Star Testing Practice Biology

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1. A team of marine scientists is studying biotic and abiotic factors that affect the stability of a deep-sea ecosystem.   The scientists discovered a species of fish that eats other fish and decaying matter. Which of these does not describe the newly discovered fish?  

Explanation

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About This Quiz
Star Testing Practice Biology - Quiz

The 'Star Testing Practice Biology' assesses key biological concepts such as cellular mitosis, membrane permeability, enzyme specificity, reaction rates, ecological impacts, and photosynthesis stages. It enhances understanding of... see morecomplex biological processes and interactions. see less

2. Which of these would most likely cause a mutation? 

Explanation

The insertion of a nucleotide into DNA is most likely to cause a mutation because it alters the sequence of the DNA molecule. Mutations occur when there are changes in the genetic material, and inserting a nucleotide can disrupt the normal sequence of DNA bases. This can lead to changes in the resulting protein or gene expression, potentially causing a variety of genetic disorders or abnormalities.

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3. The cell membrane:

Explanation

The cell membrane is selectively permeable, meaning it allows only certain materials to pass through while preventing others from entering or leaving the cell. This is crucial for maintaining the cell's internal environment and regulating the movement of substances such as nutrients, ions, and waste products. The cell membrane achieves this selectivity through various mechanisms such as protein channels, carrier proteins, and lipid bilayer structure.

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4. 5' ATCAGCGCTGGC 3'  The above sequence of DNA is part of a gene. How many amino acids are coded for by this segment?  

Explanation

The given DNA sequence is 12 nucleotides long. Each amino acid is coded by a sequence of three nucleotides called a codon. Therefore, the number of amino acids coded for by this segment would be equal to the number of codons in the sequence. Since there are four codons in the sequence (ATC, AGC, GCG, TGG), the number of amino acids coded for is 4.

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5. The central nervous system consists of  

Explanation

The central nervous system is composed of the brain and spinal cord. These two structures work together to control and coordinate the body's functions and responses. The brain is responsible for processing information, making decisions, and sending signals to the rest of the body. The spinal cord serves as a pathway for transmitting signals between the brain and the rest of the body. Together, the brain and spinal cord form the central command center of the nervous system.

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6. During a race, the body temperature of a runner increases.  The runner responds by sweating, which lowers body temperature. This process is an example of  

Explanation

During a race, the body temperature of a runner increases due to the physical exertion. In response to this increase, the body activates the sweating mechanism. Sweating helps to cool down the body by evaporating the sweat from the skin, which in turn lowers the body temperature. This process of the body regulating its internal temperature to maintain a stable and balanced state is known as homeostasis. Therefore, the correct answer is "maintenance of homeostasis".

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7. A computer model of cellular mitosis can simulate the aspects of cellular division quite well. However, microscopic observation of actual cellular mitosis can improve understanding because actual observations  

Explanation

Microscopic observation of actual cellular mitosis may reveal greater unknown complexities because computer models can only simulate the aspects of cellular division based on the information and assumptions programmed into them. Actual observations can provide new insights and unexpected findings that may not have been accounted for in the computer model. Therefore, observing cellular mitosis under a microscope can improve understanding by uncovering hidden complexities that were not previously known or considered.

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8. Which of the following is a function of the nervous system? 

Explanation

The correct answer is signaling muscle tissues to contract. The nervous system is responsible for transmitting signals from the brain to various parts of the body, including muscle tissues. These signals stimulate the muscle fibers to contract and produce movement. This function of the nervous system allows for voluntary and involuntary muscle actions, such as walking, talking, and breathing.

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9. In fruit flies, the gene for red eyes (R) is dominant and the gene for pink eyes (r) is recessive. What are the possible combinations of genes in the offspring of two red-eyed heterozygous flies (Rr)?  

Explanation

The possible combinations of genes in the offspring of two red-eyed heterozygous flies (Rr) are RR, Rr, and rr only. This is because the gene for red eyes (R) is dominant, so even if only one parent has the dominant gene, there is a chance that the offspring will inherit it. The recessive gene for pink eyes (r) will only be expressed if both parents contribute the recessive gene. Therefore, the possible combinations are RR (red-eyed), Rr (red-eyed), and rr (pink-eyed).

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10. The diagram above shows homologous chromosomes during prophase I of meiosis. Which of the following correctly describes the process being illustrated?

Explanation

The diagram shows homologous chromosomes during prophase I of meiosis, which is the process of cell division that produces gametes (sperm and egg cells). During prophase I, homologous chromosomes pair up and exchange genetic material through a process called crossing-over. This exchange of genetic material results in the mixing and recombination of alleles, leading to genetic variation in the offspring. Therefore, the correct answer is crossing-over in which alleles are exchanged.

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11. Which of these best illustrates natural selection?  

Explanation

An organism with favorable genetic variations will tend to survive and breed successfully is the best illustration of natural selection because it highlights the concept of individuals with advantageous traits being more likely to survive and pass on their genes to the next generation. This process leads to the gradual accumulation of beneficial traits in a population over time, resulting in the adaptation of the species to its environment.

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12. A protein called p53 can keep cells from dividing. To prevent cell division, this protein most likely stops  

Explanation

The protein p53 is known for its role in preventing cell division. Mitosis is the process of cell division, where a single cell divides into two identical daughter cells. Therefore, it is most likely that the protein p53 stops mitosis in order to prevent cell division.

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13. Long chains of amino acids are found in

Explanation

Proteins are made up of long chains of amino acids. Amino acids are the building blocks of proteins and are linked together through peptide bonds to form these chains. Therefore, the correct answer is proteins.

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14. Fossil evidence suggests that a number of members of one fish species from an ancient lake in Death Valley, California, became several isolated species. Each of these new species lived in a different pond. Which of the following best explains the cause of this speciation? 

Explanation

The fossil evidence suggests that the members of one fish species from an ancient lake in Death Valley, California, became several isolated species. This indicates that the cause of speciation was geographic isolation. Geographic isolation occurs when a population of organisms becomes physically separated by a geographic barrier, such as a mountain range or a body of water. This physical separation prevents gene flow between the populations, leading to genetic divergence and the formation of new species.

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15. Which of these is an example of homeostasis in a multicellular organism?  

Explanation

Regulating body temperature is an example of homeostasis in a multicellular organism because it involves maintaining a stable internal temperature despite changes in the external environment. This process is essential for the organism's survival and involves mechanisms such as sweating or shivering to adjust body temperature as needed.

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16. A new species is introduced into an area. This can have harmful effects on species already inhabiting the area. The harmful effects are most likely a result of    

Explanation

When a new species is introduced into an area, it is likely to compete with the species already inhabiting the area for resources such as food, water, and shelter. This competition can have harmful effects on the existing species, as they may experience a decrease in their access to resources and may struggle to survive. Therefore, the harmful effects of introducing a new species are most likely a result of competition.

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17. The first stage of photosynthesis in a chloroplast is

Explanation

The first stage of photosynthesis in a chloroplast is light-dependent because it requires light energy to initiate the process. During this stage, light energy is absorbed by chlorophyll molecules in the chloroplasts, which then converts it into chemical energy in the form of ATP and NADPH. These energy-rich molecules are crucial for the subsequent stages of photosynthesis, where they are used to produce glucose and other organic compounds. Without light, this initial stage cannot occur, making light-dependency the correct answer.

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18. What is the greatest danger to a patient who has had damage to the skin? 

