IB Biology: Cell Theory

A reasonable size for a membrane would be 10 nm. This is because membranes are typically very thin and composed of phospholipids arranged in a bilayer structure. The thickness of a phospholipid bilayer is approximately 5 nm, so a reasonable size for a membrane would be around 10 nm. The other options, 1 um and 100 nm, are too large to be considered a reasonable size for a membrane.

Antione van Leeuvenhoek observed the first living cells and referred to them as "animalcules" (little animals).

A reasonable size for a membrane would be 10 nm. This is because membranes are thin structures that separate different compartments or environments. A size of 10 nm is within the range of typical membrane thicknesses found in biological systems, allowing for the selective transport of molecules and ions across the membrane while maintaining its structural integrity. Sizes of 10 um and 10 pm are not typically associated with membranes, as they are either too large or too small to effectively perform the functions of a membrane.

The regulation of salt and water levels within an organism is an example of homeostasis, which is the ability of an organism to maintain a stable internal environment. This function ensures that the body's salt and water levels are kept within a narrow range, allowing cells to function properly. While growth, nutrition, and metabolism are important functions of life, they do not specifically pertain to the regulation of salt and water levels. Therefore, the correct answer is "None of the above".

An organelle is a small, specialized structure within a cell that performs specific functions. The size of an organelle is typically measured in micrometers (um), which is one millionth of a meter. 10 um would be a reasonable size for an organelle because it falls within the typical range of organelle sizes. 10 mm is too large for an organelle, as it is equivalent to 10,000 um, while 10 nm is too small, as it is equivalent to 0.01 um. Therefore, the most reasonable size for an organelle is 10 um.

An organelle is a small structure within a cell that carries out specific functions. It is reasonable for an organelle to have a size of 5 um because this is a typical size range for many organelles, such as mitochondria and lysosomes. Larger sizes like 100 um and 50 um are not typically seen for organelles, and "None of the above" is not applicable since 5 um is a reasonable size.

The modern cell theory states that all organisms are composed of one or more cells. This means that every living organism, from the simplest bacteria to complex multicellular organisms like humans, is made up of cells. This statement is a fundamental principle of biology and is widely accepted by scientists. It highlights the importance of cells as the building blocks of life and emphasizes their role in the functioning and organization of living organisms.

ATP, calcium ion, and tRNA are all smaller than a membrane in diameter. ATP is a small molecule, calcium ions are single charged particles, and tRNA is a type of RNA molecule. None of these are larger than a membrane.

The correct answer is "None of the above" because the factors listed (membrane permeability, membrane flexibility, and cell function) do not directly limit cell size. Cell size is primarily limited by the surface area-to-volume ratio, as cells need to have enough surface area to exchange materials with their environment in order to survive. While membrane permeability and flexibility can indirectly affect cell size by influencing the efficiency of material exchange, they are not direct factors that determine cell size. Similarly, the function of the cell can vary and does not necessarily dictate its size.

Differentiation is an example of the function of growth. Growth refers to the increase in size, complexity, or number of cells in an organism. Differentiation is the process by which cells become specialized and take on specific functions in the body. This process is crucial for the growth and development of multicellular organisms, as it allows cells to become specialized and perform specific tasks necessary for the overall functioning of the organism. Therefore, differentiation is an example of the growth function of life.

The cell theory states that all living organisms are composed of cells, cells are the basic unit of structure and function in living organisms, and all cells come from pre-existing cells. However, there are certain exceptions or extensions to this theory. Skeletal muscle cells are multinucleated, meaning they have multiple nuclei, which goes against the idea that cells have a single nucleus. Fungal hyphae are long, branching structures that are composed of many cells fused together, challenging the notion that cells are separate entities. Bone is made up of extracellular material, such as collagen and calcium phosphate, in addition to cells, which contradicts the idea that cells are the only components of living organisms. Therefore, all of the above options can be considered exceptions or extensions to the cell theory.

A virus is larger than a membrane in diameter. Viruses are microscopic infectious agents that are composed of genetic material (DNA or RNA) enclosed in a protein coat. They are much larger than a membrane, which is a thin layer of molecules that separates the internal and external environments of a cell or organelle. ATP (adenosine triphosphate) and rRNA (ribosomal RNA) are both smaller than a membrane and do not exceed its diameter.

A reasonable size for an organelle would be 5 um. This is because organelles are typically small structures within a cell that perform specific functions. A size of 5 um would be large enough to accommodate the necessary components and biochemical processes of the organelle, while still being small enough to fit within the confines of a cell. Sizes of 50 um and 500 nm would be too large and too small, respectively, for a typical organelle.

