1.
Which stage of the cell cycle is illustrated here?
Correct Answer
B. Cytokinesis
Explanation
Cytokinesis is the stage of the cell cycle where the cytoplasm divides, resulting in the formation of two daughter cells. In this stage, the cell undergoes physical changes to separate into two distinct cells. The other options, prophase, telophase, and anaphase, are stages that occur before or after cytokinesis and involve different processes such as chromosome condensation, nuclear envelope breakdown, and chromosome separation, respectively.
2.
Which of the following is a characteristic of telophase?
Correct Answer
C. Nuclear membrane reforms.
Explanation
Telophase is the final stage of mitosis, where the nuclear membrane reforms around the separated sets of chromosomes. During telophase, the chromosomes reach the opposite poles of the cell and decondense, forming chromatin. The nuclear envelope, which had disassembled during prophase, starts to reassemble around the chromatin, forming two separate nuclei. This marks the completion of cell division and the beginning of cytokinesis, where the cytoplasm divides to form two daughter cells. Therefore, the characteristic of telophase mentioned in the answer, "Nuclear membrane reforms," is correct.
3.
The term "mitosis" means ___.
Correct Answer
B. Division of the nucleus.
Explanation
The term "mitosis" refers to the process of cell division, specifically the division of the nucleus. During mitosis, the genetic material within the nucleus is evenly distributed into two daughter cells, allowing for growth, repair, and reproduction in organisms. This process is crucial for maintaining the proper number of chromosomes in each cell and ensuring genetic stability.
4.
Cell division is very similar in animal and plant cells . However, ___.
Correct Answer
A. Plant cells form a cell plate instead of a cleavage furrow.
Explanation
In cell division, plant cells form a cell plate instead of a cleavage furrow. This is because plant cells have a rigid cell wall surrounding them, which prevents them from pinching inwards to form a furrow like animal cells do. Instead, plant cells deposit vesicles containing cell wall material at the equator of the dividing cell, which then fuse together to form a cell plate. The cell plate gradually develops into a new cell wall, separating the two daughter cells. This process is unique to plant cells and allows them to divide and grow while maintaining their structural integrity.
5.
Which of the following is a characteristic of anaphase?
Correct Answer
C. Sister chromatids are pulled to opposite sides of the cell.
Explanation
During anaphase, the sister chromatids, which are identical copies of each chromosome, are separated and pulled towards opposite ends of the cell. This is facilitated by the contraction of the spindle fibers, which attach to the centromeres of the sister chromatids. As a result, each new daughter cell will receive a complete set of chromosomes. The nuclear membrane has already broken down in prophase, and chromosomes lining up in the middle of the cell is a characteristic of metaphase. The cytoplasm splitting occurs in cytokinesis, which follows anaphase.
6.
Which of the following is a characteristic of metaphase?
Correct Answer
B. Chromosomes line up in the middle of the cell.
Explanation
During metaphase, the chromosomes align themselves along the equator of the cell. This alignment is crucial for the subsequent separation of sister chromatids during anaphase. The nuclear membrane has already broken down during prometaphase, and the cytoplasm splitting occurs during cytokinesis, which is a separate process from metaphase. Therefore, the correct characteristic of metaphase is that chromosomes line up in the middle of the cell.
7.
Which of the following is a characteristic of prophase?
Correct Answer
A. Nuclear membrane breaks down.
Explanation
During prophase, the nuclear membrane breaks down, allowing the chromosomes to be exposed in the cytoplasm. This breakdown is necessary for the chromosomes to be able to move and align properly during cell division. The breakdown of the nuclear membrane marks the beginning of mitosis, where the cell prepares to divide into two daughter cells. Therefore, the characteristic of prophase mentioned in the answer is accurate.
8.
Which of the following is a characteristic of G1 phase?