Explanation

When a patient has damage to the skin, the greatest danger they face is the risk of infections in uncovered tissues. When the skin is damaged, it creates an opening that allows bacteria and other pathogens to enter the body, leading to infections. These infections can range from mild to severe and can cause complications and delays in the healing process. Therefore, it is crucial to keep the damaged area covered and clean to minimize the risk of infections.

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19. Striking the tendon just below the kneecap causes the lower leg to jerk. Moving an object quickly toward the face can cause the eyes to blink shut. These are examples of  

Explanation

The given examples of striking the tendon below the kneecap and moving an object quickly towards the face causing the legs to jerk and eyes to blink shut respectively are both reflex reactions. Reflex reactions are involuntary responses to specific stimuli, which occur without conscious thought. In both cases, the body automatically reacts to protect itself from potential harm.

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20. Students conducted an experiment to test the effect of antibiotics on bacteria. They placed bacteria in a petri dish that contained agar treated with an antibiotic. Only one of the bacterial colonies survived.   Which of these statements best explains why only one colony survived?    

Explanation

The statement "The bacteria in the surviving colony had genetic variations that allowed them to survive" best explains why only one colony survived. This suggests that the bacteria in the surviving colony had genetic traits or mutations that made them resistant to the antibiotic, allowing them to survive while the other bacteria were killed.

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21. Horses have 64 chromosomes in each body cell. If a horse cell undergoes meiosis, how many chromosomes should be in each gamete?  

Explanation

During meiosis, the number of chromosomes is halved. Since horses have 64 chromosomes in each body cell, the gametes produced through meiosis should have half that number, which is 32 chromosomes.

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22. The diagram below shows a cellular process that occurs in organisms.   This process is known as  

Explanation

The question asks for the name of the cellular process shown in the diagram. Since the diagram is not provided, we cannot determine the specific details of the process. However, based on the given options, the correct answer is meiosis. Meiosis is a type of cell division that occurs in organisms to produce gametes (sperm and egg cells) for sexual reproduction. It involves two rounds of division, resulting in the formation of four genetically different haploid cells.

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23. 5' G T A _   _  _ A A 3'        3' C A T G C A T T 5' This segment of DNA has undergone a mutation in which three nucleotides have been deleted. A repair enzyme would replace them with  

Explanation

The segment of DNA has undergone a mutation in which three nucleotides have been deleted. To repair this mutation, a repair enzyme would replace the deleted nucleotides with the sequence CGT.

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24. Which of these organisms would most likely be found at the bottom of a biomass pyramid?

Explanation

Green algae would most likely be found at the bottom of a biomass pyramid because they are primary producers that convert sunlight into energy through photosynthesis. As a result, they form the base of the food chain and provide energy for other organisms. Organisms higher up the pyramid, such as sea cucumbers, sand sharks, and giant squids, rely on green algae either directly or indirectly for their energy needs.

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25. Scientists have found many similarities in the proteins of turtles and sharks. These similarities suggest that turtles and sharks  

Explanation

The finding of similarities in the proteins of turtles and sharks suggests that they have a common ancestor. This means that at some point in the past, turtles and sharks shared a common lineage from which they diverged and evolved into their respective forms. The presence of similar proteins indicates a shared genetic heritage, supporting the idea of a common ancestor.

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26. The Sabin vaccine is a liquid containing weakened polio viruses. Vaccinated individuals become protected against polio because the weakened viruses  

Explanation

The Sabin vaccine is a liquid containing weakened polio viruses. When individuals are vaccinated with this vaccine, the weakened viruses stimulate the immune system to produce antibodies. These antibodies can then recognize and attack the polio virus if the person is exposed to it in the future, providing protection against polio. The weakened viruses are not strong enough to cause illness, but they do trigger the production of antibodies.

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27. Earth has undergone some catastrophic changes from time to time. Which of these most likely explains why life on Earth continued following these catastrophes?  

Explanation

A wide diversity of species existed. This means that there were many different types of organisms living on Earth. When catastrophic changes occurred, some species may have become extinct, but others were able to survive and adapt to the new conditions. The wide diversity of species allowed for a greater chance of survival and the continuation of life on Earth.

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28. Individuals with HIV sometimes contract a pneumonia infection that is rare in the rest of the population because people with HIV 

Explanation

Individuals with HIV have a weakened immune system, which makes it difficult for them to fight off infections, including pneumonia. This is why they are unable to fight off these pneumonia-causing organisms, leading to a higher risk of contracting pneumonia compared to the general population.

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29. Use the information and diagram below to answer the following item.   Animal cells contain an organelle that helps release energy. A diagram of this organelle is shown below. Which function would the energy-releasing organelle most likely have in the animal cell?  

Explanation

The energy-releasing organelle in animal cells, as shown in the diagram, is most likely involved in cellular respiration. Cellular respiration is the process by which cells convert glucose and oxygen into carbon dioxide, water, and ATP (adenosine triphosphate), which is the main energy source for cellular activities. This process occurs in the mitochondria, which is the organelle depicted in the diagram. Therefore, the energy-releasing organelle in animal cells is responsible for cellular respiration.

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30. Which of these best illustrates natural selection?  

Explanation

An organism with favorable genetic variations will tend to survive and breed successfully because natural selection favors individuals that are better adapted to their environment. These individuals are more likely to survive and reproduce, passing on their advantageous traits to the next generation. Over time, these favorable genetic variations become more common in the population, leading to the evolution of the species.

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31. What percentage of total energy (roughly) is transferred from one trophic level to the next?  

Explanation

Approximately 10% of total energy is transferred from one trophic level to the next. This is due to the inefficiency of energy transfer in an ecosystem. As organisms consume food, they only obtain a portion of the energy stored in that food, with the rest being lost as waste or used for metabolic processes. This energy loss continues as energy moves up the food chain, resulting in a decrease in the amount of energy available at each trophic level. Therefore, only around 10% of the energy is transferred to the next trophic level.

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32. The plasma membrane of a cell consists of 

Explanation

The correct answer is two layers of lipids organized with the nonpolar tails forming the interior of the membrane. The plasma membrane is composed of a phospholipid bilayer, which consists of two layers of lipids. The lipids have a polar head and a nonpolar tail. In the bilayer, the nonpolar tails are oriented towards the interior of the membrane, while the polar heads face the aqueous environment both inside and outside the cell. This arrangement creates a hydrophobic barrier that regulates the movement of substances into and out of the cell.

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33. Which of the following is a function of the nervous system? 

Explanation

The nervous system is responsible for transmitting signals throughout the body, including to muscle tissues. These signals, known as nerve impulses, stimulate the muscle fibers to contract, allowing for movement and coordination. Therefore, signaling muscle tissues to contract is a function of the nervous system.

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34. Which of these organisms are most helpful in preventing Earth from being covered with the bodies of dead organisms

Explanation

Fungi and bacteria are most helpful in preventing Earth from being covered with the bodies of dead organisms. Fungi and bacteria are decomposers that break down dead organic matter, such as dead plants and animals, into simpler substances. They play a crucial role in the nutrient cycling process by breaking down complex organic compounds and releasing nutrients back into the environment. Without the activity of fungi and bacteria, dead organisms would accumulate and not be recycled, leading to the Earth being covered with bodies of dead organisms.

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35. Two students were testing the amount of fertilizer that would best promote the growth of strawberries in a garden. Which of the following could be an unavoidable source of experimental error? 

