Science 8: Test On Cells

The correct answer is "diaphragm". The diaphragm is a part of the microscope that controls the amount of light passing through the specimen. It is located beneath the stage and can be adjusted to increase or decrease the intensity of light, allowing for better visibility and clarity of the specimen being observed.

The correct answer is F. The arrow pointing to the organelle labeled F is the one that represents the power center of the cell. This organelle is the mitochondria, which is responsible for generating energy in the form of ATP through cellular respiration. It plays a crucial role in the metabolism and overall functioning of the cell.

The correct answer is cell wall. The cell wall is a rigid structure found in plant cells, fungi, and some bacteria, but it is not present in animal cells. It provides support and protection to the cell, helping to maintain its shape and prevent it from bursting under pressure. Animal cells do not have a cell wall, instead they have a flexible cell membrane that allows for movement and interaction with their environment.

The presence or absence of a nucleus is a key characteristic that can help identify a cell as either eukaryotic or prokaryotic. Eukaryotic cells have a distinct nucleus, which contains the cell's genetic material, while prokaryotic cells lack a nucleus and have their genetic material dispersed throughout the cytoplasm. Therefore, if a cell has a nucleus, it is likely eukaryotic, and if it lacks a nucleus, it is likely prokaryotic.

The magnification of a microscope is calculated by multiplying the objective magnification with the magnification of the ocular. In this case, the objective magnification is given as 42x and the total magnification is given as 336x. Therefore, the magnification of the ocular can be found by dividing the total magnification by the objective magnification: 336x / 42x = 8. So, the magnification of the ocular is 8.

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The diagram shows a phase of the cell cycle where the sister chromatids of each chromosome separate and move towards opposite ends of the cell. This phase is called anaphase. During anaphase, the microtubules of the spindle apparatus contract, pulling the sister chromatids apart and towards the poles of the cell. The correct answer is anaphase because it accurately describes the phase depicted in the diagram.

The phase of the cell cycle that happens before prophase is interphase. Interphase is the longest phase of the cell cycle where the cell grows, carries out its normal functions, and replicates its DNA in preparation for cell division. Prophase is the first phase of mitosis where the chromatin condenses into chromosomes, the nuclear envelope breaks down, and the spindle fibers start to form.

The LPO (4x) diameter is 10 times smaller than the HPO (40x) diameter. Since the number of cells that fit across the LPO diameter is 50, we can assume that the same number of cells will fit across the HPO diameter. Therefore, the answer is 5 cells.

The MPO (10x) diameter is equal to the HPO (40x) diameter multiplied by the magnification factor, which is 4 in this case. Therefore, the MPO diameter is 400 um multiplied by 4, which equals 1600 um.

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The nucleus is not an organ because it is a cellular structure found within cells, specifically in eukaryotic cells. It is responsible for storing the genetic material and controlling the cell's activities. While organs are larger structures made up of different tissues that perform specific functions in the body, the nucleus is a smaller component within cells.

The diaphragm is a microscope part that functions for controlling the amount of light. It is located below the stage and can be adjusted to regulate the intensity of light passing through the specimen. By opening or closing the diaphragm, the user can increase or decrease the amount of light that reaches the specimen, allowing for optimal visibility and clarity during observation.

Binary fission in bacteria is a form of asexual reproduction where a single organism divides into two identical daughter cells. This process allows bacteria to rapidly increase their population and is a key mechanism for their survival and proliferation. Therefore, the correct answer is reproduction.

Cytokinesis and mitosis are both processes involved in cell division. Cytokinesis specifically refers to the division of the cytoplasm, which occurs after the nucleus has divided. During cytokinesis, the cytoplasm is divided into two daughter cells. On the other hand, mitosis is the process of dividing the nucleus, where the DNA is replicated and distributed equally into two daughter nuclei. Therefore, the correct answer is that cytokinesis is the division of the cytoplasm, while mitosis is the division of the nucleus.

The surface area-to-volume ratio of a cell model is a measure of the amount of surface area compared to the volume. It is important because it affects the cell's ability to exchange materials with its environment. A higher surface area-to-volume ratio allows for more efficient exchange of nutrients and waste products. In this case, all four ratios provided (3.66:1, 3.666:1, 3.67:1, 3.667:1) are very close to each other, suggesting that the cell model has a relatively high surface area compared to its volume.

