Biology Unit 7 Test

Bacteria is a prokaryotic cell because it lacks a nucleus and other membrane-bound organelles. Prokaryotic cells are typically smaller and simpler in structure compared to eukaryotic cells, such as plant and animal cells. Bacteria are single-celled microorganisms that can be found in various environments and can have different shapes and sizes. They reproduce asexually through binary fission and play important roles in various biological processes, including nutrient cycling and disease-causing infections.

Eukaryotic cells do have membrane-bound organelles. These organelles, such as the nucleus, mitochondria, Golgi apparatus, and endoplasmic reticulum, are surrounded by a membrane that separates their internal environment from the rest of the cell. This membrane allows for compartmentalization and specialized functions within the cell. Therefore, the statement that eukaryotic cells don't have membrane-bound organelles is false.

Prokaryotic cells are characterized by the absence of a membrane-bound nucleus. Instead, their DNA is found in the cytoplasm in a region called the nucleoid. Ribosomes are present in both prokaryotic and eukaryotic cells and are responsible for protein synthesis. Cytoplasm is the gel-like substance that fills the cell and is present in both types of cells. Therefore, the organelle that is not found in a prokaryotic cell is the membrane-bound nucleus.

The endomembrane system is a group of organelles that work together to transport and modify proteins within the cell. It includes the endoplasmic reticulum (ER), Golgi apparatus, and lysosomes. Lysosomes are responsible for breaking down cellular waste, while the ER and Golgi apparatus are involved in protein synthesis and modification. Therefore, the correct answer is "Proteins" as they are not an organelle, but rather a type of biomolecule.

The extracellular matrix is a network of glycoprotein molecules attached to the outer surface of the animal cell's plasma membrane. It provides structural support to the cell and helps maintain its shape. It also plays a role in cell signaling, cell adhesion, and cell migration. The extracellular matrix is composed of various proteins, such as collagen and fibronectin, which are secreted by the cell and form a mesh-like structure around it. This matrix acts as a scaffold for cells and tissues and is involved in many physiological processes.

Mitochondria and chloroplasts are both membrane-bound organelles found in eukaryotic cells. They are similar in their function of converting energy. Mitochondria are responsible for cellular respiration, where they convert glucose into ATP, the main energy currency of the cell. Chloroplasts, on the other hand, are found in plant cells and are responsible for photosynthesis, where they convert sunlight into glucose and oxygen. Both organelles play a crucial role in energy conversion within the cell, making the statement true.

Bound ribosomes are ribosomes that are attached to the endoplasmic reticulum (ER) membrane. They play a crucial role in protein synthesis and have multiple functions. One of the functions is the secretion of products, where they synthesize proteins that are destined to be exported from the cell. Another function is adding to the membrane, where they synthesize proteins that are inserted into the ER membrane or other cellular membranes. Therefore, the correct answer is "Two of the above" because bound ribosomes are involved in both secretion of products and adding to the membrane.

The smooth endoplasmic reticulum (SER) is responsible for various functions in the cell. It plays a crucial role in the synthesis of lipids, storage of calcium ions, and detoxification of drugs. Additionally, it is involved in the metabolism of carbohydrates. Therefore, the correct answer is "None of the above" as all the options listed are functions of the smooth endoplasmic reticulum.

The central vacuole in plants is responsible for storing various substances such as pigments, toxic compounds, organic and inorganic compounds, hydrolytic enzymes, and water. It is a large, fluid-filled organelle that occupies most of the cell's volume. The central vacuole helps maintain the cell's shape, regulate turgor pressure, store nutrients and waste products, and play a role in cell growth and development.

Cilia and flagella have a microtubular arrangement known as 9 + 2. This means that they have nine pairs of microtubules surrounding two central microtubules. This arrangement provides structural support and allows for the movement of cilia and flagella.