Explanation

An unavoidable source of experimental error in testing the amount of fertilizer that would best promote the growth of strawberries in a garden could be the variation in the strawberry plants. This means that the strawberries used in the experiment may have different genetic traits, growth rates, or health conditions, which could affect their response to the fertilizer. This variation could introduce confounding factors and make it difficult to determine the true effect of the fertilizer on the growth of the strawberries.

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36. Mendel hypothesized that reproductive cells have only one factor for each inherited trait. This hypothesis is supported by the observation that

Explanation

Mendel hypothesized that reproductive cells have only one factor for each inherited trait. This hypothesis is supported by the observation that haploid cells are produced by meiosis. Meiosis is a type of cell division that results in the formation of haploid cells, which contain only one set of chromosomes. This supports Mendel's hypothesis that reproductive cells have only one factor for each inherited trait, as each haploid cell produced through meiosis carries only one allele for each trait.

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37. Which of the following require a host cell because they are not able to make proteins on their own? 

Explanation

Viruses require a host cell because they are not able to make proteins on their own. Unlike other organisms such as blue-green algae, bacteria, and protozoans, viruses lack the necessary cellular machinery to synthesize proteins. Instead, they rely on infecting host cells and hijacking their protein synthesis machinery to produce the proteins they need for replication and survival. This dependence on a host cell is a defining characteristic of viruses.

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38. Rabbits introduced into Australia over 100 years ago have become a serious pest to farmers. Rabbit populations increased so much that  they displaced many native species of plant eaters. What is the most logical explanation for their increased numbers?  

Explanation

The most logical explanation for the increased numbers of rabbits in Australia is that there are few effective predators. This means that there are not enough natural enemies to control the rabbit population, allowing them to reproduce and thrive. Without predators to keep their numbers in check, rabbits can quickly multiply and become a serious pest to farmers and a threat to native species.

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39. Global warming causes an increase in coastal water temperatures. Increased coastal water temperature causes a decrease in reproduction of krill. Which of these would most likely experience an increase in population?

Explanation

Cytoplankton would most likely experience an increase in population. This is because global warming causes an increase in coastal water temperatures, which in turn leads to a decrease in reproduction of krill. Krill are a major food source for many marine organisms, including cytoplankton. With a decrease in krill population, there would be less competition for resources, allowing cytoplankton to thrive and potentially increase in population.

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40. A single species of squirrel evolved over time into two species, each on opposite sides of the Grand Canyon. This change was most likely due to  

Explanation

The most likely explanation for the evolution of two species of squirrel on opposite sides of the Grand Canyon is the isolation of the two groups. The Grand Canyon acts as a physical barrier, preventing gene flow between the two populations of squirrels. Over time, this isolation can lead to genetic divergence and the formation of distinct species. The other options, such as higher mutation rates on one side, low genetic diversity in the initial population, and differences in reproductive rates, do not provide a sufficient explanation for the observed evolution of two distinct species.

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41. Which of the following best describes the use of population models in biology?  

Explanation

Population models in biology are not generally easy to construct as they require a thorough understanding of the population dynamics and various factors that influence it. They also cannot represent reality precisely as they are simplifications of complex ecological systems. However, they are used precisely because observations have been made and data has been collected to develop and validate these models. The primary purpose of population models is to help predict outcomes, such as population growth, decline, or the effects of interventions or environmental changes.

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42. In humans the trait of having freckles (F) is dominant to not having freckles (f).   Which genotype and phenotype are correctly paired?    

Explanation

The correct answer is Ff—freckles. This is because the trait of having freckles is dominant, so even if an individual has one dominant allele (F) and one recessive allele (f), they will still exhibit the phenotype of having freckles.

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43. The ears of foxes help to regulate body heat. The fennec fox lives in the North African desert and has large ears that release body heat. The Arctic fox lives in cold climates and has small ears that conserve body heat.   Which of these processes led to the development of different ear sizes in foxes?    

Explanation

The development of different ear sizes in foxes can be explained by natural selection. In the case of the fennec fox, living in the North African desert, large ears help to release body heat and regulate temperature in a hot environment. On the other hand, the Arctic fox living in cold climates has small ears that conserve body heat to adapt to the cold weather. These adaptations have been favored by natural selection as they increase the survival and reproductive success of the foxes in their respective environments.

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44. In a pond, the primary producer is a green alga, Spirogyra; the primary consumer is the crustacean, Daphnia; the secondary consumer is a small fish, the bluegill; and the tertiary consumer is a larger fish, the smallmouth bass. What changes can be expected in the pond if the Daphnia are killed with pesticides?  

Explanation

If the Daphnia are killed with pesticides, it will disrupt the food chain in the pond. Daphnia are the primary consumers, and they feed on the primary producer, Spirogyra. By killing the Daphnia, the population of Spirogyra will likely increase since there is no longer a primary consumer to control its population. As a result, the population of bluegill, which is the secondary consumer, will also increase since there is more food available. However, since the smallmouth bass is the tertiary consumer and relies on the bluegill as its food source, the decrease in Daphnia population will ultimately lead to the death of the smallmouth bass population.

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45. A base sequence is shown below. ACAGTGC How would the base sequence be coded on mRNA?  

Explanation

The base sequence on mRNA is coded by replacing each base with its complementary base. In DNA, A pairs with T and C pairs with G. Therefore, in the given base sequence ACAGTGC, A is replaced with U, C is replaced with G, G is replaced with C, and T is replaced with A. This results in the mRNA base sequence UGUCACG.

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46. The deep-sea ecosystem is a stable ecosystem. Which of these is a characteristic of most stable ecosystems?  

Explanation

Stable ecosystems typically have a wide variety of organisms because a diverse range of species helps to maintain balance and resilience within the ecosystem. A greater variety of organisms means that there are more interactions and connections between different species, which can help to regulate population sizes, control the spread of diseases, and ensure the availability of resources. This diversity also increases the chances of adaptation and survival in the face of environmental changes or disturbances.

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47. If a corn plant has a genotype of Ttyy, what are the possible genetic combinations that could be present in a single grain of pollen from this plant?

Explanation

The given genotype Ttyy indicates that the corn plant has one dominant allele (T) for one trait and one recessive allele (y) for another trait. In a single grain of pollen, there can be two possible genetic combinations: Ty and ty. The dominant allele (T) can combine with the recessive allele (y) to form the combination Ty, and the recessive allele (y) can combine with itself to form the combination ty.

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48. A healthy individual is a carrier of a lethal allele but is unaffected by it. What is the probable genotype of this individual?  

Explanation

This individual is unaffected by the lethal allele, which means they must have at least one dominant normal allele to mask the effects of the lethal allele. Additionally, they are a carrier of the lethal allele, which means they must also have one recessive lethal allele. Therefore, the probable genotype of this individual is one recessive lethal allele and one dominant normal allele.

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49. Which molecule in plant cells first captures the radiant energy from sunlight?  

Explanation

Chlorophyll is the pigment molecule in plant cells that first captures the radiant energy from sunlight. It is located in the chloroplasts of plant cells and is responsible for the green color of plants. Chlorophyll absorbs light energy and initiates the process of photosynthesis, converting sunlight into chemical energy that can be used by the plant for growth and development.

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50. Which of these organisms would most likely be found at the top of an energy pyramid?  

Explanation

The shark would most likely be found at the top of an energy pyramid because it is a top predator in the marine food chain. As a carnivorous predator, the shark feeds on other organisms, such as smaller fish and marine mammals, which are lower in the food chain. Being at the top of the pyramid means that the shark has fewer predators and consumes a large amount of energy from the organisms it preys upon.

