1.
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2.
Use the information and the chart below to answer the following item.Several students are conducting an experiment to test the effect of exercise on heart rate. Students do 20 sit-ups in one minute of exercise. The data chart below shows the heart rate at one-minute intervals for each student.Each time the students did the experiment they got different results. They decided to ignore any results that were too far above or below their original prediction. They repeat these trials until a value closer to their prediction is obtained.The students’ decision to ignore data and repeat trials affects the experiment by- [1.1.4 A2]
Correct Answer
A. Introducing bias
Explanation
The students' decision to ignore data and repeat trials introduces bias into the experiment. Bias occurs when certain data points are selectively ignored or given more weight than others, leading to a skewed or inaccurate representation of the true results. In this case, by disregarding any results that were too far above or below their original prediction, the students are potentially excluding important data that could provide valuable insights or contribute to a more comprehensive understanding of the effect of exercise on heart rate. Thus, their decision introduces bias into the experiment.
3.
A student wants to perform an investigation to determine the heart rate of a rabbit. The teacher tells her the heart rate should be about 100 beats per minute. How could this information affect the investigation? [1.1.4 B]
Correct Answer
A. It could introduce bias.
Explanation
The information that the heart rate of a rabbit should be about 100 beats per minute could introduce bias in the investigation. This is because the student may unconsciously or consciously manipulate the data or experiment in a way that aligns with the expected heart rate. This can lead to inaccurate or skewed results, as the student may ignore or dismiss any data that does not support the expected heart rate. Therefore, the information could introduce bias in the investigation.
4.
A study sponsored by Chrysler contends that more Americans preferred a Chrysler to a Toyota after test driving both. The study was conducted using 100 people in each of two separate tests involving both auto makers. None of the subjects owned a foreign car. The results of this study is [1.1.4 A1]
Correct Answer
B. Biased overstating the popularity of Chrysler
Explanation
The study conducted by Chrysler is biased and overstates the popularity of Chrysler. This is because the study only involved people who did not own a foreign car, which means it did not include a representative sample of the population. Additionally, the study only compared Chrysler to Toyota, which limits the scope of the comparison and may not accurately reflect the preferences of all Americans. Therefore, the results of the study cannot be considered unbiased and are likely to overstate the popularity of Chrysler.
5.
Use the description of the experiment below to answer the following.A student washes her hands with antibacterial soap and water. Then she touches the agar in a petri dish with her thumb. The agar contains nutrients that support the growth of bacteria. Other students repeat the procedure after washing their hands with three different kinds of antibacterial soap. The petri dishes are kept warm overnight to allow bacteria to grow. The next day the students count the number of bacterial colonies in each dish.Which of these questions would best address the problem? [1.2.1 B]
Correct Answer
B. Which soap is most effective in killing bacteria?
Explanation
The question "Which soap is most effective in killing bacteria?" would best address the problem because the experiment involves testing different types of antibacterial soap to determine their effectiveness in killing bacteria. By counting the number of bacterial colonies in each petri dish, the students can compare the results and identify which soap is the most effective in killing bacteria.
6.
Which statement describes the major role of lipids within a cell? [3.1.1.C 2c]
Correct Answer
D. They are the main structural components of membranes
Explanation
Lipids are a type of biomolecule that play a crucial role in the structure and function of cell membranes. They are hydrophobic in nature and form a lipid bilayer, which acts as a barrier to regulate the movement of substances in and out of the cell. The hydrophobic tails of the lipids face inward, while the hydrophilic heads face outward, creating a stable and selective barrier. This arrangement allows lipids to control the flow of molecules and ions across the membrane, maintaining the integrity and stability of the cell. Therefore, lipids are the main structural components of membranes.
7.