Correct Answer
A. Cell growth and normal function.
Explanation
G1 phase is the first phase of the cell cycle, during which the cell grows in size and carries out its normal functions. It is a period of intense metabolic activity and preparation for DNA replication in the subsequent S phase. The nuclear membrane is already present in G1 phase and does not reform during this phase. DNA replication occurs in the S phase, which follows G1 phase. Therefore, the characteristic of G1 phase is cell growth and normal function.
9.
Which of the following is a characteristic of cytokinesis?
Correct Answer
D. The cytoplasm splits.
Explanation
Cytokinesis is the final stage of cell division where the cytoplasm divides into two daughter cells. This process ensures that each daughter cell receives a complete set of genetic material. The breakdown of the nuclear membrane, lining up of chromosomes, and separation of sister chromatids occur during earlier stages of cell division called mitosis. Therefore, the characteristic of cytokinesis is the splitting of the cytoplasm.
10.
Which of the following is a characteristic of G2 phase?
Correct Answer
B. Cell growth and preparation for mitosis.
Explanation
The G2 phase is the third phase of the cell cycle, following the S phase where DNA is replicated. During the G2 phase, the cell continues to grow and prepares for mitosis, which is the process of cell division. This includes synthesizing the necessary proteins and organelles for cell division, as well as checking for any errors in DNA replication. The other options, such as cell growth and normal function, nuclear membrane reforms, and DNA replication, are not specific to the G2 phase and can occur in other phases of the cell cycle.
11.
Some cells live their entire lives without going through mitosis. These cells are said to be in ___.
Correct Answer
A. G zero
Explanation
G zero refers to a phase in the cell cycle where cells are not actively dividing or preparing to divide. During this phase, cells may temporarily or permanently exit the cell cycle and remain in a quiescent state. This phase is also known as the resting phase, where cells can perform their specialized functions without undergoing mitosis. Therefore, the correct answer is G zero.
12.
Which stage of mitosis is illustrated on the right?
Correct Answer
C. TelopHase
Explanation
The stage of mitosis illustrated on the right is telophase. In telophase, the nuclear envelope reforms around the separated sister chromatids, forming two distinct nuclei. The chromosomes begin to decondense, and the spindle fibers disassemble. Cytokinesis, the division of the cytoplasm, also begins in telophase.
13.
Which stage of mitosis is illustrated on the right?
Correct Answer
D. AnapHase
Explanation
The stage of mitosis illustrated on the right is anaphase. Anaphase is characterized by the separation of sister chromatids, which are pulled apart by the spindle fibers towards opposite poles of the cell. This stage is marked by the visible movement of the chromosomes towards the poles, with the cell elongating as the chromosomes are pulled apart. This is a crucial stage in mitosis as it ensures that each daughter cell will receive a complete set of chromosomes.
14.
Which stage of mitosis is illustrated on the right?
Correct Answer
B. MetapHase
Explanation
The stage of mitosis illustrated on the right is metaphase. In metaphase, the chromosomes line up along the equatorial plane of the cell, forming a single line called the metaphase plate. This alignment ensures that each daughter cell will receive an equal number of chromosomes during cell division. The chromosomes are condensed and attached to spindle fibers by their centromeres. This stage is crucial for accurate chromosome segregation and is characterized by the highest level of chromosome condensation.
15.
Which of the following is a characteristic of S phase?
Correct Answer
D. DNA is replicated.
Explanation
In the S phase of the cell cycle, DNA is replicated. This means that the cell duplicates its DNA in preparation for cell division. During this phase, the DNA strands unwind and each strand serves as a template for the synthesis of a new complementary strand. This ensures that each daughter cell will receive an identical copy of the genetic material. The other options mentioned, such as cell growth, normal function, preparation for mitosis, and nuclear membrane reforms, may occur during other phases of the cell cycle but are not specific to the S phase.
16.
Which stage of mitosis is illustrated here?
Correct Answer
A. PropHase
Explanation
The image provided shows condensed and visible chromosomes, which is a characteristic of prophase in mitosis. During prophase, the nuclear envelope breaks down, and the chromosomes condense and become visible. This stage is followed by metaphase, where the chromosomes align in the center of the cell, anaphase, where the sister chromatids separate and move towards opposite poles, and telophase, where the nuclear envelope reforms around the separated chromosomes. Based on the image, it is clear that the correct answer is prophase.