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51. An abnormality involving the platelets would probably affect the process of:  

Explanation

An abnormality involving the platelets would affect the process of blood clotting. Platelets are responsible for forming blood clots to stop bleeding. If there is an abnormality in platelet function or number, it can lead to difficulties in forming clots, resulting in excessive bleeding or difficulty in stopping bleeding.

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52. Which of the following is the correct order of organization of structures in living things, from simplest to most complex?

Explanation

Living things are made up of cells, which are the basic building blocks of life. Cells come together to form tissues, which are groups of cells that work together to perform a specific function. Organs are made up of different types of tissues and work together to perform a specific function in the body. Organ systems are groups of organs that work together to carry out a particular function in the body. Finally, an organism is made up of all the organ systems working together to support life. Therefore, the correct order of organization of structures in living things, from simplest to most complex, is cells, tissues, organs, organ systems, organism.

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53. The number of autosomes and type of sex chromosome normally present in a human egg cell is  

Explanation

The correct answer is 22+X. This is because a human egg cell contains 22 autosomes, which are chromosomes that are not involved in determining sex, and one X sex chromosome. The presence of the X chromosome determines the individual's biological sex as female.

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54. The cell membrane of the red blood cell will allow water, oxygen, carbon dioxide, and  glucose to pass through. Because other substances are blocked from entering, this membrane is called  

Explanation

The cell membrane of the red blood cell is referred to as semi-permeable because it allows certain substances like water, oxygen, carbon dioxide, and glucose to pass through while blocking other substances from entering. This selective permeability is essential for maintaining the cell's internal environment and regulating the movement of molecules in and out of the cell.

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55. A food chain is shown below.   Grass -- crickets --  field mice -- hawks   For the food chain shown, which of the following changes would have the most severe consequences?  

Explanation

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56. In aerobic respiration, the Krebs cycle (citric acid cycle) takes place in 

Explanation

The Krebs cycle, also known as the citric acid cycle, is a part of aerobic respiration that occurs in mitochondria. Mitochondria are the powerhouse of the cell and are responsible for generating energy in the form of ATP. This cycle takes place in the mitochondrial matrix, where it oxidizes acetyl-CoA and produces NADH, FADH2, and ATP. Therefore, the correct answer is mitochondria.

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57. Which of the following best describes meiosis?

Explanation

Meiosis is a type of cell division that specifically occurs in the reproductive structures of an organism. It is responsible for the production of gametes (sperm and eggs) and involves two rounds of division, resulting in the formation of four genetically unique daughter cells. Unlike mitosis, which occurs in various tissues for growth and repair, meiosis is limited to the reproductive organs and is essential for sexual reproduction.

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58. Eukaryotic cells are differentiated from prokaryotic cells because eukaryotic cells  

Explanation

Eukaryotic cells are differentiated from prokaryotic cells because they have nuclei. Unlike prokaryotic cells, which lack a true nucleus, eukaryotic cells have a distinct membrane-bound nucleus that houses the cell's genetic material. This nucleus allows for more complex genetic control and regulation of cellular processes.

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59. Based only on the sex chromosomes in typical human egg and sperm cells at fertilization, the probability of producing a female is 

Explanation

The probability of producing a female is 50% because the sex of a human is determined by the presence of either an X or a Y chromosome. Females have two X chromosomes (XX), while males have one X and one Y chromosome (XY). During fertilization, the egg can contribute an X chromosome, and the sperm can contribute either an X or a Y chromosome. Since there is an equal chance of the sperm carrying either an X or a Y chromosome, the probability of producing a female is 50%.

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60. In certain breeds of dogs, deafness is due to a recessive allele (d) of a particular gene, and normal hearing is due to its dominant allele (D). What percentage of the offspring of a normal heterozygous (Dd) dog and a deaf dog (dd) would be expected to have normal hearing? 

Explanation

When a normal heterozygous (Dd) dog mates with a deaf dog (dd), there is a 50% chance for each offspring to inherit the dominant allele (D) from the heterozygous parent, resulting in normal hearing. The other 50% chance is for the offspring to inherit the recessive allele (d) from both parents, resulting in deafness. Therefore, 50% of the offspring would be expected to have normal hearing.

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61. Which of these secretes a hormone that regulates the rate of metabolism of the body?  

Explanation

The thyroid secretes a hormone called thyroxine, which plays a crucial role in regulating the body's metabolism. This hormone helps control the rate at which the body uses energy, affects growth and development, and regulates body temperature. The thyroid gland is located in the neck and is responsible for producing and releasing this hormone into the bloodstream.

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62. The kidneys regulate the levels of many chemicals and ions in the body. Which term best describes this process?  

Explanation

The term "homeostasis" best describes the process in which the kidneys regulate the levels of many chemicals and ions in the body. Homeostasis refers to the ability of an organism to maintain stable internal conditions despite changes in the external environment. In this case, the kidneys play a crucial role in filtering waste products, balancing electrolytes, and regulating the pH level of the blood, all of which contribute to maintaining homeostasis in the body.

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63. The fight-or-flight response includes greater heart output and a rise in blood pressure. This response is due to 

Explanation

The fight-or-flight response is a physiological reaction triggered in response to a perceived threat or danger. It prepares the body for action by increasing heart output and raising blood pressure. Adrenaline, also known as epinephrine, is a hormone secreted by the adrenal glands in response to stress or fear. It plays a crucial role in activating the fight-or-flight response by increasing heart rate, constricting blood vessels, and mobilizing energy reserves. Therefore, adrenaline secreted by the adrenal glands is the correct explanation for the observed physiological responses.

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64. Glucose is a building block of carbohydrates. Which of these best describes glucose?  

Explanation

Glucose is best described as a monosaccharide. Monosaccharides are the simplest form of carbohydrates and are composed of a single sugar molecule. Glucose is a monosaccharide that is commonly found in foods and is an important source of energy for the body. It is also a key component of larger carbohydrates such as starch and cellulose.

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65. Normal thymine (T) is found in the old strand. It is replaced by an abnormal molecule (T*) in the new strand. The abnormal molecule (T*) binds to guanine (G) instead of binding to adenine (A). This is an example of

Explanation

This is an example of a mutation because a mutation refers to a change in the DNA sequence. In this case, the normal thymine (T) in the old strand is replaced by an abnormal molecule (T*) in the new strand, causing a change in the DNA sequence. This abnormal molecule then binds to guanine (G) instead of adenine (A), which is a deviation from the normal pairing in DNA. Therefore, this change in the DNA sequence due to the abnormal molecule is considered a mutation.

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66. The table below lists the typical diploid number of chromosomes of several different organisms. Diploid Chromosome  Number Goldfish  94 Potato  48 Human   46 Pea  14 Fruit fly 8 Which of the following is the best explanation for why the chromosome number is an even number in each of these organisms?  

Explanation

The diploid chromosome number represents pairs of chromosomes, one from each parent, so it is always an even number. This is because during sexual reproduction, each parent contributes one set of chromosomes to their offspring. The offspring then inherit one chromosome from each parent, resulting in a pair of chromosomes. Therefore, the diploid chromosome number will always be an even number in organisms.

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67. Scientists found that, over a period of 200 years, a mountain pond was transformed into a meadow. During that time, several communities of organisms were replaced by different communities. Which of these best explains why new communities were able to replace older communities?  