Biologists study unicellular organisms because they are small and easily grown in the laboratory, they are the simplest organisms which carry on all of the functions of life, and they reproduce quickly.

All of the options listed are larger than a bacterium. The endoplasmic reticulum is a network of membranes within the cell that is involved in protein synthesis and lipid metabolism. Vacuoles are membrane-bound organelles that store water, ions, and other molecules in plant and animal cells. An animal cell is a eukaryotic cell that contains various organelles, including the nucleus, mitochondria, and cytoplasm. Therefore, all of these options are larger than a bacterium.

All of the above options (Lysosome, Nucleus, and Golgi apparatus) are larger than a bacterium. Lysosome is an organelle found in cells that is larger than a bacterium. Nucleus is the central organelle in a cell that contains genetic material and is also larger than a bacterium. Golgi apparatus is another organelle in cells that is responsible for packaging and modifying proteins, and it is also larger than a bacterium. Therefore, all of the above options are correct and larger than a bacterium.

A reasonable size for a molecule would be 1 nm. This is because molecules are typically very small, with sizes ranging from a few nanometers to a few angstroms. Therefore, 1 nm is a reasonable size for a molecule as it falls within this range.

The correct answer is "None of the above" because maintaining a constant internal environment is a characteristic of homeostasis, which is not specifically mentioned as a function of life in the given options. Metabolism refers to the chemical processes that occur within an organism, response refers to the ability to react to stimuli, and nutrition refers to obtaining and processing nutrients. While homeostasis is a crucial aspect of maintaining life, it is not explicitly stated as a separate function in the given options.

All of the above options - Ribosome, Virus, and Membrane - are larger than a nucleotide. A nucleotide is a small building block of DNA or RNA, consisting of a sugar, a phosphate group, and a nitrogenous base. Ribosomes are large molecular complexes that are involved in protein synthesis and are composed of RNA and proteins. Viruses are infectious agents that are much larger than nucleotides, consisting of genetic material (DNA or RNA) surrounded by a protein coat. Membranes are thin, flexible structures that surround cells and organelles, and they are composed of lipids and proteins.

A reasonable size for a bacterium would be 1 um. Bacteria are very small organisms and their size typically ranges from 1 to 10 um. Therefore, 1 um would be a reasonable size for a bacterium.

The approximate thickness (diameter) of DNA is 2 nm. DNA is a double-stranded molecule that consists of two strands twisted around each other in a double helix structure. The diameter of the DNA helix is about 2 nanometers, which is equivalent to 2 billionths of a meter. This size allows DNA to fit inside the nucleus of a cell and also facilitates its replication and transcription processes.

A reasonable size for a bacterium would be 1 um. Bacteria are microscopic organisms, and their size typically ranges from 0.2 um to 10 um. Therefore, 1 um falls within this range and would be considered a reasonable size for a bacterium.

A cell is a basic unit of life, and its size can vary depending on the organism and the type of cell. The options given in the question are specific measurements in millimeters, which may not be universally applicable to all cells. Some cells, like red blood cells, can be around 7-8 micrometers in diameter, while others, like nerve cells, can be several centimeters long. Therefore, none of the given options can be considered a reasonable size for a cell as it depends on the specific context.

Bone is sometimes considered an exception to the cell theory because it contains large amounts of nonliving extracellular material. While bone does contain cells, it also has a significant amount of extracellular matrix, including collagen and calcium salts, which provide structural support. This nonliving material plays a crucial role in the strength and rigidity of bone, making it an exception to the cell theory, which states that cells are the fundamental units of life.

The regulation of pH levels in an organism is not an example of any of the functions of life listed in the options. Metabolism refers to the chemical processes that occur within an organism to maintain life, while response refers to the ability of an organism to react to stimuli. Growth refers to the increase in size or number of cells in an organism. However, the regulation of pH levels is a specific function that helps maintain homeostasis within an organism, ensuring that the internal environment remains stable.

A reasonable size for a molecule would be 1 nm. This is because molecules are typically composed of atoms, which have sizes on the order of 0.1 to 0.3 nm. Therefore, a molecule made up of multiple atoms would generally have a size on the order of a few nanometers. The other options, 100 nm and 10 nm, are much larger than the typical size of a molecule and would likely represent larger structures such as nanoparticles or aggregates of molecules.

Bone is sometimes considered an exception to the cell theory because it contains large volumes of nonliving material. While bone does contain cells, it is primarily composed of a mineralized extracellular matrix, which is nonliving material. This matrix provides strength and support to the bone, and the cells within the bone are responsible for maintaining and remodeling this matrix. Therefore, the presence of large volumes of nonliving material in bone sets it apart from other tissues that adhere strictly to the cell theory.

