Kosice - Biology - 1 To 50

Lysosomes are organelles that contain hydrolytic enzymes used for intracellular digestion. They act in lytic processes in the cell, meaning they break down and digest various materials such as proteins, lipids, carbohydrates, and organelles. Lysosomes are present in animal cells and are responsible for digesting worn out organelles, as mentioned in option h. Therefore, options a, b, f, and h are all correct explanations for lysosomes.

The cell nucleus contains the DNA and proteins, which form chromatin. It also has a nuclear envelope on its surface and is surrounded by a double membrane.

The correct answers are c. all cells come from existing cells, d. all living things are made of cells, and e. cells are the basic units of structure and function in all living organisms. These statements are part of the cell theory, which states that all living organisms are composed of cells, cells are the basic units of structure and function in all living organisms, and cells can only arise from pre-existing cells through cell division.

The Golgi apparatus is responsible for transporting, modifying, and packaging proteins and lipids into vesicles for delivery to targeted destinations. It is also important for lysosome formation and the formation of secretory vesicles. Additionally, it is made up of approximately four to eight cisternae.

The Golgi apparatus, lysosomes, and vacuoles are all examples of membranous organelles. The Golgi apparatus is responsible for modifying, sorting, and packaging proteins and lipids for transport within the cell or secretion outside of the cell. Lysosomes contain enzymes that break down waste materials and cellular debris. Vacuoles are membrane-bound sacs that store water, nutrients, and waste materials. These organelles are all surrounded by a membrane, which is a defining characteristic of membranous organelles.

Endocytosis is a process in which the cell takes in substances from the external environment by engulfing them. It can occur through different mechanisms, such as pinocytosis and phagocytosis. Pinocytosis refers to the ingestion of fluid or dissolved substances by the cell, while phagocytosis involves the engulfment of solid particles. Endocytosis requires the rearrangement of the cytoplasmic membrane and cytoskeleton to form a vesicle that brings the ingested substances into the cell. It is an active transport process that requires energy in the form of ATP. Additionally, endocytosis can involve carrier proteins to facilitate the transport of specific substances into the cell.

Proteosynthesis, also known as protein synthesis, is the process by which cells build proteins. Ribosomes are the cellular organelles responsible for protein synthesis. They are found in the cytoplasm of the cell and on the rough endoplasmic reticulum. Mitochondria, on the other hand, are responsible for generating energy in the form of ATP and do not directly participate in protein synthesis. Therefore, the correct answers for proteosynthesis to take place are c. ribosomes and d. mitochondria.

Membranous organelles are organelles that are surrounded by a membrane. Vacuoles, lysosomes, and mitochondria are all examples of membranous organelles. Ribosomes, bacterial nucleus, centriole, cytoskeleton, and nucleolus do not have a membrane surrounding them, so they do not belong to the category of membranous organelles.

The correct answer is d. prokaryotic and eukaryotic. Prokaryotic cells are simple cells that do not have a nucleus or membrane-bound organelles, while eukaryotic cells are more complex cells that have a nucleus and membrane-bound organelles. This classification is based on the differences in the structure and organization of these two types of cells.

Diffusion and osmosis are both examples of passive transport of substances because they do not require the input of energy (ATP) to occur. In both processes, molecules move through the cytoplasmic membrane from an area of higher concentration to an area of lower concentration. Additionally, neither diffusion nor osmosis involve rearrangement of the cytoplasmic membrane or cytoskeleton.

In a hypotonic solution, the concentration of solutes outside the cell is lower than inside the cell. This creates a concentration gradient that causes water to move into the cell through osmosis. As a result, the cell swells and increases in volume. If the influx of water is too much, the cell may burst, a process known as osmotic lysis. Therefore, options b, c, f, and g are all correct explanations for what happens to an animal cell in a hypotonic solution.

Passive transport refers to the movement of substances across the cell membrane without the use of energy. This includes processes such as diffusion (movement of molecules from an area of high concentration to an area of low concentration), osmosis (movement of water molecules across a selectively permeable membrane), and the passage of solutes down their concentration gradient. It is also typical for the passage of water molecules, gases, and ethanol.

Eukaryotic cells are characterized by having membrane-bounded organelles, such as mitochondria, endoplasmic reticulum, and Golgi apparatus, which perform specific functions within the cell. They also have a nucleus bounded by a double membrane, which contains the cell's DNA and serves as a control center for cellular activities. The presence of a nucleus is a defining feature of eukaryotic cells. Additionally, eukaryotic cells have their internal space compartmentalized into organelles, allowing for efficient organization and separation of cellular processes.