Explanation

Over a period of 200 years, the mountain pond transformed into a meadow, and during that time, different communities of organisms replaced older communities. This suggests that the habitat underwent significant changes in its abiotic characteristics, such as temperature, humidity, or soil composition. These changes in the environment likely favored the survival and growth of new species, allowing them to replace the older communities that were not well adapted to the altered conditions.

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68. Which of these correctly matches the molecule with its function?    

Explanation

Enzymes are proteins that act as catalysts, speeding up chemical reactions in the body. They do not store genetic information (which is the function of DNA and RNA), supply energy to cells (which is the function of vitamins and carbohydrates), or manufacture cell membranes (which is the function of lipids). Therefore, the correct match is enzyme—a protein that speeds up chemical reactions.

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69. Many bacteria live in fresh water. Which of these statements best describes what will happen when freshwater bacterial cells are placed in salt water?  

Explanation

When freshwater bacterial cells are placed in salt water, the salt water has a higher concentration of solutes than the bacterial cells. This creates a concentration gradient, causing water to move out of the bacterial cells through osmosis. As a result, the cells will lose water and shrink.

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70. Which of these substances moves across cell membranes by osmosis?  

Explanation

Water moves across cell membranes by osmosis because it is a small molecule that can pass through the lipid bilayer of the cell membrane. Osmosis is the movement of water from an area of lower solute concentration to an area of higher solute concentration, in order to equalize the solute concentration on both sides of the membrane. This process is important for maintaining the balance of water and solutes inside and outside of cells.

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71. All the following are found in both plant and animal cells, except  

Explanation

The cell wall is a rigid structure found in plant cells that provides support and protection. It is made up of cellulose and is responsible for maintaining the shape of the cell. Animal cells do not have a cell wall, instead they have a flexible cell membrane that regulates the movement of substances in and out of the cell. Mitochondria and the ER are present in both plant and animal cells and are involved in various cellular processes. Therefore, the correct answer is cell wall.

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72. Most carbohydrates in the human body are    

Explanation

Carbohydrates are one of the main sources of energy for the human body. When consumed, they are broken down into glucose, which is then used by cells to produce ATP, the molecule responsible for storing and releasing energy. Therefore, most carbohydrates in the body are consumed as a source of energy.

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73. Which of these is produced as a result of fertilization?

Explanation

Fertilization is the process by which a sperm cell and an egg cell combine to form a zygote. During fertilization, the genetic material from both the sperm cell and the egg cell combine, resulting in a zygote with the full complement of chromosomes. Since a gamete (sperm or egg) contains half the number of chromosomes as a zygote, the correct answer is that a zygote has twice the number of chromosomes as a gamete.

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74. The bacterium Agrobacterium infects plants, and a portion of its DNA is inserted into the plant's chromosomes. This causes the plant to produce gall cells, which manufacture amino acids that the bacterium uses as food. This process is a natural example of  

Explanation

The process described in the question involves the bacterium Agrobacterium inserting a portion of its DNA into the plant's chromosomes, causing the plant to produce gall cells that manufacture amino acids for the bacterium. This process is an example of genetic manipulation because it involves the intentional modification of an organism's genetic material by an external agent, in this case, the bacterium.

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75. Of the following, which cells are the smallest?  

Explanation

Bacterial cells are the smallest cells among the options listed. Bacteria are single-celled microorganisms that are typically smaller in size compared to other cells.

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76. The cell wall of plant cells is made up of:  

Explanation

The cell wall of plant cells is made up of cellulose. Cellulose is a complex carbohydrate that provides structural support and protection to plant cells. It forms a rigid network of fibers that make up the cell wall, giving it strength and stability. Cellulose is made up of linked glucose molecules, which are arranged in a way that allows for the formation of hydrogen bonds between adjacent cellulose molecules. This arrangement gives the cell wall its characteristic strength and resistance to mechanical stress.

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77. What causes tomatoes to ripen much more slowly in a refrigerator than they do if left on a table at room temperature? 

Explanation

Low temperatures reduce the action of ripening enzymes. When tomatoes are kept in a refrigerator, the cold temperature slows down the activity of enzymes responsible for ripening. This inhibits the natural ripening process and causes tomatoes to ripen much more slowly compared to when they are left on a table at room temperature.

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78. The human body functions properly when organ systems work together. Which organ system works with the muscular system to control muscle contraction?

Explanation

The muscular system works together with the nervous system to control muscle contraction. The nervous system sends signals from the brain to the muscles, telling them when to contract and relax. This coordination allows for smooth and coordinated movement of the body. The circulatory system transports oxygen and nutrients to the muscles, the excretory system removes waste products, and the reproductive system is not directly involved in controlling muscle contraction.

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79. Refer to the diagram above.  Which of these best completes this concept map?

Explanation

A plant cell would be the best completion for this concept map because it is a type of cell that is distinct from the other options listed. The diagram likely shows a comparison or classification of different types of cells, and including a plant cell would provide a comprehensive representation of the different cell types.

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80. The phase of mitosis that is characterized by the arrangement of all chromosomes along the equator of the cell is called

Explanation

Metaphase is the correct answer because it is the phase of mitosis where all the chromosomes align along the equator of the cell. During metaphase, the spindle fibers attach to the centromeres of the chromosomes, causing them to line up in a single file line at the center of the cell. This alignment is crucial for the accurate separation of chromosomes during the subsequent phase of mitosis.

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81. What is the probability that a heterozygous man with blood type A and a homozygous women with blood type B have children with blood type O?  

Explanation

The blood type O is recessive, meaning that in order for a child to have blood type O, both parents must have at least one O allele. In this case, the heterozygous man with blood type A cannot pass on an O allele, as he only has A alleles. The homozygous woman with blood type B also cannot pass on an O allele, as she only has B alleles. Therefore, the probability of them having children with blood type O is 0%.

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82. Carbon dioxide is produced as cells break down nutrients for energy. Which of the following pairs of systems would participate in removing the carbon dioxide from the body? 

Explanation

The circulatory and respiratory systems would participate in removing carbon dioxide from the body. The circulatory system carries carbon dioxide from the cells to the lungs, where it is then removed from the body through the respiratory system.

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83. A signal that the bladder is full is sent to the central nervous system by  

Explanation

Sensory neurons are responsible for transmitting signals from the bladder to the central nervous system when it is full. These neurons are specialized to detect changes in the bladder's stretch receptors and send this information to the brain. This signal triggers the sensation of needing to urinate, allowing the individual to be aware of their bladder's fullness and take appropriate action.

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84. A cell from heart muscle would probably have an unusually high proportion of

Explanation

Heart muscle cells, also known as cardiomyocytes, require a large amount of energy to constantly contract and pump blood. Mitochondria are the powerhouses of the cell, responsible for producing the energy molecule ATP through cellular respiration. Therefore, it is expected that heart muscle cells would have an unusually high proportion of mitochondria to meet their high energy demands.

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85. Which of the following sequences represents chromosome number during fertilization? 

Explanation

During fertilization, the chromosome number is doubled. This is represented by the sequence "n+n→2n", where "n" represents the haploid number of chromosomes and "2n" represents the diploid number of chromosomes.

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86. Prokaryotic cells possess all of the following except  

Explanation

Prokaryotic cells do not possess a nuclear membrane because they lack a true nucleus. Unlike eukaryotic cells, which have a distinct nucleus enclosed by a nuclear membrane, prokaryotic cells have their genetic material (DNA) located in the cytoplasm. This lack of a nuclear membrane allows for easier access and control of the genetic material in prokaryotic cells.