The cell theory consists of three main ideas. First, the cell is the basic unit of structure and function in living things. This means that all living organisms are composed of cells and that cells perform all the necessary functions for life. Second, all living things are made up of one or more cells. This implies that cells are the building blocks of life and are responsible for the structure and organization of organisms. Third, cells come from previously existing cells. This principle states that cells can only arise from pre-existing cells through cell division. These three ideas form the foundation of the cell theory and are crucial in understanding the structure and function of living organisms.

The correct order in the cell cycle is interphase, prophase, metaphase, anaphase, telophase, and cytokinesis. Interphase is the longest phase where the cell grows and DNA is replicated. Prophase is the first stage of mitosis where the chromosomes condense and the nuclear envelope breaks down. Metaphase is the stage where the chromosomes line up in the middle of the cell. Anaphase is when the sister chromatids separate and move towards opposite ends of the cell. Telophase is the stage where the nuclear envelope reforms and the chromosomes decondense. Finally, cytokinesis is the division of the cytoplasm to form two daughter cells.

Cell A is most likely a leaf cell because it is the only cell in the table that has a "/" symbol, indicating that it is present. The other cells have an "x" symbol, indicating that they are absent.

Sister chromatids are joined by a centromere. During the cell division process, the DNA in a chromosome is replicated, resulting in two identical copies called sister chromatids. These sister chromatids are held together at the centromere until they separate during cell division. Therefore, sister chromatids are the correct answer for what is joined by a centromere.

Homologous chromosomes are a pair of chromosomes that have the same gene sequence and structure. This means that they contain the same genes in the same order, although they may have different alleles. Homologous chromosomes are inherited from each parent and are involved in genetic recombination during meiosis. They align and exchange genetic material during a process called crossing over, which contributes to genetic diversity. Therefore, the correct answer is that homologous chromosomes are a pair of chromosomes with the same gene sequence and structure.

The correct answer is anaphase, prophase, metaphase, and telophase. These are the four phases of mitosis in the cell cycle. During prophase, the chromosomes condense and the nuclear envelope breaks down. In metaphase, the chromosomes line up at the center of the cell. Anaphase is characterized by the separation of sister chromatids, which are pulled to opposite ends of the cell. Finally, in telophase, the nuclear envelope reforms and the chromosomes decondense.

DNA replication occurs during the interphase of the cell cycle. Interphase is the phase between cell divisions where the cell grows and prepares for division. During interphase, the DNA is duplicated so that each daughter cell will receive a complete set of genetic information. Metaphase, anaphase, and cytokinesis are all stages of mitosis, where the duplicated DNA is separated and distributed to the daughter cells. Therefore, the correct answer is interphase.

The revolving nosepiece of a microscope allows you to shift objectives. This part holds the different objective lenses and can be rotated to switch between them. By rotating the nosepiece, you can easily change the magnification power of the microscope and focus on different details of the specimen being observed. This feature is essential for adjusting the microscope to obtain clear and detailed images at different magnifications.

The objective with the larger diameter or field of view will provide a wider view of the specimen. In this case, the LPO (4x) objective has a lower magnification compared to the MPO (10x) and HPO (40x) objectives. Generally, objectives with lower magnification have a larger diameter or field of view, allowing for a broader view of the specimen. The ocular (10x) refers to the eyepiece and does not affect the diameter or field of view of the objective.

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All of the options listed, bacteria, fungi, animals, and plants, are made up of one or more cells. However, viruses are not considered living organisms and do not have cells. They are instead composed of genetic material (DNA or RNA) surrounded by a protein coat. Therefore, the correct answer is virus.

Homologous chromosomes are pairs of chromosomes that have the same genes in the same order, although the alleles may be different. In the given diagram, chromosomes A and C are shown to have similar patterns and lengths, indicating that they are homologous chromosomes. Therefore, A and C form a homologous pair.

The basic difference between prokaryotic and eukaryotic cells is that eukaryotic cells have a nucleus, while prokaryotic cells do not. The presence of a nucleus in eukaryotic cells allows for the compartmentalization of DNA and other cellular components, which enables more complex cellular functions. Prokaryotic cells, on the other hand, lack a nucleus and have their DNA freely floating in the cytoplasm. This structural difference is one of the key distinctions between these two types of cells.