17.
All of the following are stages of Interphase except ___.
Correct Answer
D. M
Explanation
The stages of the cell cycle include G1, S, and G2, which collectively make up interphase. During interphase, the cell grows, replicates its DNA, and prepares for cell division. The M phase, or mitosis, is the stage where the cell actually divides into two daughter cells. Therefore, M is not a stage of interphase.
18.
Which of the following is not part of M phase?
Correct Answer
D. Synthesis
Explanation
The correct answer is Synthesis. Synthesis is not part of M phase, which is the phase of the cell cycle where cell division occurs. During M phase, the cell goes through prophase, anaphase, and cytokinesis. Synthesis, on the other hand, is part of the interphase, specifically the S phase, where DNA replication takes place.
19.
The term used to describe the imaginary plane along which chromosomes line up during metaphase is called the ___.
Correct Answer
A. MetapHase plate
Explanation
The term used to describe the imaginary plane along which chromosomes line up during metaphase is called the metaphase plate. During metaphase, the chromosomes align along this plane in the center of the cell before they are separated and pulled to opposite ends during anaphase. The metaphase plate is important for ensuring accurate distribution of genetic material to the daughter cells during cell division.
20.
During telophase the cell membrane begins to "pinch" inward, forming a ___.
Correct Answer
A. Cleavage furrow
Explanation
During telophase, the cell membrane begins to "pinch" inward, forming a cleavage furrow. This furrow is a groove that appears in the cell's surface, dividing it into two daughter cells. The cleavage furrow is responsible for the physical separation of the cytoplasm and organelles, eventually leading to the formation of two separate cells. This process is crucial for cell division and the formation of new cells.
21.
If a cell cannot move enough material through its membrane to survive, then the ratio of its surface area to volume is ___.
Correct Answer
C. Too small
Explanation
If a cell cannot move enough material through its membrane to survive, it suggests that the cell's surface area is not sufficient to support the volume of the cell. This implies that the ratio of the cell's surface area to its volume is too small. A smaller surface area to volume ratio means that there is less surface area available for the exchange of nutrients and waste, making it difficult for the cell to meet its metabolic needs.
22.
Before a cell can proceed to mitosis from the gap 2 stage of the cell cycle, it must ___.
Correct Answer
A. Pass a critical checkpoint
Explanation
Before a cell can proceed to mitosis from the gap 2 stage of the cell cycle, it must pass a critical checkpoint. This checkpoint ensures that the cell has properly replicated its DNA during the S phase and that there are no errors or damage in the DNA. If the cell fails to pass this checkpoint, it may undergo repair or apoptosis (cell death) to prevent the propagation of damaged DNA. Passing this critical checkpoint is essential for the cell to progress to mitosis and divide into two daughter cells.
23.
During interphase a cell grows, duplicates organelles, and ___.
Correct Answer
B. Copies DNA
Explanation
During interphase, a cell undergoes various processes to prepare for cell division. One of these processes is the duplication of organelles, where the cell creates additional copies of its organelles. However, the main focus of interphase is the replication of DNA. This is crucial for cell division as each new cell needs a complete set of genetic material. Therefore, during interphase, the cell copies its DNA to ensure that each new cell will have an identical copy of the genetic information.
24.
Why do the cells lining the stomach divide more quickly than those in the liver?
Correct Answer
D. They undergo more wear and tear.
Explanation
The cells lining the stomach divide more quickly than those in the liver because they undergo more wear and tear. The stomach is constantly exposed to acidic digestive juices and mechanical stress from food digestion, causing the cells to wear out and need frequent replacement. In contrast, the liver is not subjected to the same level of wear and tear, leading to slower cell division.
25.
Proteins from outside a cell that stimulate it to divide are called ___.