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87. All living things need nitrogen. The nitrogen gas in Earth's atmosphere must be changed into ammonia before most living things can use it. Which of these organisms can change nitrogen gas into ammonia?  

Explanation

Bacteria are capable of converting nitrogen gas into ammonia through a process called nitrogen fixation. This process involves the bacteria converting nitrogen gas into a form that can be used by other organisms. Bacteria play a crucial role in the nitrogen cycle by making nitrogen available to other living organisms in the form of ammonia.

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88. There are many different enzymes located in the cytoplasm of a single cell. How is a specific enzyme able to catalyze a specific reaction? 

Explanation

Enzymes are able to catalyze specific reactions because they have a specific binding site that is complementary to the shape and chemical properties of their specific substrate. This allows the enzyme to bind specifically to the substrate and form an enzyme-substrate complex. The enzyme then facilitates the conversion of the substrate into the desired product by lowering the activation energy required for the reaction to occur. This specificity is crucial for the efficient functioning of metabolic pathways and ensures that each reaction occurs at the right time and place within the cell.

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89. In deep ocean trenches, bacteria produce organic materials from inorganic compounds through the process of  

Explanation

Chemosynthesis is the process in which bacteria produce organic materials from inorganic compounds. This process occurs in deep ocean trenches where sunlight cannot reach. Unlike photosynthesis, which uses sunlight as an energy source, chemosynthesis uses the energy from chemical reactions to convert inorganic compounds into organic compounds. This allows bacteria to survive in extreme environments where sunlight is not available.

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90. Use the information below to answer the following question.   A particular toxin prevents cellular production of usable energy. Cells that are affected by this toxin are unable to carry out many of their normal functions.   Which of these organelles would be most directly harmed by this toxin

Explanation

Mitochondria are responsible for producing usable energy in the form of ATP through cellular respiration. If a toxin prevents cellular production of usable energy, it would directly harm the mitochondria, as they are unable to carry out their normal function of energy production. This would lead to a decrease in ATP production and impair many cellular functions that require energy.

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91. Semi-conservative replication of DNA refers to the idea that  

Explanation

In semi-conservative replication of DNA, each half of the original DNA molecule is joined with a new complementary DNA strand. This means that during replication, the two strands of the DNA molecule separate and each strand serves as a template for the synthesis of a new complementary strand. As a result, each new DNA molecule formed contains one original strand and one newly synthesized strand. This process ensures the preservation of the original genetic information while allowing for the creation of identical copies of the DNA molecule.

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92. Which statement about enzymes is not correct?

Explanation

Enzymes are not destroyed when they are used and do not need to be synthesized for each reaction. Enzymes are catalysts that facilitate chemical reactions by lowering the activation energy required for the reaction to occur. They are not consumed or altered during the reaction and can be reused multiple times. Therefore, enzymes are not destroyed and do not need to be synthesized for each reaction.

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93. Both DNA and RNA  

Explanation

Both DNA and RNA contain phosphate. Phosphate groups are an essential component of nucleotides, the building blocks of DNA and RNA. These phosphate groups are responsible for forming the backbone of the DNA and RNA molecules, linking the nucleotides together to create the double helix structure. Therefore, the presence of phosphate is crucial for the structure and function of both DNA and RNA.

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94. A Polysaccharide is a polymer composed of

Explanation

A polysaccharide is a type of polymer that is composed of glucose molecules. Glucose is a simple sugar that serves as a building block for polysaccharides. Polysaccharides are large, complex carbohydrates that play important roles in energy storage and structural support in living organisms. They are formed through the bonding of multiple glucose molecules, creating long chains or branching structures. Examples of polysaccharides include starch, glycogen, and cellulose.

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95. Which of these is a function of the circulatory system in a mammal?    

Explanation

The circulatory system in a mammal plays a crucial role in regulating body temperature. It helps in distributing heat throughout the body, ensuring that all organs and tissues are maintained at an optimal temperature for their proper functioning. This is achieved through the circulation of blood, which carries heat from the core of the body to the extremities and also helps in dissipating excess heat through the process of sweating. By regulating temperature, the circulatory system helps to maintain homeostasis and ensures the overall well-being of the mammal.

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96. Which of these does not occur during meiosis?

Explanation

During meiosis, the production of identical gametes does not occur. Meiosis is a process of cell division that occurs in reproductive cells to produce gametes (sperm and eggs). It involves two rounds of division, resulting in four non-identical haploid cells. This process allows for the production of new gene combinations through crossing-over of homologous chromosomes and reduction of the chromosome number by half. Identical gametes would defeat the purpose of sexual reproduction, which aims to introduce genetic diversity.

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97. Which of these would have the least effect on natural selection in a subspecies of giraffes that is geographically isolated from other subspecies of giraffes?  

Explanation

Chromosome number refers to the number of chromosomes in an organism's cells. In a subspecies of giraffes that is geographically isolated from other subspecies, the chromosome number would have the least effect on natural selection. This is because chromosome number does not directly impact an organism's ability to survive and reproduce in its environment. The availability of niches, existing predators, and available food resources are all factors that can influence natural selection by affecting the fitness and adaptability of the giraffes in the subspecies.

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98. The genetic information for making a protein must move from the nucleus to the cytoplasm. Which of these moves this information to the cytoplasm?  

Explanation

RNA is responsible for moving genetic information from the nucleus to the cytoplasm. RNA molecules, specifically messenger RNA (mRNA), are transcribed from DNA in the nucleus and then transported to the cytoplasm where they serve as a template for protein synthesis. Ribosomes, which are composed of RNA and proteins, are responsible for translating the mRNA into proteins. However, in terms of moving genetic information, it is the RNA molecule itself that carries the information from the nucleus to the cytoplasm.

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99. In most stable freshwater environments, populations of Daphnia are almost entirely female and reproduce asexually. However, males are observed in low oxygen environments or when food is scarce. Based on these observations, a researcher suggests that male Daphnia develop in response to unfavorable environmental conditions. This is an example of a  

Explanation

The researcher's suggestion that male Daphnia develop in response to unfavorable environmental conditions is a hypothesis. A hypothesis is a proposed explanation or prediction based on observations or evidence. In this case, the researcher is proposing that the presence of males in low oxygen or scarce food environments is a response to these unfavorable conditions. This hypothesis can be tested through further research and experimentation to determine its validity.

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100. A cell is observed through a microscope. The cell is found to have a cell wall, a cell membrane, and numerous ribosomes. The cell does not have a nucleus. This cell is most likely from a  

Explanation

The cell described in the question has a cell wall, a cell membrane, and numerous ribosomes. These characteristics are commonly found in bacteria. Bacteria are prokaryotic organisms, meaning they do not have a nucleus. Therefore, the cell described is most likely from a bacterium.

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101. Which of the following pairs of materials is required for a cell to carry on respiration?  

Explanation

Glucose and oxygen are required for a cell to carry on respiration. Respiration is the process by which cells break down glucose molecules to release energy. Glucose is the source of energy for the cell, and oxygen is necessary for the complete breakdown of glucose. Through respiration, cells convert glucose and oxygen into carbon dioxide and water, releasing energy in the process. Therefore, glucose and oxygen are the correct pair of materials required for respiration.

