Cp Bio 2 - Unit 2a Test (Fall 2014)

The structure labeled A is the cell wall. The cell wall is a rigid outer layer found in plant cells, fungi, and some bacteria. It provides support and protection to the cell, helping to maintain its shape and prevent it from bursting under osmotic pressure. The cell wall is made up of cellulose and other polysaccharides, and it is located outside the cell membrane. Unlike the cell membrane, the cell wall is not selectively permeable and allows substances to pass through small pores.

Centrioles are cylindrical structures found in animal cells that play a crucial role in cell division. They are responsible for organizing the microtubules that form the spindle apparatus during mitosis, which helps in the separation of chromosomes. Centrioles are usually located near the nucleus and are composed of microtubule triplets arranged in a cylindrical pattern. Therefore, the structure labeled F in the given question is centrioles.

Mitochondrion is the correct answer because it is a double-membraned organelle found in eukaryotic cells. It is commonly referred to as the "powerhouse" of the cell as it is responsible for producing energy in the form of ATP through cellular respiration. The structure labeled D in the question is most likely referring to the mitochondrion, as it matches the description and function of this organelle.

The cytoskeleton is a network of proteins that provides support and shape to a cell. It is responsible for maintaining the cell's structural integrity and plays a crucial role in cell movement, division, and signaling. The cytoskeleton consists of three main components: microfilaments, intermediate filaments, and microtubules. These protein filaments work together to give the cell its shape and allow it to carry out various functions.

The correct answer is "Viruses are the smallest type of cell." This statement is not part of the Cell Theory because viruses are not cells. Viruses are considered to be acellular entities because they cannot carry out essential life processes on their own and require a host cell to replicate. Therefore, they do not fit the criteria of being a cell and are not included in the Cell Theory.

During telophase, the cell membrane begins to "pinch" inward, forming a cleavage furrow. This furrow is a groove that develops in the cell membrane, dividing the cytoplasm into two separate cells. The formation of the cleavage furrow is an important step in cytokinesis, the process of cell division, as it marks the beginning of the physical separation of the two daughter cells. The other options, such as cell plate and metaphase plate, are not formed during telophase and are not related to the process of cytokinesis.

The major principle upon which cell theory is based is that all organisms are made of cells. This principle states that cells are the basic building blocks of life and that all living organisms are composed of one or more cells. This principle was proposed by scientists Schleiden and Schwann in the 19th century and has since been widely accepted in the field of biology. It forms the foundation of our understanding of the structure and function of living organisms.

Cytoplasm is the correct answer because it refers to the jelly-like substance that is contained inside the cell membrane. It is a semi-fluid substance that fills the space between the cell membrane and the nucleus, and it plays a crucial role in supporting various cellular activities such as metabolism, transportation of molecules, and cell shape maintenance. The cytoplasm contains various organelles and is the site for many cellular processes.

The structure labeled E is the Golgi body. The Golgi body is responsible for modifying, sorting, and packaging proteins and lipids for transport to their final destinations within the cell or for secretion outside the cell. It consists of a series of flattened membranous sacs called cisternae. The Golgi body is involved in the formation of lysosomes and the synthesis of cell wall materials in plant cells.

The cells lining the stomach divide more quickly because they undergo more wear and tear. The stomach is constantly exposed to the acidic environment and mechanical stress caused by digestion. In order to maintain the integrity of the stomach lining and replace damaged cells, the cells divide at a faster rate. This rapid division ensures that there are always enough cells available to protect the stomach from damage and maintain its function.

Ribosomes can be found on the surface of the endoplasmic reticulum. This is because the endoplasmic reticulum plays a vital role in protein synthesis, and ribosomes are responsible for protein synthesis. The endoplasmic reticulum is a network of membranes, and the ribosomes attach to its surface, allowing for the production of proteins that are then transported throughout the cell.

The nucleus is the storehouse for most of a cell's genetic information. It contains the cell's DNA, which carries the instructions for the cell's growth, development, and functioning. The DNA is organized into chromosomes within the nucleus. The nucleus also controls the cell's activities by regulating gene expression and directing the synthesis of proteins. Overall, the nucleus plays a crucial role in maintaining the genetic integrity and functioning of the cell.

The structure labeled B is the smooth endoplasmic reticulum. The smooth ER is responsible for various functions such as lipid metabolism, detoxification of drugs and toxins, and calcium ion storage. It lacks ribosomes on its surface, distinguishing it from the rough ER. The nucleus is the control center of the cell, and the mitochondrion is responsible for energy production.