All of the options mentioned (Virus, Organelle, DNA) are larger than the average molecule. A virus is a complex structure made up of genetic material (DNA or RNA) enclosed in a protein coat, often with additional components. Organelles are specialized structures within cells that perform specific functions, such as the nucleus or mitochondria. DNA, which stands for deoxyribonucleic acid, is a molecule that carries genetic information in all living organisms. Therefore, all of these options are larger than the average molecule.

An organelle is larger than a bacterium. Organelles are specialized structures within a cell that perform specific functions. They are typically larger than bacteria, which are microscopic single-celled organisms. Viruses are smaller than bacteria and cannot be considered larger. Membranes, on the other hand, can vary in size and are not necessarily larger than bacteria. Therefore, the correct answer is organelle.

None of the options listed (cell membrane, mRNA, tRNA) are larger than a virus. A virus is typically larger in size compared to these components. The cell membrane is a thin layer that surrounds the cell and is smaller than a virus. mRNA and tRNA are molecules involved in protein synthesis and are much smaller than a virus. Therefore, the correct answer is none of the above.

A reasonable size for a virus would be 100 nm. This is because viruses are extremely small infectious agents that can only be seen under a microscope. They are typically measured in nanometers (nm), which is one billionth of a meter. 100 nm is a reasonable size for a virus as it falls within the typical range of virus sizes, which can vary from around 20 nm to 300 nm.

All of the options listed (animal cell, endoplasmic reticulum, and vesicle) are larger than a membrane in diameter. An animal cell is a complete unit that contains various organelles, including a membrane. The endoplasmic reticulum is a network of membranes within the cell that is involved in protein synthesis and lipid metabolism. A vesicle is a small, fluid-filled sac that is also surrounded by a membrane. Therefore, all of these options are larger than a single membrane.

A ribosome is larger than a codon. A codon is a sequence of three nucleotides that codes for a specific amino acid during protein synthesis. Nucleotides are the building blocks of DNA and RNA, and ATP is a molecule that provides energy for cellular processes. However, ribosomes are complex structures made up of proteins and RNA molecules, and they are responsible for translating the genetic code carried by codons into proteins. Therefore, a ribosome is larger than a codon.

Differentiation is not an example of any of the functions of life mentioned in the options. Reproduction refers to the ability to produce offspring, homeostasis refers to the ability to maintain a stable internal environment, and response refers to the ability to react to stimuli. Differentiation, on the other hand, is the process by which cells become specialized and take on specific functions in the body. It is a process that occurs during development and is essential for the formation of different tissues and organs. Therefore, the correct answer is "None of the above".

Differentiation is an example of the function of growth. In biology, growth refers to an increase in size or complexity of an organism over time. Differentiation is a process in which cells become specialized and take on specific functions in the body. During growth, cells divide and differentiate, leading to the development of different tissues and organs. Therefore, differentiation is a key aspect of the growth process in living organisms.

All of the options listed in the answer, ribosome, tRNA, and membrane, are larger than a codon. A codon is a sequence of three nucleotides on mRNA that codes for a specific amino acid during protein synthesis. Ribosomes are large molecular complexes that facilitate protein synthesis and are composed of multiple subunits. tRNA molecules are larger than codons as they consist of about 70-90 nucleotides and carry amino acids to the ribosome during translation. Membranes are also larger than codons as they are structures composed of lipids and proteins that surround and enclose cells or cellular compartments. Therefore, all of the options listed are larger than a codon.

All of the options listed (virus, codon, and ribosome) are larger than a nucleotide. A nucleotide is the basic building block of DNA and RNA, consisting of a sugar, a phosphate group, and a nitrogenous base. A virus is a microscopic infectious agent that consists of genetic material (DNA or RNA) enclosed in a protein coat, which is much larger than a nucleotide. A codon is a sequence of three nucleotides that specifies the incorporation of a specific amino acid into a protein during translation, also larger than a single nucleotide. A ribosome is a cellular structure made of RNA and proteins, responsible for protein synthesis, and is much larger than a nucleotide.

The correct answer is 100 nm. This is a reasonable size for a virus because viruses are generally much smaller than cells. They typically range in size from about 20 nm to 300 nm. Therefore, 100 nm falls within this typical range and would be a reasonable size for a virus.

A codon is a sequence of three nucleotides found in DNA or RNA that codes for a specific amino acid. It is larger than a single nucleotide because it consists of three nucleotides. A nucleotide is the basic building block of DNA and RNA, consisting of a sugar, a phosphate group, and a nitrogenous base. Calcium ion and phosphate are not larger than a nucleotide as they are not composed of nucleotides. Therefore, the correct answer is Codon.