What molecules control the reaction rate of photosynthesis? [3.1.1 D3]
Correct Answer
B. Enzymes
Explanation
Enzymes control the reaction rate of photosynthesis. Enzymes are biological molecules that act as catalysts, speeding up chemical reactions in living organisms. In the case of photosynthesis, enzymes are responsible for facilitating the conversion of sunlight, carbon dioxide, and water into glucose and oxygen. Without enzymes, the reaction rate of photosynthesis would be significantly slower, hindering the ability of plants to produce energy through this process.
8.
In the early 1900s, many children had a disease called rickets. Research showed that the children had a deficiency of a vitamin that is necessary for the proper formation of bones.Which of these vitamins was lacking in the diets of these children? [3.1.1 G3]
Correct Answer
C. Vitamin D
Explanation
In the early 1900s, many children had a disease called rickets, which is characterized by weak and deformed bones. Research showed that these children had a deficiency of a specific vitamin that is essential for proper bone formation. Vitamin D is the vitamin that was lacking in the diets of these children. Vitamin D plays a crucial role in the absorption of calcium and phosphorus, which are necessary for the development and strength of bones. Therefore, the absence of vitamin D in their diets led to the development of rickets.
9.
Glucose is a building block of carbohydrates. Which of these best describes glucose?[3.1.1 C1b]
Correct Answer
C. Monosaccharide
Explanation
Glucose is best described as a monosaccharide. Monosaccharides are the simplest form of carbohydrates and are made up of a single sugar molecule. Glucose is a type of monosaccharide that is commonly found in nature and serves as an important energy source for living organisms. It is a primary fuel for cellular respiration and is essential for various metabolic processes in the body.
10.
Some adult insects are unable to swim but are able to walk on top of water. What characteristic of water enables these insects to walk on top of water? [3.1.1.B b]
Correct Answer
C. Surface tension
Explanation
Surface tension is the characteristic of water that enables insects to walk on top of it. Surface tension is the property of a liquid that allows it to resist an external force, causing it to form a "skin" or layer on its surface. This creates a sort of "invisible barrier" that allows insects with the right adaptations, such as water-repellent legs or small body weight, to distribute their weight and walk on the surface of the water without sinking.
11.
Use the diagram below to answer the following item.Which of these is a nucleotide? 3.1.1 E2]
Correct Answer
D. 4
12.
Which of these is the process by which water moves across a selectively permeable membrane? [3.1.2 A2]
Correct Answer
A. Osmosis
Explanation
Osmosis is the process by which water moves across a selectively permeable membrane. It occurs when there is a difference in solute concentration on either side of the membrane, causing water molecules to move from an area of lower solute concentration to an area of higher solute concentration. This movement of water helps to balance the concentration of solutes on both sides of the membrane. Transpiration is the process by which water is lost from plants through their leaves, capillary action is the movement of liquid through narrow spaces without the assistance of external forces, and active transport is the movement of molecules across a membrane against their concentration gradient, requiring energy.
13.
Cells in the stomach produce pepsin, an enzyme, to help digest food. Pepsin works best at a pH of 2. Which of these graphs most likely shows what will happen to the activity of pepsin as the pH of the stomach is increased? [3.1.2.A 5b]
Correct Answer
A. A
14.
Which of these processes produces carbon dioxide? [3.1.3 D]
Correct Answer
C. Respiration
Explanation
Respiration is the process that produces carbon dioxide. During respiration, organisms break down glucose in the presence of oxygen to release energy. One of the byproducts of this process is carbon dioxide, which is then expelled from the body. Mitosis is a cell division process, the water cycle is the movement of water in the environment, and photosynthesis is the process by which plants convert carbon dioxide into glucose.
15.
In deep ocean trenches, bacteria produce organic materials from inorganic compounds through the process of- [3.1.3C]
Correct Answer
C. Chemosynthesis
Explanation
Chemosynthesis is the correct answer because in deep ocean trenches, where sunlight cannot penetrate, bacteria use the energy from inorganic compounds to produce organic materials. This process is known as chemosynthesis. Unlike photosynthesis, which requires sunlight, chemosynthesis allows organisms to survive and thrive in extreme environments such as deep ocean trenches. Respiration and homeostasis are not directly related to the production of organic materials from inorganic compounds in this context.
