down to release energy. This process requires the uptake of oxygen and the release of carbon dioxide, leading to a negative uptake (release) of CO2. Therefore, the correct answer is that cellular respiration is taking place.

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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 a type of nitrogenous base. Purine bases include adenine (A) and guanine (G). These bases are responsible for the genetic information stored in DNA and RNA molecules. They form hydrogen bonds with their complementary bases (thymine (T) in DNA, and uracil (U) in RNA) to maintain the double-stranded structure of DNA and the single-stranded structure of RNA. Therefore, the similarity in purine bases is a significant structural similarity between 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 mate and produce offspring that can also reproduce, it suggests that they share enough genetic similarity to be considered the same species. The other statements, such as inhabiting the same general area, having a similar outward appearance, or consuming the same type of diet, may be indicators of similarity but do not necessarily confirm that the populations are 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 answer correctly states that Lysine (Lys) in Person A is replaced with Glutamic Acid (Glu) in Person B. This is because there is a difference of one nucleotide between their mRNA sequences, specifically the nucleotide "U" in Person A is replaced with "G" in Person B. This change in the mRNA sequence leads to a different codon being formed, resulting in a different amino acid being incorporated into the protein.

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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 independently inherited. The fact that the offspring include tall white-flowered pea plants indicates that the traits for height and flower color have segregated independently during the formation of gametes and have recombined in the offspring. This is consistent with Mendel's law of independent assortment, which states that different traits are inherited independently of each other.

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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
Methylation of some regions of DNA prevents transcription by adding a methyl group to the DNA molecule, which can inhibit the binding of transcription factors and RNA polymerase to the DNA. This prevents the transcription of genes in those regions, leading to a decrease in the production of specific proteins. This regulation of gene expression allows cells to specialize by selectively activating or deactivating certain genes, enabling different cell types to develop with unique functions and characteristics.

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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 copies of the gene responsible for pigmentation are non-functional, resulting in the absence of pigment in the skin.

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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
If both parents are heterozygous, they would have one dominant and one recessive allele for coat color. This would explain why they produced both black and albino offspring. The black offspring would inherit the dominant allele from the heterozygous parents, while the albino offspring would inherit the recessive allele.

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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.

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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
Color blindness is a recessive trait that is carried on the X chromosome. In this scenario, the mother is a carrier of the color-blindness allele (Xb) and the father does not carry the allele. Since the father does not carry the allele, he cannot pass it on to any of his children. However, since the mother is a carrier, there is a 50% chance that any daughter they have could be color blind, as daughters inherit one X chromosome from each parent. Therefore, a color-blind daughter is a possible outcome.

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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 are organisms that can synthesize organic compounds from inorganic substances, such as carbon dioxide and sunlight, through processes like photosynthesis. This ability allowed them to obtain energy and nutrients directly from their environment, without relying on consuming other organisms. In contrast, heterotrophs rely on consuming other organisms or organic matter for their energy and nutrient needs. By being able to produce their own food, autotrophs had a more reliable and independent source of sustenance, giving them an advantage in survival and reproduction.

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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 genotype of the F1 individuals is AaBb x AaBB. This means that one parent is heterozygous for both traits (AaBb) and the other parent is heterozygous for one trait and homozygous dominant for the other (AaBB). When these individuals are crossed, the possible genotypes of the F2 generation are AaBb, AaBB, AABb, and AABB. Since AaBb is one out of the four possible genotypes, the expected ratio of AaBb individuals in the F2 generation is 1/4 or 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, and Individual 1 has a combination of both dominant (A) and recessive (a) alleles.

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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
The example that best illustrates the process of natural selection is when giraffe necks varied in length, and the shorter-necked giraffes were at a disadvantage. This is because natural selection involves the survival and reproduction of individuals with traits that are better suited for their environment. In this case, the shorter-necked giraffes would have a harder time reaching food and may struggle to survive, while the longer-necked giraffes would have an advantage and be more likely to pass on their genes to the next generation.

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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
Directional selection is occurring in this cricket population. This is because the trait of having flat wings, which prevents the crickets from singing and being detected by parasitic flies, has increased in frequency over time. This suggests that there is a selective advantage for crickets with flat wings, leading to a directional shift in the population towards this trait.

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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.

D. Larger horses produced a slightly greater number of surviving offspring.
Explanation
The fossil record indicates that the size of horses increased over time. This suggests that larger horses had a slight advantage in terms of survival and reproduction. They were able to produce a slightly greater number of surviving offspring compared to smaller horses. This led to a gradual increase in the overall size of the horse population over generations.

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• Mar 20, 2023
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• Apr 29, 2013
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