The cytoskeleton is made up of microfilaments, microtubules, and intermediate filaments. Intermediate filaments provide structural support and help maintain cell shape. They are made up of various proteins, such as keratins, vimentin, and lamin, and are involved in various cellular processes, including cell migration, cell division, and mechanical strength.

Fimbriae are responsible for attaching bacteria to surfaces. Fimbriae are hair-like structures found on the surface of many bacteria that help them adhere to surfaces. They act as tiny hooks or anchors, allowing the bacteria to attach to various surfaces such as host tissues or inanimate objects. This attachment is important for the bacteria to establish infections or form biofilms, which are communities of bacteria that adhere to surfaces and are often difficult to remove. Flagella are responsible for bacterial movement, cilia are found in eukaryotic cells and are involved in cell movement or moving substances along the cell surface, and ribosomes are responsible for protein synthesis.

The statement that Golgi Apparatus is made up of membranous sacs called crinsta is incorrect. Golgi Apparatus is actually made up of membranous sacs called cisternae, not crinsta. Therefore, the correct answer is False.

Ribosomes are the only organelles listed that are not membranous and are found in both prokaryotic and eukaryotic cells. While peroxisomes, chloroplasts, and mitochondria are all membranous organelles that are not found in prokaryotic cells, ribosomes are unique in that they are non-membranous and can be found in both types of cells. Additionally, ribosomes are not part of the endomembrane system, which includes organelles such as the endoplasmic reticulum and Golgi apparatus that are involved in the synthesis, modification, and transport of proteins.

Collagen is the correct answer because it is the most abundant glycoprotein in the extracellular matrix. It provides structural support and strength to tissues and organs. Collagen fibers are found in various connective tissues throughout the body, such as skin, bones, tendons, and cartilage. They contribute to the overall integrity and function of these tissues, making collagen an essential component of the extracellular matrix.

Plasmodesmata are protein pores found in the cell walls of adjacent plant cells. These pores allow for communication and transport of molecules between the cells, enabling them to function as a coordinated unit. Gap junctions are found in animal cells and allow for communication between adjacent cells. Desmosomes are specialized junctions that provide mechanical strength to tissues. Tight junctions are found in animal cells and help to create a barrier between cells. Therefore, the correct answer is Plasmodesmata.

The second type of enzymes in peroxisomes is responsible for detoxification by breaking down H2O2 into H2O and O2. This process helps to eliminate the harmful effects of H2O2 and maintain cellular homeostasis.

Tay-Sachs disease is a genetic disorder characterized by a deficiency of an enzyme called hexosaminidase A (Hex-A), which leads to the accumulation of a fatty substance called GM2 ganglioside in the brain and nerve cells. This accumulation causes progressive damage to the cells, leading to severe neurological problems. It is not caused by a lack of enzymes that can digest proteins, but rather by the deficiency of Hex-A enzyme. Therefore, the statement that Tay-Sachs patients have lysosomes that lack the enzymes that can digest proteins is false.

Desmosomes are junctions that hold cells into strong sheets and allow space between them. Unlike tight junctions, desmosomes provide strong adhesion between cells while still allowing for some space between them. This allows for flexibility and movement within tissues. Therefore, the correct answer is false.

The extracellular matrix (ECM) is a complex network of proteins and carbohydrates that provides structural support to cells and tissues. It plays a crucial role in various cellular functions, including cell communication, regulation of cell behavior via proteins, and cell recognition. However, cell motility refers to the ability of cells to move and migrate, which is not a function of the ECM. Therefore, the correct answer is "Cell motility".

Integrin is a protein found in the plasma membrane that plays a crucial role in signal transduction. It acts as a bridge between the extracellular matrix and the cytoskeleton, allowing signals to be transmitted from the outside of the cell to the inside. This communication is essential for the cell to respond appropriately to its environment and carry out various functions such as cell adhesion, migration, and differentiation. Therefore, integrin is the correct answer as it is responsible for transmitting signals to the cytoskeleton, enabling the cell to work on a suitable response.