16.
Which of the following can control the rate of reaction in photosynthesis? [3.1.1 D3]
Correct Answer
B. Enzymes
Explanation
Enzymes can control the rate of reaction in photosynthesis. Enzymes are biological catalysts that speed up chemical reactions without being consumed in the process. In photosynthesis, enzymes such as RuBisCO and ATP synthase play crucial roles in the conversion of carbon dioxide and water into glucose and oxygen. These enzymes facilitate the necessary chemical reactions by lowering the activation energy required for the reactions to occur. Therefore, enzymes are essential in regulating and controlling the rate of photosynthesis.
17.
Which of the following pairs of materials is required for a cell to carry on respiration? [3.1.3 E3]
Correct Answer
B. Glucose and oxygen
Explanation
Glucose and oxygen are required for a cell to carry on respiration. Respiration is a process in which cells break down glucose molecules to release energy. This energy is produced through a series of chemical reactions that occur in the presence of oxygen. Glucose is the source of fuel for respiration, while oxygen acts as the final electron acceptor in the electron transport chain, allowing the production of ATP, the cell's main energy currency. Therefore, the combination of glucose and oxygen is necessary for respiration to occur.
18.
The diagram below shows part of the carbon cycle. Use the diagram to answer the following. [3.1.3B] Which of these would lead to an increase in carbon dioxide in the atmosphere?
Correct Answer
A. A decrease in respiration
Explanation
A decrease in respiration would lead to an increase in carbon dioxide in the atmosphere. Respiration is the process by which organisms release carbon dioxide into the atmosphere. Therefore, if respiration decreases, less carbon dioxide would be released, causing an increase in its concentration in the atmosphere.
19.
Use the information below to answer the following item.Hummingbirds need large amounts of energy to flap their wings between 60 and 200 times per second. Their wings beat so rapidly that it is difficult to see them move. They often appear suspended in air for extended periods of time without changing their location. Hummingbirds have long bills and grooved tongues to reach into flowers to feed on flower nectar. They also feed on insects.The body system most directly interacting with the skeletal system to enable hummingbirds to beat their wings between 60 and 200 times per second is the [3.2.1C5]
Correct Answer
B. Muscular
Explanation
The correct answer is muscular. The muscular system is responsible for the movement of the wings in hummingbirds. The rapid flapping of their wings between 60 and 200 times per second is made possible by the contraction and relaxation of the muscles attached to the wings. These muscles provide the necessary energy and force for the wings to beat at such a high frequency, allowing hummingbirds to hover in the air and maintain their position for extended periods of time.
20.
Birds, mammals, and theropod dinosaurs can maintain a constant body temperature. The ability to maintain a constant body temperature is an example of- [3.2.1D]
Correct Answer
D. Homeostasis
Explanation
The ability to maintain a constant body temperature is known as homeostasis. Homeostasis is the process by which an organism regulates its internal environment to maintain a stable and balanced state. In the case of birds, mammals, and theropod dinosaurs, they have the ability to regulate their body temperature regardless of the external temperature, ensuring that their bodily functions can operate optimally. This is crucial for their survival and overall well-being.
21.
Streptococcus is a type of bacteria that causes strep throat in humans. Which of these is the type of reproduction used by Streptococcus? [3.2.1E1]
Correct Answer
B. Binary fission
Explanation
Streptococcus uses binary fission as its type of reproduction. Binary fission is a form of asexual reproduction where a single organism divides into two identical daughter cells. In this process, the bacterial cell replicates its DNA and then divides into two separate cells, each containing a copy of the genetic material. This allows for rapid multiplication of the bacteria population.
22.