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102. Use the information and the diagram below to answer the following question.   Part of the process of protein synthesis is shown below. The different structures in this process are numbered 1 through 5. Structure 2 in the diagram represents a  

Explanation

The diagram shows the process of protein synthesis, and structure 2 represents a ribosome. Ribosomes are responsible for the synthesis of proteins in a cell. They are made up of RNA and protein and are found in the cytoplasm of both prokaryotic and eukaryotic cells. Ribosomes play a crucial role in translating the genetic information from mRNA into a sequence of amino acids to form a protein. Therefore, the correct answer is ribosome.

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103. Mutations within a DNA sequence are 

Explanation

Mutations within a DNA sequence are natural processes that produce genetic diversity. This is because mutations are changes in the DNA sequence that can result in new variations of genes. These variations can lead to differences in traits and characteristics, which contribute to genetic diversity within a population. Mutations can occur spontaneously or be induced by external factors such as radiation or chemicals. They can be beneficial, neutral, or harmful to an organism, but overall, they play a crucial role in evolution by introducing new genetic variations that can be selected for or against in different environments.

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104. A sperm cell of a moth has 112 chromosomes. How many chromosomes are in the moth's wing cells?  

Explanation

The number of chromosomes in a sperm cell is half of the number of chromosomes in a somatic cell. Since a sperm cell of a moth has 112 chromosomes, the moth's wing cells would have double that amount, which is 224 chromosomes.

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105. A student observes a unicellular organism under a microscope. After a while, the organism begins to split into two cells, as shown in the diagram. Which of these best describes the process shown in the diagram?  

Explanation

The process shown in the diagram is binary fission. Binary fission is a form of asexual reproduction where a single organism divides into two identical daughter cells. This process is commonly observed in unicellular organisms such as bacteria and protists.

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106. If a human baby boy inherits a recessive allele from his mother, in which circumstance would he most likely show the trait coded for by the recessive allele? 

Explanation

This is because if the recessive allele is on the X chromosome, the baby boy only needs to inherit one copy of the allele from his mother to show the trait. Since males have one X chromosome and one Y chromosome, they do not have another X chromosome to mask the effects of the recessive allele.

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107. Which of these statements best explains how genes and proteins are related?  

Explanation

Genes are segments of DNA that contain the instructions for making proteins. Proteins, on the other hand, are the molecules that perform various functions in the body. The genes provide the blueprint for the production of proteins by specifying the sequence of amino acids that make up the protein. Therefore, genes and proteins are related in that genes code for the production of proteins.

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108. Vessels that carry oxygenated blood away from the heart are called  

Explanation

Arteries are the blood vessels that carry oxygenated blood away from the heart. They have thick, muscular walls that help to pump blood throughout the body. Veins, on the other hand, carry deoxygenated blood back to the heart, while capillaries are the smallest blood vessels that connect arteries and veins. Vacuoles are not related to the transportation of blood in the human body.

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109. Maltose can be broken down into glucose molecules by the enzyme maltase. Which of the following would slow the reaction rate

Explanation

Diluting with water would slow the reaction rate because it would decrease the concentration of maltose, reducing the chances of maltase enzyme molecules coming into contact with maltose molecules. This would result in fewer successful collisions between the enzyme and substrate, leading to a slower rate of reaction.

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110. A student observes a unicellular organism under a microscope. After a while, the organism begins to split into two cells, as shown in the diagram.   Which of these structures does the organism shown above use to move itself?  

Explanation

The organism shown in the diagram uses cilia to move itself. Cilia are hair-like structures that extend from the surface of the cell and can be used for movement. They beat in a coordinated manner, creating a wave-like motion that propels the organism forward.

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111. After a volcanic eruption has covered an area with lava, which of the following is the most likely order of succession in the repopulation of the area

Explanation

After a volcanic eruption, the first organisms to colonize the area are typically lichens. Lichens are pioneer species that can survive in harsh conditions and help to break down rocks and create soil. Once the lichens have established themselves, grasses can begin to grow and further stabilize the soil. As the soil becomes more developed, shrubs can take root and provide more habitat for other organisms. Finally, trees can grow and complete the succession process. Therefore, the most likely order of succession in the repopulation of the area after a volcanic eruption is lichens → grasses → shrubs → trees.

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112. Which of these best describes the correct sequence in the expression of a trait?  

Explanation

In the expression of a trait, the correct sequence is protein → gene → trait. This means that a protein is produced based on the instructions encoded in a gene, and this protein ultimately leads to the expression of a trait.

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113. Use the information below to answer the following item.   Many bird species in the forests of eastern North America have very large geographic ranges. Bird species in tropical forests have very small geographic ranges. Many forest areas within the ranges of these birds are being destroyed. Scientists believe that the destruction of forests affects birds with small ranges more than birds with large ranges.   As a result of the destruction of forests, birds with a small geographic range are most likely to  

Explanation

The destruction of forests affects birds with small geographic ranges more than birds with large ranges. This suggests that birds with small ranges are more vulnerable to habitat loss and are likely to adapt to a new environment in order to survive.

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114. When two amino acids bond

Explanation

When two amino acids bond, they undergo a condensation reaction. In this reaction, water is released as a byproduct, rather than taken in. The amino acids join together through a peptide bond, forming a dipeptide. Hydrolysis, on the other hand, is the process of breaking down a molecule by adding water. Therefore, the correct answer is that a dipeptide is formed through condensation, not hydrolysis.

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115. Sweat and skin secretions contain a mixture of molecules that kills or limits the growth of many types of microbes. This control of microbes is an example of  

Explanation

Sweat and skin secretions contain molecules that have antimicrobial properties, meaning they can kill or inhibit the growth of many types of microbes. This defense mechanism is considered nonspecific because it does not target specific pathogens, but rather acts against a wide range of microbes. It is a general defense mechanism that helps protect the body from infection.

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116. Some snake venoms are harmful because they contain enzymes that destroy blood cells or tissues. The damage caused by such a snakebite could best be slowed by 

Explanation

Snake venoms contain enzymes that destroy blood cells or tissues, leading to damage in the affected area. Applying ice to the bite area can help slow down the spread of venom and reduce swelling by constricting blood vessels. This can help minimize the damage caused by the snakebite and provide some relief to the victim. Drinking large amounts of water, inducing vomiting, or increasing blood flow to the area would not be effective in slowing down the damage caused by the venom.

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117. Red-green color blindness affects about 7.0% of the human male population. It affects approximately 0.4% of the human female population. These data suggest that red-green color blindness is a    

Explanation

Red-green color blindness affects a higher percentage of males than females, indicating that it is more commonly inherited by males. This suggests that the trait is carried on the X chromosome, as males have only one X chromosome while females have two. If the trait was carried on the Y chromosome, it would only be inherited by males and affect a higher percentage of males than females. Therefore, red-green color blindness is a recessive trait carried on the X chromosome.

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118. Striped fish are affected by biotic and abiotic factors in their environment. Which of these factors is biotic?  

Explanation

Biotic factors refer to living organisms or their products that can affect the survival and behavior of other organisms. In this case, water temperature is the correct answer as it is influenced by living organisms such as aquatic plants, algae, and animals. These organisms can affect the temperature of the water through their metabolic activities, such as respiration and photosynthesis. Therefore, water temperature is considered a biotic factor that can impact striped fish in their environment.

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119. Which of these is a nucleotide?  

Explanation

A nucleotide is a building block of DNA and RNA. It consists of a sugar molecule (deoxyribose in DNA and ribose in RNA), a phosphate group, and a nitrogenous base. Option 4 is a nucleotide because it is the only option that includes a nitrogenous base along with a sugar and a phosphate group.