Correct Answer
B. Growth factors
Explanation
Growth factors are proteins that are produced by cells and stimulate the division and growth of other cells. They can be released by neighboring cells or by cells in distant parts of the body and act as signals to promote cell division. Growth factors play a crucial role in regulating the cell cycle and ensuring proper cell growth and development. They are important in various physiological processes such as tissue repair, embryonic development, and immune response.
26.
Kinases and cyclins are internal factors that ___.
Correct Answer
B. Control the cell cycle
Explanation
Kinases and cyclins are internal factors that regulate the cell cycle. Kinases are enzymes that add phosphate groups to other molecules, including cyclins, which are proteins that control the progression of the cell cycle. Together, they play a crucial role in coordinating the various stages of the cell cycle, such as DNA replication, cell growth, and cell division. By controlling the cell cycle, kinases and cyclins ensure that cells divide and grow properly, preventing abnormalities and maintaining the overall balance and integrity of the organism.
27.
Which statement about the process of binary fission is true?
Correct Answer
C. It does not take place in multicellular organisms.
Explanation
Binary fission is a form of asexual reproduction that occurs in single-celled organisms such as bacteria and protists. It involves the division of a single cell into two identical daughter cells. In multicellular organisms, reproduction typically occurs through sexual reproduction, which involves the fusion of gametes from two parents. Therefore, binary fission does not take place in multicellular organisms.
28.
In a single-celled organism, mitosis is used for ___.
Correct Answer
B. Reproduction
Explanation
Mitosis is the process by which a single cell divides and produces two identical daughter cells. In the context of a single-celled organism, reproduction is the most suitable explanation for the use of mitosis. Through mitosis, the organism can reproduce by dividing and creating new individuals that are genetically identical to the parent cell. This allows the organism to increase its population and ensure the survival of its species. Development, growth, and repair can also involve mitosis, but they are not specific to the purpose of reproduction in a single-celled organism.
29.
One difference between a cancer cell and a normal cell is that ...
Correct Answer
A. Cancer cells divide uncontrollably.
Explanation
Cancer cells divide uncontrollably, which is a key characteristic that distinguishes them from normal cells. In contrast, normal cells have a regulated cell division process, where they divide only when necessary for growth or repair. This uncontrolled division in cancer cells leads to the formation of tumors and the spread of cancer throughout the body. The inability of cancer cells to regulate their division is a fundamental aspect of their abnormal behavior and contributes to the aggressive nature of cancer.
30.
Proteins that bind to cells and stimulate cell division are called ___.
Correct Answer
C. Growth factors
Explanation
Growth factors are proteins that bind to cells and stimulate cell division. They play a crucial role in regulating cell growth, proliferation, and differentiation. Enzymes are biological molecules that catalyze chemical reactions, kinases are a type of enzyme that phosphorylate proteins, and carcinogens are substances that can cause cancer. Therefore, the correct answer is growth factors.
31.
What is the term for the programmed death of cells?
Correct Answer
A. Apoptosis
Explanation
Apoptosis is the term used to describe the programmed death of cells. It is a natural process that occurs in multicellular organisms to remove damaged or unnecessary cells. This process is essential for maintaining tissue homeostasis and is regulated by a series of cellular events that lead to cell death. Apoptosis plays a crucial role in development, immune response, and the prevention of diseases such as cancer.
32.
Substances known to produce or promote cancer are called ___.
Correct Answer
D. Carcinogens
Explanation
Carcinogens are substances that are known to produce or promote cancer. They can be found in various forms such as chemicals, radiation, or certain viruses. Exposure to carcinogens increases the risk of developing cancer by damaging the DNA and disrupting the normal functioning of cells. It is important to identify and minimize exposure to carcinogens in order to prevent the development of cancer.
33.
The most common form of reproduction among prokaryotes is ___.
Correct Answer
A. Binary fission
Explanation
Binary fission is the most common form of reproduction among prokaryotes. In this process, a single prokaryotic cell divides into two identical daughter cells. The parent cell replicates its genetic material and then divides into two separate cells. Each daughter cell receives a copy of the genetic material, resulting in two genetically identical cells. This method of reproduction allows prokaryotes to rapidly increase their population size and is an efficient way for them to pass on their genetic information.