Which system in the frog produces chemicals that regulate functions in different parts of its body? [3.2.1A 3]
Correct Answer
C. Endocrine
Explanation
The endocrine system in frogs produces chemicals that regulate functions in different parts of its body. This system consists of various glands that secrete hormones into the bloodstream, which then travel to target organs or tissues to regulate their activities. These hormones are responsible for controlling growth, development, metabolism, reproduction, and other physiological processes in the frog's body.
23.
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? [3.2.1.C3]
Correct Answer
A. Cilia
Explanation
The organism shown in the diagram is using cilia to move itself. Cilia are small, hair-like structures that cover the surface of the organism and beat in coordinated waves to create movement. They are often found in unicellular organisms and some types of cells in multicellular organisms. In this case, the splitting of the organism into two cells suggests that it is using cilia to propel itself forward and divide into two separate cells.
24.
Which of these structures transport water throughout the plant? [3.2.1 A2]
Correct Answer
C. Vascular tissues
Explanation
Vascular tissues transport water throughout the plant. These tissues include xylem and phloem. Xylem transports water and minerals from the roots to the rest of the plant, while phloem transports sugars and other organic compounds from the leaves to other parts of the plant. Epidermal tissues are the outermost layer of cells in plants and serve as a protective barrier. The circulatory system is specific to animals and is responsible for transporting blood and nutrients. Flagella are whip-like structures found in some cells that help with movement and are not involved in water transport in plants.
25.
A healthy circulatory system is able to deliver excess oxygen and nutrients to cells. Which cell organelle requires oxygen to carry out cellular respiration? [3.2.1F2d]
Correct Answer
C. Mitochondria
Explanation
Mitochondria are the cell organelles responsible for carrying out cellular respiration, a process that requires oxygen. During cellular respiration, mitochondria break down glucose and other molecules to produce energy in the form of ATP. This process takes place in the inner membrane of the mitochondria, where oxygen is used to generate ATP through a series of chemical reactions. Therefore, mitochondria require oxygen to carry out cellular respiration and produce energy for the cell.
26.
Which organelle in a cactus cell converts solar energy into useable energy? [3.2.1F2d]
Correct Answer
C. Chloroplast
Explanation
The correct answer is chloroplast. Chloroplasts are organelles found in plant cells, including cactus cells, that are responsible for converting solar energy into useable energy through the process of photosynthesis. They contain a pigment called chlorophyll that absorbs sunlight, which is then used to convert carbon dioxide and water into glucose and oxygen. This glucose is then utilized by the cell as a source of energy for various cellular processes.
27.
Which of these is an example of homeostasis in a multicellular organism? [3.2.1F2d]
Correct Answer
D. Regulating body temperature
Explanation
Regulating body temperature is an example of homeostasis in a multicellular organism. Homeostasis refers to the ability of an organism to maintain a stable internal environment despite external changes. In this case, regulating body temperature ensures that the organism's internal temperature remains within a certain range, regardless of external temperature fluctuations. This is important for the proper functioning of cellular processes and overall health.
28.
The diagram below shows stages of cell division of a unicellular organism. How does the chromosome number of the amoeba in stage 1 compare to an amoeba in stage 6?[3.2.1E5]
Correct Answer
B. The same number of chromosomes
Explanation
The correct answer is "the same number of chromosomes." In cell division, the chromosome number remains constant throughout the stages. Therefore, the amoeba in stage 1 and stage 6 would have the same number of chromosomes.
29.
A fly has 78 chromosomes. How many chromosomes are in its wings? [3.2.15]
Correct Answer
C. 78
Explanation
The answer is 78 because the question states that a fly has 78 chromosomes, not specifying where those chromosomes are located. Therefore, it can be assumed that the wings of the fly also contain the same number of chromosomes as the rest of its body.
30.
What is the primary role of the endocrine system? [3.2.1D4]
Correct Answer
A. To produce chemicals that affect other parts of the body
Explanation
The primary role of the endocrine system is to produce chemicals, known as hormones, that are released into the bloodstream and affect various organs and tissues in the body. These hormones regulate numerous bodily functions such as growth, metabolism, reproduction, and mood. By producing and releasing these chemicals, the endocrine system helps to maintain homeostasis and ensure the proper functioning of the body's systems.