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120. What is one role of tRNA in the cell?

Explanation

tRNA plays a crucial role in the cell by preparing messenger RNA (mRNA) for the ribosomes. It does this by binding to specific amino acids and carrying them to the ribosomes during protein synthesis. This process ensures that the correct amino acids are assembled in the correct order according to the instructions encoded in the mRNA. tRNA also has an anticodon region that recognizes and pairs with the corresponding codon on the mRNA, allowing for accurate translation of the genetic code. Therefore, tRNA acts as a link between the genetic information in mRNA and the synthesis of proteins at the ribosomes.

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121. Which of these is an example of a homozygous recessive genotype?  

Explanation

An example of a homozygous recessive genotype is rr. In this case, both alleles for a particular trait are the same and recessive, resulting in the expression of the recessive trait. The genotype Rr, on the other hand, is a heterozygous genotype where one allele is dominant (R) and the other is recessive (r).

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122. Use the information below to answer the following question.   A particular toxin prevents cellular production of usable energy. Cells that are affected by this toxin are unable to carry out many of their normal functions.   If cells were exposed to this toxin, which of these processes would probably be least affected?    

Explanation

Diffusion is the process by which molecules move from an area of higher concentration to an area of lower concentration. It does not require cellular energy and occurs passively. Therefore, even if cells are exposed to a toxin that prevents cellular production of usable energy, diffusion can still occur as it does not rely on cellular functions.

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123. If a paleontologist finds fossils of many different species existing in the same area at approximately the same time, the paleontologist can conclude that the ecosystem in this area had a high degree of 

Explanation

If a paleontologist finds fossils of many different species existing in the same area at approximately the same time, it suggests that the ecosystem in this area had a high degree of geographic isolation. This means that the area was likely isolated from other areas, such as by physical barriers like mountains or bodies of water, preventing the movement of species in and out of the area. This isolation would have allowed for the evolution and diversification of different species within the area.

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124. Gray wolves were reintroduced into Yellowstone National Park in 1995. Two years later, the population of coyotes had decreased by 50%. Coyotes were found in all habitats of the park before the gray wolves were reintroduced. Now, coyotes are most often found in the hills and mountains. Which of these describes the role of the vole in the Yellowstone ecosystem?  

Explanation

The vole's role in the Yellowstone ecosystem is that of a herbivore. This means that it primarily consumes plants and vegetation as its source of food. This is inferred from the given information about the reintroduction of gray wolves and the subsequent decrease in the coyote population. The change in coyote behavior, where they are now most often found in the hills and mountains, suggests that they have adapted to avoid direct competition with the gray wolves. As a result, the vole, being a herbivore, may have experienced a change in its habitat and food availability due to the altered predator-prey dynamics in the ecosystem.

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125. A small population of chimpanzees lives in a habitat that undergoes no changes for a long period. How will genetic drift probably affect this population? 

Explanation

Genetic drift is the random change in allele frequencies in a population due to chance events. In a small population that undergoes no changes for a long period, genetic drift is likely to occur. Over time, genetic drift can lead to an increase in the number of alleles for specific traits in the population. This is because certain alleles may become more or less common purely by chance, leading to an increase in the overall number of alleles for specific traits in the population. This can result in an increase in genetic diversity for those specific traits.

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126. Which cellular organelle is responsible for packaging the proteins that the cell secretes

Explanation

The cell membrane is responsible for packaging the proteins that the cell secretes. The cell membrane contains specialized structures called vesicles that transport proteins from the endoplasmic reticulum to the Golgi apparatus. These proteins are then modified, sorted, and packaged into new vesicles in the Golgi apparatus. These vesicles are then transported to the cell membrane, where they fuse with the membrane and release their contents outside the cell. Therefore, the cell membrane plays a crucial role in the packaging and secretion of proteins.

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127. A scientist removed the cell membranes from bacteria cells in a culture. She analyzed the cell membranes for specific molecules. Which of these was probably the most common type of molecule present in the bacteria cell membranes?    

Explanation

Carbohydrates are the most common type of molecule present in bacteria cell membranes. This is because carbohydrates play a crucial role in cell membrane structure and function. They are found in the form of glycolipids and glycoproteins, which help stabilize the membrane and facilitate cell-cell recognition and signaling. Additionally, carbohydrates can serve as an energy source for bacteria.

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A team of marine scientists is studying biotic and abiotic factors...
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Glucose is a building block of carbohydrates. Which of these best...
Normal thymine (T) is found in the old strand. It is replaced by an...
The table below lists the typical diploid number ...
Scientists found that, over a period of ...
Which of these correctly matches the molecule with its function? ...
Many bacteria live in fresh water. Which of these statements best...
Which of these substances moves across cell membranes by osmosis? ...
All the following are found in both plant and animal cells, except ...
Most carbohydrates in the human body are    
Which of these is produced as a result of fertilization?
The bacterium Agrobacterium infects plants, and a portion of its DNA...
Of the following, which cells are the smallest?  
The cell wall of plant cells is made up of:  
What causes tomatoes to ripen much more...
The human body functions properly when organ systems work together....
Refer to the diagram above.  Which of these best completes this...
The phase of mitosis that is characterized by the arrangement of ...
What is the probability that a heterozygous man with blood type A and...
Carbon dioxide is produced as cells break down nutrients for energy....
A signal that the bladder is full is sent to the central nervous...
A cell from heart muscle would probably ...
Which of the following sequences represents ...
Prokaryotic cells possess all of the following except  
All living things need nitrogen. The nitrogen gas in Earth's...
There are many different enzymes located in ...
In deep ocean trenches, bacteria produce organic materials from...
Use the information below to answer the following question. ...
Semi-conservative replication of DNA refers to the idea that ...
Which statement about enzymes is not correct?
Both DNA and RNA  
A Polysaccharide is a polymer composed of
Which of these is a function of the circulatory system in a mammal? ...
Which of these does not occur during meiosis?
Which of these would have the least effect on ...
The genetic information for making a protein must move from the...
In most stable freshwater environments, ...
A cell is observed through a microscope. The cell is found to have a...
Which of the following pairs of materials is required for a cell to...
Use the information and the diagram below to answer the following...
Mutations within a DNA sequence are 
A sperm cell of a moth has 112 chromosomes. How many chromosomes are...
A student observes a unicellular organism under a microscope. After a...
If a human baby boy inherits a recessive allele...
Which of these statements best explains how genes and proteins are...
Vessels that carry oxygenated blood away from the heart are called ...
Maltose can be broken down into glucose molecules by the enzyme...
A student observes a unicellular organism under a microscope. After a...
After a volcanic eruption has covered an area with lava, which of the...
Which of these best describes the correct sequence in the expression...
Use the information below to answer the following item. ...
When two amino acids bond
Sweat and skin secretions contain a mixture of ...
Some snake venoms are harmful because they contain enzymes that...
Red-green color blindness affects about 7.0% of the human male...
Striped fish are affected by biotic and abiotic ...
Which of these is a nucleotide?  
What is one role of tRNA in the cell?
Which of these is an example of a homozygous recessive genotype? ...
Use the information below to answer the following question. ...
If a paleontologist finds fossils of many ...
Gray wolves were reintroduced into Yellowstone National Park in 1995....
A small population of chimpanzees lives in a ...
Which cellular organelle is responsible for packaging the proteins...
A scientist removed the cell membranes from bacteria cells in a...
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