Cytokinesis is the final stage of cell division where the cytoplasm divides into two daughter cells. During this process, the cell membrane pinches inward, forming a cleavage furrow, which eventually splits the cytoplasm into two separate cells. This allows the genetic material to be evenly distributed between the daughter cells, completing the cell division process. Therefore, the characteristic of cytokinesis is that the cytoplasm splits.

Plant cells form a cell plate instead of a cleavage furrow during cell division. This is because plant cells have a rigid cell wall surrounding the cell membrane, which prevents the formation of a cleavage furrow. Instead, a cell plate made of cell wall material is formed in the middle of the dividing plant cell, which eventually develops into a new cell wall separating the two daughter cells. This process is unique to plant cells and is one of the key differences in cell division between animal and plant cells.

The Golgi apparatus is responsible for processing and delivering proteins within the cell. It receives proteins from the endoplasmic reticulum and modifies them by adding sugars and other molecules. It then packages these modified proteins into vesicles and transports them to their final destination within the cell or outside of the cell. Therefore, the main function of the Golgi apparatus is to process and deliver proteins.

Lysosomes are organelles that contain enzymes responsible for breaking down old cell parts. These enzymes, known as hydrolytic enzymes, are capable of breaking down various biomolecules such as proteins, lipids, carbohydrates, and nucleic acids. This process, known as autophagy, helps in recycling cellular components and eliminating waste materials. Lysosomes play a crucial role in maintaining cellular homeostasis and are often referred to as the "digestive system" of the cell. Centrosomes are involved in cell division, vacuoles store water and other substances, while chloroplasts are responsible for photosynthesis in plant cells.

Egg fertilization is not a form of reproduction by asexual mitosis because it involves the fusion of a sperm and an egg, resulting in the formation of a zygote. Asexual reproduction by mitosis does not involve the fusion of gametes, but rather the production of genetically identical offspring from a single parent cell.

Facilitated diffusion is the process in which molecules move across the cell membrane from an area of higher concentration to an area of lower concentration with the help of transport proteins. Unlike active transport, which requires energy, facilitated diffusion does not require any energy input from the cell. Therefore, facilitated diffusion is the correct answer as it is the only process listed that does not require energy from the cell.

Transport proteins are involved in both passive and active transport. Passive transport refers to the movement of molecules across a cell membrane without the input of energy. Transport proteins facilitate this process by allowing molecules to passively diffuse through the membrane. On the other hand, active transport requires the input of energy to move molecules against their concentration gradient. Transport proteins also play a crucial role in active transport by using energy to pump molecules across the membrane. Therefore, the correct answer is passive and active transport.

The stages of Interphase are G1, S, and G2. During G1, the cell grows and carries out normal functions. In the S phase, DNA replication occurs. G2 is the stage where the cell prepares for division. M phase, or mitosis, is the stage where the cell actually divides into two daughter cells. Therefore, M is not a stage of Interphase.

A membrane-bound sac used to transport substances into and out of cells is a vesicle. Vesicles are small sacs made of lipid bilayers that are involved in various cellular processes such as endocytosis, exocytosis, and intracellular transport. They can bud off from the cell membrane or other organelles to transport molecules such as proteins, lipids, and waste materials. Vesicles play a crucial role in maintaining the cell's internal environment and regulating the flow of molecules in and out of the cell.

Starfish is the correct answer because they have the ability to reproduce through a process called asexual mitosis. Asexual reproduction involves the production of offspring without the involvement of gametes or the fusion of genetic material from two parents. In the case of starfish, they can regenerate lost body parts and even split into two separate individuals, each capable of growing into a new starfish. This process allows starfish to reproduce rapidly and efficiently in suitable environments.

Synthesis is not part of M phase because M phase, also known as mitosis, is the stage in the cell cycle where cell division occurs. During M phase, the cell goes through prophase, metaphase, anaphase, and telophase, which are all involved in the physical separation of the duplicated chromosomes. Synthesis, on the other hand, occurs during the S phase of the cell cycle, where DNA replication takes place. Therefore, synthesis is not part of M phase.