31.
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 1 is produced in what part of the cell? [3.2.1F2a]
Correct Answer
C. Nucleus
Explanation
Structure 1 is produced in the nucleus. The diagram shows that the process of protein synthesis begins in the nucleus, where DNA is transcribed into messenger RNA (mRNA). Structure 1 represents the mRNA molecule, which is formed in the nucleus before it is transported to the cytoplasm for further steps in protein synthesis. The other options, vacuole, cytoplasm, and mitochondria, are not involved in the initial production of mRNA.
32.
A protein called p53 can keep cells from dividing. To prevent cell division, this protein most likely stops- [3.2.1E4]
Correct Answer
B. Mitosis
Explanation
The protein p53 is known for its role in preventing cell division. Mitosis is the process by which cells divide, so it is likely that p53 stops mitosis in order to prevent cell division. Osmosis is the movement of water across a membrane, respiration is the process of converting energy from food into a usable form, and mutation refers to a change in DNA sequence. None of these processes directly relate to the role of p53 in preventing cell division.
33.
Doctors lower a patient’s body temperature during some surgical procedures. Which of these is the most likely benefit of lowering body temperature for surgery? [3.2.2B]
Correct Answer
A. A decrease in blood circulation
Explanation
Lowering a patient's body temperature during surgical procedures can lead to a decrease in blood circulation. This is beneficial because it helps to reduce bleeding during the procedure, making it easier for the surgeon to operate. Additionally, decreased blood circulation can also reduce the risk of tissue damage and inflammation, as well as decrease the body's oxygen and nutrient requirements during the surgery.
34.
As a response to cellular damage caused by injury, body tissue becomes inflamed, appears red, and feels warm. These changes are the result of blood circulating to the inflamed tissue.In response to the increase in temperature, which of the following is most likely to occur in cells surrounding the damaged tissue? [3.2.2B]
Correct Answer
C. Increase in the metabolic rate of the tissue
Explanation
When tissue becomes inflamed, there is an increase in temperature due to increased blood circulation. This increase in temperature can lead to an increase in the metabolic rate of the surrounding cells. The metabolic rate refers to the rate at which cells carry out their normal biochemical reactions and processes. An increase in metabolic rate can help support the repair and healing process of the damaged tissue by providing more energy and resources for cellular activities. Therefore, an increase in the metabolic rate of the tissue is the most likely response to the increase in temperature caused by inflammation.
35.
Sea stars are genetically different from each other and from their parents. These genetic differences are the result of- [3.3.1A]
Correct Answer
C. Sexual reproduction
Explanation
Sexual reproduction is the correct answer because it is the process by which genetic differences occur in sea stars. During sexual reproduction, two parent organisms contribute genetic material to create offspring with a unique combination of genes. This leads to genetic diversity among sea stars and their offspring, making them genetically different from each other and from their parents. Mitosis is a type of cell division that results in identical copies of cells, cloning is the production of genetically identical organisms, and asexual reproduction does not involve the combination of genetic material from two parents.
36.
Which of these is produced as a result of fertilization? [3.3.1B]
Correct Answer
A. A zygote with twice the number of chromosomes as a gamete
Explanation
Fertilization is the process of combining a male gamete (sperm) with a female gamete (egg) to form a zygote. During fertilization, the sperm and egg each contribute half of the genetic material, resulting in a zygote with the full set of chromosomes. Since a gamete only contains half the number of chromosomes as a zygote, the correct answer is "a zygote with twice the number of chromosomes as a gamete".
37.