The correct answer is a. plasmalemma, e. cell wall, f. cytoplasmic membrane. These are the basic cell surfaces found in eukaryotic cells. The plasmalemma, also known as the plasma membrane, is the outermost boundary of the cell that separates the cell from its environment. The cell wall is a rigid structure that provides support and protection to the cell. The cytoplasmic membrane, also known as the endoplasmic reticulum, is involved in protein synthesis and lipid metabolism. These three structures are essential for the functioning and survival of eukaryotic cells.

Bacteria are considered the simplest cellular organisms because they lack a nucleus and other membrane-bound organelles, making them prokaryotes. They can only form unicellular organisms, meaning they do not have the capability to form multicellular organisms. Bacteria also lack membranous compartments within a cell, indicating that they do not have specialized structures like mitochondria or endoplasmic reticulum. Additionally, bacteria are usually surrounded by a strong cell wall, providing them with protection and structural support.

Plant cells have a central vacuole, which is a large, membrane-bound organelle that stores water, nutrients, and waste products. Animal cells do not have a central vacuole. Additionally, plant cells have chloroplasts, which are responsible for photosynthesis and contain chlorophyll. Animal cells do not have chloroplasts. The other organelles listed (mitochondria, endoplasmic reticulum, Golgi apparatus, nucleolus, lysosomes, and ribosomes) are found in both plant and animal cells.

Biomembranes consist of a double layer of lipids, specifically phospholipids, which form the main structural component of the membrane. This lipid bilayer is embedded with integral and peripheral proteins, which play various roles such as transport, signaling, and structural support. Additionally, the biomembranes also contain molecules of proteins that are immersed within the double layer of phospholipids, further contributing to the overall structure and function of the membrane.

The jelly-like substance inside the cell is called cytoplasm. It is a semi-fluid material that fills the space between the nucleus and the cell membrane. Cytoplasm contains various organelles, such as mitochondria and ribosomes, and it is where many cellular processes, such as protein synthesis and metabolism, take place. Cytosol, on the other hand, refers specifically to the liquid component of the cytoplasm, excluding the organelles. Therefore, both options a and c are correct as they refer to different aspects of the same substance.

Smooth endoplasmic reticulum does not have the outer side of the membrane studded with ribosomes. It participates in the synthesis of lipids and functions in lipid production and metabolism. Additionally, it plays a role in the intracellular transport of some substances.

The cytoskeleton of a cell enables for spatial division of organelles in the cell by providing a framework and structure that helps organize and separate the organelles. It is also employed in the process of phagocytosis, which is the engulfment and digestion of particles by a cell. Additionally, the cytoskeleton is employed in the process of pinocytosis, which is the engulfment of fluid or solutes by a cell. Lastly, the cytoskeleton has kinetic, mechanical, and supportive functions, meaning it is responsible for providing movement, mechanical support, and stability to the cell.

The rough endoplasmic reticulum is the site of protein synthesis because it is studded with ribosomes on its outer side, which are responsible for the synthesis of proteins. It also plays a role in the intracellular and intercellular transport of substances, as it is involved in the movement of proteins and other molecules within the cell and between cells. It is a membrane-bounded organelle of the cell, unlike option h.

Mitochondria are organelles that are present only in eukaryotic cells. They have two membranes and are known as the energy center of the cell. They are also responsible for metabolic-respiratory processes in the cell. The number of mitochondria present in a cell directly correlates with the level of cell metabolic activity.

Ribosomes are submicroscopic particles that do not belong to membrane-bounded organelles of the cell. They are only visible in an electron microscope. Ribosomes are macromolecular structures composed of rRNA and proteins.

The cytoskeleton of the cell is necessary for all types of cellular active movements because it provides structural support and allows for the movement of cellular components. It represents a dynamic structure of the cell because it can constantly change and remodel itself to adapt to different cellular processes. It belongs to fibrous structures because it is composed of long, thread-like filaments. It is formed by microtubules, microfilaments, and intermediate filaments, which are all components of the cytoskeleton and contribute to its function.

Dictyosomes, also known as Golgi apparatus, are found in eukaryotic cells and are part of the endomembrane system in the cytoplasm. They are composed of stacks of flat, membrane bounded cisternae.

The nucleus of eukaryotic cells contains chromatin, which is a complex of DNA and proteins that make up the genetic material of the cell. It is also the control center of the cell, regulating all cellular activities and coordinating the cell's functions. Additionally, the nucleus contains the majority of the cell's genetic material, including the genes that determine the cell's characteristics and functions. However, the nucleus is not present in all cells of our body, as some highly specialized cells, such as red blood cells, do not have a nucleus.

In a hypertonic solution, the concentration of solutes outside the plant cell is higher than inside the cell. As a result, water moves out of the cell through osmosis, causing the cell to lose water. This loss of water can lead to the cell undergoing plasmolysis, where the plasma membrane shrinks away from the cell wall. Additionally, the loss of water can cause the internal volume of the cell to decrease. In extreme cases, the plasma membrane may detach from the cell wall, resulting in the cell losing water and the plasma membrane detaching from the cell wall.