The cell pictured here is a prokaryote. Prokaryotes are single-celled organisms that lack a nucleus and other membrane-bound organelles. They are typically smaller and simpler in structure compared to eukaryotic cells. The absence of a nucleus means that the genetic material of prokaryotes is not enclosed within a membrane. Additionally, prokaryotes do not have membrane-bound organelles such as mitochondria or endoplasmic reticulum.

The central vacuole is a feature found only in plant cells. It is a large, fluid-filled organelle that occupies most of the cell's volume. It plays a crucial role in maintaining the cell's shape, storing nutrients, regulating water balance, and even providing structural support. While mitochondria, nucleus, and centrioles are found in both plant and animal cells, the central vacuole is unique to plant cells, making it the correct answer.

G2 phase is the third phase of the cell cycle, following the S phase where DNA is replicated. During G2 phase, the cell continues to grow and prepare for cell division. This includes synthesizing proteins and organelles needed for mitosis, as well as checking for any DNA damage. The nuclear membrane reforms during the end of G2 phase in preparation for mitosis. Therefore, the characteristic of G2 phase is cell growth and preparation for mitosis.

The correct answer is cell wall. Animal cells do not have a cell wall, unlike plant cells. The cell wall is a rigid structure that surrounds plant cells, providing support and protection. Animal cells, on the other hand, have a flexible cell membrane that allows for movement and flexibility.

Structure B is labeled as chloroplast because chloroplasts are responsible for photosynthesis in plant cells. They contain chlorophyll, which gives them a green color, and they convert sunlight into energy for the plant. The other options, such as cell wall, nucleus, and vacuole, do not have the same functions or characteristics as chloroplasts.

Kinases and cyclins are internal factors that play a crucial role in controlling the cell cycle. Kinases are enzymes that regulate the progression of the cell cycle by phosphorylating specific proteins, while cyclins are proteins that bind to and activate kinases at specific points in the cell cycle. Together, they form a complex regulatory network that ensures the orderly progression of the cell cycle, including DNA replication, mitosis, and cell division. Therefore, the correct answer is that kinases and cyclins control the cell cycle.

The structure labeled C is the vacuole. The vacuole is a membrane-bound organelle found in plant cells and some other eukaryotic cells. It is responsible for storing various substances such as water, nutrients, and waste products. The vacuole also helps maintain cell turgor pressure, which is important for cell shape and support. Additionally, the vacuole can play a role in detoxification and defense mechanisms within the cell.

The stage of mitosis that is illustrated on the right is anaphase. This is because in anaphase, the sister chromatids are separated and pulled towards opposite poles of the cell by the spindle fibers. This is clearly shown in the illustration on the right, where the chromosomes are seen moving away from each other towards the ends of the cell.

A prokaryotic cell does not have a nucleus. Unlike eukaryotic cells, prokaryotic cells lack a membrane-bound nucleus that contains their DNA. Instead, their DNA is found in the cytoplasm, which is the fluid-filled region of the cell. Prokaryotic cells have a simpler structure compared to eukaryotic cells, with their genetic material floating freely in the cytoplasm. This allows for more rapid replication and adaptation to changing environments.

During the S phase of the cell cycle, DNA replication occurs. This means that the DNA molecule is duplicated, resulting in two identical copies. This is an essential process for cell division, as each daughter cell needs to have a complete set of genetic information. The other options mentioned, such as cell growth and preparation for mitosis, and the reforming of the nuclear membrane, are not specific characteristics of the S phase. Therefore, the correct answer is that DNA is replicated during the S phase.

Omnipotent is not a type of stem cell. Stem cells are categorized based on their potential to differentiate into different cell types. Pluripotent stem cells can differentiate into almost any cell type, multipotent stem cells can differentiate into a limited range of cell types, and totipotent stem cells can differentiate into any cell type, including extraembryonic tissues. However, omnipotent is not a recognized term in stem cell biology.

The stage of mitosis illustrated on the right is telophase. This is indicated by the presence of two separate groups of chromosomes at opposite ends of the cell, which suggests that the chromosomes have finished moving towards the poles. Additionally, the nuclear envelope is beginning to reform around each group of chromosomes, indicating the completion of nuclear division.

G zero refers to the phase in the cell cycle where cells are not actively dividing. In this phase, cells may temporarily or permanently exit the cell cycle and enter a non-dividing state. They can remain in this state for an extended period or indefinitely, performing their specialized functions without undergoing mitosis. Therefore, G zero is the correct term to describe cells that live their entire lives without going through mitosis.