34.
Which of the following statements is true of asexual reproduction?
Correct Answer
B. It produces genetically identical offspring.
Explanation
Asexual reproduction is a type of reproduction where offspring are produced without the involvement of gametes or the fusion of genetic material from two parents. In this process, a single parent organism produces offspring that are genetically identical to itself. This is because the offspring are created through processes like binary fission, budding, or fragmentation, where the parent's genetic material is replicated and passed on without any recombination or variation. Therefore, the statement "It produces genetically identical offspring" is true for asexual reproduction.
35.
Starfish that reproduce by splitting into pieces are reproducing by ___.
Correct Answer
A. Fragmentation
Explanation
Starfish that reproduce by splitting into pieces are reproducing by fragmentation. Fragmentation is a form of asexual reproduction where an organism breaks into fragments, and each fragment develops into a new individual. In the case of starfish, when a starfish is injured or disturbed, it can regenerate its lost parts, and each part can grow into a new starfish. This process of reproduction by splitting into pieces is known as fragmentation.
36.
Vegetative reproduction, budding, and fragmentation are examples of
Correct Answer
A. Asexual mitotic reproduction.
Explanation
Vegetative reproduction, budding, and fragmentation are all methods of asexual mitotic reproduction. In these processes, a new individual is produced from a single parent without the involvement of gametes or fertilization. Asexual mitotic reproduction results in offspring that are genetically identical to the parent, as there is no mixing of genetic material. This is in contrast to sexual reproduction, which involves the fusion of gametes and leads to increased genetic variation. Therefore, the correct answer is asexual mitotic reproduction.
37.
Which sequence shows the progression from least complex structure to most complex structure?
Correct Answer
B. Cell → tissue → organ → organ system
Explanation
The correct answer is cell → tissue → organ → organ system. This sequence starts with the basic unit of life, which is the cell. Cells then join together to form tissues, which perform specific functions. Tissues further combine to form organs, which carry out more complex tasks. Finally, organs work together to create organ systems, which are the highest level of organization in the body.
38.
Which phrase best describes an organ system?
Correct Answer
A. Group of organs that work together
Explanation
An organ system is a group of organs that work together to perform specific functions in the body. Each organ within the system has its own unique structure and function, but they all collaborate and interact to carry out a particular task. This cooperation allows for the efficient functioning of the body as a whole.
39.
Which of the following is a direct result of a normal cell’s ability to express only certain genes?
Correct Answer
A. Cells can differentiate and specialize.
Explanation
The ability of a normal cell to express only certain genes allows it to differentiate and specialize. This means that the cell can develop into a specific type of cell with a specialized function, such as a muscle cell or a nerve cell. This process is crucial for the development and functioning of multicellular organisms, as it allows for the division of labor among different cell types.
40.
Stem cells are important to multicellular organisms because of their ___.
Correct Answer
A. Capacity to differentiate
Explanation
Stem cells are important to multicellular organisms because of their capacity to differentiate. This means that they have the ability to develop into various specialized cell types, such as muscle cells, nerve cells, or blood cells. This differentiation process is crucial for the growth, development, and repair of tissues and organs in the body. Stem cells can replenish and replace damaged or old cells, contributing to the overall functioning and health of the organism. Their capacity to differentiate is what makes them valuable in medical research and potential therapies for various diseases and conditions.
41.
Which type of stem cell can grow into any other cell type?
Correct Answer
A. Totipotent
Explanation
Totipotent stem cells have the ability to differentiate into any type of cell in the body, including both embryonic and extra-embryonic cells. This means they can give rise to all cell types, including those found in the placenta and other supporting tissues. Pluripotent stem cells, on the other hand, can differentiate into any cell type in the body except for extra-embryonic cells. Multipotent stem cells can only differentiate into a limited number of cell types within a specific tissue or organ. Omnipotent is not a recognized term in stem cell biology.