Cells make pseudopodia by means of the cytoskeleton, during phagocytosis, by means of microfilaments, and for detection and engulfing of antigens, e.g. white blood cells. Pseudopodia are temporary protrusions of the cell membrane that help in cell movement, engulfing particles, and detecting antigens. The cytoskeleton, including microfilaments, plays a crucial role in the formation and extension of pseudopodia during these processes.

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When an animal cell is placed in a hypertonic solution, the concentration of solutes outside the cell is higher than inside the cell. As a result, water molecules move out of the cell through osmosis, causing the cell to lose water. This loss of water leads to the shrinking of the cell and a decrease in its volume. Therefore, options a, d, and f are correct explanations for an animal cell in a hypertonic solution.

Mitochondria are organelles with a double membrane, meaning they have an outer membrane and an inner membrane. They also synthesize their own specific proteins, meaning they can produce proteins that are unique to them. The molecules of DNA are located in the matrix of the mitochondria, which is the innermost compartment. The enzyme complex for the Krebs cycle, also known as the citric acid cycle, is present in the matrix of the mitochondria. Additionally, the enzymes of oxidative phosphorylation, which is the final step in cellular respiration, are localized on the mitochondrial cristae, which are the folds of the inner membrane.

Prokaryotic cells are characterized by several features. They may contain thylakoids, which are membranous structures that are involved in photosynthesis. They also contain prokaryotic ribosomes, which are responsible for protein synthesis. Prokaryotic cells have a cytoplasmic membrane, which separates the cell from its external environment. They also have a nucleoid, which is the region where the genetic material is located. However, prokaryotic cells do not have organelles that are compartmentalized by membranes, and their DNA molecules are typically circular and not linear.

The correct answer is c. nucleus, d. chloroplasts, f. mitochondria. The nucleus is the main organelle responsible for storing DNA in the cell. It contains the cell's genetic material and controls the cell's activities. Chloroplasts are organelles found in plant cells that also store DNA. They are responsible for photosynthesis and converting sunlight into energy. Mitochondria are known as the powerhouses of the cell and also store DNA. They are responsible for producing energy through cellular respiration.

Mitochondria have two biomembranes. The inner membrane is folded, forming structures called cristae, which increase the surface area for chemical reactions involved in energy production. The outer membrane is smooth and surrounds the inner membrane, providing protection and support to the mitochondria. Therefore, the correct answers are c. two and e. two - the inner one folded and the outer one smooth.

b. Nucleic acids, including DNA, contain sugar groups such as deoxyribose or ribose.
e. Ribosomes can become linked by an mRNA molecule to form polyribosomes, which allows for the simultaneous translation of multiple copies of the same protein.
f. The cytoplasmic membrane is composed of a phospholipid double layer and contains peripheral and integral proteins.
h. The cell wall, found in plants and some other organisms, is permeable, allowing for the passage of certain substances.

The rate of simple diffusion through the cytoplasmic membrane is influenced by the difference in molecule concentration inside and outside of the cell, the concentration gradient, and the temperature. The difference in molecule concentration creates a driving force for molecules to move from an area of higher concentration to an area of lower concentration. The concentration gradient refers to the difference in concentration between two areas, and a steeper gradient leads to faster diffusion. Temperature affects the kinetic energy of molecules, and higher temperatures increase their movement and therefore the rate of diffusion.

Diffusion is the passive movement of molecules from an area of higher concentration to an area of lower concentration. Gases, such as oxygen and carbon dioxide, are small molecules that can easily pass through the biomembrane by diffusion. Ethanol is also a small molecule that can diffuse across the biomembrane. Additionally, small hydrophobic molecules, like lipids, can pass through the biomembrane by diffusion. Water, being a small molecule, can also pass through the biomembrane by diffusion. Therefore, the correct options are c. gases, d. ethanol, e. oxygen across the alveolar walls into the blood, f. small molecules that are hydrophobic, and g. water.

Transport proteins of the plasma membrane are very specific to the transported substances, meaning that they are designed to only transport certain molecules or ions. They specifically transport some substances into the cell, meaning that they actively move these substances across the membrane. They also transport substances that are unable to pass into the cell by simple diffusion, meaning that they help regulate the movement of larger or charged molecules. Additionally, transport proteins are used in facilitated diffusion, which is a passive process where molecules move down their concentration gradient with the help of transport proteins.

A hypotonic solution refers to a solution with a lower concentration of solutes compared to the surrounding medium. This causes water to move into the cell through osmosis, leading to the swelling and potential bursting of animal cells. In the case of red blood cells, the hypotonic solution causes them to lyse or burst due to the influx of water. Distilled water is an example of a hypotonic solution. Additionally, the hypotonic solution causes osmotic water intake by the cell, further contributing to the swelling and potential bursting of animal cells.