Malignant tumors have the ability to spread and invade other parts of the body, a process known as metastasis. This means that cancer cells from the primary tumor can break away, travel through the bloodstream or lymphatic system, and form new tumors in different organs or tissues. This characteristic distinguishes malignant tumors from benign tumors, which do not have the ability to metastasize. Therefore, the statement "They can cause tumors in other parts of the body" accurately describes the behavior of malignant tumors.

The term "mitosis" refers to the process of cell division, specifically the division of the nucleus. During mitosis, the genetic material in the nucleus is duplicated and then divided equally into two daughter cells. This process is crucial for growth, repair, and maintenance of multicellular organisms.

The correct answer is metaphase. In metaphase, the chromosomes line up along the equator of the cell, forming a single line called the metaphase plate. This is illustrated in the image on the right, where the chromosomes are clearly aligned in a row. During metaphase, the spindle fibers attach to the centromeres of the chromosomes, preparing for their separation in the next stage of mitosis.

Telophase is the final stage of mitosis, where the nuclear membrane reforms around the newly formed daughter nuclei. During telophase, the chromosomes have already separated and moved to opposite poles of the cell. The nuclear envelope, which had broken down during prophase, now starts to reassemble, enclosing the separated chromosomes within 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 given answer is accurate.

During prophase, the nuclear membrane breaks down. This is a characteristic of prophase because the breakdown of the nuclear membrane allows the chromosomes to be more accessible and visible. As the nuclear membrane disintegrates, the chromosomes become condensed and can be seen clearly under the microscope. This breakdown of the nuclear membrane is an essential step in preparing the cell for division, as it allows the chromosomes to separate and move to opposite ends of the cell during later stages of mitosis.

The given cell is an eukaryote cell because it has a distinct nucleus enclosed within a membrane and other membrane-bound organelles. Eukaryote cells are found in plants, animals, fungi, and protists, and are characterized by their complex internal structure. This distinguishes them from prokaryote cells, such as bacterial cells, which lack a nucleus and membrane-bound organelles.

The stage of mitosis illustrated on the right is prophase. During prophase, the nuclear envelope breaks down, the chromosomes condense and become visible, and the spindle fibers begin to form. This is the first stage of mitosis and is characterized by the preparation of the cell for division.

The term used to describe the imaginary plane along which chromosomes line up during metaphase is called the metaphase plate. This is the location where the chromosomes align in the center of the cell before they are separated during cell division. The metaphase plate is crucial for ensuring that each daughter cell receives the correct number of chromosomes. The other options, cell plate, cleavage furrow, and envelope, are not related to the alignment of chromosomes during metaphase.

Flagella are not found in plant cells. Flagella are whip-like structures that help in cell movement, and they are typically found in certain types of bacteria and protists. While plant cells have various organelles like mitochondria, chloroplasts, and Golgi apparatus, they do not possess flagella. Plant cells have other structures like cell walls, central vacuoles, and plastids, which serve different functions.

A solution that is hypotonic to a cell has fewer solutes than the cell. This means that the concentration of solutes in the solution is lower compared to the concentration of solutes in the cell. As a result, water will move into the cell through osmosis, causing the cell to swell or potentially burst if the influx of water is too high.

During embryonic development, cells differentiate into specific cell types based on their location in the embryo. This process is known as positional information. Different regions of the embryo produce different signals and gradients of molecules that provide cues for cells to adopt specific fates and differentiate into specialized cell types. The cells receive these signals and respond by activating specific genes, which ultimately determine their fate and function in the developing organism. Therefore, the location of cells within the embryo plays a crucial role in their differentiation.

A normal cell's ability to express only certain genes is a direct result of its ability to differentiate and specialize. This means that different cells in an organism have different functions and characteristics because they express different sets of genes. This process allows cells to develop into specific types, such as muscle cells or nerve cells, and perform specialized tasks in the body. It also enables the formation of different tissues and organs, contributing to the overall complexity and functionality of multicellular organisms.

Cytokinesis is the stage of the cell cycle where the cytoplasm of the cell is divided into two daughter cells. In this stage, the cell undergoes physical changes, such as the formation of a cleavage furrow in animal cells or a cell plate in plant cells, to separate the cytoplasm and organelles. The other options, prophase, telophase, and anaphase, are different stages of mitosis where the chromosomes condense, the nuclear envelope reforms, and the sister chromatids separate, respectively. Therefore, based on the description, the correct answer is cytokinesis.