Anaphase is the stage of mitosis or meiosis in which the sister chromatids or homologous chromosomes separate and move towards opposite poles of the cell. This process is crucial for the equal distribution of genetic material to the daughter cells. In anaphase, the microtubules of the spindle apparatus shorten, pulling the chromosomes apart and elongating the cell. The correct answer to the question would be a visual representation or description of this process, showing the separation and movement of chromosomes towards opposite poles.

Genes are sections of DNA that contain the instructions for building proteins and other molecules in the body. DNA is the molecule that carries the genetic information in the form of a double helix structure. Chromosomes are structures made up of DNA and proteins that store and organize the genetic material in the nucleus of a cell. Therefore, the correct answer is that genes are sections of DNA which coils and condenses into chromosomes.

Cell B is most likely taken from a human cheek because it contains a "x" in the column for "absent" in both the "chloroplast" and "cell wall" rows. This indicates that it is a eukaryotic cell, which is characteristic of human cheek cells. The presence of a "x" in the "nucleus" row also supports this, as the nucleus is a defining feature of eukaryotic cells.

The plant cell has the largest size compared to the other options listed. Plant cells are typically larger than bacteria and animal cells because they have additional structures such as a cell wall, central vacuole, and chloroplasts. These structures contribute to the overall size of the plant cell, making it larger than the other options. Viruses, on the other hand, are much smaller than cells and cannot be considered as a contender for the largest size.

The correct answer is C and E. In a microscope, the total magnification is determined by the combination of the magnification of the objective lens (part C) and the eyepiece lens (part E). The objective lens is located at the lower end of the microscope and provides the initial magnification of the specimen. The eyepiece lens is located at the upper end of the microscope and further magnifies the image produced by the objective lens. Therefore, the combination of these two lenses determines the total magnification when viewing a specimen.

Yeasts are unicellular and eukaryotic organisms. This means that they are composed of a single cell and their cells have a nucleus and other membrane-bound organelles. Yeasts are a type of fungus and are commonly used in baking and brewing. They reproduce asexually through budding, where a small daughter cell grows off the parent cell. Yeasts play important roles in various industries and also have significance in scientific research, particularly in the study of genetics and cell biology.

Cell division is necessary for growth in multicellular eukaryotic organisms because it allows for the production of more cells, which leads to an increase in overall size. Additionally, cell division is important for the replacement of worn-out cells, as old cells can be replaced with new ones through the process of cell division. Lastly, having a large surface area to volume ratio (SA:V) is advantageous for efficient nutrient exchange and waste removal, and cell division can help maintain a large SA:V ratio by producing more cells.

During anaphase, the sister chromatids, which are replicated copies of each chromosome, separate and move towards opposite poles of the cell. This splitting of sister chromatids ensures that each daughter cell receives a complete set of chromosomes during cell division. The movement of sister chromatids towards opposite poles is facilitated by the contraction of spindle fibers, which pull the chromatids apart. This process ensures the accurate distribution of genetic material and is a crucial step in cell division.

The cell membrane is a universal feature of all cells, as it serves as a protective barrier and regulates the movement of substances in and out of the cell. Cytoplasm is also found in all cells and is the gel-like substance that fills the cell and contains various organelles. DNA, the genetic material, is present in all cells and carries the instructions for cell function. Ribosomes are essential for protein synthesis and can be found in all cells. Therefore, these four options - cell membrane, cytoplasm, DNA, and ribosomes - can be found in all kinds of cells.

When a cell gets bigger, the volume increases faster than the surface area. This is because volume is calculated by cubing the length, while surface area is calculated by squaring the length. As a result, the increase in volume is more significant compared to the increase in surface area. Additionally, as the cell grows, the SA:V ratio decreases. This is because the surface area increases at a slower rate than the volume, causing the ratio of surface area to volume to decrease.

Plant and animal cells both have a nucleus, which is a membrane-bound organelle that contains the cell's DNA. Bacterial cells, on the other hand, do not have a true nucleus. Additionally, both plant and animal cells have mitochondria, which are responsible for generating energy in the form of ATP. Bacterial cells do not have mitochondria.