The presence or absence of freckles is determined by one gene. The allele for freckles (F) is dominant and the allele for the absence of freckles (f) is recessive.A couple has several children. All of the children have freckles because their parents' genotypes can only produce children with freckles.Which of these are most likely the genotypes of the two parents? [3.3.2D]
Correct Answer
B. FF and ff
Explanation
The presence or absence of freckles is determined by one gene, with the allele for freckles (F) being dominant and the allele for the absence of freckles (f) being recessive. Since all of the children have freckles, it means that they must have received the dominant allele for freckles from one of their parents. Therefore, one parent must have the genotype FF, while the other parent must have the genotype ff. This is because if one parent had the genotype Ff, there would be a 25% chance of their children not having freckles.
38.
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 [3.3.2C]
Correct Answer
D. Recessive trait carried on the X chromosome
Explanation
Red-green color blindness affects a higher percentage of males compared to females, indicating that it is more common in males. This suggests that the trait is likely carried on the X chromosome since males only have one X chromosome and females have two. Inheritance patterns of X-linked traits are typically recessive, meaning that a person needs to inherit two copies of the gene (one from each parent) to exhibit the trait. Therefore, red-green color blindness is a recessive trait carried on the X chromosome.
39.
Use the information and Punnett square below to answer the following question.In guinea pigs, the allele for black fur (B) is dominant. The allele for brown fur (b) is recessive. Two guinea pigs were crossed as shown in the Punnett square below. Numbers 1, 2, 3, and 4 represent the types of offspring produced from the cross.What is the probability that an offspring from this cross would have brown fur?
Correct Answer
A. 0%
Explanation
The Punnett square shows that all of the possible offspring from this cross have the genotype Bb, meaning they will have black fur. Since the allele for brown fur (b) is recessive and there are no offspring with the genotype bb, the probability of an offspring having brown fur is 0%.
40.
Use the information and the pedigree below to answer the following item.In humans, the allele for having feet with normal arches is dominant (A). The allele for flat feet is recessive (a). The pedigree below shows the occurrence of normal arches and flat feet in four generations of a family. In the pedigree, individuals are identified by the generation and individual numbers. For example, Individual 2 in Generation I is identified as I-2.Which of these individuals in the pedigree is a male with the genotype aa? [3.3.2F]
Correct Answer
D. III 5
Explanation
Individual III-5 is a male with the genotype aa because he has flat feet, which is a recessive trait. Since he has flat feet, it means he has inherited the recessive allele for flat feet from both of his parents. Therefore, his genotype must be aa.
41.
In humans the trait of having freckles (F) is dominant to not having freckles (f).Which genotype and phenotype are correctly paired? [3.3.2C]
Correct Answer
C. Ff—freckles
Explanation
The genotype Ff represents a heterozygous individual, meaning they have one dominant allele (F) and one recessive allele (f). The phenotype freckles is correctly paired with this genotype because having the dominant allele (F) results in the expression of the trait. The recessive allele (f) would only result in the absence of freckles if it is present in both copies (ff genotype).
42.
Which of these statements best explains how genes and proteins are related? [3.3.3 A]
Correct Answer
A. Genes are segments of DNA that code for proteins
Explanation
Genes are segments of DNA that contain the instructions for making proteins. Proteins, on the other hand, are the end products of gene expression. Genes provide the template for the synthesis of proteins by specifying the order and sequence of amino acids. This process occurs through the transcription of DNA into mRNA and the subsequent translation of mRNA into proteins. Therefore, genes and proteins are closely related, with genes serving as the blueprint for protein synthesis.
43.
A strand of DNA has a nucleotide base sequence of TAC-CGG-AGT. Which of the following is the complementary mRNA nucleotide sequence produced from the strand of DNA? [3.3.3B]
Correct Answer
D. AUG-GCC-UCA
Explanation
The given DNA strand has the sequence TAC-CGG-AGT. In mRNA, the complementary base pairs are used, so T pairs with A, A pairs with U, C pairs with G, and G pairs with C. Therefore, the complementary mRNA sequence would be AUG-GCC-UCA.