42.
Which is the term for the group of proteins that organizes and condenses long strands of DNA into tight coils?
Correct Answer
A. Histones
Explanation
Histones are the proteins responsible for organizing and condensing long strands of DNA into tight coils. They play a crucial role in packaging DNA into a compact and organized structure called chromatin, which allows for efficient storage and regulation of genetic information.
43.
During which phase of mitosis do sister chromatids separate from each other?
Correct Answer
C. AnapHase
Explanation
During anaphase, sister chromatids separate from each other and move towards opposite poles of the cell. This is facilitated by the contraction of the spindle fibers attached to the centromeres of the chromatids. As the chromatids separate, they are now considered individual chromosomes. Anaphase is a crucial stage in mitosis as it ensures that each daughter cell receives the correct number of chromosomes.
44.
Which statement is true about the rates of cell division in eukaryotes?
Correct Answer
A. They vary greatly within an organism.
Explanation
The statement that rates of cell division in eukaryotes vary greatly within an organism is true. Eukaryotes have different rates of cell division in different tissues and organs, depending on their specific functions and needs. For example, cells in the bone marrow divide rapidly to produce new blood cells, while cells in the brain divide much more slowly. Additionally, rates of cell division can also be influenced by external factors such as injury or disease. Therefore, the rate of cell division can vary significantly within an organism.
45.
Which of the following limits the maximum size of a cell?
Correct Answer
A. The ratio of cell surface area to volume
Explanation
The ratio of cell surface area to volume limits the maximum size of a cell. This is because as a cell increases in size, its volume increases at a faster rate than its surface area. This means that the cell's ability to exchange nutrients and waste products with its environment becomes less efficient. Therefore, cells need to maintain a high surface area to volume ratio in order to adequately support their metabolic needs.
46.
In vertebrates, differentiation of cells is influenced by ___.
Correct Answer
A. Where the cells migrate.
Explanation
The differentiation of cells in vertebrates is influenced by where the cells migrate. The location where the cells migrate to plays a crucial role in determining their fate and the specific functions they will perform. Different regions of an organism's body provide different signals and cues that guide the differentiation process. The surrounding environment and neighboring cells also play a role in influencing cell differentiation based on their location. Therefore, the migration of cells to specific locations is a key factor in determining their ultimate differentiation and specialization.
47.
Which of the following reproduce asexually through mitosis?
Correct Answer
B. Many multicellular eukaryotes
Explanation
Many multicellular eukaryotes reproduce asexually through mitosis. This means that they produce offspring that are genetically identical to the parent, without the involvement of gametes or fertilization. Examples of multicellular eukaryotes that reproduce asexually through mitosis include certain plants, fungi, and animals. This mode of reproduction allows for rapid population growth and colonization of new habitats.
48.
After being scraped or cut, the skin is able to heal. What biological process best accounts for the replacement of skin cells?
Correct Answer
A. Mitosis
Explanation
Mitosis is the biological process that best accounts for the replacement of skin cells. Mitosis is a type of cell division that allows cells to replicate and produce identical daughter cells. In the case of skin healing, mitosis enables the damaged skin cells to divide and regenerate, allowing for the replacement of the injured or cut skin. This process ensures that the skin can heal and restore its integrity and functionality.
49.
Which of the following is not a class of stem cells?
Correct Answer
D. Follicular
Explanation
Follicular stem cells are not a class of stem cells. The options provided include adult, embryonic, and zygote stem cells, which are well-known and recognized classes of stem cells. However, follicular stem cells refer to a specific type of stem cells found in hair follicles and are not considered a separate class of stem cells.
50.
Which of the following is not a characteristic of stem cells?
Correct Answer
D. Divide uncontrollably
Explanation
The characteristic of stem cells that is not mentioned in the given options is "divide uncontrollably". Stem cells have the ability to divide and renew themselves for long periods of time, remain undifferentiated, and develop into a variety of specialized cell types. However, they do not divide uncontrollably, as their division is tightly regulated and controlled.