The nuclear envelope in eukaryotic cells surrounds the genetic material and nucleolus, as stated in option a. It consists of two lipid bilayers - the inner nuclear membrane and the outer nuclear membrane, as mentioned in option b. It also has many small openings called nuclear pores, as mentioned in option d. Option f is also correct as it states that the nuclear envelope is a double membrane that encloses the nuclear genome. Lastly, option h is correct as it states that the nuclear envelope contains nuclear pores.

Lysosomes are membrane-bound organelles containing hydrolytic enzymes that are responsible for digestion within animal cells. These enzymes break down various molecules, such as proteins, lipids, and carbohydrates, into smaller components that can be used by the cell. Lysosomes also play a role in the recycling of cellular components through a process called autophagy. Therefore, option g (lysosomes) and option h (membrane organelles containing hydrolytic enzymes) are the correct answers for the digestion center of animal cells.

Active transport across the cytoplasmic membrane refers to the process of moving substances against their concentration gradient, which requires the expenditure of energy in the form of ATP. Calcium ions, as well as sodium and potassium ions, are transported into the cells through active transport mechanisms. This involves the use of transport proteins called solute pumps, which utilize ATP to move these ions across the membrane. Therefore, options d, e, f, and g are correct as they describe the typical characteristics of active transport across the cytoplasmic membrane.

The cytoplasmic membrane is usually the only biomembrane in prokaryotic cells, as stated in option a. It is responsible for regulating the intake of substances into the cell, as mentioned in option b. The term "plasmalemma" is another name for the cytoplasmic membrane, which is stated in option c. The cytoplasmic membrane belongs to basic cellular surfaces, as mentioned in option e. It also contains receptors that allow cells to receive signals, as stated in option f. Therefore, options a, b, c, e, and f are all correct explanations for the given answer.

Prokaryotic cells do not have membrane-bounded organelles such as plastids, nucleus, nucleolus, and mitochondria. They also do not have a cytoplasmic membrane. However, they do have ribosomes and DNA. Prokaryotic cells are simpler in structure compared to eukaryotic cells, which have membrane-bound organelles and a nucleus.

Animal cells contain lysosomes filled with enzymes that degrade polymers into their monomeric subunits in the cell. This is important for breaking down large molecules into smaller components that can be used by the cell for energy or building new molecules. Animal cells also do not have a cell wall, unlike plant cells which have a rigid cell wall made of polysaccharides. Additionally, animal cells may contain myofibrils, tonofibrils, and neurofibrils, which are all involved in the structure and function of muscle cells and nerve cells.

The mitotic apparatus of the cell consists of several structures that are involved in cell division. The astrosphere is a structure that forms during mitosis and is responsible for organizing the mitotic spindle. Centrioles are cylindrical structures that play a key role in the formation of the spindle fibers. The mitotic spindle is a network of microtubules that helps separate the chromosomes during cell division. Therefore, options c, d, and f are all part of the mitotic apparatus.

Vacuoles are organelles found in eukaryotic cells and are surrounded by a membrane called the tonoplast. They serve as storage organelles and can store waste materials. Vacuoles also carry out hydrolysis, which is the breakdown of macromolecules by enzymes. They are more important in eukaryotic cells rather than prokaryotic cells. Plant cell protoplasts produce vacuoles. They are not filled with cytosol or stroma, as these are found in other organelles such as the cytoplasm and chloroplasts respectively.

Chloroplasts are the organelles responsible for photosynthesis in plant cells. They contain chlorophyll, which captures sunlight and converts it into chemical energy in the form of glucose. Therefore, it is logical that photosynthesis takes place in chloroplasts. Additionally, chloroplasts have their own DNA and ribosomes, enabling them to synthesize their own proteins and nucleic acids. This explains why the correct answers are a. photosynthesis, c. synthesis of their specific proteins, and g. synthesis of their own nucleic acids.

The nucleolus is a region within the nucleus of a cell. It is made up of ribosomal RNA (rRNA) and proteins. It is responsible for the synthesis and assembly of ribosomes, which are essential for protein synthesis. The nucleolus is a dynamic structure that is involved in the production of ribosomes and therefore plays a crucial role in cellular processes. It disappears during cell division, as the nuclear membrane breaks down and the nucleolus disassembles.

The cell wall is a rigid outer layer that surrounds the plant cell. It is primarily composed of cellulose and provides structural support to the cell. It is permeable for water and substances soluble in water, allowing them to pass through. It is also a product of the protoplast of the plant cell, meaning it is synthesized and secreted by the cell itself. Additionally, the cell wall maintains the shape of the cell, providing stability and protection.