44.
Which of these make up the primary link between a gene and the expression of a trait? [3.3.3C]
Correct Answer
B. Protein
Explanation
Proteins are the primary link between a gene and the expression of a trait. Genes contain the instructions for making proteins, and these proteins play a crucial role in determining the traits or characteristics of an organism. They are involved in various biological processes, such as enzyme activity, cell signaling, and structural support. Therefore, proteins are directly responsible for translating the information encoded in genes into observable traits.
45.
Which of the following is correctly matched with its function? [3.3.3B]
Correct Answer
D. MRNA - carries genetic codes from nucleus to the ribosomes
Explanation
mRNA is correctly matched with its function as carrying genetic codes from the nucleus to the ribosomes. mRNA is transcribed from DNA in the nucleus and carries the genetic information in the form of codons, which are then translated by ribosomes to synthesize proteins. This process is known as protein synthesis or translation. Therefore, mRNA plays a crucial role in the transfer of genetic information and the production of proteins within the cell.
46.
Look at the DNA sequence below.GAA TTC GCAWhat do the G and A represent in the DNA sequence? [3.3.3B]
Correct Answer
C. Nitrogen bases
Explanation
The DNA sequence consists of the letters G, A, T, and C, which represent the nitrogen bases in DNA. These nitrogen bases are the building blocks of DNA and determine the genetic code. In this sequence, G and A represent two of the four nitrogen bases, guanine and adenine, respectively. The other two bases are thymine (T) and cytosine (C). The order and combination of these bases are responsible for the genetic information encoded in DNA.
47.
An Olympic gold medalist in cross-country skiing has a gene which causes him to produce 50% more hemoglobin than the average person. Which of these most likely caused this trait? [3.3.4A]
Correct Answer
D. A mutation carried by the skier
Explanation
The most likely cause for the Olympic gold medalist in cross-country skiing to produce 50% more hemoglobin than the average person is a mutation carried by the skier. This mutation would result in a genetic alteration that affects the production of hemoglobin, leading to the increased levels observed in the skier. The other options, such as the special diet, climate, or training routine, are less likely to directly influence the production of hemoglobin in such a significant way.
48.
Scientists can insert and remove nucleotides from a DNA strand. Which of these identifies this process? [3.3.4C]
Correct Answer
B. Gene splicing
Explanation
Gene splicing is the process of removing or inserting nucleotides in a DNA strand. It involves cutting the DNA at specific points and joining different segments together. This process is commonly used in genetic engineering to manipulate genes and create new combinations of DNA sequences. It allows scientists to modify the genetic code and create organisms with desired traits or produce specific proteins. Therefore, gene splicing is the correct identification for the process of inserting and removing nucleotides from a DNA strand.
49.
One kind of chromosomal mutation can occur during meiosis when a pair of chromosomes that carry genes for the same trait fail to separate. Which of these represents the sex chromosomes of a male organism when this type of chromosomal mutation has occurred? [3.3.4B]
Correct Answer
A. XXY
Explanation
During meiosis, when a pair of chromosomes that carry genes for the same trait fail to separate, it results in a condition called non-disjunction. In this case, the sex chromosomes of a male organism would be XXY. This is known as Klinefelter syndrome, where the individual has an extra X chromosome. This chromosomal mutation leads to various physical and developmental differences in males.
50.
When the segment of human DNA that codes for insulin production is inserted into bacterial DNA, the bacterium begins producing human insulin.Which of these best identifies the process by which human DNA is inserted into bacterial DNA? [3.3.4C]
Correct Answer
A. Gene splicing
Explanation
Gene splicing is the process by which human DNA is inserted into bacterial DNA. This involves cutting out the segment of human DNA that codes for insulin production and inserting it into the bacterial DNA. As a result, the bacterium starts producing human insulin. Gene splicing allows for the transfer of specific genes between different organisms, enabling the production of desired proteins or traits in the recipient organism.