None of the options provided - membrane, virus, and bacterium - are larger than an organelle. An organelle is a specialized subunit within a cell that performs a specific function. Membranes are thin structures that enclose organelles and other cellular components. Viruses are much smaller than cells and cannot be considered larger than organelles. Bacteria, although larger than viruses, are still smaller than most organelles found within eukaryotic cells. Therefore, the correct answer is none of the above.

All of the options listed (virus, lysosome, and vacuole) are larger than a membrane in diameter. A virus is a microscopic infectious agent that is larger than a membrane. Lysosomes are organelles within cells that contain digestive enzymes and are also larger than a membrane. Vacuoles are membrane-bound sacs found in cells that can vary in size, but they are generally larger than a membrane. Therefore, all of the options provided are larger than a membrane.

The correct answer is Antonie van Leeuwenhoek. He observed the first living cells using a microscope and referred to them as "animalcules" because they appeared to him like little animals.

Lysosome is larger than a virus. Lysosomes are organelles found in cells that contain digestive enzymes. They play a role in breaking down waste materials and cellular debris. Lysosomes are larger in size compared to viruses, which are microscopic infectious agents that can only replicate inside the cells of living organisms. Membrane and ATP are not larger than a virus, so they are not the correct options.

A vesicle is larger than a virus. A vesicle is a small membrane-bound sac that can transport and store various substances within a cell. It is larger than a virus, which is a small infectious agent that can only replicate inside the living cells of other organisms. The other options, membrane and calcium ion, do not necessarily refer to a specific size and can vary in size depending on the context.

Virus is larger than tRNA because tRNA is a small molecule involved in protein synthesis, while viruses are much larger and can be seen under a microscope. Viruses are composed of genetic material (either DNA or RNA) surrounded by a protein coat, and some viruses also have an outer envelope. In contrast, tRNA is a single-stranded RNA molecule that carries amino acids to the ribosome during protein synthesis. Therefore, virus is the correct answer as it is larger than tRNA.

The given options for the size of a molecule are 10 um, 1 um, and 100 nm. However, these sizes are not reasonable for a molecule. Molecules are generally much smaller, with sizes ranging from angstroms (0.1 nm) to nanometers (1-100 nm). Therefore, the correct answer is "None of the above" as none of the given options represent a reasonable size for a molecule.

The endoplasmic reticulum is larger than a virus. The endoplasmic reticulum is a membrane-bound organelle found in eukaryotic cells. It is involved in the synthesis, folding, and transport of proteins and lipids. It consists of a network of interconnected tubules and flattened sacs, making it larger in size compared to a virus, which is much smaller and can only be seen under a microscope. mRNA and cell membrane are also smaller than the endoplasmic reticulum.

The given options for the size of a bacterium are 1 mm, 100 um, and 10 nm. However, none of these options would be a reasonable size for a bacterium. Bacteria are typically much smaller than 1 mm, with most ranging from 1 to 10 um (micrometers) in size. A micrometer is equal to 1000 times smaller than a millimeter, so 100 um is a more reasonable size range for a bacterium. 10 nm is even smaller than a bacterium and is typically used to describe the size of molecules or viruses. Therefore, the correct answer is None of the above.

The given options for the size of a virus are 1 mm, 1 um, and 1 nm. However, none of these options would be a reasonable size for a virus. Viruses are much smaller than 1 mm, which is equivalent to 1,000,000 um or 1,000,000,000 nm. In fact, viruses typically range in size from about 20 nm to 300 nm. Therefore, the correct answer is "None of the above".

All of the options provided (100 um, 50 um, and 10 um) would be reasonable sizes for a cell. Cells can vary in size depending on the type of organism and the specific cell type. For example, human cells can range from 10 um to 100 um in diameter. Therefore, all of the given options could represent reasonable sizes for a cell.

A reasonable size for a membrane would typically be in the range of nanometers to micrometers. The options provided in the question are 10 um (micrometers), 1 um, and 100 nm (nanometers). All of these options fall within the reasonable size range for a membrane. Therefore, the correct answer should be "All of the above" rather than "None of the above."

Skeletal muscle is considered an exception to the cell theory because it is formed by the fusion of several cells, making it a syncytium. Additionally, skeletal muscle is formed of very large fibers, which are multi-nucleated cells. Therefore, it contains cells that each have several nuclei. Hence, the correct answer is "All of the above."

Homeostasis is the correct answer because it refers to the ability of an organism to maintain a stable internal environment despite external changes. It involves regulating various physiological processes such as temperature, pH, and nutrient levels within a narrow range to ensure optimal functioning of cells and tissues. This process is essential for the survival and proper functioning of living organisms. Metabolism and growth are important functions of life, but they do not specifically involve maintaining a constant internal environment like homeostasis does.